CN100505910C - Hierarchical softcell wireless network and access control method therefore - Google Patents

Abstract

A hierarchical softcell wireless network and a access control method therefore are provided. The network comprises a signal covering plane, a softcell plane and a service requirement plane, wherein a control center controls wireless resource use and operate mode of distributed antennas to form multi-layer softcells overlapping geographically; service requirement plane centralizes services of different velocity scenes distributed geographically; the access control method of the hierarchical softcell network according to the present invention mapps a user terminal to a certain softcell in the softcells that is suitable for the terminal to service based on mapping relationship between velocity feature and softcell layer by estimating the velocity of the terminal. The hierarchical softcell wireless network considers network performance, practicability and complexity synthetically, and can reduce system interference, use wireless resource efficiently, equalize loads, control handover load level of the network and improve system capacity and service quality.

Description

Soft cell-radio network of a kind of layering and connection control method thereof

Technical field

The present invention relates to Radio Access Network and mobile communication system, relate in particular to super three generations/the 4th third-generation mobile communication system.

Background technology

There are many problems in the legacy cellular communication network, for example: rise and fall problems such as the service quality difference of big caused near-far interference, central user and edge customer is big of signal power plane, the root of these problems is because the sub-district in the legacy cellular communication network covers and the signal of antenna for base station covers close-coupled together, make network to the different business scene unification treat, thereby lost the flexibility of differentiated service demand scene.

The second generation and 3-G (Generation Three mobile communication system) are comparatively abundant to the utilization of Radio Resources such as frequency, time slot, code channel, but its transmission rate and service quality still can not satisfy tomorrow requirement far away.Along with the increase day by day of sustainable growth of number of mobile users purpose and mobile multi-media service demand, the bottleneck problem of Radio Access Network can be more and more serious.

The employed frequency range of next generation wireless communication system will be higher than the frequency range that present system adopted, and the skyborne decay of electromagnetic wave becomes more serious, and under same transmitting power, the effective coverage range of aerial radiation signal can be littler; In addition, according to the stricter mobile phone radiation standard that China will soon execute, specific absorption rate (SAR, Specific Absorption Rate) requires strict more, promptly require irradiation of electromagnetic waves power lower, thereby cause further reducing of radius of society, therefore, in following mobile communications network, radius of society diminishes, base station density is bigger, the Cell Site Placement difficulty, and network construction cost is higher.

Because above restriction, it is very difficult only reaching following two-forty, high-quality transfer of data demand and immanent wide area covering requirement by the transmission technology of improving existing cellular communications networks, therefore must consider to adopt the distributed access way of many antennas, realize network diversity and handover easily, thereby greatly improve power system capacity and resource utilization.

Summary of the invention

Problems such as, business scenario bad adaptability low at the resource utilization that exists in the legacy cellular communication network, the present invention proposes a kind of Radio Access Network of novelty, is called the soft sub-district of layering (HSC, Hierarchical SoftCell) wireless network.

The soft cell-radio network of a kind of layering of the present invention, it comprises:

Signal overlay planes 1-1, soft sub-district plane 1-2 and business demand plane 1-3;

Described business demand plane 1-3 refers to the business demand under the various speed scenes that distribute on the region;

Described signal overlay planes 1-1 refers to by spaced antenna group 2-3 and covers by the seamless signal that the transmitting/receiving wireless signal forms;

According to moving velocity of terminal the user in the described business demand plane 1-3 is divided into the customer group that the K kind has the friction speed feature, wherein K 〉=1;

Corresponding above-mentioned K kind has the customer group of friction speed feature, forms the soft sub-district plane 1-2 that comprises the soft sub-district of K layer;

2-1 of control centre and spaced antenna group 2-3 carry out the signal transmission by transmission medium 2-2;

The soft cell-radio network of described a kind of layering further comprises:

Described soft sub-district plane 1-2 is based upon on the basis of signal overlay planes 1-1, and the 2-1 of control centre gives the soft sub-district of each layer according to the quadrature distribution principle with allocation of radio resources, thereby forms overlapping on the region, the soft sub-district of non-interfering K layer;

The soft sub-district of each layer in the soft sub-district of described K layer all is to be made of n soft sub-district, wherein n 〉=1;

When having the customer group of friction speed feature, can evenly divide according to moving velocity of terminal division K kind;

When having the customer group of friction speed feature, can carry out non-homogeneous division according to moving velocity of terminal division K kind;

The business that described K kind is had the customer group of friction speed feature projects to suitable soft cell layer, and by corresponding soft sub-district in the soft sub-district of this layer it is served;

The customer group of described friction speed feature refers to the customer group of moving velocity of terminal in the friction speed scope;

Serve the higher customer group of moving velocity of terminal with the soft cell layer that constitutes than the soft sub-district of large tracts of land;

Serve the lower customer group of moving velocity of terminal with the soft cell layer that constitutes than the soft sub-district of small size;

The described 2-1 of control centre finishes signal processing and the controlled function that signal post needs, and simultaneously the employed Radio Resource of spaced antenna group 2-3 under its linchpin is managed and unifies and dispatch;

The 2-1 of control centre of the soft cell-radio network of described layering can adopt the managing distributed antenna groups 2-3 of centralized control mode;

The 2-1 of control centre of the soft cell-radio network of described layering can adopt the managing distributed antenna groups 2-3 of distributed control mode;

The 2-1 of control centre of the soft cell-radio network of described layering can adopt the managing distributed antenna groups 2-3 of graduation control mode;

Described transmission medium 2-2 can be media such as wireless optical fiber, millimeter wave, free space optical link, also can be the mixed media that mixes above-mentioned multiple media;

The method of salary distribution of described allocation of radio resources has fixed allocation, dynamic assignment and mixed ways of distribution;

Described fixed allocation mode refers in planning mode in advance and gives each soft sub-district in the soft sub-district of each layer and the every layer of soft sub-district with whole usable radio resources fixed allocation;

Described fixed allocation mode comprises the distribution of the soft minizone of each layer and the distribution two parts in every layer of soft sub-district, at first whole Radio Resources are divided into the K part according to the quadrature distribution principle, distribute to the soft sub-district of described K layer accordingly, be resource allocation methods for the distribution in every layer of soft sub-district then, the available resources of the soft sub-district of this layer are distributed to each soft sub-district in the soft sub-district of this layer according to conventional cellular network;

Described fixed allocation mode is that the usable spectrum resource is divided into nonoverlapping K part, distribute to the soft sub-district of described K layer accordingly, finish the frequency division layering,, the frequency spectrum resource of distributing to each soft cell layer is further distributed to each soft sub-district in its layer then according to the frequency division multiple access principle;

Described fixed allocation mode is that sheet sometime is divided into nonoverlapping K section, the operating time of certain one deck in the soft sub-district of corresponding described K layer of each section period, finish the time-division layering, then according to the principle of frequency division/time-division combination multi-access mode, the usable spectrum resource of each soft cell layer and time are further distributed to each soft sub-district in its layer;

Described dynamic assignment mode refers to whole usable radio resources in control centre's 2-1 place unified management, carries out dynamically in the soft minizone of each layer, allocation of radio resources as required;

Described mixed ways of distribution refer to a part of Radio Resource at first fixed allocation give each soft sub-district to be adapted to basic business demand, keep the business demand that a part of Radio Resource is used to happen suddenly at the 2-1 of control centre simultaneously, this part reservation of resource is carried out dynamic assignment, flexible dispatching between the soft sub-district of each layer;

Described quadrature distributes and comprises: the compound mode of frequency division multiple access, time division multiple access, code division multiple access, OFDM and aforesaid way;

Described soft sub-district refers to the overlay area of using same Radio Resource emission to form by antenna element adjacent on one or more regions;

The radius of described soft cell coverage area and the shape of overlay area can be decided according to the velocity characteristic of portable terminal;

The radius of described soft cell coverage area is that the velocity characteristic of the portable terminal supported according to described soft sub-district is determined;

The shape of described soft cell coverage area is by the translational speed decision of portable terminal in all directions.

