WO2010048836A1

WO2010048836A1 - Method and base station for switching between half-duplex and multicast cooperating relay modes

Info

Publication number: WO2010048836A1
Application number: PCT/CN2009/073787
Authority: WO
Inventors: 袁弋非; 李国红; 霍迪
Original assignee: 中兴通讯股份有限公司
Priority date: 2008-10-31
Filing date: 2009-09-07
Publication date: 2010-05-06
Also published as: CN101389140A; CN101389140B

Abstract

A method and a base station for switching between a half-duplex relay mode and a multicast cooperating relay mode are provided. The method involves the following steps: the base station estimates the channel rates on the link of base station-relay station, that of the link of relay station-mobile terminal and that of the link of base station-mobile terminal respectively according to the channel quality information of these three links (110); and the base station calculates the effective channel rate on the link of base station-relay station-mobile terminal in a half-duplex relay mode and that in a multicast cooperating relay mode respectively, according to the estimated channel rates of these three links (120); and the base station executes the mode switching judgment according to the effective channel rate in the half-duplex relay mode, the effective channel rate in the multicast cooperating relay mode, the channel quality of the link of base station-mobile terminal, and the preset switching strategy, and when the switching condition is satisfied, the switching is executed between the half-duplex relay mode and the multicast cooperating relay mode (130). And thus, the relay modes switching can be realized in a double-hop relay system, which can send down-link signals in a half-duplex relay mode or in a multicast cooperating relay mode.

Description

Method for switching half-duplex and multicast cooperative relay mode and base station

The present invention relates to the field of mobile communications, and more particularly to a two-hop relay system and a method of switching a relay mode employed in the system.

Background technique

As a potential technical solution that can improve the throughput of cell edge users and better achieve high data rate coverage, relay technology has received extensive attention in various international standardization organizations. Currently, although in the discussion of 3GPP LTE-Advanced, some companies have proposed some general relay solutions, the relay systems that process data at different levels, for example, are respectively amplified by the physical layer (layer 1). And forwarding, media access layer (layer 2) decoding and re-encoding and network layer (layer 3) relay mode forwarding data in the relay station and relay system, how to effectively improve the system capacity, is a problem to be further studied.

From the discussion of the international standardization organization on relay technology and the published technical materials, in the above three data forwarding processing mode relay stations (layer 1 relay station / layer 2 relay station / layer 3 relay station), in the medium access layer ( That is, the layer 2 relay) has more ideas for processing and forwarding data. According to the duplex mode, it can be divided into a half-duplex relay mode and a multicast cooperative relay mode between the base station and the relay station. Data relay mode, with different system performance improvements and gains.

In the prior art, some independent scenarios are deployed in a certain relay mode. However, the mobile communication environment is a time-varying system. The use of a fixed relay mode limits the performance of the relay system. In particular, the channel conditions and geographical environments of different terminals in the network are different, and a fixed The relay mode greatly limits the effect of the relay system to improve network performance.

Summary of the invention

To solve the prior art problem, the present invention provides a method for switching a half-duplex and a multicast cooperative relay mode in a two-hop relay system, and a base station in the system, which can fully utilize a relay system. To improve the performance of the network.

The present invention provides a method for switching a relay mode, which is applied to a two-hop relay system having the capability of transmitting a downlink signal in a half-duplex relay mode and a multicast cooperative relay mode, the handover method comprising: - channel quality information on the three links of the relay station, the relay station-mobile terminal and the base station-mobile terminal, estimating the channel rate on the three links;

The base station calculates an effective channel rate on the base-relay-mobile terminal link in the half-duplex relay mode and the multicast cooperative relay mode according to the estimated channel rates of the three links;

The base station performs mode switching according to the effective channel rate in the half-duplex relay mode and the multicast cooperative relay mode, the channel quality of the base station-mobile terminal link, and the set handover policy. When the handover condition is met, the half is performed. Switching between duplex relay mode and multicast cooperative relay mode;

Thereby, the switching of the relay mode is implemented in the two-hop relay system that transmits the downlink signal in the half duplex relay mode and the multicast cooperative relay mode.

