CN103139800A

CN103139800A - Node adjustment method, device and system of relay cellular network

Info

Publication number: CN103139800A
Application number: CN2011103986451A
Authority: CN
Inventors: 张天魁; 杨星; 冯春燕; 栗忠峰
Original assignee: Huawei Technologies Co Ltd; Beijing University of Posts and Telecommunications
Current assignee: Huawei Technologies Co Ltd; Beijing University of Posts and Telecommunications
Priority date: 2011-12-05
Filing date: 2011-12-05
Publication date: 2013-06-05

Abstract

The invention discloses a node adjustment method, a device and a system of a relay cellular network, and belongs to the field of communication. The node adjustment method, the device and the system comprise the following steps: after a node is selected and the relay cellular network is accessed to a user terminal according to channel quality, if a channel quality indicator value of the user terminal is smaller than a preset threshold value, jamming intensity of jamming caused on the user terminal from each jamming node causing jamming on accessed nodes of the user terminal in the relay cellular network is calculated; according to the jamming intensity, a jamming node which causes the largest jamming on the user terminal and is not transferred from the user terminal during adjustment is selected from jamming nodes; and the number of the user terminal served by the jamming node is adjusted until the channel quality indicator value of the user terminal is larger than or equal to the preset threshold value or each jamming node is transferred from one user terminal. Calculated quantity and feedback quantity can be small, main interference sources can be found out for adjusting, a resource utilization rate is improved, and same frequency interference in a system can be restrained effectively.

Description

Node adjustment method, device and system of relay cellular network

Technical Field

The present invention relates to the field of communications, and in particular, to a method, an apparatus, and a system for adjusting a node of a relay cellular network of the relay cellular network.

Background

In a new generation of wireless communication system, a RN (Relay Node) can be configured as a new Node into a conventional cellular network to form a Relay cellular network, so as to improve cell edge user performance, expand cell coverage and improve system capacity. In the relay cellular network, there are not only BS (Base Station) and UE (User Equipment) nodes existing in the conventional cellular network, but also RNs, in addition to direct links between the BS and the UE, relay links, that is, links between the BS and the RN, and access links, that is, links between the RN and the UE in the network. In the relay cellular network, a user selecting the RN as an access point is called a relay user, and a user selecting the BS as a data access node is called a direct user. Introduction of RNs can introduce more complex co-channel interference within and between cells than conventional cellular networks, including co-channel interference that may exist between RN-UE links and BS-UE links, as well as between different RN-UE links.

In the prior art, a method for coordinating interference between cells in a wireless communication network with a relay station is provided, which includes interference coordination between a base station and a relay, and the method includes the steps of dividing a cell coverage area into three layers, namely an inner layer, a transition layer and an outer layer, selecting a limited interference source in each area, layering the cells to which the limited interference sources belong, setting a resource reservation allocation mode, a service quality priority number and a path loss compensation factor, and finally determining and adjusting power according to interference signal strength to achieve the purpose of interference suppression. However, when selecting the limited interference source of the user, the method needs to measure the interference of the BS and the RN in all the neighboring cells to determine the interference source with larger interference, and has the disadvantages of large calculation amount, large feedback amount and reduced utilization rate of system resources.

Disclosure of Invention

The embodiment of the invention provides a node adjusting method, a device and a system of a relay cellular network, which can efficiently select relay nodes and realize the suppression of co-channel interference in the relay cellular network.

In one aspect, an embodiment of the present invention provides a node adjustment method for a relay cellular network, where the method includes:

after a user terminal selects a node according to channel quality to access a relay cellular network, if a channel quality indicated value of the user terminal is smaller than a preset threshold value, calculating the interference strength of interference caused by each interference node which causes interference to the node accessed by the user terminal in all nodes of the relay cellular network to the user terminal;

and selecting the interference nodes which cause the maximum interference to the user terminal and are not tuned away from the user terminal in the adjustment from the interference nodes according to the interference strength, and adjusting the number of the user terminals served by the interference nodes until the channel quality indicated value of the user terminal is higher than or equal to a preset threshold value or each interference node is tuned away from one user terminal.

In another aspect, an embodiment of the present invention further provides a node adjustment apparatus for a relay cellular network, where the apparatus includes:

the device comprises a data transmission unit, a main control processing unit and an adjusting unit; wherein,

the data transmission unit is used for receiving a channel quality indicated value measured by the user terminal and fed back by the user terminal;

the main control processing unit is configured to calculate, when it is determined that the channel quality indication value fed back by the user terminal and received by the data transmission unit is smaller than a preset threshold value, interference strength of interference caused by each interference node causing interference to the user terminal, where the interference is caused by a node to which the user terminal is accessed, in the relay cellular network; selecting the interference node which causes the largest interference to the user terminal and has not been tuned away from the user terminal in the adjustment from the interference nodes according to the interference strength, and sending an adjustment instruction for adjusting the number of the user terminals served by the selected interference node to the adjustment unit;

and the adjusting unit is used for adjusting the number of the user terminals served by the interference nodes selected by the main control processing unit after receiving the adjusting instruction of the main control processing unit until the channel quality indicating value of the user terminal is higher than or equal to a preset threshold value or each interference node is separated from one user terminal.

In yet another aspect, an embodiment of the present invention further provides a communication system, including: the node adjusting device of the relay cellular network is communicatively connected to the base station or the relay node.