The connection control method of the soft cell-radio network of layering of the present invention comprises:

When the some user terminals in the business demand plane have demand for services, the 2-1 of control centre at first obtains the moving speed estimation value of described terminal, then according to the mapping relations of moving velocity of terminal estimated value and soft cell layer, described terminal traffic demand is projected to corresponding soft cell layer, determine the concrete soft sub-district of inserting in the pairing soft cell layer according to terminal location again, the a certain channel resource allocation that the last 2-1 of control centre will insert in the soft sub-district is given described user terminal, and a plurality of antennas of controlling described soft sub-district simultaneously use described channel to provide service as terminal;

Described connection control method further comprises:

The moving speed estimation value of described terminal can be measured by the 2-1 of control centre and estimate, also can measure by terminal self and estimate;

In the process that a plurality of antennas in the described soft sub-district and described user terminal communicate, all antennas of corresponding soft sub-district needn't be in state of activation simultaneously, the 2-1 of control centre can be according to the geographical position at terminal place according to reducing principle such as interference, and some antenna of controlling soft sub-district selectively is described subscriber terminal service.

In sum, for soft sub-district of the present invention, the velocity characteristic that soft sub-district covers by the terminal of needs service is determined, uses by a plurality of combination of antennas by wireless resource allocation and realizes that soft sub-district covers.This has removed the close-coupled relation between covering of single antenna signal and the covering of soft sub-district, thereby can use Radio Resource more effective and neatly, improve the overall performance of network, and can be adapted to the business demand of various speed scenes according to the soft sub-district that the moving velocity of terminal feature forms better.

The realization of signal overlay planes 1-1 allows to make up the overlapping soft sub-district of multilayer on the region with same distribution type antenna groups 2-3.User in the business demand plane is divided into the customer group with friction speed feature by its velocity characteristic, and the customer group with friction speed feature projects in the corresponding soft cell layer, can the efficient balance load.The soft cell layer that forms with the soft cell coordination work of one deck guarantees to provide immanent service for the customer group with a certain velocity characteristic; The seamless covering of signal overlay planes 1-1 guarantees all standing of the soft sub-district of each layer on the region, thereby realizes on any position, the seamless access of user terminal under any speed scene.With respect to conventional cellular communication system, the soft sub-district of layering more efficient use space resources, improved power system capacity, also guaranteed simultaneously system's realizability and handled the low characteristics of complexity.

Description of drawings

Fig. 1 is the logic function floor map of the soft cell-radio network of layering;

Fig. 2 is the soft cell-radio network physical structure of a layering connection layout;

Fig. 3 is a soft sub-district formation method schematic diagram in the soft cell-radio network of layering;

Fig. 4 is the soft cell-radio network resource distribution mode of a layering example one;

Fig. 5 is the soft cell-radio network resource distribution mode of a layering example two;

Fig. 6 is the access control flow chart of the soft cell-radio network of layering;

Fig. 7 be soft cell-radio network of layering and conventional cellular network Capacity Ratio;

Fig. 8 is soft sub-district of each layer and the comparison of conventional cellular network carrier/interface ratio performance in the soft cell-radio network of layering;

Fig. 9 is that the blocking rate of soft cell-radio network of layering and conventional cellular network compares;

Figure 10 is that the switching probability of soft cell-radio network of layering and conventional cellular network compares.

Figure 11 is that the cutting off rate of soft cell-radio network of layering and conventional cellular network compares;

Embodiment

As shown in Figure 1, the soft cell-radio network of layering of the present invention comprises three logic function planes: signal overlay planes 1-1, soft sub-district plane 1-2 and business demand plane 1-3;

As shown in Figure 2, the part of the soft cell-radio network physical structure of layering of the present invention comprises: the 2-1 of control centre, transmission medium 2-2 and spaced antenna group 2-3.Described spaced antenna group 2-3 comprises many antenna elements of zones of different geographically that distribute; Described transmission medium 2-2 can be media such as wireless optical fiber, millimeter wave, free space optical link, it bears the task that spaced antenna group 2-3 and the 2-1 of control centre are coupled together, comprise the radiofrequency signal of spaced antenna group 2-3 is collected the 2-1 of control centre and the armed radiofrequency signal of the 2-1 of control centre is sent to spaced antenna group 2-3, guarantee that the information link between spaced antenna group 2-3 and the 2-1 of control centre is unimpeded; Certainly, also can be according to actual conditions, adopt hybrid mode to finish being connected between the 2-1 of control centre and the spaced antenna group 2-3, for example adopt the hybrid mode of millimeter wave and ROF, connect near the distributed antenna unit in control centre 2-1 center and adopt millimeter wave, and adopt ROF to connect for the distributed antenna unit of far-end.

Described business demand plane 1-3 has concentrated the business demand under the various speed scenes that distribute on the region.According to the velocity characteristic of user terminal, the portable terminal of various scenes is unified in the 1-3 of business demand plane, as fixing access, nomadic access, middling speed moves and various speed scenes such as high speed mobile terminal access.

Described signal overlay planes 1-1 refers to by the formed seamless signal of a large amount of antenna element radiated electromagnetic waves that extensively distribute on the region and covers.The seamless covering of signal on the region is the basis that wide-area services is provided for portable terminal.Because the loss of electromagnetic wave in communication process, the signal that makes an antenna element launch can not arrive geographic Zone Full, thereby cause an antenna element that certain effective coverage range can only be arranged, concrete effective coverage range is to be determined by factors such as aerial radiation power, antenna pattern and communication environments.In order to make signal can cover geographic All Ranges effectively, can cover by the seamless signal of all coverages on realizing geography at a large amount of antenna element of configuration that distributes on the region, thereby guarantee not exist in the coverage blind area.

Described soft sub-district plane 1-2 is based upon on the signal overlay planes 1-1 basis, and it is made of a plurality of soft sub-districts.Described soft sub-district refers to the unified RRM strategy according to the 2-1 of control centre, control antenna adjacent on one or more regions and use same Radio Resource to launch formed overlay area, this overlay area be to use that a plurality of antenna elements of same Radio Resource emission effectively cover separately and.As shown in Figure 3, little dotted line hexagon covers the useful signal covering that 3-1 is a single antenna, and using the same shade overlay area 3-2 that Radio Resource synthesized by adjacent a plurality of antennas is exactly a soft sub-district.

According to soft sub-district formation method, utilize the resource reuse thought in the conventional cellular network, the Radio Resource that the 2-1 of control centre control spaced antenna group 2-3 uses, form a plurality of soft sub-districts that belong to same aspect, on the basis of seamless signal overlay planes 1-1, the soft sub-district of this layer is seamless on the region;

Described soft sub-district plane 1-2 can comprise the soft sub-district of K (K 〉=1) layer; The 2-1 of control centre gives the soft sub-district of each layer according to orthogonal wireless resource allocation principle with allocation of radio resources, thereby forms overlapping on the region, the soft sub-district of non-interfering K layer.The purpose of layering is in order to adapt to the speed scene of business demand, to improve the overall performance of system.For example, expect high power system capacity, should form sub-district, thereby make the density height of resource reuse, but the high customer group of translational speed this moment will inevitably cause too much handover load than small size; Consider that the offered load expense that handover causes will lack, generally should form the larger area sub-district being adapted to the high customer group of translational speed, but since this moment resource reuse density low, thereby cause power system capacity little.In addition, the characteristics of the terminal traffic of friction speed scene are different, are slowly to change as static and the channel circumstance low speed portable terminal, can carry out more accurate channel estimating, thereby realize high speed data transfers; And the translational speed of car wireless terminal is fast, and channel variation is difficult to carry out precise channels and estimates that transmission rate is generally lower than very fast.For making full use of system resource, improve overall performance, be necessary that the soft sub-district that forms different levels serves the portable terminal with friction speed feature.The difference of the soft sub-district of different layers is embodied in the not equal of the difference of soft cell size, shape and transmission technology.

The soft sub-district of each layer all comprises a soft sub-district at least, as shown in Figure 1, soft sub-district plane 1-2 can be divided into the 1st layer of soft sub-district 1-4, the 2nd layer of soft sub-district 1-5 ..., the soft sub-district 1-6 of K layer, wherein, the soft sub-district of each layer all is to be made of a plurality of soft sub-district that belongs to the soft sub-district of this layer; As shown in Figure 1, the 1st layer of soft sub-district 1-4 is made up of the individual soft sub-district 1-7 of the n that belongs to the 1st layer of soft sub-district 1-4 (n 〉=1), the soft sub-district 1-6 of K layer is made up of the individual soft sub-district 1-8 of the m that belongs to the soft sub-district 1-6 of K layer (m 〉=1), certainly, the soft sub-district of other layer is also by forming (not painting) with the individual soft sub-district of j (j 〉=1) of layer.

