CN103491620B - Based on the distributed uplink power control method of user-driven in a kind of heterogeneous network - Google Patents

Abstract

The present invention is a user-led distributed uplink power control method in a heterogeneous network. The method is characterized in that the uplink users of the macro cell are divided into Central user group and edge user group, all micro cell users within the coverage of the macro cell are not grouped; secondly, all micro cell users and the macro cell central user group share the system center user spectrum, and the macro cell edge user group occupies the edge user dedicated spectrum; Finally, all micro cell users and macro cell center users adopt a user-led distributed uplink power control method, and each user at the edge of the macro cell performs uplink transmission with maximum transmit power. This method makes full use of the cell coverage and interference conditions of different users in the network, selects the appropriate spectrum resource reuse scheme and power control strategy, and effectively improves the overall efficiency of all uplink users in the heterogeneous network while ensuring frequency reuse. transmission performance.

Description

A User-led Distributed Uplink Power Control Method in Heterogeneous Networks

technical field

The invention belongs to the technical field of wireless communication, relates to the design of suppressing interference by using power control in heterogeneous uplink, and mainly aims at the uplink interference problem between macro cell users and micro cell users in heterogeneous network.

Background technique

Due to the increasing shortage of spectrum resources, in order to improve the spectrum efficiency of the existing system, the future broadband mobile communication system will introduce a multi-level hierarchical network architecture with different coverage capabilities and ranges, which can effectively meet the requirements of flexible system deployment, increase the total system capacity and improve user performance. need. The heterogeneous network architecture refers to the deployment of one or more micro-cell base stations with low transmit power within the range of macro cells covered by traditional base stations according to requirements, for small-scale hotspot coverage, etc. These micro cell base stations share the dedicated frequency band of the mobile communication system with the macro base station, so that the overall spectrum utilization rate of the system can be improved and the user transmission rate within the coverage area of the micro cell base station can be enhanced.

In an uplink heterogeneous system, since users accessing a macro base station share a frequency band with users accessing a micro cell, any macro/micro base station will receive uplink interference from users accessing other cells. Especially for those users who are at the coverage edge of one cell or multiple cells, the uplink transmission power used by them is relatively large, so it will cause relatively serious inter-cell interference. In a traditional homogeneous network, the uplink power control of the system is that each user configures the transmit power intensity according to its own quality of service (QoS) requirements and the large-scale path loss between the user and the main base station. If the user is far away from the main base station and the path loss is large, the user will increase its transmit power to a certain extent to ensure that the signal-to-noise ratio of the user's uplink signal received by the base station is at an expected level. However, in a heterogeneous network, some micro cells with low power and small coverage may be randomly distributed inside the macro base station. If the serving user at the edge of the macro cell increases the transmission power, since there is coverage of the micro cell nearby, it will cause obvious interference to the uplink user signal received in the micro cell, thereby affecting the user performance within the coverage area of the micro cell.

In addition, since the effective spectrum of the existing system is fully reused by micro cells and macro cells, co-channel interference in the heterogeneous system is relatively serious, causing the overall system performance to decline rapidly, and the existing uplink power control scheme cannot take into account the user's influence on adjacent cells. Therefore, in the uplink heterogeneous system, we need a dynamic power control scheme that can take into account the interference to adjacent cell users. According to the channel fading of different users in the heterogeneous system and its interference to adjacent cell users Features, select an appropriate uplink dynamic power control scheme, so as to effectively suppress the same-frequency interference between different cells in the heterogeneous system, and improve the overall performance of the system.

Contents of the invention

Technical problem: The purpose of the present invention is to provide a user-led distributed uplink power control method in a heterogeneous network. This method improves the total system capacity and performance, and can better improve the system performance of the macro cell. In this method, the feedback delay is relatively small, the implementation complexity is low, and the system is easy to implement.

Technical solution: In the uplink heterogeneous network system, if you want to use the spectrum multiplexing in the heterogeneous network to improve the overall performance of the system, the best way is to select the appropriate Spectrum resource reuse scheme and power control strategy, which can effectively improve the overall transmission performance of all uplink users in the heterogeneous network while ensuring frequency reuse. This method selects the spectrum resource reuse scheme and power control strategy according to the cell coverage and interference conditions of different users in the network, and effectively improves the overall transmission performance of all uplink users in the heterogeneous network while ensuring frequency reuse. The user-led distributed uplink power control method is performed in the following steps:

1.) Divide macro cell users into central users and edge users; each user k measures its own signal-leakage-to-noise ratio SLNR value according to the following formula:

${\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\frac{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; k</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

in is the transmit power initialized by the user, the power value of the last transmission can actually be used, PL _k represents the large-scale path loss between the user and its serving base station, and Indicates the path loss from the user to other cell base stations, L represents the total number of base stations in the system including macro base stations and micro cell base stations, ^σ2 represents the noise power, each user in the macro cell according to its own η _k value and the given The threshold value SLNR _th is compared, if η _k ≥ SLNR _th , then the user is a macro cell center user; otherwise, the user is a macro cell edge user; j is the base station number, including macro base stations and micro cell base stations;