Further, the foregoing switching method may further have the following features: the switching policy is: when the current working in the half duplex relay mode, such as the effective channel rate value of the half duplex relay mode and the multicast cooperative relay mode are effective If the ratio of the channel rate value is lower than the set rate proportional threshold, and the channel quality of the base station-mobile terminal link is higher than the set channel quality threshold, the mode is switched to the multicast cooperative relay mode; or

When currently working in the multicast cooperative relay mode, the ratio of the effective channel rate value of the half duplex relay mode to the effective channel rate value of the multicast cooperative relay mode is higher than the set rate proportional threshold or the base station-mobile terminal. If the channel quality of the link is lower than the set channel quality threshold, it switches to the half-duplex relay mode.

Further, the foregoing handover method may further have the following feature: the channel quality information of the three links is a channel quality indicator.

Further, the foregoing switching method further includes:

When initializing, the base station selects a relay mode to be enabled according to the calculated effective channel rate and the selected selection policy in the two relay modes, and the selection strategy is:

When the ratio of the effective channel rate value of the half duplex relay mode to the effective channel rate value of the multicast cooperative relay mode is lower than the rate proportional threshold, and the channel quality of the base station-mobile terminal link is higher than the channel quality When the threshold is limited, the multicast cooperative relay mode is selected; or

When the ratio of the effective channel rate value of the half duplex relay mode to the effective channel rate value of the multicast cooperative relay mode is higher than the rate proportional threshold or the channel quality of the base station-mobile terminal link is lower than the channel quality threshold, select half Duplex relay mode.

Further, the foregoing switching method may further have the following features: The rate proportional threshold ranges from 0.7 to 0.9, and the channel quality threshold ranges from 0 to 5 dB.

The present invention also provides a base station, including a first sending module, a second sending module, and a relay mode control module, where:

The first sending module is configured to perform downlink signal transmission according to a half duplex relay mode; the second sending module is configured to perform downlink signal transmission according to a multicast cooperative relay mode; and the relay mode control module is configured The mode switching is performed according to the current channel quality of the three links of the base station-relay station, the relay station-mobile terminal, and the base station-mobile terminal, and the set switching policy. When the switching condition is met, between the two relay modes Switching, the output control signal enables the transmitting module corresponding to the mode switched to and stops the original transmitting module;

Thereby switching between the half duplex relay mode and the multicast cooperative relay mode is realized.

Further, the foregoing base station may further have the following features, the relay mode control module includes three channel rate estimating units, an effective channel rate calculating unit, and a mode switching determining unit, where:

The three channel rate estimating units are respectively configured to estimate channel rates on the three links according to channel qualities on the three links of the base station-relay station, the relay station-mobile terminal, and the base station-mobile terminal, and output the valid to the effective Channel rate calculation unit;

The effective channel rate calculation unit is configured to calculate an effective channel on the base station-relay-mobile terminal link in the half-duplex relay mode and the multicast cooperative relay mode according to the estimated channel rates of the three links Rate, and output to the relay mode decision unit;

The mode switching decision unit is configured to perform mode switching according to an effective channel rate in two relay modes, a channel quality of a base station-mobile terminal link, and a set switching policy, and perform a half double when the switching condition is met. Switching between the worker relay mode and the multicast cooperative relay mode.

Further, the foregoing base station may further have the following features, where the mode switching decision unit is used. The switching strategy is:

When currently working in the half-duplex relay mode, the ratio of the effective channel rate value of the half-duplex relay mode to the effective channel rate value of the multicast cooperative relay mode is lower than the set rate proportional threshold, and the base station-mobile If the channel quality of the terminal link is higher than the set channel quality threshold, the mode is switched to the multicast cooperative relay mode; or

Further, the foregoing base station may also have the following features:

The relay mode control module further includes a mode selection unit connected to the effective channel rate calculation unit, the mode selection unit configured to receive an effective channel rate and a base station-mobile terminal chain in the two relay modes The channel quality of the road, select one of the following selection strategies to enable the trunk mode:

When the ratio of the effective channel rate value of the half duplex relay mode to the effective channel rate value of the multicast cooperative relay mode is lower than the rate proportional threshold, and the channel rate of the base station-mobile terminal link is higher than the channel quality threshold, Multicast cooperative relay mode; or

Further, the foregoing base station may further have the following feature: the rate switching threshold used by the mode switching decision unit ranges from 0.7 to 0.9, and the channel quality threshold ranges from 0 to 5 dB.