The soft cell-radio network of layering is according to the translational speed of user terminal, all business demands on business demand plane are divided into the customer group with friction speed feature, terminal traffic with the friction speed feature projects to suitable soft cell layer then, promptly is linked into the soft cell layer that is adapted to this velocity characteristic; Then according to terminal location, determine that corresponding soft sub-district serves it, done offered load so balanced preferably.In general, serve the higher customer group of translational speed with the soft sub-district of larger area, and to serve the lower customer group of translational speed than the soft sub-district of small size.For example, as shown in Figure 1, the area of soft sub-district 1-8 that constitutes the soft sub-district 1-6 of K layer is greater than the area of the soft sub-district 1-7 that constitutes the 1st layer of soft sub-district 1-4, then the soft sub-district 1-6 of K layer generally is used for the higher customer group of service terminal translational speed, and the 1st layer of soft sub-district 1-4 is used for the lower customer group of service terminal translational speed.

Because the customer group of various velocity characteristics may reside on the region Anywhere, so the seamless covering on the region all must be realized in the soft sub-district of each layer.Behind the seamless signal overlay planes 1-1 on the spaced antenna group 2-3 formation region, only need employed Radio Resource, the soft sub-district that just can realize the seamless covering of multilayer by the 2-1 of control centre control spaced antenna group 2-3.It is pointed out that layout that signal overlay planes 1-1 forms the spaced antenna group 2-3 relied on needs not to be is evenly arranged on the whole region, can predict reasonable Arrangement spaced antenna group 2-3 according to practical business conditions of demand and future development.The layout that the principle that must observe is antenna groups must satisfy all antenna elements and can realize effective seamless covering on the region with the signal of certain power emission.

Although formed the overlapping soft sub-district of multilayer on logical level, the basis that they relied on all is the identical formed signal overlay planes of spaced antenna group 2-3 1-1; This point is different with the hierarchy of conventional cellular network, and layering is to realize that by the base station of arranging different layers promptly macrocell layer is realized by macro cell base station there, and microcell level is realized by microcell base station.

After wireless network is introduced the notion of the soft sub-district of layering,, therefore can use Radio Resource effectively, improve the autgmentability and the flexibility of network, simplify the complexity of the network planning and design because the sub-district is to control formation by the 2-1 of control centre in soft mode.

It may be noted that at this, in the description of this specification aspects such as soft cell-radio network notion, structure, working method for layering, unless otherwise indicated, generally all be to discuss at down link (control centre is to the link of portable terminal), promptly a plurality of antennas are launched portable terminal simultaneously; The situation of up link (portable terminal is to the link of control centre), be a plurality of antenna elements transmitting of mobile terminal receive simultaneously, for notion and the building method of describing the soft cell-radio network of layering, with the description of down link be similarly, therefore do not provide the description of up link specially.

To describe in detail below about allocation of radio resources mode in soft sub-district planar layer mode, the soft sub-district of each layer and the corresponding relation between customer group and soft cell layer.

For realizing the communication between the multi-user, many multi-access modes have been proposed, as frequency division multiple access (FDMA, Frequency Division Multiple Access), time division multiple access (TDMA, Time Division MultipleAccess), code division multiple access (CDMA, Code Division Multiple Access), space division multiple access (SDMA, Space Division Multiple Access), OFDM (OFDMA, Orthogonal FrequencyDivision Multiple Access) etc.The above-mentioned technology of the soft cell-radio network of layering need utilizing equally realizes the communication between the multi-user, but since this moment forming soft sub-district overlapping on the multilayer region simultaneously on the same distribution type antenna groups 2-3, so the allocation of radio resources of the soft cell-radio network of layering comprises that interlayer distributes and layer in distribute two parts.Table 1 is listed between the soft cell layer that the soft cell-radio network of layering may adopt and the allocation of radio resources mode in the layer.

Table 1

Allocation of radio resources mode with interlayer in the layer that table 1 provides all is the single dividing mode that adopts, can certainly adopt the compound mode of various multiple access technologies, as adopt frequency division to distinguish the soft sub-district of different layers, and the compound mode of FDMA/TDMA can be adopted in the inside, soft sub-district of certain one deck.Multi-access mode between different layers can be different in addition, soft cell-radio network of layering that is divided into three layers of soft sub-district for example, adopt frequency division to distinguish the soft sub-district of each layer, but for each layer, the allocation of radio resources mode that adopts is: adopt FDMA in the soft sub-district of ground floor, adopt TDMA in the second layer, adopt CDMA in the 3rd layer.Owing to there is multiple multiple access technology, therefore there is the combination of many kinds of allocation of radio resources modes, those of ordinary skill in the art is easy to just expect thus alternative allocation of radio resources mode, here just is not described one by one.

The basic principle that needs are observed is: carry out allocation of radio resources between soft cell layer according to the quadrature distribution principle, guarantee that the Radio Resource between each layer is a quadrature, non-interfering; The allocation of radio resources of inside, the soft sub-district of each layer can be finished in the conventional mode, thought according to resource reuse, under the condition that satisfies the interference level requirement, the limited resources of distributing to soft cell layer are reused the resource allocation that realizes in the soft cell layer, and the radio resource unit that different with conventional cellular network is in the soft sub-district uses simultaneously at several antenna elements.

Therefore wireless resource allocation and scheduling are finished in a concentrated manner by the 2-1 of control centre in the soft cell-radio network of layering, can realize effectively, allocation of radio resources flexibly, obtain high resource utilization.The wireless resource allocation mode has fixed allocation, dynamic assignment and both hybrid modes.

Fixed allocation is given each soft sub-district in the soft sub-district of each layer and the every layer of soft sub-district in the mode of planning in advance with whole usable radio resources fixed allocation; The dynamic assignment mode refers to whole usable radio resources in control centre's 2-1 place unified management, carry out dynamically in the soft minizone of each layer, allocation of radio resources as required, this moment Radio Resource service efficiency than fixed allocation mode height, but the complexity that realizes also can improve; Mixed ways of distribution refers to give each soft sub-district to be adapted to basic business demand a part of Radio Resource fixed allocation, keep the business demand that a part of Radio Resource is used to happen suddenly in control centre simultaneously, this part reservation of resource is carried out dynamic allocation scheme, can be in the soft sub-district of each layer flexible dispatching, mixed ways of distribution has carried out the compromise consideration in conjunction with the advantage of fixed allocation and dynamic assignment to wireless resource utility efficiency and system handles complexity.

Also it should be noted that, in Fig. 2, only drawn a 2-1 of control centre, but need to decide in concrete the enforcement according to the scale of real network.For networking among a small circle, can adopt centralized management control; For the network that covers big zone, it is infeasible that all 2-1 of control centre of antenna element introducing are focused on.Can adopt following two kinds of methods to solve this problem, the one, the notion of the distributed control of introducing distributes on the region and places a plurality of control centres, adopts High-speed Optical Fiber Link to connect between them and carries out information exchange; And these control centres logically are unified, and the information that they are relied in network management and allocation of radio resources process is identical, has so just solved the high problem of complexity that focuses on.The 2nd, introduce the thought that the graduation management is controlled, with the present structural similarity that telephone network adopted, introduce one-level control centre, sectional center, three grades of control centres etc., network management in the one-level control centre control zonule, the sectional center has connected the many distributed antenna units under a plurality of control centres and its administration, mainly finish the network management in the big overlay area, by that analogy.

For more clearly explaining the notion of the soft cell-radio network of layering, provide two examples of the soft cell-radio network of layering that forms in fixing allocation of radio resources mode below.

Example one adopts the frequency division mode that layering is carried out on plane, soft sub-district, also adopts the mode of frequency division to carry out allocation of radio resources in the soft sub-district with one deck simultaneously.

At first the terminal in the business demand plane is divided into the customer group with friction speed feature according to translational speed, designs the soft sub-district number of plies that plane, soft sub-district is comprised.For example, establish { v _{I, max}, i=1,2 ..., K} set be to the portable terminal velocity interval [0, V _Max] division, i.e. a 0≤v _{1, max}≤ v _{2, max}≤ ... ≤ v _{K, max}=V _Max, V wherein _MaxThe maximum that can effectively serve for network allows moving velocity of terminal, then designs the soft sub-district of K layer, the moving velocity of terminal feature that the soft sub-district of each layer adapted to be respectively [0, v _1max], (v _1max, v _2max], (v _2max, v _3max] ..., (v _{(K-1) max}, v _Kmax], translational speed is that 0 terminal is represented fixedly access way.Go up face velocity for convenient expression and divide, the terminal velocity feature above the correspondence with K kind velocity characteristic brief note is

The radius r of the single soft sub-district in every layer of soft sub-district _iBe proportional to the velocity characteristic of the customer group that this layer support

Both concrete proportionality coefficients are determined by the disposal ability of the soft cell-radio network of layering.She Ji purpose is to move the handover that causes and the network operation complexity of introducing in order to control by terminal like this, the handover load of whole network is in the controlled level, and make the soft cell-radio network of score layer can serve highspeed user's terminal by layering, can be adapted to static again and the high-speed transfer demand low speed user terminal, effectively utilize Radio Resource, fully the potentiality of digging system capacity.The notion of soft radius of society is different from the notion of radius in the circle herein, because speed has direction, so soft radius of society, refers on the moving direction soft cell edge distance to soft center of housing estate with respect to moving direction.For example on highway, speed along the highway direction is fast, and it is little perpendicular to the speed of highway, therefore the soft cell edge along highway is big to the distance of soft center of housing estate, and just short to the distance of soft center of housing estate perpendicular to the soft cell edge of highway direction, this moment, the shape of soft sub-district was similar to ellipse.