2.) The spectrum bandwidth of the entire system is divided into the central user transmission frequency band and the edge user dedicated frequency band. All micro cell users and macro cell central user groups share the system central user spectrum, and the macro cell edge user group occupies the edge user dedicated spectrum;

3.) For all cell users, the transmission frequency band is evenly allocated;

4.) For the macro cell center user and all micro cell users, the uplink transmit power is:

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; adjusted</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; PL</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 10</span>}{{\mathrm{<span\; class="notranslate">\; log</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}}^{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \}</span>$

where P _max is the maximum transmission power allowed by the user, $P_0^{\mathrm{adjusted}}=\max \{P_0^{\min },\min \{P_0^{\max },P_0+k\&Center\; Dot;\mathrm{SLNR}\left\}\right\}$ In order to adaptively preset the target received power according to the value of the user signal-to-leakage-to-noise ratio, and are the preset minimum and maximum values of P ₀ respectively, P ₀ is the initial target received power, and k≥0 is an adjustment , α is the path loss compensation factor (0<α ≤ 1), M is the number of resource blocks RB allocated to the user, and PL is the path loss from the base station to the user;

5.) For macro cell edge users, the user transmit power is set to the maximum allowable value P _max .

Beneficial effect:

(1) A user-led distributed uplink power control method in the heterogeneous network proposed by the present invention has improved the total system capacity performance, and its performance has been improved by about 10% to 20% according to different policy scenarios.

(2) For the network uplink fractional power control method (FPC) in the existing communication standard, the invention can better improve the system performance of the macro cell while obtaining similar system performance of the micro cell.

(3) The invention is a user-led distributed uplink power control method, the feedback delay is relatively small, the implementation complexity is low, and the system is easy to implement.

Description of drawings

FIG. 1 is a schematic diagram of user interference in a heterogeneous uplink system.

FIG. 2 shows a flowchart of the user-led distributed uplink power control method.

Figure 3 shows the CDF curves of all user rates when Ratio=0.1.

Figure 4 shows the CDF curves of all user rates when Ratio=0.2.

detailed description

The technical method of the patent invention is simulated on a heterogeneous network system platform. The specific implementation method of the method given by the present invention is mainly simulated and tested. In addition, for comparison, the results of two classical power control methods are also given. The specific comparison algorithm is:

Method (1)–Pmax: all users transmit at maximum power;

Method (2)-FPC: Use the uplink power control method defined in the standard, and the parameters are shown in the table below;

Method (3) - the method of the present invention: the algorithm provided by the present invention, the specific steps are the same as the content of the invention above.

The simulation parameters of the invention are shown in Table 1. Wherein, Ratio is the ratio of the edge user frequency band to the total frequency band.

This method selects the spectrum resource reuse scheme and power control strategy according to the cell coverage and interference conditions of different users in the network, and effectively improves the overall transmission performance of all uplink users in the heterogeneous network while ensuring frequency reuse. The user-led distributed uplink power control method is performed in the following steps:

1.) Divide macro cell users into central users and edge users; each user k measures its own signal-leakage-to-noise ratio SLNR value according to the following formula:

${\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>\frac{\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; \&NotEqual;</span>\mathrm{<span\; class="notranslate">\; k</span>}}{\overset{\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; p</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; PL</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

in is the transmit power initialized by the user, the power value of the last transmission can actually be used, PL _k represents the large-scale path loss between the user and its serving base station, and Indicates the path loss from the user to other cell base stations, L represents the total number of base stations in the system including macro base stations and micro cell base stations, ^σ2 represents the noise power, each user in the macro cell according to its own η _k value and the given The threshold value SLNR _th is compared, if η _k ≥ SLNR _th , then the user is the central user of the macro cell; otherwise, the user is the edge user of the macro cell; j is the base station number (including the macro base station and the micro cell base station);

2.) The spectrum bandwidth of the entire system is divided into the central user transmission frequency band and the edge user dedicated frequency band. All micro cell users and macro cell central user groups share the system central user spectrum, and the macro cell edge user group occupies the edge user dedicated spectrum;

3.) For all cell users, the transmission frequency band is evenly allocated;

4.) For the macro cell center user and all micro cell users, the uplink transmit power is:

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; min</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{\mathrm{<span\; class="notranslate">\; adjusted</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; PL</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 10</span>}{{\mathrm{<span\; class="notranslate">\; log</span>}}_{\mathrm{<span\; class="notranslate">\; 10</span>}}}^{\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; \}</span>$

where P _max is the maximum transmission power allowed by the user, $P_0^{\mathrm{adjusted}}=\max \{P_0^{\min },\min \{P_0^{\max },P_0+k\&Center\; Dot;\mathrm{SLNR}\left\}\right\}$ In order to adaptively preset the target received power according to the value of the user signal-to-leakage-to-noise ratio, and are the preset minimum and maximum values of P ₀ respectively, P ₀ is the initial target received power, and k≥0 is an adjustment , α is the path loss compensation factor (0<α≤1), M is the number of resource blocks (RB) allocated to the user, and PL is the path loss from the base station to the user;

5.) For macro cell edge users, the user transmit power is set to the maximum allowable value P _max .

