WO2010072019A1

WO2010072019A1 - Method for implementing uplink coordinated multi point transmission and reception by combining inter-cell interference coordination

Info

Publication number: WO2010072019A1
Application number: PCT/CN2008/002147
Authority: WO
Inventors: 李晓辉; 薛鑫; 季清
Original assignee: 西安电子科技大学
Priority date: 2008-12-26
Filing date: 2008-12-31
Publication date: 2010-07-01
Also published as: CN101483873A; CN101483873B

Abstract

A method for implementing uplink Coordinated Multi Point Transmission and Reception(CoMP) by combining Inter-Cell Interference Coordination(ICIC). The method includes steps as follow: 1) a site determines whether a user is an edge user or a center user by detecting a Signal to Interference plus Noise Radio(SINR) of the user, and allocates a working frequency band used by the user according to a frequency division method of ICIC; 2) the user transmits data to the cell according to the allocated working frequency band; 3) the site determines whether or not the cell that the user belongs to or the service of the user supports CoMP, and if no one supports CoMP, then the base station extracts data with a linear or a non-linear method, and if CoMP can be supported then going to step 4); 4) the cell receives the transmitted data and processes the data. The method guarantees the compatibility of the CoMP scheme and the ICIC scheme, and can increase the cell edge throughput and system average throughput.

Description

Method for implementing uplink multi-point cooperation combined with inter-cell interference coordination

The invention belongs to the field of mobile communications. It relates to an uplink multi-point cooperation implementation method combining inter-cell interference coordination. On the basis of inter-cell interference coordination, the uplink throughput of the cell edge users is greatly improved by multi-point cooperation between multiple cells.

Background technique

In the current LTE (Long Term Evolution), the throughput of cell edge users is much lower than that of users in the central area. In order to improve the data rate transmitted by users at the cell edge and improve the throughput and average throughput efficiency of the entire system, LTE-Advanced (Long Term Evolution-Advanced, LTE-A) will be CoMP (Coordinated Multi Point Transmission). And Reception, Multi-point Collaboration) Technology 歹 'J is one of its important candidate technologies, its main purpose is to improve cell edge throughput through multi-point collaboration.

Multi-point cooperation can be divided into multi-point cooperation between base stations and multi-point cooperation within base stations. Multi-point coordination within a base station refers to users in each cell accessing the network through a site (SITE), and multiple sites can be managed by one base station. The present invention is mainly directed to a multi-point cooperation mode in a base station, as shown in Fig. 1, but can be easily extended to a mode of cooperation between base stations.

In the multipoint coordination (CoMP) mode, users use the same frequency transmission in different cells, so they can use the same frequency network (SFN) to support the multi-point cooperation mode, as shown in Figure 2.

The problem with this solution is: Not all users and services want to adopt the mode of multi-point cooperation; the network side may not support multi-point cooperation, so this solution can support multi-point coordinated transmission of users in all cells. Performance gains can be obtained, but for situations where multipoint coordination is not supported, there is a large inter-cell interference that is especially severe for cell edge users.

Inter-Cell Interference Coordination (ICIC) is an important method for reducing co-channel interference of cell edge users. Currently, Soft Frequency Reuse (SFR) or Fractional Frequency Reuse (FFR) is considered as inter-cell interference in OFDM (Orthogonal Frequency Division Multiplexing) mobile communication systems. Coordination (ICIC), an important technology to improve cell edge user throughput and system throughput. Figure 3 shows a frequency band division method that enables inter-cell interference coordination (ICIC). The edges of three cells use different frequencies, which reduces the edge interference of edge users. This ICIC solution solves the problem of co-channel interference between cells to a certain extent.

However, cell edges in ICIC use different frequency bands, which is contradictory to band sharing in CoMP. Then there are some ways to combine ICIC and CoMP, as shown in Figure 4 and Figure 5.

In the method of Figure 4, cell edge users use the same frequency, and edge users between two cells can improve performance by using coordinated multi-point transmission. However, since there are many different frequency bands in the entire cell, there is a problem that the frequency switching is too frequent for the mobile user.