Suppose that the moving velocity of terminal scope that whole network system is served is 0～150Km/h, it is divided into three sections, plane, then soft sub-district is corresponding to be divided into three layers of soft sub-district to adapt to the customer group with friction speed feature.The division of subscriber teminal speed feature can evenly be divided and non-homogeneous division.In order to realize conveniently, can adopt even division, translational speed is the soft sub-district of the corresponding ground floor of terminal of 0～50Km/h, and translational speed is the soft sub-district of the corresponding second layer of terminal of 50～100Km/h, and translational speed is corresponding the 3rd layer of soft sub-district of the terminal of 100～150Km/h; In the reality, general low speed user will be more than the highspeed user, for effectively utilizing Radio Resource, can carry out non-homogeneous division, correspond respectively to the user terminal that translational speed is 0～30Km/h, 30～75Km/h, 75～150Km/h as ground floor, the second layer and the 3rd layer of soft sub-district.

This example adopts the mode of evenly dividing, plane, whole soft sub-district is divided into three layers of soft sub-district, wherein the soft sub-district of ground floor is used for the customer group that the service terminal translational speed is 0～50km/h, the soft sub-district of the second layer is used for the customer group that the service terminal translational speed is 50～100km/h, the 3rd layer of soft sub-district is used for the customer group that the service terminal translational speed is 100～150km/h, according to the mapping relations between the customer group in above-mentioned soft cell layer and the business demand plane with friction speed feature, when accessing terminal request, according to terminal velocity information, insert in the corresponding soft cell layer by control centre's 2-1 control terminal and to serve.

As shown in Figure 4, suppose that total usable spectrum resource is (F ₁, F ₄), adopt the frequency division layered mode, with frequency range (F ₁, F ₂) frequency band 4-1 distribute to the soft sub-district of ground floor, frequency range (F ₂, F ₃) frequency band 4-2 distribute to the soft sub-district of the second layer, frequency range (F ₃, F ₄) frequency band 4-3 distribute to the 3rd layer of soft sub-district.Because same antenna can be launched the signal of different frequency simultaneously, that is to say that same antenna can be launched (F simultaneously ₁, F ₄) signal in the frequency range on the different frequent points, therefore, according to top frequency division layered mode, same antenna can be launched the signal of the different frequency that belongs to ground floor, the second layer and the 3rd layer of soft sub-district simultaneously.For example, the same antenna can the while tranmitting frequency be F _a(F _aBe to belong to (F ₁, F ₂) a certain frequency in the scope) and signal S ₁, frequency is F _b(F _bBe to belong to (F ₂, F ₃) a certain frequency in the scope) and signal S ₂, frequency is F _c(F _cBe to belong to (F ₃, F ₄) a certain frequency in the scope) and signal S ₃, because frequency is F _aSignal S ₁Belong to the soft sub-district of ground floor, frequency is F _bSignal S ₂Belong to the soft sub-district of the second layer, frequency is F _cSignal S ₃Belonging to the 3rd layer of soft sub-district, therefore have the signal that belongs to three soft sub-districts of layer respectively simultaneously on same geographical position, be non-interfering between them, and this realizes by same antenna element.

The three unities below has been discussed has in vertical direction been had the feasibility of being launched the soft cell signal of a plurality of different layers by same antenna element simultaneously, this also illustrates and utilizes same distribution type antenna groups can form the soft sub-district of non-interfering multilayer overlapping on the region simultaneously.In the horizontal direction, promptly the problem that involves of every layer of soft sub-district mainly is the realization of determining of the size of single soft sub-district and shape and the seamless covering of each layer on the region.

Soft sub-district design in the soft cell layer is to carry out according to following 2: the terminal characteristics of the customer group that (1) is served according to the soft sub-district of each layer mainly are to design according to the terminal velocity feature; (2) in general, serve the higher customer group of moving velocity of terminal, serve the lower customer group of moving velocity of terminal with the soft cell layer that the soft sub-district than small size constitutes with the soft cell layer that the soft sub-district of larger area constitutes.

The velocity characteristic that be to adapt to terminal, the terminal velocity feature that is adapted to according to the soft sub-district of this layer

Determine soft radius of society r _i, r _iBe proportional to

Both concrete proportionality coefficients are determined by the disposal ability of network.Because signal is in the loss of communication space, the signal that antenna element is launched has certain effective coverage range, suppose that the signal of antenna element on the region is covered as circular covering, and radius is r ₀, then will form radius is r _iThe needed number of antennas in soft sub-district can basis Obtain, wherein

Smallest positive integral greater than x is got in expression, and concrete needed number of antennas so just can determine to be adapted to velocity characteristic by the decisions such as overlapping degree that concrete shape, antenna alignment mode, the adjacent antenna of soft sub-district covers

Comprise what antenna elements in the single soft sub-district of customer group.

Suppose that belonging to the soft sub-district that the customer group of 0～50Km/h scope need form for speed comprises three antennas, need during then to a certain Terminal Service of this velocity characteristic customer group adjacent three antennas simultaneously tranmitting frequency be (F ₁, F ₂) in the signal S of a certain frequency, total signal S effectively cover be exactly transmit that three antenna elements of S effectively cover separately and, this and the covering covering of corresponding soft sub-district just.In like manner the soft sub-district that need form as if the customer group that belongs to 50～100Km/h scope for speed comprises nine antennas, promptly needs adjacent nine antennas while tranmitting frequency to be (F ₂, F ₃) in the signal of a certain frequency serve user terminal; Belong to the soft sub-district that the customer group of 100～150Km/h scope need form for speed and comprise 27 antenna elements, then need adjacent 27 antennas simultaneously tranmitting frequency be (F ₃, F ₄) the signal of a certain frequency in the scope serves user terminal.

The formation foundation and the implementation method of single soft sub-district in the soft sub-district of each layer more than have been described.On the basis of the formed signal overlay planes of spaced antenna group 2-3 1-1, as long as each antenna element all participates in the structure of the soft sub-district of arbitrary layer, according to the formation method of soft sub-district and the allocation of radio resources and the occupation mode of interlayer, just can realize the soft sub-district of multilayer, and the whole region of all seamless covering, the soft sub-district of each layer.A kind of situation of the limit is that the covering that the 2-1 of control centre controls each antenna element is exactly that a soft sub-district covers, and the soft subzone network of single antenna that form this moment deteriorates to traditional cellular network; Different is, many soft sub-districts of control centre's management, and unlike sub-district of a base stations control in the conventional cellular network.The flexibility of soft sub-district derive from its implementation flexibly, soft sub-district realizes by one or several antenna element is effectively covered to synthesize, and this syntheticly finished by the 2-1 of control centre control allocation of radio resources and occupation mode.What need to propose is, does not have under the redundant situation at antenna, and each antenna element must be in the seamless covering that could realize the soft sub-district of each layer in the soft sub-district of different layers simultaneously.

The shape of the soft sub-district of each layer, a plurality of antennas of just selecting how to distribute on the region are realized soft sub-district, can form the soft sub-district of respective shapes as the antenna element group of selecting square arrangement, circular arrangement or rectangular arranged.The design of soft small area shape is relevant with the speed of customer group on all directions that the soft sub-district of each layer supported, because the selection of soft radius of society has comprised the moving direction information of user terminal.In general, for convenience of implementation, can unify with circular cover, hexagon covers or square covering waits and designs; But for some special occasions, can treat with a certain discrimination, so that effectively utilize resource, can adopt ellipse or rectangle to design as the covering of street, highway, therefore when fixing planning plane, soft sub-district, the statistical nature that need take all factors into consideration customer group is to form the soft sub-district of suitable size and shape.