It can be seen from the above technical solutions that, in the embodiment of the present invention, after a user terminal accesses a node selected according to channel quality, if a channel quality indicated value of the user terminal is smaller than a preset threshold value, an interference strength of interference caused by each interference node causing interference to the node accessed by the user terminal among all nodes of the relay cellular network is calculated, and then a node with the largest interference is found according to the interference strength to adjust the number of user terminals served by the node, thereby realizing suppression of co-frequency interference in the relay cellular network. The method can find out the main interference source for adjustment by reducing the calculated amount and the feedback amount, effectively inhibit the same frequency interference in the relay cellular network system on the premise of improving the utilization rate of system resources, and ensure the communication quality. The method solves the problems that in the existing method for selecting the relay node for inhibiting the same frequency interference in the relay cellular network, when the interference source of a user is selected, the interference of BS and RN in all adjacent cells needs to be measured to judge the interference source with larger interference, the calculated amount and the feedback amount are large, and the utilization rate of system resources is low.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.

Fig. 1 is a flowchart of an adjustment method of a relay cellular network according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a relay cellular network provided in an embodiment of the present invention;

fig. 3 is a diagram illustrating a transparent frame format in a relay cellular network according to an embodiment of the present invention;

fig. 4 is a diagram illustrating a non-transparent frame format in a relay cellular network according to an embodiment of the present invention;

fig. 5 is another flowchart illustrating a node adjustment method of a relay cellular network according to an embodiment of the present invention;

fig. 6 is a schematic diagram of relay interference in a relay cellular network according to an embodiment of the present invention;

fig. 7 is a schematic diagram of a node adjustment apparatus of a relay cellular network according to an embodiment of the present invention;

fig. 8 is a schematic diagram of a node adjustment system of a relay cellular network according to an embodiment of the present invention.

Detailed Description

The technical solutions in the present invention are clearly and completely described below with reference to specific embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

The following describes embodiments of the present invention in further detail.

Example 1

The present embodiment provides a method for adjusting a node of a relay cellular network, which can adjust the node of the relay cellular network through a smaller calculation amount and a smaller feedback amount, so as to efficiently suppress co-channel interference in a system, and the method includes:

after a user terminal accesses a relay cellular network according to a Channel Quality selection node, if a Channel Quality Indicator (CQI) of the user terminal is smaller than a preset threshold, a node adjustment device of the relay cellular network calculates interference strength of interference caused by each interference node causing interference to the user terminal, where the interference is caused by the node accessed by the user terminal, in the relay cellular network. In the embodiment of the present invention, the node adjusting apparatus may be a home register similar to an HLR in a relay cellular network, or may be a physical entity in a base station, etc.

The node adjusting device may select, according to the interference strength, an interference node that causes the largest interference to the user terminal and that has not been tuned away from the user terminal in the current adjustment from the interference nodes, adjust the number of user terminals served by the interference node, and continuously circulate the process until the channel quality indication value of the user terminal is higher than or equal to a preset threshold value or the interference nodes have been tuned away from one user terminal, indicating that the interference cannot be further reduced, after the circulation process, all the interference nodes are tuned away from one user terminal, so that the current adjustment is ended.

The flow of the above method is specifically shown in fig. 1, and the method can be applied to a relay cellular network, and includes the following steps:

step 1, after a user terminal UE accesses a relay cellular network according to a channel quality selection node, if a channel quality indicated value of the user terminal is smaller than a preset threshold value, step 2 is carried out;

the node selected in step 1 may be a base station BS or a relay node RN.

Step 2, a node adjusting device of the relay cellular network calculates the interference strength of interference caused by each interference node which causes interference to a node accessed by the user terminal in the relay cellular network to the user terminal; then step 3 is carried out;

step 3, the node adjusting device of the relay cellular network selects the interference node which causes the largest interference to the user terminal and has not tuned away the user terminal in the adjustment from all the interference nodes according to the interference intensity; then, carrying out step 4;

step 4, the node adjusting device of the relay cellular network adjusts the number of the user terminals served by the interference node; then, carrying out step 5;

step 5, the node adjusting device of the relay cellular network judges whether the channel quality indicated value of the user terminal is higher than or equal to a preset threshold value or each interference node is separated from one user terminal, if yes, step 6 is executed; if not, executing the step 3;

and 6, finishing the adjustment.

In step 1 of the method, the ue may select a sending node with the largest Signal to Interference plus Noise Ratio (SINR) from nodes in the relay cellular network as an access node for accessing. The mode of selecting a certain node to access according to the channel quality not only considers all attenuation factors of signals in the transmission process, but also considers the influence of noise and interference, can solve the influence of random factors such as shadow fading, small-scale fading and the like on the system performance, and cannot influence the system performance in the actual communication environment.

In step 1 of the method, after the user equipment selects the node for access, the measured channel quality indicated value is compared with a preset threshold value, and if the measured channel quality indicated value is smaller than the preset threshold value, the channel quality indicated value is fed back to the relay cellular network system.

It can be known that, in practice, when accessing the relay cellular network, the user terminal may select a node closest to the relay cellular network from the nodes of the relay cellular network as an access point for accessing.

In step 2 of the method, the finding out an interfering node causing interference to a node to which the user terminal is accessed may include:

step 21, finding out effective nodes which can cause effective interference from all nodes of the relay cellular network;

step 22, determining each interference node causing interference to the node accessed by the user terminal from each effective node according to the topological relation between the node accessed by the user terminal and each effective node.