In addition, there is a method of extracting a part of a frequency band used by an ICIC cell edge as a CoMP use frequency band. As shown in FIG. 5, the advantage of this method is that only a dedicated frequency band is allocated for a CoMP user from a cell edge frequency band. It can provide the benefits of multi-point collaboration of users while avoiding interference between non-multipoint coordinated user cells. However, this solution also has major drawbacks:

1. The frequency band used by CoMP users for multi-point collaboration can no longer be used by the central user. If there are no multi-point cooperative users in the system or the cell does not support multi-point collaboration, it will cause waste of frequency resources.

2. It is necessary to divide the dedicated frequency band and it is not fully compatible with ICIC and CoMP solutions.

Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a frequency multiplexing method suitable for multi-point cooperation and frequency switching, which solves the deficiencies of the existing ICIC and CoMP combining methods described in the background art.

The technical solution of the present invention is: The present invention is an uplink multi-point cooperation implementation that combines inter-cell interference coordination, and the special method is as follows: The method includes the following steps:

1) The station (SITE) determines whether the user is an edge user or a center user by measuring the user's SINR (Signal to Interference plus Noise Radio), and allocates the working frequency band used by the user according to the ICIC band division method;

2) The user sends data to the cell according to the allocated working frequency band;

3) The station or the base station determines whether the cell in which the user is located and whether its service supports CoMP. If CoMP is not supported, the data of the user is extracted by using a traditional linear or non-linear detection method. If CoMP is supported, the process proceeds to step 4);

4) The cell receives the transmitted data and processes the data. In the above step 4), when the cell receives only the data sent by the edge user, it is determined whether the cell is the serving cell of the edge user. If the cell is not the serving cell of the edge user, that is, the cell is a coordinated cell, the data is transmitted to the serving cell of the edge user; if the cell is the serving cell of the edge user, the data transmitted by the coordinated cell is combined. Detection.

In the above step 4), when the cell receives only the data sent by the central user, the data sent by the central user is detected and extracted according to a linear or non-linear processing method.

In the above step 4), when the cell receives the data sent by the central and edge users at the same time, the shell lj:

4.1) extracting data sent by the central user, if the data sent by the user is correctly received, performing interference cancellation on the received data, and transmitting the data after canceling the interference to the serving cell of the edge user, for joint detection by the edge user;

4.2) If the data sent by the central user is incorrect, the data is not transmitted to the serving cell of the edge user, and the serving cell performs joint detection according to the data received by itself or the data of other cells.

The above sites are multi-antenna.

The above user is a single antenna or multiple antennas; when multiple antennas, the user transmits by single stream or multiple streams. The number of intra-frequency intra-cell users is single-user or multi-user.

The present invention adopts multi-point cooperation of sharing frequency resources between a cell edge user and a neighboring cell center user. This multi-point cooperation mode first avoids the process of dividing a dedicated frequency band for multi-point coordinated users; secondly, it can utilize central user performance. The performance of the edge user is improved by the interference cancellation, that is, the performance of the central user is better than that of the edge user, and the probability of correctly receiving the information is higher than that of the edge user, then the uplink of one cell edge user and the neighboring cell center user is the same frequency. The effect of multi-point collaborative joint detection is better than that of edge users. Therefore, the present invention has the following advantages:

1. Compatibility with the ICIC scheme is guaranteed: The present invention makes full use of the existing frequency soft reuse (SFR) scheme and is fully compatible with the existing SFR-based ICIC scheme. Since no additional frequency bands are allocated in the invention, the user can move freely between cells supporting multi-point cooperation and non-multi-point cooperation without requiring a new band configuration. Users who want multi-point cooperation do not need to consider whether the cell in which the cell and the neighboring cell support multi-point cooperation when allocating the frequency band, and only need to allocate the frequency band according to the SFR, which greatly simplifies the frequency band division process.

2. A multi-point cooperation mode in which a central user and an edge user share a frequency band resource between different cells: The present invention is a multi-point cooperation mode in which a central user and an edge user cooperate with each other. While ensuring the performance of the cell center user, the performance of the cell edge user can be greatly improved. Due to the method that is fully compatible with ICIC, with partial power compensation technology, the signal strength of the edge users arriving at the site is often lower than that of the central user, and the performance of the central user is not increased compared with the case of not using multi-point cooperation. Impact.