Notice that the speed of user on all directions of different regions with same velocity characteristic may be different, as: for the car-mounted terminal user, the speed of all directions can be very high when broader region; But the speed along the highway direction on highway is very high, and just very low perpendicular to the speed on the highway direction, the soft cell layer that therefore is adapted to the car-mounted terminal service can be difform in the soft sub-district of broad region and in the soft sub-district at highway place.

The soft sub-district of independent one deck of the soft cell-radio network of layering is equivalent to traditional cellular communications networks, therefore the allocation of radio resources mode in the plane layer of soft sub-district can adopt traditional multiple access technology, difference is that the Radio Resource of distributing to soft sub-district this moment is used simultaneously by one or several antenna element, covers so that form soft sub-district.

This example is described the multi-access mode that adopts FDMA in the layer, in conjunction with the thought of resource reuse, the frequency resource that is allocated to the soft sub-district of each layer is further distributed.The frequency duplex factor as one of supposing the soft sub-district of ground floor is N ₁, the frequency duplex factor as one of the soft sub-district of the second layer is N ₂, the frequency duplex factor as one of the 3rd layer of soft sub-district is N ₃N ₁, N ₂, N ₃Can determine according to the desired carrier/interface ratio of system, analytical method is the same with analytical method in the conventional cellular network, different is to exist a plurality of antennas simultaneously with identical Radio Resource work in the soft sub-district frequently together this moment, and this is different from, and co-frequency cell is the situation of single antenna work in the conventional cellular network.

As shown in Figure 4, according to the desired Channel Elements width of system, the frequency spectrum resource 4-1 that will belong to the soft sub-district of ground floor is divided into a series of Channel Elements 4-5.For explaining conveniently, suppose the N in the soft cell cluster ₁The Radio Resource number is identical in the individual soft sub-district, supposes that promptly the channel number of dividing altogether is N ₁* L comprises L Channel Elements in each soft sub-district.Frequency duplex factor as one N according to the soft sub-district of this layer ₁, all Channel Elements 4-5 are divided into N ₁Group 4-4:f _1-1, f _1-2..., Each organizes f _1-iL the Channel Elements that has comprised whole Channel Elements group 4-5; In general should observe adjacent channel frequently in the time of division group and not be arranged in same soft sub-district, not be arranged in the principle of adjacent soft sub-district simultaneously as far as possible, Fig. 4 has illustrated this principle.The Channel Elements group f of first the soft sub-district in the soft cell cluster of the soft sub-district of ground floor _1-1Comprise f _1-1-1, f _1-1-2..., f _1-1-LChannel 4-6, the Channel Elements group f of second soft sub-district in bunch _1-2Comprise f _1-2-1, f _1-2-2..., f _1-2-LChannel 4-7 ..., N in bunch ₁The Channel Elements group of individual soft sub-district Comprise

Channel 4-8, f _1-i-jThe carrier frequency of j channel in the individual soft sub-district of i in the soft cell cluster of the soft sub-district of expression ground floor.After frequency planning is intact, soft cell cluster is divided in the soft sub-district of ground floor, then according to the mode of rule, with f _1-1, f _1-2...,

Be assigned to the allocation of radio resources of promptly finishing the soft sub-district of ground floor in each bunch in the corresponding soft sub-district.Similarly, frequency spectrum resource 4-2, the 4-3 for the soft sub-district of second and third layer carries out wireless resource allocation in the layer according to same principle.

So just formed the soft cell-radio network of the layering with three layers of soft sub-district, three layers of soft sub-district are overlapping on the region, be adapted to have the customer group of friction speed feature respectively, and the employed Radio Resource in the soft sub-district of each layer is quadrature, can not interfere with each other between each layer.According to above description, can construct the soft cell-radio network of layering easily with the soft sub-district of K layer.

Example two: adopt time division way to carry out the layering on plane, soft sub-district, in soft sub-district, adopt FDMA/TDMA combination multi-access mode to carry out allocation of radio resources simultaneously with one deck.

Divide according to the speed that is similar to example one, customer group is divided into three classes, corresponding, need on the signal overlay planes, make up the customer group that the corresponding speed feature is served in three layers of soft sub-district.The soft sub-district building method of the soft cell-radio network of layering is the same, and promptly the 2-1 of control centre controls one or several adjacent antenna units with same Radio Resource emission synthetic soft sub-district covering.This example is that with the difference of example one Radio Resource that the antenna in the soft sub-district uses simultaneously is different, and in the example one, resource distribution mode adopts FDMA, the soft sub-district of synthetic formation of using the adjacent antenna units of same channel work in the layer; The resource distribution mode that adopts in this routine middle level is FDMA/TDMA, and promptly one or several adjacent antenna units is used same channel and transmitted in identical time slot, and the signal that is synthesized is covered as the covering of soft sub-district.

As shown in Figure 5, this routine layering realizes by time division way.The time slot section TS1 that 5-1 is represented distributes to the soft sub-district of ground floor, the time slot section TS2 that 5-2 is represented distributes to the soft sub-district of the second layer, the time slot section TS3 that 5-3 is represented distributes to the 3rd layer of soft sub-district, the 2-1 of control centre control spaced antenna group 2-3 transmits in corresponding time slot section, and the signal of different time slot section emissions is served the portable terminal that inserts the soft sub-district of different layers.Duplex mode can adopt TDD, FDD or FDD/TDD.When adopting TDD, need further be divided into uplink and downlink two parts, adopt FDD, then need carry out corresponding time slot and divide in the up link frequency range of correspondence to each time slot section.Only consider down link herein, Fig. 5 has also just illustrated the allocation of radio resources of down link, is similarly for up link, no longer describes herein.

Resource distribution mode in the layer adopts the FDMA/TDMA compound mode, at first carries out bandwidth assignment, is similar to example one, according to the carrier/interface ratio requirement of the system soft sub-district of each layer, determines the frequency duplex factor as one N of the soft sub-district of each layer ₁, N ₂, N ₃, owing to adopted the mode layering of time-division this moment, so whole frequency spectrum resources that the soft sub-district of each layer can using system.Concerning the soft sub-district of ground floor, according to the frequency range of the desired channel cell of system, total frequency spectrum resource is divided into a series of channel cell 5-4, for explaining conveniently, suppose the N in the soft cell cluster ₁The Radio Resource number is identical in the individual soft sub-district, and promptly establishing the number of channels of dividing altogether is N ₁* L.Because the frequency duplex factor as one N in the soft sub-district of ground floor ₁, all channel cell 5-4 are divided into N ₁Group 5-5:f _1-1, f _1-2...,

Each organizes f _1-iL the channel that has comprised all channel cell group 5-4; In general should observe adjacent channel frequently in the time of division group and not be arranged in same soft sub-district, not be arranged in the principle of adjacent soft sub-district simultaneously as far as possible, Fig. 5 has also illustrated this principle.The channel-group f of first the soft sub-district in the soft cell cluster of the soft sub-district of ground floor _1-1Comprise f _1-1-1, f _1-1-2..., f _1-I-LChannel 5-6.The channel-group f of second soft sub-district in bunch _1-2Comprise f _1-2-1, f _1-2-2..., f _1-2-LChannel 5-7 ..., N in bunch ₁The channel-group of individual soft sub-district Comprise Channel 5-8, f _1-i-jThe carrier frequency of j channel in the individual soft sub-district of i in the soft cell cluster of the soft sub-district of expression ground floor.Soft cell cluster is divided in the soft sub-district of ground floor, then according to the mode of rule, with f _1-1, f _1-2...,

Be assigned in each bunch in the corresponding soft sub-district.

Principle according to TDMA, carry out the further refinement of time slot for each channel, as shown in Figure 5, on the basis of the time slot section TS1 that distributes to the soft sub-district of ground floor, further division time slot unit TS1-1, TS1-2 ..., TS1-M, therefore minimum available channel unit is some time slots of some channels.

Suppose a certain use f in the soft sub-district of ground floor _1-1The soft sub-district of channel-group, the downlink transmission when a certain portable terminal is served can be at f _1-1-iTransmit in the TS1-j time slot corresponding on the channel, transmission is to carry out simultaneously on those several antenna elements that form this soft sub-district, because these several antennas are that being easy to synchronously between antenna transmits accomplished under the control of same control centre.The allocation of radio resources of the soft sub-district of other layers and working method are similarly, and be not shown among Fig. 5, no longer describes herein.