In the step 21, finding out effective nodes that can cause effective interference with each other from all nodes of the relay cellular network by the following method includes:

forming a relay interference matrix M of R multiplied by R according to the number R of all relay nodes in the relay cellular network, so as to relay the node RN_iAnd RN_jAs element w of the relay interference matrix M_ij(ii) a Wherein RN_iAnd RN_jThe large scale interference value between is the relay node RN_iReceiving a Relay node RN_jA power value of the transmission signal;

element w in relay interference matrix M_iiSet to 0; w if the relay nodes of the same sector k in the relay cellular network share the spectrum resource_ij＝0(i，j∈e_k) Wherein e is_kIs the set of relay nodes in sector k. W if the spectrum resources are multiplexed among the relay nodes of the same sector k in the relay cellular network_ij≠0(i，j∈e_k) Wherein e is_kIs a set of relay nodes in sector k; elements w which are not equal to 0 and are smaller than a preset interference threshold eta in the relay interference matrix M_ijSetting the element w to be 0, wherein the element w is not equal to 0 and is greater than or equal to a preset interference threshold eta_ijIs set to 1;

the elements w which are not equal to 0 in the relay interference matrix M are obtained_ijCorresponding relay node RN_i、RN_jAnd determining as the effective interference node.

In step 22, determining, from the effective nodes, each interference node causing interference to the node to which the user terminal is accessed according to the topological relationship between the node to which the user terminal is accessed and each effective node may be:

finding out each element of a row corresponding to a node accessed by the user terminal in the relay interference matrix M;

and each relay node corresponding to the element with the nonzero element value in the elements is determined as an interference node which causes interference to the node accessed by the user terminal.

In the above method, the calculating the interference strength of the interference caused by each interference node to the ue z may include:

when the relay resource in the sector is allocated as the shared spectrum resource, the interference strength I of the user terminal interfered by each interference node is calculated by adopting the following formula 1_jzWherein the user terminal is represented by z:

I_{jz} = \frac{\min {\frac{\underset{x &Element; U_{j}}{Σ} d (x)}{b_{j}}, \frac{d (z)}{s_{z}}} \times \frac{m_{j}}{n_{j}} H_{jz} p_{j}}{\frac{d (z)}{s_{z}}}

formula 1;

in the above formula 1, the parameters respectively represent: i is_jzFor normalized interference, U, caused by relay node j to user terminal z_jSet of relay users served by relay node j, b_jAverage rate of data transmission for relay node j, d (z) data demand for user terminal z, s_zAverage rate of data reception, m, for user terminal z_jNumber of user terminals served by relay node j, n_jThe total number of relay users sharing channel resources with the user terminal served by the relay node j; wherein, when the relay nodes in the same sector share the channel resource,

e_ka relay node set in a sector k; when multiplexing channel resources between relay nodes of the same sector, n_j＝m_j，H_jzFor large scale channel fading coefficient, p, from relay node j to user terminal z_jIs the transmit power of the relay node j;

or, when the relay resource in the sector is allocated as the multiplexing spectrum resource, the following formula 2 may be adopted to calculate the interference strength I of the interference caused by each interference node on the user terminal_jzWherein the user terminal is represented by z:

I_{jz} = \frac{\min {\frac{\underset{x &Element; U_{j}}{Σ} d (x)}{b_{j}}, \frac{d (z)}{s_{z}}} H_{jz} p}{\frac{d (z)}{s_{z}}}

formula 2;

in the above formula 2, each parameter represents: i is_jzFor normalized interference, U, caused by relay node j to user terminal z_jSet of relay users served by relay node j, b_jAverage rate of data transmission for relay node j, d (z) data demand for user terminal z, s_zAverage rate of data reception, m, for user terminal z_jNumber of relay users served by relay node j, n_jTotal number of relay users sharing channel resources with relay users served by relay node j, H_jzLarge scale channel fading coefficient, p, for relaying j to user terminal z_jIs the transmit power of the relay node j.

In the above method, selecting, according to the interference strength, an interference node from the interference nodes that causes the largest interference to the ue and has not tuned away from the ue in the current adjustment, and adjusting the number of ues served by the interference node until the channel quality indication value of the ue is higher than or equal to a preset threshold value or each interference node has tuned away from one ue includes:

selecting an interference node which causes the largest interference to the user terminal and has not been tuned away by one user terminal in the adjustment from all the interference nodes according to the interference strength, and adjusting the number of the user terminals served by the interference node; the adjustment mode can be as follows: if the relay cellular network adopts a transparent frame format, changing the access mode of a user terminal closest to a base station in a user terminal served by the interference node (at this moment, the interference node can be a relay node) into a direct connection access mode, namely changing the user terminal originally accessed into the relay node into the base station closest to the base station, and enabling the channel quality indicated value of the adjusted user terminal to be not less than the set ratio compared with the value before adjustment; if the channel quality indicated value of the user terminal before adjustment is 50 and the set ratio is 0.5, the channel quality indicated value of the user terminal after adjustment should not be less than 25;

if the relay cellular network adopts a non-transparent frame format, the access mode of the user terminal closest to the relay node in the direct connection user terminals served by the interference node (at this time, the interference node can be a base station) is changed into a relay access mode, that is, a certain user terminal originally accessed to the base station is changed into the relay node closest to the user terminal.

And ending the adjustment until the channel quality indicated value of the user terminal is higher than or equal to a preset threshold value or each interference node is separated from one user terminal.

In the adjusting method, the interference strength causing interference to the user terminal is calculated only according to the effective interference nodes, the node with the maximum interference is found out, and the number of the user terminals served by the node with the maximum interference is adjusted, so that the same frequency interference in the relay cellular network is suppressed. The method can find out the main interference source for adjustment with smaller calculated amount and feedback amount, improves the utilization rate of resources, effectively inhibits the same frequency interference in the relay cellular network, and ensures the communication quality of the relay cellular network.