3. Improve the performance of edge users without degrading the performance of the central user: Since the central user can correctly decode the interference to the edge users after the correct decoding, the edge users can make good use of the benefits brought by CoMP. Combine the code before or after decoding to obtain the gain of performance. DRAWINGS

Figure 1 (a) Schematic diagram of a multi-site coordinated working mode of two cells in the prior art;

Figure 1 (b) Schematic diagram of a three-cell multi-point cooperative working mode in the prior art;

2 is a schematic diagram of a multi-point cooperative working mode based on the same frequency network (SFN) in the prior art; FIG. 3(a) is a schematic diagram 1 of a frequency band dividing method for inter-cell interference coordination in the prior art; FIG. 3(b) is an existing FIG. 4 is a schematic diagram of multi-point cooperative frequency band division based on the same type of frequency band division in the prior art; FIG. 5 is a frequency band used in the multi-point cooperative working mode from the cell edge in the prior art; Schematic diagram of extracting the CoMP band;

Figure 6 is a schematic view of the method of the present invention;

Figure 7 (a) Cooperative mode of shared frequency band resources between central users and edge users between two cells; Figure 7 (b) Cooperative mode of shared frequency band resources between central users and edge users between three cells; Figure 8 (a) Neither of the three cells Schematic diagram supporting multi-point collaboration;

Figure 8 (b) Schematic diagram of the cell 3 in the three cells not supporting multi-point cooperation;

Figure 8 (c) Schematic diagram of three cells supporting multi-point cooperation;

Figure 8 (d) Schematic diagram of edge users supporting multi-point collaboration, central users not supporting multi-point collaboration; Figure 9 Schematic diagram of user data processing procedures supporting multi-point collaboration.

detailed description

Referring to Figure 6, the specific steps of the method of the present invention are as follows:

1) The station determines whether the user is an edge user or a central user by measuring the SINR of the user, and allocates a working frequency band used by the user according to a method of frequency division of the ICIC;

2) The user sends data to the cell according to the allocated working frequency band, regardless of the small size of the user. Whether the zone and neighboring cells support CoMP;

3) Determine whether the user's cell is supported by the site or the base station and whether its service supports CoMP. If CoMP is not supported, the data sent by the user is processed in a conventional manner, and data is extracted by linear or non-linear detection methods. If CoMP is supported, the process proceeds to 4);

4) If the user in the step 3) is located in the cell and its service supports CoMP, the CoMP is divided into three cases, namely:

4.1) When the cell receives only the data sent by the edge user, it determines whether the cell is the serving cell of the edge user. If the cell is not the serving cell of the edge user, the data is transmitted to the serving cell of the edge user; if the cell is the serving cell of the edge user, the data transmitted by the other coordinated cells is jointly detected.

4.2) When the cell receives only the data sent by the central user, it detects and extracts the data sent by the central user according to the traditional linear or non-linear processing method.

4.3) When the cell receives data sent by the central and edge users at the same time, Bay IJ:

4.3.1) extracting data sent by the user of the center, if the data sent by the user is correct, performing interference cancellation, and transmitting the data after canceling the interference to the serving cell of the edge user for joint decoding of the edge user;

4.3.2) If the data sent by the central user is incorrect, no data is transmitted to the serving cell, and the serving cell performs joint detection according to the data received by itself or the data of other cells.

In the whole process of the present invention, the station is often multi-antenna to achieve interference cancellation in steps 3) and 4); the user can have single antenna or multiple antennas; when multiple antennas, users can adopt single stream and multiple streams Sending; The number of intra-frequency users in a cell can be single or multiple.

The present invention employs multi-point cooperation of sharing frequency resources between a cell edge user and a neighboring cell center user. This multi-point collaboration method first avoids the process of dividing the dedicated frequency band for the multi-point cooperative users. Secondly, it can utilize the central user performance to improve the edge user performance, that is: the performance of the central user is better than that of the edge user, and the edge user Compared with the cooperation, the probability that the data is correctly received is higher, so that the interference of the central user to the edge user can be better offset in the uplink joint detection, so the cooperation effect is better.

In the following, we take three cases as an example, and give several possible multi-point cooperative/non-multi-point cooperation modes, and give ICIC and CoMP compatibility schemes. Figure 8 (a) - (c) shows the transmission of user data from the user terminal to each site in several representative multi-point cooperative/non-multipoint cooperation modes, no matter which mode, the invention adopts The band division method remains unchanged.