Table 1 Simulation parameter list

Figure 1 shows a simple schematic diagram of an interference model in a heterogeneous network. Among them, MUE1 and MUE2 have the same distance from the macro base station, but MUE1 is closer to the two micro cell base stations; under traditional power control (FPC), MUE1 and MUE2 transmit the same power, and the interference of MUE1 to the micro cell is higher than that of MUE2 to the micro cell. The interference of the small cell is much larger; by adopting the power control method of the present invention, the interference of the MUE1 to the small cell can be effectively controlled.

Fig. 2 is an algorithm flow chart of the present invention. According to the signal-leakage-to-noise ratio (SLNR) measured by the macro cell users themselves, the uplink users of the macro cell are divided into a central user group and an edge user group, and all micro cell users within the coverage of the macro cell are not grouped. All micro-cell users and macro-cell center user groups share system center user spectrum, and adopt a user-led distributed power control method; macro-cell edge user groups occupy edge user-specific spectrum, and each user performs uplink transmission with maximum transmit power.

Figure 3 and Figure 4 show the CDF curves of macro cell users and micro cell users when Ratio=0.1 and 0.2 respectively. Comparing the two traditional power control schemes, in the case of transmitting with the maximum power, the interference from the macro cell users to the micro cell users is relatively large, and the system capacity of the micro cell is relatively small. However, using FPC and our proposed resource allocation scheme, the capacity of the macro cell is reduced compared to the case of Pmax, but due to the use of power control, the interference of the macro cell to the micro cell is reduced, and the system capacity of the micro cell is improved. . In general, a user-led distributed uplink power control method in a heterogeneous network proposed by us can improve the total capacity of the system. According to different policy scenarios, the performance can be improved by about 10% to 20%. In addition, compared with the existing FPC scheme, the algorithm we propose can better improve the system performance of the macro cell while obtaining similar system performance of the micro cell.

Corresponding to Figure 3, the following table 1Ratio=0.1

Corresponding to Figure 4, the following table 2Ratio=0.2

Claims (1)

1. based on the distributed uplink power control method of user-driven in a heterogeneous network, it is characterized in that the method is according to different user in network self residing cell coverage area and disturbed condition, select frequency spectrum resource multiplexing scheme and power control strategy, ensureing to be effectively improved in heterogeneous network while channeling the overall transfer performance of all uplink user, the distributed uplink power control method of this user-driven sequentially includes the following steps:

1.) macrocell user is divided into central user and edge customer；Each user k measures the letter leakage noise ratio SLNR value of oneself according to following formula:

${\mathrm{\&eta;}}_k=\frac{\stackrel{\&OverBar;}{p}\&CenterDot;{\mathrm{PL}}_k}{\underset{j=1,j\&NotEqual;k}{\overset{L}{\&Sigma;}}\stackrel{\&OverBar;}{p}\&CenterDot;{\mathrm{PL}}_k^j+{\mathrm{\&sigma;}}^2}$

WhereinIt is the initialized transmitting power of this user, actual performance number when can use last transmission, PL_kRepresent that user is to the large scale path loss between its serving BS, andRepresent that this user path loss to other cell base station, L expression system include macro base station and microcell base station at interior total base station number, σ²Represent noise power, each user η according to oneself in macrocell_kValue and given threshold value SLNR_thCompare, if η_k≥SLNR_th, then this user is macrocell central user；Otherwise, this user is macrocell edge customer；J is base station number, including macro base station and microcell base station；

2.) whole system spectral bandwidth being divided into central user transmission band and edge customer dedicated frequency band, all Microcell users and macrocell central user group shared system central user transmission band, macrocell edge customer group takies edge customer dedicated frequency band；

3.) for all community users, uniform distribution uses transmission band；

4.) for macrocell central user and all Microcell users, its uplink transmission power is:

$P=min\{P_{max},P_0^{adjusted}+\mathrm{\&alpha;}\&CenterDot;PL+10{{\log }_{10}}^M\}$

Wherein P_maxFor user allow maximum transmission power,

For believing that the value self adaptation goal-selling of leakage noise ratio receives power according to user,WithRespectively P₀Predeterminable minima and maximum, P₀Receiving power for initial target, a >=0 is an adjustmentParameter, α is path loss compensating factor (0 < α≤1), and M is allocated to the Resource Block RB number of user, and PL is the path loss that user is arrived in base station；

5.) for macrocell edge customer, its uplink transmission power is the maximum transmission power P that user allows_max。