The above method is further explained in connection with the adjustment procedure of the relay node in the relay cellular network:

the adjusting method according to the embodiment of the present invention may be applied to a relay cellular network, for example, the relay cellular network having the network topology shown in fig. 2, where the relay cellular network shown in fig. 2 may have 3 sectors per cell, a dotted line in fig. 2 indicates a boundary of 3 sectors in each cell, and a multiplexing spectrum resource is used between sectors. The base station BS is located in the center of the cell, and sector antennas are used for transmitting data for the direct connection user terminal and the relay node RN respectively. The relay nodes RN in each sector are distributed at the edge of the sector, and serve relay user terminals around the relay nodes RN by using omnidirectional antennas. In the relay cellular system, a transparent frame format shown in fig. 3 may be generally adopted, in the transparent frame format, one subframe (with a length of T) is divided into two equal-length time slots, in time slot 1, there are BS-UE and BS-RN links, and the BS sends information to the UE and the RN respectively, and in time slot 2, there is an RN-UE link, and the RN sends information to the UE. The non-transparent frame format shown in fig. 4 is different from the transparent frame format shown in fig. 3 in that a BS-UE link exists in addition to the RN-UE link in the time slot 2, so that the relay user terminal is interfered not only by the RN but also by the BS.

And in order to meet higher requirements on spectrum efficiency, the reuse degree of frequency resources in the relay cellular network is also tighter, for example: the UE receiving the BS signal with higher SINR will be directly communicated with the BS as a direct-connected UE, and the link quality between the relay and the base station is usually better, so that frequency reuse can be performed between sectors on the BS-UE link and on the BS-RN link, but this will also make the above interference situation worse.

It can be appreciated that the adjustment method of the embodiment of the present invention can also be applied to a relay cellular network that divides multiple sectors (e.g., 4 sectors, 5 sectors, or more sectors) per cell.

The steps for adjusting the node of the relay cellular network by using the method of the embodiment of the present invention are described as follows, the relay cellular network may adopt the transparent frame format shown in fig. 3, and only the RN-UE link exists in the timeslot 2, so the relay user terminal is only interfered by the relay node RN, and the flow of the method is shown in fig. 5:

step 101, performing relay selection based on SINR for each user terminal:

after a user terminal selects a node with good channel condition from nodes of a relay cellular network to access, if a channel quality indicated value of the user terminal is smaller than a preset threshold value, feeding back the channel quality indicated value of the user terminal to the relay cellular network;

the user terminal can select a node with better channel condition (generally selecting a node with the maximum SINR) to access according to the signal-to-interference-and-noise ratio (SINR), and provides the service data requirement information of the user terminal to the respective accessed node;

step 102, finding out each interference node causing effective interference to the node accessed by the user terminal UE:

the relay interference matrix can be established according to the relay cellular network topological structure, and can be established in advance or only established once during the first adjustment, and then can be used repeatedly, and is not required to be established every time of adjustment. The relay interference matrix takes a large-scale interference value among the relay nodes RN as an element, and represents the interference relationship among the relay nodes RN in the relay interference matrix through the relay interference matrix so as to determine the range of the relay user terminal subjected to effective relay interference; therefore, effective nodes which cause interference among all nodes can be conveniently found out through the relay interference matrix, and interference nodes which cause effective interference on nodes accessed by the user terminal can be found out;

the basis for establishing the relay interference matrix is as follows: because the transmission power of the relay node RN is relatively low, the user terminals (i.e., relay users) served by the relay node RN are generally concentrated near the relay node RN; the distribution characteristics of the relay nodes RN and the user terminals determine that the distance between the user terminal and its access RN is much smaller than the distance between RNs (as shown in fig. 6, the distance between RN1 and U1 is much smaller than the distance between RN1 and RN 2), so that the interference to the RN set accessed by a certain user terminal is large, the interference to this user terminal is also large, and the interference generated by some relay nodes due to the longer distance is small and negligible. Therefore, when calculating the interference suffered by the user terminal and searching the RN with larger interference to the user terminal, only the RN set with larger interference to the access RN of the user terminal is needed to be searched, so that the complexity is reduced and the feedback quantity is reduced when searching the main interference source.

The method for establishing the relay interference matrix may be:

(1) establishing a relay interference matrix M of R multiplied by R according to the number R of all relay nodes in the relay cellular network, wherein R is the total number of RNs in the system; element w in the matrix_ijIs a large scale interference value between RNi and j, where w_ii0. If the spectrum resource is shared between RNs of the same sector, w_ij＝0(i，j∈e_k) Wherein e is_kIs the set of RNs in sector k; w if the spectrum resources are multiplexed between RNs in the same sector_ij≠0(i，j∈e_k)；

(2) Interference exists among all RNs in the system, the interference generated by some RNs is very small, and in order to reduce the complexity of an algorithm, an interference threshold eta can be defined, and only the interference which is not less than eta is considered, so that the relay interference is called as effective relay interference; changing the element smaller than eta in the relay interference matrix M into 0; the other elements are changed to 1;

if w is_ijNot equal to 0, the relay nodes i, j are called effective interference relay nodes of the other side, so that all effective interference nodes in the relay cellular network can be found out; for relay node i, defining the set of its interfering relay nodes as R_i＝{j}，w_ijNot equal to 0, the number of interfering relays owned by each relay node is called interference degree, the value of the interference degree is the number of nonzero elements of a corresponding row in the relay interference matrix M, and the interference degree is a nonnegative integer.

Step 103, calculating whether the CQI of the user terminal z is smaller than a set CQI threshold value θ by using a relay interference function, if so, executing step 104, and if not, executing step 105:

and calculating a channel quality indication value of the user terminal, wherein the user terminal can be represented by z, and an interference node causing the maximum interference to the user terminal z can be found out, so that the interference is suppressed by coordinating the interference between cells and utilizing the coordination management and use limit of resources.