Compared with the prior art, according to the present invention, performance gain and capacity improvement in the relay mode with half-duplex and multicast coordination in relay forwarding can be achieved, and significant system gain can be obtained. In addition, the system is easy to implement based on existing mobile communication systems, and the cost of deployment is simple and the function upgrade is low. BRIEF abstract

1A and 1B are schematic diagrams showing the operation of the downlink half-duplex relay mode and the multicast cooperative relay mode, respectively.

2 is a functional block diagram of a base station in a two-hop relay system according to an embodiment of the present invention.

Figure 3 is a block diagram showing the structure of the mode control module of Figure 2.

4 is a block diagram showing the structure of a mode control module of another embodiment.

Figure 5 is a flow chart of a method of an embodiment of the present invention.

Preferred embodiment of the invention

The basic idea of the present invention is to simultaneously use a half-duplex and multicast cooperative relay mode in a two-hop relay system, and the base station switches between the two relay modes when the handover condition is satisfied according to the current channel condition. To work in the most suitable relay mode.

The present invention will be further described in conjunction with the accompanying drawings and embodiments in the claims. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The two-hop relay system of this embodiment is shown in Figs. 1A and 1B, and only the downlink case will be discussed here. The system includes: a base station 101, a relay station 102, and a mobile terminal 103. The base station 101 can transmit data to the relay station 102 and the mobile terminal 103, the relay station 102 forwards data between the base station 101 and the mobile terminal 103, and the mobile terminal 103 receives data from the base station 101 and the relay station 102 in the downlink.

Currently, in the half-duplex relay mode, in a first time period, such as a certain subframe time, the base station 101 transmits data to the relay station 102; in the second time period, such as the agreed time of another subframe. The relay station 102 transmits data to the mobile terminal 103. At this time, the base station 101 is in an idle state for the second time period, and does not occupy the frequency resources of the relay station and the mobile terminal link.

In the multicast cooperative relay mode, the base station 101 transmits data to the relay station 102 and the mobile terminal 103 in the first time period, and then, in the second time period, the base station 101 and the relay station 102 simultaneously transmit data to the mobile terminal 103. Here, in the second time period, the base station 101 will retransmit the data block transmitted at the first time period, and the relay station 102 transmits the data block received from the base station 101 at the first time period. Some related system simulation studies show that the multicast cooperative relay mode has higher system capacity, but the applicants believe that the relay system has its advantages in the half-duplex relay mode and the multicast cooperative relay mode. This is the result of a comprehensive evaluation based on both the increase in system capacity and the reliability of the signaling channel.

To clearly describe the use of R _eNB, - between _{_{NodeR, R N odeR-UE,}} ReNB-UE (l), shows a base station and a relay station between the relay station and the mobile terminal, the first period and the second base station and the mobile terminal The channel rate on the link between the base station and the mobile terminal during the two time periods.

According to the research results of related data, when the transmission between the base station and the relay station uses in-band transmission, in the multicast cooperative relay mode, the time-frequency resource is shared with the traffic channel, and the base station-relay-mobile terminal link The effective channel rate can be expressed by the following formula 1: Equation 1

Equation 2 shows the effective channel rate representation on the base-relay-mobile terminal link in half-duplex relay mode:

R eR ^NodeR-UE

Eff ( half -duplex) _ ^eNB-Nod

_ Ό _/ ^ ^—一^

^K eNB-NodeR + ^K NodeR-UE In general, when the channel condition/environment between the base station and the mobile terminal does not change significantly during the first time period and the second time period, R ^M^ ^ will not There is a big difference. Therefore, in the multicast cooperative relay mode, the gain relative to the half-duplex relay mode mainly comes from

+) IRNodeR-UE.

The above enumerated formula is only a calculation method of the effective channel rate. Other methods include empirical formulas, statistical lookup tables, and the like. However, in the related data, an advantage in the half-duplex relay mode is not recognized, that is, in the half-duplex mode, the base station does not transmit any data during the second period, which reduces/decreases the surrounding Cell interference has contributed, in other words, increased system throughput. At the same time, the half-duplex relay mode is also advantageous for a terminal in a poor environment, that is, when transmitting in a multicast cooperative relay mode, the R _e -u of the terminal in a poor geographical environment is Far below R--, so that the gain of the multicast cooperative relay mode becomes small and unimportant. The above scenario exists even if the factor that the half-duplex relay mode reduces interference to other cells is not considered. In addition, due to the poor geographical environment, the downlink signaling channel (PDCCH) reception is also very unreliable. In this case, it is preferable to use the relay station to transmit those scheduling information to the terminal, that is, the scheduling information is used in half duplex. Relay mode to transmit is more reliable than using multicast cooperative mode for transmission.