In various modes, the main difference is that the processing methods on the network side are different. Figure 8 (a) - (c) is mainly for the analysis of whether the site supports multi-point collaboration, and Figure 8 (d) considers the use of edge users. Multi-point cooperation, the central cell does not adopt multi-point cooperation - In Figure 8 (a), each site independently decodes the data of each user, and does not require data transmission between sites;

In FIG. 8(b), cell 3 does not participate in multi-point cooperation, and cell 1 and cell 2 support multi-point cooperation. At this time, users and stations in cell 3 can cooperate with multi-point cooperation of cell 1 and cell 2. The interaction between the cell 1 and the cell 2 needs to be performed, and the information of the interaction may be the data before decoding and the data after decoding.

In Figure 8(c), all three cells participate in multi-point cooperation, and the data received from the user (which may be pre-decoded or decoded) is transmitted between the stations.

In the mode shown in Figure 8 (c), if all users collaborate, the amount of data transferred between sites is large, and the performance is improved less, so the more practical situation is Figure 8 (d), in which three cells participate. Multi-point collaboration, but the central user's data is only processed in its serving cell, no multi-point collaboration, only edge users participate in multi-point collaboration. Each cell extracts the central user data and performs interference cancellation, and then transfers the data of multiple coordinated users (either before or after decoding) between the sites.

Figure 9 shows the data transfer process for multi-point collaborative users in Figure 8 (d).

According to the method of the present invention, the prior art method can also implement CoMP, compared to the inventive method:

In the same-frequency network solution, the multi-point collaboration function can be realized through steps 2) to 4), but it will cause great interference to the situation where multi-point cooperation is not supported.

CoMP can also be implemented in the scheme of dividing the special frequency band, but signaling for controlling the dedicated frequency band needs to be added in these steps, and the processing method of step 4) is different, the key is that CoMP and ICIC are incompatible, the user's Sending is not transparent.

Claims

Claim

1. An uplink multi-point cooperation implementation method combining inter-cell interference coordination, wherein: the method comprises the following steps:

1) The station determines whether the user is an edge user or a central user by measuring the SINR of the user, and allocates a working frequency band used by the user according to the frequency division method of the ICIC;

3) Determine whether the cell where the user is located by the station or the base station and whether its service supports CoMP. If CoMP is not supported, the data is extracted by linear or non-linear methods. If CoMP is supported, proceed to step 4);

4) The cell receives the transmitted data and processes the data.

The method for implementing the uplink multi-point cooperation in the inter-cell interference coordination according to claim 1, wherein: in the step 4), when the cell receives only the data sent by the edge user, it is determined whether the cell is the If the cell is not the serving cell of the edge user, the data is transmitted to the serving cell of the edge user; if the cell is the serving cell of the edge user, the data of the serving cell and the coordinated cell are jointly detected. .

The uplink multi-point cooperation implementation method of the inter-cell interference coordination according to claim 1, wherein: in the step 4), when the cell receives only the data sent by the central user, the traditional linear or The nonlinear processing method detects and extracts data sent by the central user.

The uplink multi-point cooperation implementation method for inter-cell interference coordination according to claim 1, wherein in the step 4), when the cell receives the data sent by the center and the edge user at the same time, then:

4.1) extracting data sent by the center user, if the data sent by the user is correct, performing interference cancellation, and transmitting the data after canceling the interference to the serving cell of the edge user for joint detection;

4.2) If the data sent by the central user is incorrect, no data is transmitted to the serving cell, and the serving cell performs joint detection according to the data received by itself or the data of other cells.

The method for implementing uplink multi-point cooperation in combination with inter-cell interference coordination according to claim 1 or 2 or 3 or 4, wherein: the station is multi-antenna.

The method for implementing uplink multi-point cooperation in combination with inter-cell interference coordination according to claim 5, wherein: the user is a single antenna or multiple antennas; when multiple antennas are used, the user uses a single stream or multiple streams. .

The method for implementing uplink multi-point cooperation in combination with inter-cell interference coordination according to claim 6, wherein: the number of intra-frequency users in the cell is single-user or multi-user.