The relay interference function can give the relation between the interference generated by the relay and the number of the user terminals (namely relay users), so that the probability of overlapping the channel frequency of a strong interference source and the channel frequency of the relay users can be reduced by controlling the number of the user terminals, and the purpose of inhibiting the relay interference is achieved. The relay interference function may be derived from: in the relay node selection, in order to achieve the purpose of suppressing the relay interference, a relationship between the relay node selection and the interference strength generated by the relay node is represented, a proportional fair scheduling algorithm is adopted for channel allocation of user terminals (namely, relay users), and the probability that each user terminal (namely, relay user) is allocated to a certain channel in the user terminals (namely, relay users) sharing the same spectrum resources is equal, so that the probability that each relay node RN occupies the certain channel is related to the number of user terminals served by the relay node RN.

The process of deriving the relay interference function may be as follows:

in the relay cellular network, the number of user terminals (i.e., relay users) served by a node RNj in a sector k is set to m_jThe total number of the user terminals sharing the channel resource with the user terminal (i.e. relay user) served by RNj is n_jThen the probability that RNj of sector k transmits data on one channel is

Wherein, when the relay nodes in the same sector k share the channel resource,when channel resources are multiplexed between RNs of the same sector k, n_j＝m_j；

Assuming that all RNs adopt equal-power transmission, and the transmission power on each channel is p; for user terminal z at RNi, the effective relay interference it experiences comes from R_iWherein for

The probability that RNj transmits data on a certain channel is

Channel gain from RNj to user terminal z is H_jz(ii) a RNi, the intensity of RNj experienced by a user terminal z on a single channel is H_jzThe probability of interference of p is:

{PI}_{jz} (m_{j}) = \frac{m_{j}}{n_{j}} H_{jz} p

formula A

PI of the above formula A_jzThe probability that the user terminal z is interfered by the node RNj is characterized. The strength of the interference generated by the node RN may also be related to the operating time of the interfering relay and the interfered user terminal, and the interference may only occur when the interfering relay and the interfered user terminal operate simultaneously. The persistent interference strength of the node RN is thus defined as: the probability of the interference strength generated by the RN on a certain channel is multiplied by the working time of the RN and the interfered user terminal on the channel; the continuous interference strength can reflect the relay interference effect in the actual relay cellular network, and the interference generated by the node RN is more reasonable to evaluate.

The user takes into account the limited data requirements of the userThe data amount required by the terminal x is d (x), and the total data amount required to be sent by the node RNj is

Wherein U is_jRepresenting the set of user terminals served by RNj. The operating time of the user terminal z is

Wherein s is_zFor the data reception rate of the user terminal z,

the large-scale SINR obtained for user terminal z access node RNi. If the rate of sending information to the node RNj by the base station is b_jIf the data transmission rates of the two hops of the node RN are equal, the duration of the information sent by the node RNj is equal to

Therefore, the working time of the node RNj and the user terminal z is:

T_{jz} = \min {T_{j}, T_{i}} = \min {\frac{\underset{x &Element; U_{j}}{Σ} d (x)}{b_{j}}, \frac{d (z)}{s_{z}}}

the continuous interference strength of the node RNj to the user terminal z is:

{LI}_{jz} = T_{jz} \times {PI}_{jz} = \min {\frac{\underset{x &Element; U_{j}}{Σ} d (x)}{b_{j}}, \frac{d (z)}{s_{z}}} \times \frac{m_{j}}{n_{j}} H_{jz} p

in calculating the CQI of the interfered user terminal z, LI is calculated_jzNormalizing the working time of the user terminal to obtain the normalized interference intensity of the node RNj suffered by the user terminal z:

I_{jz} = \frac{{LI}_{jz}}{T_{z}} = \frac{\min {\frac{\underset{x &Element; U_{j}}{Σ} d (x)}{b_{j}}, \frac{d (z)}{s_{z}}} \times \frac{m_{j}}{n_{j}} H_{jz} p}{\frac{d (z)}{s_{z}}}

formula B

The sum of the sustained interference strengths generated by the nodes RNj is:

{LI}_{j} = \underset{i &Element; R_{j}, z &Element; U_{i}}{Σ} {LI}_{jz} = \underset{i &Element; R_{j}, z &Element; U_{i}}{Σ} \min {\frac{\underset{x &Element; U_{j}}{Σ} d (x)}{b_{j}}, \frac{d (z)}{s_{z}}} \times \frac{m_{i}}{n_{j}} H_{jz} p

formula C

If for

If d (x) d (y) q, that is, the data requirement of all the user terminals (i.e., relay users) is equal, the node RN_jWith the user terminal z having a common working time of

The three equations A, B, C function above are reduced to:

{LI}_{jz} = T_{jz} \times {PI}_{jz} = \min {\frac{m_{j}}{b_{j}}, \frac{q}{s_{z}}} \times \frac{m_{j}}{n_{j}} H_{jz} pq

formula A1

I_{jz} = \frac{{LI}_{jz}}{T_{i}} = \min {\frac{m_{j}}{b_{j}}, \frac{1}{s_{z}}} \times \frac{m_{j}}{n_{j}} H_{jz} {ps}_{z}

Formula B1

{LI}_{j} = \underset{i &Element; R_{j}, z &Element; U_{i}}{Σ} {LI}_{jz} = \underset{i &Element; R_{j}, z &Element; U_{i}}{Σ} \min {\frac{m_{j}}{b_{j}}, \frac{1}{s_{z}}} \times \frac{m_{j}}{n_{j}} H_{jz} pq

Formula C1

According to the relay interference matrix established in the step 102, an interference relay set is provided for the access node RN of each user terminal (namely, a relay user), and when the relay resource in the sector is allocated as a shared spectrum resource, the interference of the node RN in the interference relay set on the user terminal is calculated by adopting the formula B (namely, an interference function); when the relay resource in the sector is allocated as the multiplexing spectrum resource, the formula C1 (i.e. interference function) is used to calculate the interference of the node RN in the interfering relay set on the ue, and further calculate the CQI.