In the two-hop relay system of the present embodiment, the relay station and the mobile terminal can directly use the relay station and the mobile terminal in the original system, and details are not described herein again. The base station needs to perform a functional upgrade. In this embodiment, the base station is used to communicate with the relay station and the mobile terminal, and can work in a half-duplex relay mode or a multicast cooperative relay mode, when the set switching policy is met. , will switch from the current relay mode to another relay mode.

As shown in FIG. 2, the base station further includes: two sending modules, that is, a first sending module and a second sending module, and a relay mode control module, where:

The first sending module is configured to perform downlink signal transmission in a half-duplex relay mode, that is, to send data to the relay station in the first time period; and to be in an idle state in the second time period.

The second sending module is configured to send the downlink signal according to the multicast cooperative relay mode, that is, send the data to the relay station and the mobile terminal in the first time period, and then resend the transmission in the first time period in the second time period. Data to the mobile terminal;

The relay mode control module is configured to perform mode switching according to the current channel quality of the three links of the base station-relay station, the relay station-mobile terminal, and the base station-mobile terminal, and when the set switching policy is met, in the two relays Switching between modes, the output control signal enables the transmitting module corresponding to the mode switched to and stops the original transmitting module;

As shown in FIG. 3, the relay mode control module further includes three channel rate estimating units, an effective channel rate calculating unit, and a mode switching determining unit, where:

The three channel rate estimating units are respectively configured to estimate a channel on the corresponding link according to a channel quality indicator (CQI: Channel Quality Indicator) on the three links of the base station-relay station, the relay station-mobile terminal, and the base station-mobile terminal. rate station -? the relay station (R _E ed _oder, relay station - terminal (i.e., R deR-UE) and R the base station - terminal (including ReNB-UE R _e NB-UE in the above equation (2)), and outputs the effective channel Rate calculation unit. According to the design of current mobile communication systems, it is easy Channel quality information between the base station and the terminal, the relay station and the terminal, and the base station and the relay station are obtained. The effective channel rate calculation unit is configured to calculate an effective channel rate on the base-relay-mobile terminal link in the half-duplex relay mode and the multicast cooperative relay mode according to the estimated channel rates of the three links ( Can be calculated according to the above formula or other feasible methods), and output to the relay mode decision unit;

The mode switching decision unit is configured to perform mode switching according to an effective channel rate in two relay modes, a channel quality of the base station-mobile terminal link, and a set switching policy, and perform half-duplex when the switching condition is met. Following the switching between mode and multicast cooperative relay mode.

In this embodiment, the set switching strategy is as follows:

When the ratio of the effective channel rate value of the half duplex relay mode to the effective channel rate value of the multicast cooperative relay mode is lower than the rate proportional threshold, and the channel quality (CQI) of the base station-mobile terminal link is higher than the channel quality threshold And when currently working in the half duplex mode, switch to the multicast cooperative relay mode;

When the ratio of the effective channel rate value of the half duplex relay mode to the effective channel rate value of the multicast cooperative relay mode is higher than the rate proportional threshold or the channel quality of the base station-mobile terminal link is lower than the channel quality threshold (two ones) ) , and when currently working in the multicast cooperative relay mode, switch to the half duplex relay mode.

The rate proportional threshold can be chosen from 0.7 to 0.9. The channel quality threshold can be determined in conjunction with an estimate of the PDCCH performance, such as 0 to 5 dB.

In addition, a mode selection unit may be added in the relay mode control module, and the module is connected to the effective channel rate calculation unit, and also receives the effective channel rate in the two relay modes of the output, according to the two effective channel rates and The channel quality of the base station-mobile terminal link, and the set selection policy selects the relay mode that should be enabled. This selection strategy can be set to simultaneously compare two thresholds. They are the rate proportional threshold and the channel quality threshold, respectively. which is:

When the ratio of the effective channel rate value of the half duplex relay mode to the effective channel rate value of the multicast cooperative relay mode is lower than the rate proportional threshold, and the channel quality of the base station-mobile terminal link is higher than the channel quality threshold, Multicast cooperative relay mode;

The effective channel rate value of the half-duplex relay mode and the effective channel rate of the multicast cooperative relay mode The half-duplex relay mode is selected when the ratio of the rate is higher than the rate proportional threshold or the channel quality of the base-mobile terminal link is lower than the channel quality threshold.