In above example, all do not consider the influence of wireless channel environment to the Radio Resource occupation mode, in the reality, need to introduce of the influence of corresponding treatment technology, but the basic skills of the soft cell-radio network structure of layering is described in the above example with resistance wireless fading channel time varying channel.

Below with reference to Fig. 6, the access control flow process of the soft cell-radio network of relevant layering is described in further detail:

The initial network planning and design phase must be carried out careful statistical analysis to the speed scene of business demand, determine the dividing mode of terminal velocity feature, design size, shape, transmission technology of the number of plies on plane, soft sub-district and corresponding soft sub-district etc., when adopting the fixed wireless resource allocation, also need finish wireless resource allocation;

Step S6-1, the some terminals in the business demand plane have demand for services;

Step S6-2, the 2-1 of control centre carries out velocity estimation to this terminal, and this can measure by network controls center 2-1 and estimate, also can be undertaken reporting to the 2-1 of control centre after the velocity estimation by terminal self;

Step S6-3 according to the mapping relations of moving velocity of terminal and soft cell layer, projects to corresponding soft cell layer with the terminal traffic demand,

Step S6-4 determines the concrete soft sub-district of inserting in the pairing soft cell layer according to terminal location;

For example, in the soft cell-radio network of layering of example one statement, if the translational speed of the terminal A of demand for services is arranged is 90km/h, the 2-1 of control centre is according to the corresponding relation of its three layers of soft sub-districts and moving velocity of terminal so: the soft sub-district of ground floor is used for the customer group that the service terminal translational speed is 0～50km/h, the soft sub-district of the second layer is used for the customer group that the service terminal translational speed is 50～100km/h, the 3rd layer of soft sub-district is used for the customer group that the service terminal translational speed is 100～150km/h, then terminal A is mapped to the soft sub-district of the second layer, because the soft sub-district of each layer all is seamless covering on the region, therefore terminal A must be in the covering of a certain soft sub-district of the soft sub-district of the second layer, the soft sub-district of access that this soft sub-district is exactly terminal A;

The a certain channel resource allocation that step S6-5, the 2-1 of control centre will insert in the soft sub-district is given terminal A, and a plurality of antennas of controlling this soft sub-district simultaneously use this channel to provide service as terminal A;

It should be noted that, in terminal A and process that a plurality of antennas in the corresponding soft sub-district communicate, all antennas of corresponding soft sub-district needn't be in state of activation simultaneously, the 2-1 of control centre can be according to the geographical position at terminal place according to reducing principle such as interference, control some antenna selectively and be terminal A service, the communication resource that selected antenna uses during to Terminal Service is the same.

According to the notion and the connection control method of the soft cell-radio network of above-described layering, carried out simulation analysis from power system capacity, carrier/interface ratio, blocking rate, switching probability and five aspects of cutting off rate, and compared with the respective performances of traditional cellular network.The soft cell-radio network of layering has all been obtained than conventional cellular network more performance aspect above five as can be seen from comparison.

The soft cell-radio network of layering in the emulation adopts the frequency division layering, uses the multi-access mode of FDMA/TDMA in the layer.

(1) capacity analysis

The simulation parameter that is adopted is as follows: requiring the overlay area gross area is 20km ², the covering radius of individual antenna is 25m, is made as circular the covering, then the area coverage of each antenna is A=1963.5m ², it is overlapping to suppose that covering between individual antenna does not have, and then requires to need in the overlay area to arrange 10186 antenna elements of 20/0.0019635 ≈.The available bandwidth of whole system is 5MHz, and the bandwidth of each channel is 200KHz, and each channel comprises 8 time slots.The multiplexing factor of the soft sub-district of each layer all is 9 in the soft subzone network of layering, and K is the layering number.

Suppose interlayer area ratio in the soft cell-radio network of layering, the area upper strata, single soft sub-district that is adjacent soft cell layer is 2 than the increase multiplying power of lower floor, then the area coverage of the soft sub-district in the soft sub-district of each layer of the soft cell-radio network of K layer layering be respectively A, 2A, 4A, 8A ..., 2 ^K-1A, A are the area coverage of an antenna element, under the channel assignment scheme that adopts uniformly, fixes, according to:

Obtain number of available channels total in the general requirements overlay area.

Wherein, S: total overlay area that requires is 20km in the emulation ²

W _i: be the distribution bandwidth of the soft sub-district of i layer, adopted fixedly uniform distribution, promptly the available bandwidth in each layer equates, total bandwidth is 5MHz, and then the available bandwidth of the soft sub-district of each layer is (5/K) MHz;

B: be the frequency bandwidth of a channel, be made as 200KHz.

N _T: the number of time slot for each channel is made as 8;

N _i: the frequency duplex factor as one that is the soft sub-district of i layer.This analysis is mainly in keep with the capacity advantage of the soft cell-radio network of layering, analyze for convenient, the unified multiplexing factor that adopts under the soft cell structure of single antenna of the multiplexing factor of the soft sub-district of K layer, this value are that to reach the multiplexing factor that demand on signal quality requires to reach be the same with traditional cellular network.When all adopting the same multiplexing factor for the soft sub-district of layering, co-channel interference only can reduce, and promptly service quality can improve, and can not reduce, and this can be found out that therefore capacity comparative result herein is that guard, believable by Fig. 8.

A _i: the soft sub-district area in the soft cell-radio network of layering in the soft sub-district of i layer.

Conventional cellular network has adopted the individual layer cell configuration, corresponding to the size of soft sub-district in the soft cell-radio network of layering, the capacity when conventional cellular network has been analyzed K kind different districts size, be respectively A, 2A, 4A, 8A ..., 2 ^K-1A, according to

Obtain conventional cellular network number of available channels in total overlay area when corresponding cell size.

Wherein, S: total overlay area that requires;

W: be total distribution bandwidth;

B: the frequency bandwidth that is a channel.

N _T: be the number of time slot of each channel;

N: adopt the multiplexing factor under the single antenna cell structure, promptly conventional cellular network is to reach demand on signal quality to require the multiplexing factor that reaches.

A _i: the sub-district area in the conventional cellular network.

The Capacity Ratio that Fig. 7 has drawn two kinds of network systems, abscissa K represents the number of plies of the soft cell-radio network of layering, A _iSub-district area in the expression conventional cellular network; Ordinate is total overlay area 20km ²Interior number of available channels.7-1 has represented the volume change situation of showing that the soft cell-radio network of layering increases along with the number of plies; 7-2 represents the volume change situation that conventional cellular network increases along with the sub-district area.

Because conventional cellular network is in order to adapt to the high speed mobile subscriber, it is too little that the sub-district area can not be done, generally more than 4A, table 2 is that the soft cell-radio network of layering is raised the efficiency with respect to the capacity of conventional cellular network, by Fig. 7 and table 2 as can be seen, the soft cell-radio network of layering has very big capacity potentiality than conventional cellular network.

Table 2

(2) carrier/interface ratio analysis

Fig. 8 has illustrated the comparison of carrier/interface ratio in the carrier/interface ratio of the soft sub-district of different layers, the soft sub-district of layering and the conventional cellular network.Herein to be assumed to be level high more, single soft sub-district area is big more, the ratio of increase is 2, area upper strata, the single soft sub-district of promptly adjacent soft cell layer is 2 than the increase multiplying power of lower floor.Because forming, the soft sub-district in the soft cell-radio network of layering forms jointly by a plurality of antennas, under the constant condition of individual antenna unit transmitting power, constitute by many more antennas for the big more soft sub-district of area is inevitable, and under the identical condition of the multiplexing factor, this means the co-channel interference spacing from increase, thereby cause the raising of carrier/interface ratio

Fig. 8 has drawn the carrier/interface ratio performance of different soft cell layer in the soft cell-radio network of layering and the carrier/interface ratio of conventional cellular network.8-1,8-2 ..., 8-8 represents the carrier/interface ratio performance of first to the 8th layer of soft sub-district in the soft cell-radio network of layering respectively; What 8-9 represented is the carrier/interface ratio performance of conventional cellular network.

Find out that by Fig. 8 the number of plies is high more, by the synthetic soft cell layer of many more antennas under the identical situation of the multiplexing factor, the carrier/interface ratio performance is good more, and is equivalent to single antenna base station cell in the conventional cellular network for the soft cell layer of single antenna that K=1 represents, so their carrier/interface ratio equates.

The soft sub-district that is formed by many antennas has obtained under the same multiplexing factor than the better carrier/interface ratio performance of conventional cellular network as seen from Figure 8, this means under same carrier/interface ratio performance requirement, the multiplexing factor of the soft cell layer that soft sub-district area is big can reduce, thereby improves the capacity of system.