In order to ensure the performance of the user, in the embodiment of the present invention, a CQI threshold θ of the user terminal (i.e., a relay user) may be set, and if the CQI of the user terminal z of the node RNi is smaller than the set CQI threshold θ, which indicates that the interference is too large, the interfering node needs to be adjusted.

Step 104, adjusting the number of user terminals served by the interference node, and reducing the interference suffered by the user terminal z;

for the transparent frame format, if the relay node accessed by the user terminal z smaller than the set CQI threshold value theta is RNi, finding each interference node R according to the relay interference matrix and the relay interference function_iThe number of the served user terminals is adjusted by the relay interference node RNj which has the maximum normalized interference to the user terminal z and has not been tuned away from the user terminal; the node RNs in the same sector share or multiplex the whole frequency band, because only the RN-UE link exists in the 2 nd time slot, the access mode of the user closest to the base station in the relay user terminal served by the RNj can be changed into a direct connection access mode, and meanwhile, in order to ensure the performance of the adjusted user, the adjustment can be carried out only when the ratio of the adjusted channel SINR to the channel SINR before the adjustment is not less than a certain ratio. The result of such an adjustment is a reduction in the number of relay user terminals served by the interfering relay, and a reduction in m according to the relay interference function_j、n_j、

And the parameters are equal, so that the continuous interference strength of the interference relay node to the user terminal can be reduced.

In step 105, if the adjustment termination condition is satisfied, the current adjustment is terminated if the adjustment termination condition is satisfied, and if the adjustment termination condition is not satisfied, the number of the user terminal Z is incremented by one (that is, Z is Z +1, which indicates that the next user terminal is to be processed), and the process returns to step 103.

In order to prevent the ue of a relay node from being adjusted too much and seriously degrading the system performance, each relay node RN may be limited to tune away only one ue (i.e. a relay user). Therefore, the end condition of the adjustment method may be: the CQI of all the user terminals is higher than a set threshold value theta or all the adjustable relay nodes are adjusted away from one user terminal.

Example 2

This embodiment provides a node adjustment method for a relay cellular network, which is basically the same as the adjustment method provided in embodiment 1 above, except that the method may be used in a relay cellular network that uses a non-transparent frame format, and the method may include:

step 201 is the same as step 101 shown in fig. 5 given in example 1, see example 1 and fig. 5;

step 202, finding out each interference node causing effective interference to a node accessed by User Equipment (UE);

in a relay cellular network adopting a non-transparent frame format, an RN-UE link and a BS-UE link exist in a time slot 2 at the same time, a relay user can be interfered by a base station except for a relay, and the main interference suffered by the relay user at the moment is the interference from the base station because the transmission power of the base station is far greater than that of the relay, so that the base station relay interference matrix needs to be introduced under the condition;

the base station relay interference matrix is a matrix which takes a large-scale interference value between the BS and the RN as an element and represents the interference relationship between the BS and the RN for determiningTo the extent that the relay user is subject to effective base station interference. The establishment process is similar to the establishment process of the relay interference matrix, and a BxR base station relay interference matrix BM is established by using all base station numbers B and all relay node numbers R in a relay cellular network, wherein the element is bw_ij；

If bw_biNot equal to 0, then BS_bThe interfering base stations, called relay nodes RNi, are defined as the set of interfering base stations R for relay node RNi_i＝{b}，w_biNot equal to 0. The number of interfering base stations owned by each relay node is called interference degree, the value of the interference degree is the number of non-zero elements of a corresponding row in a base station relay interference matrix BM, and the interference degree is a non-negative integer.

Step 203: calculating the CQI of the relay user by utilizing a relay interference function;

calculating the interference strength of the base station to the relay user by using the relay interference function given in the embodiment 1, thereby finding out the base station causing the maximum interference to the relay user terminal;

step 204: adjusting the number of the found user terminals of the base station causing interference to the user terminals;

for the non-transparent frame format, there is a BS-UE link in addition to the RN-UE link in the 2 nd slot; therefore, corresponding improvements are also made for the adjustment method of the interference source, and the specific method is as follows: if the relay node accessed by the relay user terminal which is smaller than the set CQI threshold value is RNi, finding the interference base station b with the maximum normalized interference to the relay user terminal according to the relay interference matrix of the base station, and adjusting the number of the direct connection user terminals served by the interference base station b: finding BS_bA user terminal u closest to a relay node in the same sector in the served direct-connection user terminals is accessed through the relay node RNj instead if the relay node closest to the user terminal u is RNj; meanwhile, in order to ensure the performance of the adjusted user terminal, the adjustment is performed only when the ratio of the adjusted channel SINR to the SINR before the adjustment is not less than a certain ratio.

Step 205: judging whether the finishing condition is met, if so, finishing the adjustment, and if not, returning to the step 203;

in order to prevent the system performance from being seriously degraded due to excessive adjustment of the ue, each relay node RN is limited to only tune into one relay ue, and therefore, the end condition of the adjustment method is: the CQI of all relay user terminals is above a set threshold or all adjustable relay nodes have been tuned in to one user terminal.

The method of the embodiment can also realize that the problem of the interference of the relay user terminal caused by the base station is effectively solved with smaller calculated amount and feedback amount, the utilization rate of system resources is improved, and the communication quality of the relay cellular network is ensured.