Of course, the above mode switching and selection strategy is only an example, and is not intended to limit the present invention. In other embodiments, other manners may be used.

In another embodiment, as shown in FIG. 4, a PDCCH performance estimating unit is added to the relay mode control module, and the unit estimates the performance of the PDCCH in the base station-mobile terminal link according to the CQI on the base station-terminal link. The parameter is, for example, a PDCCH error rate and is output to the mode switching decision unit, and the mode switching decision unit uses the performance parameter of the PDCCH as a parameter in the decision condition when performing the mode decision. In addition, the performance parameter of the PDCCH may also be output to the mode selection unit (not shown), and when the mode selection unit selects the enabled relay mode, the performance parameter of the PDCCH is also used as a parameter in the decision condition. The performance estimation of the PDCCH can be obtained by looking up the table based on the link simulation result.

Correspondingly, as shown in FIG. 5, the method for switching the half-duplex and multicast cooperative relay mode in the two-hop relay system of the present invention includes the following steps:

Step 110: The base station estimates channel rates on the three links according to channel quality indicators on the three links of the base station-relay station, the relay station-mobile terminal, and the base station-mobile terminal.

Step 120: The base station calculates, according to the estimated channel rates of the three links, an effective channel rate in a half-duplex relay mode and an effective channel on a base station-relay-mobile terminal link in a multicast cooperative relay mode. Rate

Step 130: The base station performs mode switching according to an effective channel rate in two relay modes, a channel quality of the base station-mobile terminal link, and a set handover policy, and performs a half duplex relay mode when the handover condition is met. Switching between the multicast cooperative relay mode and the multicast.

When the base station is initialized, the relay mode to be enabled may also be selected according to the two effective channel rates and the channel rate of the base station-mobile terminal and the set selection policy. Examples of specific switching strategies and selection strategies are shown above.

It can be seen that the present invention proposes a handover mechanism of two-hop half-duplex and multicast cooperative relay mode. For the mobile communication relay system, in the relay mode of layer 2, two data transmission modes are used, that is, a half-duplex relay mode between the base station and the relay station, the mobile terminal, and the base station and the relay Multicast cooperative relay mode between stations and mobile terminals. The present invention particularly studies the necessity of supporting the above two relay modes, and proposes a mechanism for switching between the above two relay modes.

In the present invention, the half-duplex relay mode is adapted to a mobile terminal in a very harsh geographical environment. At this time, the detection of the downlink control channel (PDCCH) is very unreliable, and the performance gain by the relay station is Mainly due to good relay station and terminal link quality. In addition, the half-duplex relay mode reduces the interference of the base station to other cells, which is beneficial for increasing system capacity. The multicast cooperative relay mode is applicable to mobile terminals in a medium geographical environment. At this time, the detection of the downlink control channel (PDCCH) is relatively good, and the channel rate difference between the base station and the terminal and between the relay station and the terminal is relatively good. Within an order of magnitude. Therefore, it is also determined to select a half-duplex relay mode or a multicast cooperative relay mode to increase the base station-terminal channel quality threshold as a second reference.

Industrial applicability

Compared with the prior art, the present invention can achieve performance gain and capacity improvement in the relay mode with half-duplex and multicast coordination in relay forwarding, and significant system gain can be obtained. In addition, the system is easy to implement based on existing mobile communication systems, and the cost of deployment is simple and the upgrade is very low.

Claims

Claim

A method for switching a relay mode, the method comprising:

The base station estimates channel rates on the three links according to channel quality information on the three links of the base station-relay station, the relay station-mobile terminal, and the base station-mobile terminal;

Calculating, according to the estimated channel rates on the three links, the effective channel rate on the base station-relay-mobile terminal link in the half-duplex relay mode and the multicast cooperative relay mode; and the base station according to the half The effective channel rate in the duplex relay mode and the multicast cooperative relay mode, the channel quality of the base station-mobile terminal link, and the set handover policy are used for mode switching, and when the handover condition is satisfied, half-duplex is performed. Switching between mode and multicast cooperative relay mode;

2. The handover method according to claim 1, wherein the handover policy is:

When working in the half-duplex relay mode, the ratio of the effective channel rate value in the half-duplex relay mode to the effective channel rate value in the multicast cooperative relay mode is lower than the set rate proportional threshold, and the base station - if the channel quality of the mobile terminal link is higher than the set channel quality threshold, then switch to the multicast cooperative relay mode; or

When working in the multicast cooperative relay mode, for example, the ratio of the effective channel rate value in the half duplex relay mode to the effective channel rate value in the multicast cooperative relay mode is higher than the set rate proportional threshold, or the base station - If the channel quality of the mobile terminal link is lower than the set channel quality threshold, then switch to the half-duplex relay mode.