(3) blocking rate analysis

Fig. 9 has illustrated the blocking rate of soft cell-radio network of layering and conventional cellular network to compare.The parameter that adopts in the analysis is: total area coverage that requires is 20km ², total available bandwidth is 5MHz, and the bandwidth of each channel is 200KHz, and each channel comprises 8 time slots.The multiplexing factor unification of the soft sub-district of each layer is 9.The covering radius of individual antenna is 25m, is made as circular the covering, and then the area coverage of individual antenna is 1963.5m ², 10186 antenna elements of whole overlay area domestic demand ornaments.The distribution of supposing the customer group of various velocity characteristics is that the total service load of per unit area is λ=1000Erl/km uniformly ², the service load in then each antenna element covers is 1.9365Erl, wherein Erl represents the Irish unit in the traffic theory.

In the soft cell-radio network of layering, suppose that the service load with friction speed feature customer group that every layer of soft sub-district adapts to equates that then the call business load of per unit area is λ in the soft sub-district of i layer _i=(the Erl/km of λ/K) ², so the average blocking probability of the soft sub-district of layering is:

Conventional cellular systems adopts the fixed-size cell structure of individual layer, and then blocking probability is:

$P_{b\_\mathrm{conv}}=P(\frac{W\·N_t}{B\·N_I},A_l\mathrm{\λ})$

Wherein P () represents Irish B formula.More than corresponding symbol definition the same with what define in the capacity analysis.

The blocking rate that Fig. 9 has drawn two kinds of networks compares, and abscissa K represents the number of plies of the soft cell-radio network of layering, A _iSub-district area in the expression conventional cellular network.9-1 represents shows the blocking rate variation tendency that the soft cell-radio network of layering increases along with the number of plies; 9-2 represents the blocking rate variation tendency of conventional cellular network along with the increase of sub-district area.

The soft cell-radio network of layering with respect to adopting the fixing conventional cellular network of cell size, has been obtained preferable performance by forming the soft cell layer of the customer group be adapted to have the friction speed feature simultaneously as seen from Figure 9.

(4) switching probability analysis

Figure 10 has illustrated the performance of handoffs of soft cell-radio network of layering and conventional cellular network to compare, and the simulation parameter of employing is as follows: the sub-district of establishing conventional cellular network is circular, and constant radius is 100 meters; The soft cell-radio network of layering is arranged different big or small soft sub-districts to the customer group of every kind of friction speed feature, and soft sub-district all is assumed to be circular.In emulation, adopt even speed to divide, with 0～50km/h, be divided into 10 class customer groups, be respectively 0～5,5～10 ..., 45～50km/h, judge that the foundation of the soft radius of society be adapted to friction speed feature customer group is r _i=[(1.7v _Imax+ v _Imin)/2.7] t, t characterizes be terminal from soft center of housing estate to the edge required time, with respect in the conventional cellular network the user terminal of the highest translational speed 50km/h from the center of housing estate to the cell edge, approximately need about 7.2 seconds, setting is t=10 second for this section period in the soft cell-radio network of layering, has determined to adapt to the interior soft radius of society of soft cell layer of friction speed feature customer group thus.For the customer group of each velocity characteristic, generate a large number of users in the emulation, under two kinds of networks, each generation user is investigated 5 seconds respectively and see whether switch, thereby determine its switching probability.

Figure 10 drawn in two kinds of networks switching probability relatively, 10-1 represented the switching probability under the friction speed scene under the soft cell-radio network of layering, 10-2 has represented the switching probability under the friction speed scene under the conventional cellular network.

As seen from Figure 10 in the conventional cellular network, adopt the sub-district of fixed size, be applicable to the terminal that low speed moves, but along with the raising of the translational speed of portable terminal, switch load presents the trend of quick growth; And when adopting the soft cell-radio network of layering, the business of friction speed feature maintains in the acceptable level switch load of whole network by the soft cell layer services of the different sizes that are adapted to it all the time.

(5) cutting off rate analysis

Figure 11 has illustrated the The simulation experiment result of soft cell-radio network of layering and conventional cellular network cutting off rate to contrast.Suppose that the user arrives obedience Poisson and distributes, according to the arrival rate (λ of two kinds of networks _TraditionAnd λ _HSC) enter each automatic network at random.After the user produces, at first distribute one at interval [V for it _Li, V _Hi] (i=1,2 ..., 9,10) in equally distributed random number as its speed, V _Li=(i-1) * and 5km/h, V _Hi=i * 5km/h, and produce one at the moving direction of interval [0,2 π] interior equally distributed random number as portable terminal.Then, the random number of the exponential distribution of an obedience of generation parameter μ is as its air time.The enough usefulness of Radio Resource of hypothesis network in the emulation, and adopt the received signal power of shadow fading Model Calculation portable terminal,

For conventional cellular network, each user only communicates with a base station, when detecting received power P _r(d)＜P _rDuring _ threshold, switch, satisfy P if can not find in the process of switching _r(d) 〉=P _rDuring _ threshold base station, then think conversation loss; For the soft cell-radio network of layering, select 3 antennas in the sub-district is user's service at every turn, carries out incoherent merging from the received signal power of 3 antennas, if the received power P after merging _r＜P _rDuring _ threshold, carry out antenna and switch, satisfy P if can not find in the process of switching _r〉=P _rDuring _ threshold antenna, then think conversation loss.

Finish the back basis in emulation $P_{\mathrm{drop}}=\frac{N_{\mathrm{drop}\_\mathrm{handdoff}}}{N_{\mathrm{total}\_\mathrm{user}}}$ Obtain the cutting off rate of system, wherein N _{Drop_handoff}For the number of users of call drop, N take place _{Total_user}Be number of users total in the system.

Figure 11 drawn in two kinds of networks the call drop likelihood ratio, 11-1 represented the cutting off rate under the friction speed scene under the soft cell-radio network of layering, 11-2 has represented the cutting off rate under the friction speed scene under the conventional cellular network.Table 3 is soft cell-radio network of layering and conventional cellular network cutting off rate simulation parameter;

Table 3

From top description as can be seen, the soft cell-radio network of layering of the present invention is from the beehive net theoretical developments, but it is different with conventional cellular network.The sub-district cover to be to be covered by the single antenna signal and to be determined in the conventional cellular network, the single antenna signal cover with the sub-district cover be close-coupled together; And for the soft cell-radio network of layering, the single antenna signal covers just basis of signals, soft sub-district cover be by user terminal velocity characteristic determined, according to wireless resource allocation and occupation mode, use same Radio Resource work to form simultaneously by one or more antennas.The soft cell-radio network of layering has been removed the close-coupled relation between covering of single antenna signal and the covering of soft sub-district, thereby can use Radio Resource more effective and neatly, improve the overall performance of network, and can be adapted to business demand better according to the soft sub-district that the velocity characteristic of user terminal forms.

The covering of soft sub-district be by one or more adjacent antenna units separately useful signal cover synthesized, the total covering of signal in the space that antenna element in soft sub-district is transmitted to the mobile subscriber determined soft sub-district to cover, therefore user's mobile meeting makes in its coverage that is in different antennae, but because each antenna use is same Radio Resource, therefore moving among a small circle of user terminal makes it be in the different antenna footprints, but this can not cause the generation that Radio Resource that terminal is used switches; And the single antenna sub-district is adopted at the legacy cellular networking, and the signal of single antenna covers the sub-district that has determined cellular network and covers, and portable terminal is in when different antennas covers just must carry out the switching of Radio Resource.With respect to the sub-district of single antenna construction in the conventional cellular network, it is smooth that the soft cell-radio network of layering has the signal power plane, disturbs advantages such as low, handover load stable and controllable.

In addition, the hierarchy of the soft cell-radio network of layering also is different from the hierarchy in the conventional cellular network.Conventional cellular network is because the single antenna signal covers and the sub-district covering tightly is coupled, realize being adapted to the different big or small sub-districts of different business scene, just must adopt different antennas, therefore in the conventional cellular network, although the covering on the region of macrocell and Microcell is overlapping, but their covering is to realize that by antenna for base station separately this has just caused the raising of system hardware complexity and software complexity.As will carrying out the information interaction of macro cell base station and microcell base station when interlayer switches, and in the soft cell-radio network of layering, the switching of interlayer only need be handled with centralized system by the 2-1 of control centre, implements more convenient.