Example 3

The present embodiment provides a node adjustment apparatus for a relay cellular network, which can be used in the relay cellular network to adjust a node and suppress co-channel interference in the relay cellular network. The apparatus may be used to implement the method provided by the above-mentioned embodiment of the present invention, as shown in fig. 7, the apparatus includes: a data transmission unit 31, a main control processing unit 32 and an adjustment unit 33;

the data transmission unit 31 is connected to the main control processing unit 32, and is configured to receive a channel quality indication value measured by the user terminal, which is fed back by the user terminal;

a main control processing unit 32, respectively connected to the data transmission unit 31 and the adjustment unit 33, configured to calculate, when it is determined that the channel quality indication value fed back by the user terminal and received by the data transmission unit 31 is smaller than a preset threshold value, interference strength of interference caused by each interference node, which causes interference to a node to which the user terminal is accessed, in all nodes of the relay cellular network to the user terminal; selecting the interference node which causes the largest interference to the user terminal and has not been tuned away from the user terminal in the adjustment from the interference nodes according to the interference strength, and sending an adjustment instruction for adjusting the selected interference node to the adjustment unit;

an adjusting unit 33, connected to the main control processing unit 32, configured to adjust the number of the user terminals served by the interference node selected by the main control processing unit after receiving the adjustment instruction of the main control processing unit until the channel quality indication value of the user terminal is higher than or equal to a preset threshold value or each interference node has adjusted (tuned away or tuned in) one user terminal.

As shown in fig. 7, the main control processing unit 32 in the above apparatus may include: an obtaining module 321, a channel quality indicator value calculating module 322, a judgment processing module 323 and a comparison processing module 324;

the obtaining module 321 is connected to the channel quality indicator value calculating module 322, and configured to obtain each interference node that causes interference to a node to which the user terminal is accessed, from among all nodes of the relay cellular network;

the judgment processing module 323 is connected to the channel quality indication value calculation module 322, and is configured to judge whether a channel quality indication value fed back by the user terminal and received by the data transmission unit 31 is smaller than a preset threshold value, and if so, send an instruction to the channel quality indication value calculation module 322;

the channel quality indication value calculating module 322 is connected to the comparing and processing module 324, and configured to calculate, after receiving the instruction sent by the determining and processing module 323, interference strength of interference caused by each interference node to the user terminal according to each interference node which is acquired by the acquiring module 321 and causes interference to a node to which the user terminal is accessed;

a comparing and processing module 324, configured to select, according to the interference strength of the interference caused by each interference node to the ue, which is calculated by the channel quality indication value calculating module 322, an interference node which causes the largest interference to the ue and has not been tuned away from the ue in the current adjustment from the interference nodes, and send an adjustment instruction for adjusting the selected interference node to the adjusting unit 33.

The main control processing unit 32 may further include: an effective node obtaining module 325, configured to find out, from all nodes of the relay cellular network, effective nodes that may cause effective interference with each other. The valid node obtaining module 325 may specifically find each valid node causing interference from all nodes of the relay cellular network by the methods of step 101 to step 105 given in the above embodiment 1.

The node adjusting device of the embodiment can find out the main interference source in the relay cellular network for adjustment by using smaller calculated amount and feedback amount, and effectively suppress co-channel interference in the system, thereby improving the utilization rate of resources and ensuring the communication quality of the relay cellular network. The node adjusting apparatus in this embodiment may be a network side device, may exist alone, or may be a physical entity in other network devices, which is not limited in this embodiment of the present invention, and for example, may be used as a home register similar to an HLR in an actual relay cellular network, that is, a register for storing node information accessed by a user, may adjust an access node of the user, or may be a physical entity in a base station, and the like.

Example 4

The present embodiment provides a node adjustment system of a relay cellular network, including: the system comprises a base station, a relay node and a user terminal, wherein the user terminal is in communication connection with the base station or the relay node, and the system also comprises: a node adjusting device 41 of the relay cellular network, wherein the node adjusting device 41 may adopt the node adjusting device given in the above embodiment 3, and the node adjusting device 41 may be in communication connection with the base station or the relay node. One form of construction of the system is shown in figure 8. Or may also or may be a physical entity in the base station, etc. It can be known that the system is used in a relay cellular network formed by a base station and a relay node, and each cell may be divided into a plurality of sectors (e.g. 4 sectors, 5 sectors or more). The system can find out each interference node directly causing interference to the node accessed by the user terminal from all effective interference nodes through a node adjusting device when the channel quality indicated value of the user terminal is smaller than a preset threshold value after the user terminal accesses the node selected according to the channel quality, calculate the interference strength causing interference to the user terminal only according to the effective interference nodes, then find out the node with the maximum interference, and adjust the number of the user terminals served by the node to inhibit the same frequency interference in the relay cellular network. The main interference source in the relay cellular network can be found out and adjusted by smaller calculated amount and feedback amount, so that the utilization rate of resources is improved, the same frequency interference in the system is effectively inhibited, and the communication quality of the relay cellular network is ensured.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A node adjustment method of a relay cellular network, the method comprising:

after a user terminal selects a certain node to access a relay cellular network according to channel quality, if the channel quality indicated value of the user terminal is smaller than a preset threshold value, calculating the interference strength of interference caused by each interference node which causes interference to the node accessed by the user terminal in the relay cellular network to the user terminal;

2. The method according to claim 1, wherein each of the interfering nodes causing interference to the node accessed by the user terminal in all the nodes of the relay cellular network comprises:

finding out effective nodes which can cause effective interference from all nodes of the relay cellular network;

and determining each interference node causing interference to the node accessed by the user terminal from each effective node according to the topological relation between the node accessed by the user terminal and each effective node.