The handover method according to claim 1 or 2, wherein the channel quality information on the three links is a channel quality indicator.

4. The handover method of claim 1, the method further comprising:

During initialization, the base station selects a relay mode to be enabled according to the calculated effective channel rate on the base station-relay-mobile terminal link and the selected selection policy in the calculated half-duplex relay mode and the multicast cooperative relay mode. The selection strategy is:

Effective channel rate value in half-duplex relay mode and valid signal in multicast cooperative relay mode When the ratio of the channel rate value is lower than the rate proportional threshold, and the channel quality of the base station-mobile terminal link is higher than the channel quality threshold, the multicast cooperative relay mode is selected; or

When the ratio of the effective channel rate value in the half duplex relay mode to the effective channel rate value in the multicast cooperative relay mode is higher than the rate proportional threshold, or the channel quality of the base station-mobile terminal link is lower than the channel quality threshold , select the half duplex relay mode.

5. The switching method according to claim 2 or 4, wherein

The rate proportional threshold ranges from 0.7 to 0.9, and the channel quality threshold ranges from 0 to 5 dB.

A base station, where the base station includes: a first sending module, a second sending module, and a relay mode control module, where

The first sending module is configured to perform downlink signal transmission according to a half duplex relay mode; the second sending module is configured to perform downlink signal transmission according to a multicast cooperative relay mode; and

The relay mode control module is configured to perform a mode switching decision according to a current channel quality of the three links of the base station-relay station, the relay station-mobile terminal, and the base station-mobile terminal, and a set handover policy, when the handover condition is met, Switching between the two relay modes, outputting a control signal, enabling the transmitting module corresponding to the switched mode and stopping the original transmitting module;

7. The base station according to claim 6, wherein

The relay mode control module includes three channel rate estimation units, an effective channel rate calculation unit, and a mode switching decision unit, where:

The effective channel rate calculation unit is configured to calculate an effective channel rate on the base-relay-mobile terminal link in the half-duplex relay mode and the multicast cooperative relay mode according to the channel rates on the three links And outputting the effective channel rate to the relay mode decision unit; The mode switching decision unit is configured to perform mode switching according to an effective channel rate in a half duplex relay mode and a multicast cooperative relay mode, a channel quality of a base station-mobile terminal link, and a set handover policy. When the switching condition is satisfied, switching between the half duplex relay mode and the multicast cooperative relay mode is performed.

8. The base station according to claim 7, wherein the mode switching decision unit is configured to perform a mode switching decision using one of the following switching policies:

When working in the multicast cooperative relay mode, for example, the ratio of the effective channel rate value in the half-duplex relay mode to the effective channel rate value in the multicast cooperative relay mode is higher than the set rate proportional threshold or the base station - If the channel quality of the mobile terminal link is lower than the set channel quality threshold, the mode is switched to the half duplex relay mode.

9. The base station according to claim 7, wherein

The relay mode control module further includes a mode selection unit, and the mode selection unit is connected to the effective channel rate calculation unit;

The mode selection unit is configured to receive an effective channel rate in a half duplex relay mode and a multicast cooperative relay mode and a channel quality of a base station-mobile terminal link, and select a relay mode to be enabled according to one of the following selection policies :

When the ratio of the effective channel rate value in the half duplex relay mode to the effective channel rate value in the multicast cooperative relay mode is lower than the rate proportional threshold, and the channel rate of the base station-mobile terminal link is higher than the channel quality threshold , select the multicast cooperative relay mode; or

When the ratio of the effective channel rate value in the half duplex relay mode to the effective channel rate value in the multicast cooperative relay mode is higher than the rate proportional threshold or the channel quality of the base station-mobile terminal link is lower than the channel quality threshold, Select the half duplex relay mode.

10. The base station according to claim 8 or 9, wherein