Consider present technology status and the technical development of the coming years, fixedly Planning Model is adopted in the design of the soft cell-radio network of layering, be that single soft sub-district is fixed on the region, not dynamic change of soft sub-district in the soft sub-district of each layer with the change of user terminal location, according to planning in advance, terminal need be carried out corresponding handoff operation when the soft moving between cells of difference.Because the size of soft sub-district and the velocity characteristic of portable terminal adapt at this moment, therefore within the scope that the expense of handover can the system of being controlled at can be born, this just when utilizing the soft subzone network of layering to obtain superperformance, has guaranteed system's realizability again and has handled complexity low.

Claims (28)

1, the soft cell-radio network of a kind of layering, it is characterized in that: it comprises:

Signal overlay planes (1-1), plane, soft sub-district (1-2) and business demand plane (1-3);

Described business demand plane (1-3) refers to the business demand under the various speed scenes that distribute on the region;

Described signal overlay planes (1-1) refers to by spaced antenna group (2-3) and covers by the seamless signal that the transmitting/receiving wireless signal forms;

According to moving velocity of terminal the user in the described business demand plane (1-3) is divided into the customer group that the K kind has the friction speed feature, wherein K 〉=1;

Corresponding above-mentioned K kind has the customer group of friction speed feature, forms the plane, soft sub-district (1-2) that comprises the soft sub-district of K layer;

Control centre (2-1) and spaced antenna group (2-3) carry out the signal transmission by transmission medium (2-2); Its connection control method is: when the some user terminals in the business demand plane have demand for services, control centre (2-1) at first obtains the moving speed estimation value of described terminal, then according to the mapping relations of moving velocity of terminal estimated value and soft cell layer, described terminal traffic demand is projected to corresponding soft cell layer, determine the concrete soft sub-district of inserting in the pairing soft cell layer according to terminal location again, the a certain channel resource allocation that last control centre (2-1) will insert in the soft sub-district is given described user terminal, and a plurality of antennas of controlling described soft sub-district simultaneously use described channel to provide service as terminal.

2, the soft cell-radio network of layering according to claim 1 is characterized in that:

Plane, described soft sub-district (1-2) is based upon on the basis of signal overlay planes (1-1), and control centre (2-1) gives the soft sub-district of each layer according to the quadrature distribution principle with allocation of radio resources, thereby forms overlapping on the region, the soft sub-district of non-interfering K layer.

3, the soft cell-radio network of layering according to claim 1 is characterized in that:

The soft sub-district of each layer in the soft sub-district of described K layer all is to be made of n soft sub-district, wherein n 〉=1.

4, the soft cell-radio network of layering according to claim 1 is characterized in that:

When having the customer group of friction speed feature, can evenly divide according to moving velocity of terminal division K kind.

5, the soft cell-radio network of layering according to claim 1 is characterized in that:

When having the customer group of friction speed feature, can carry out non-homogeneous division according to moving velocity of terminal division K kind.

6, the soft cell-radio network of layering according to claim 1 is characterized in that:

The business that described K kind is had the customer group of friction speed feature projects to suitable soft cell layer, and by corresponding soft sub-district in the soft sub-district of this layer it is served.

7, according to claim 1,4, the soft cell-radio network of 5 or 6 described layerings, it is characterized in that:

The customer group of described friction speed feature refers to the customer group of moving velocity of terminal in the friction speed scope.

8, the soft sub-district of layering according to claim 6 Wi-Fi is characterized in that:

Serve the higher customer group of moving velocity of terminal with the soft cell layer that constitutes than the soft sub-district of large tracts of land.

9, the soft cell-radio network of layering according to claim 6 is characterized in that:

Serve the lower customer group of moving velocity of terminal with the soft cell layer that constitutes than the soft sub-district of small size.

10, the soft cell-radio network of layering according to claim 1 is characterized in that:

Described control centre (2-1) finishes signal processing and the controlled function that signal post needs, and simultaneously the employed Radio Resource of spaced antenna group (2-3) under its linchpin is managed and unifies and dispatch.

11, the soft cell-radio network of layering according to claim 1 is characterized in that:

The control centre (2-1) of the soft cell-radio network of described layering can adopt the managing distributed antenna groups of centralized control mode (2-3).

12, according to the soft cell-radio network of the described layering of claim 1, it is characterized in that:

The control centre (2-1) of the soft cell-radio network of described layering can adopt the managing distributed antenna groups of distributed control mode (2-3).

13, the soft cell-radio network of layering according to claim 1 is characterized in that:

The control centre (2-1) of the soft cell-radio network of described layering can adopt the graduation managing distributed antenna groups of control mode (2-3).

14, the soft cell-radio network of layering according to claim 1 is characterized in that:

Described transmission medium (2-2) can be wireless optical fiber, millimeter wave, free space optical link media, also can be the mixed media that mixes above-mentioned multiple media.

15, the soft cell-radio network of layering according to claim 2 is characterized in that:

The method of salary distribution of described allocation of radio resources has fixed allocation, dynamic assignment and mixed ways of distribution.

16, the soft cell-radio network of layering according to claim 15 is characterized in that:

Described fixed allocation mode refers in planning mode in advance and gives each soft sub-district in the soft sub-district of each layer and the every layer of soft sub-district with whole usable radio resources fixed allocation.

17, the soft cell-radio network of layering according to claim 15 is characterized in that:

Described fixed allocation mode comprises the distribution of the soft minizone of each layer and the distribution two parts in every layer of soft sub-district, at first whole Radio Resources are divided into the K part according to the quadrature distribution principle, distribute to the soft sub-district of described K layer accordingly, be resource allocation methods for the distribution in every layer of soft sub-district then, the available resources of the soft sub-district of this layer are distributed to each soft sub-district in the soft sub-district of this layer according to conventional cellular network.

18, the soft cell-radio network of layering according to claim 15 is characterized in that:

Described fixed allocation mode is that the usable spectrum resource is divided into nonoverlapping K part, distribute to the soft sub-district of described K layer accordingly, finish the frequency division layering,, the frequency spectrum resource of distributing to each soft cell layer is further distributed to each soft sub-district in its layer then according to the frequency division multiple access principle.

19, the soft cell-radio network of layering according to claim 15 is characterized in that:

Described fixed allocation mode is that sheet sometime is divided into nonoverlapping K section, the operating time of certain one deck in the soft sub-district of corresponding described K layer of each section period, finish the time-division layering, then according to the principle of frequency division/time-division combination multi-access mode, the usable spectrum resource of each soft cell layer and time are further distributed to each soft sub-district in its layer.

20, the soft cell-radio network of layering according to claim 15 is characterized in that:

Described dynamic assignment mode refers to locates unified management with whole usable radio resources in control centre (2-1), carries out dynamically in the soft minizone of each layer, allocation of radio resources as required.

21, the soft cell-radio network of layering according to claim 15 is characterized in that:

Described mixed ways of distribution refer to a part of Radio Resource at first fixed allocation give each soft sub-district to be adapted to basic business demand, keep the business demand that a part of Radio Resource is used to happen suddenly in control centre (2-1) simultaneously, this part reservation of resource is carried out dynamic assignment, flexible dispatching between the soft sub-district of each layer.

22, the soft cell-radio network of layering according to claim 2 is characterized in that:

Described quadrature distributes and comprises: the compound mode of frequency division multiple access, time division multiple access, code division multiple access, OFDM and aforesaid way.

23, the soft cell-radio network of layering according to claim 3 is characterized in that:

Described soft sub-district refers to the overlay area of using same Radio Resource emission to form by antenna element adjacent on one or more regions.

24, the soft cell-radio network of layering according to claim 23 is characterized in that:

The radius of described soft cell coverage area and the shape of overlay area can be decided according to the velocity characteristic of portable terminal.

25, the soft cell-radio network of layering according to claim 24 is characterized in that:

The radius of described soft cell coverage area is that the velocity characteristic of the portable terminal supported according to described soft sub-district is determined.

26, the soft cell-radio network of layering according to claim 24 is characterized in that:

The shape of described soft cell coverage area is by the translational speed decision of portable terminal in all directions.

27, the soft cell-radio network of layering according to claim 1 is characterized in that:

The moving speed estimation value of described terminal can be passed through control centre (2-1) and measure estimation, also can measure by terminal self and estimate.

28, the soft cell-radio network of layering according to claim 1 is characterized in that:

In the process that a plurality of antennas in the described soft sub-district and described user terminal communicate, all antennas of corresponding soft sub-district needn't be in state of activation simultaneously, control centre (2-1) can disturb principle according to reducing according to the geographical position at terminal place, and some antenna of controlling soft sub-district selectively is described subscriber terminal service.

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