3. The method of claim 2, wherein the step of finding out the effective nodes that cause effective interference with each other from all the nodes of the relay cellular network comprises:

element w in relay interference matrix M_iiSet to 0; if the relay nodes of the same sector k in the relay cellular network share the frequency spectrum resource, enabling w_ij＝0(i，j∈e_k) Wherein e is_kIs a set of relay nodes in sector k; if the relay node of the same sector k in the relay cellular networkInter-multiplexing of spectral resources, then w_ij≠0(i，j∈e_k) Wherein e is_kIs a set of relay nodes in sector k;

elements w which are not equal to 0 and are smaller than a preset interference threshold eta in the relay interference matrix M_ijSet to 0, and the other element w_ijIs set to 1;

the element w not equal to 0 in the relay interference matrix M_ijCorresponding relay node RN_i、RN_jAre active nodes that can effectively interfere with each other.

4. The method according to claim 2 or 3, wherein the determining, from the active nodes, each interfering node causing interference to the node accessed by the user terminal according to the topological relation between the node accessed by the user terminal and the active nodes comprises:

and determining each relay node corresponding to the element with the nonzero element value in each element as an interference node causing interference to the node accessed by the user terminal.

5. The method of claim 1, wherein the calculating the interference strength of the interference caused by each interference node, which causes interference to the node to which the user terminal is accessed, in all nodes of the relay cellular network comprises:

when the relay resource in the sector of the relay cellular network is allocated as the shared spectrum resource, according to

Determining the interference strength of the user terminal caused by interference of each interference node as I_jz(ii) a Or,

when the relay cellular network isWhen the relay resource in the sector is allocated as the multiplexing frequency spectrum resource, the method is based on

Determining the interference strength of the user terminal caused by interference of each interference node, wherein the user terminal is represented by z; i is_jzFor normalized interference, U, caused by relay node j to user terminal z_jSet of relay users served by relay node j, b_jAverage rate of data transmission for relay node j, d (z) data demand for user terminal z, s_zAverage rate of data reception, m, for user terminal z_jNumber of relay users served by relay node j, n_jThe total number of relay users sharing channel resources with the relay users served by the relay node j; wherein, when the relay nodes in the same sector share the channel resource,

e_ka relay node set in a sector k; when multiplexing channel resources between relay nodes of the same sector, n_j＝m_j，H_jzFor large scale channel fading coefficient, p, from relay node j to user terminal z_jIs the transmit power of the relay node j.

6. The method of claim 1, wherein the selecting, according to the interference strength, an interfering node from the interfering nodes that causes the largest interference to the ue and has not tuned away from the ue in the current adjustment comprises:

and selecting the interference node which causes the largest interference to the user terminal and has not been tuned away by one user terminal in the adjustment from the interference nodes.

7. The method of claim 1, wherein the adjusting the number of ues served by the interfering node comprises:

a user terminal is tuned away from the user terminals served by the interfering node.

8. The node adjustment method of the relay cellular network according to claim 7, wherein the tuning away one of the user terminals served by the interfering node comprises:

if the relay cellular network adopts a transparent frame format, changing an access mode of a user terminal closest to a base station in a relay user terminal served by the interference node into a direct access mode, and comparing a channel quality indicated value of the adjusted user terminal with that before adjustment to be not less than a set ratio; or,

and if the relay cellular network adopts a non-transparent frame format, changing the access mode of the user terminal closest to the relay node in the direct connection user terminals served by the interference node into a relay access mode.

9. A node adjustment apparatus of a relay cellular network, the apparatus comprising:

the main control processing unit is configured to calculate, when it is determined that the channel quality indication value fed back by the user terminal and received by the data transmission unit is smaller than a preset threshold value, interference strength of interference caused by each interference node causing interference to the user terminal among all nodes of the relay cellular network; selecting the interference node which causes the largest interference to the user terminal and has not been tuned away from the user terminal in the adjustment from the interference nodes according to the interference strength, and sending an adjustment instruction for adjusting the number of the user terminals served by the selected interference node to the adjustment unit;

10. The node adjustment apparatus of a relay cellular network according to claim 9, wherein the master processing unit includes:

the device comprises an acquisition module, a channel quality indicated value calculation module, a judgment processing module and a comparison processing module;

the acquiring module is configured to acquire each interference node causing interference to a node to which the user terminal is accessed, from among all nodes of the relay cellular network;

the judging and processing module is used for judging whether the channel quality indicated value fed back by the user terminal received by the data transmission unit is smaller than a preset threshold value, and if so, sending an instruction to the channel quality indicated value calculating module;

the channel quality indicated value calculating module is configured to calculate, after receiving the instruction sent by the determining and processing module, an interference strength of interference caused by each interference node to the user terminal according to each interference node which is acquired by the acquiring module and causes interference to a node to which the user terminal is accessed;

and the comparison processing module is used for selecting the interference node which causes the largest interference to the user terminal and has not been adjusted away from the user terminal in the adjustment from the interference nodes according to the interference strength of the interference caused to the user terminal by each interference node calculated by the channel quality indicated value calculation module, and sending an adjustment instruction for adjusting the number of the user terminals served by the selected interference node to the adjustment unit.

11. The node adjustment apparatus of a relay cellular network according to claim 9, wherein the master processing unit further includes:

and the effective node acquisition module is used for finding out effective nodes which can cause effective interference from all nodes of the relay cellular network.

12. A communication system, comprising: the node adjustment device of the relay cellular network according to any of the preceding claims 9 to 11, wherein the adjustment device is communicatively connected to the base station or the relay node.