CN105917594A

Movatterモバイル変換

Info

Publication number: CN105917594A
Application number: CN201480073526.0A
Authority: CN
Inventors: 布鲁诺·克勒克斯; 代明波; 朴在铉; 大卫·马瑞泽; 刘鹍鹏
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2014-12-11
Filing date: 2014-12-11
Publication date: 2016-08-31
Also published as: WO2016090611A1

Abstract

Translated fromChinese

本发明实施例公开了一种基站、移动台及其方法。一种移动台的通信方法，该移动台由基站服务，该基站具有至少一个传输点，每个该传输点配备有多个发射天线，该方法包括基于信道增益，从每个被选择的传输点的多个发射天线中为该传输点确定发射天线的最佳子集；以及向该基站报告该最佳子集中的发射天线的量化信道状态信息CSI。本发明实施例能够减少反馈开销。

The embodiment of the invention discloses a base station, a mobile station and a method thereof. A communication method for a mobile station served by a base station having at least one transmission point each equipped with a plurality of transmit antennas, the method comprising, based on channel gain, from each selected transmission point Determine the best subset of transmit antennas for the transmission point among the multiple transmit antennas; and report the quantized channel state information (CSI) of the transmit antennas in the best subset to the base station. The embodiments of the present invention can reduce feedback overhead.

Description

Translated fromChinese

基站、移动台及其方法Base station, mobile station and method thereof

技术领域technical field

本发明涉及移动通信技术领域，并且更具体地，涉及基站、移动台及其方法。The present invention relates to the technical field of mobile communication, and more specifically, to a base station, a mobile station and methods thereof.

背景技术Background technique

多天线系统，如大规模MIMO(多输入多输出)，在未来5G等通信系统中是一项具有发展前景的技术，它能够在频谱效率和简单TX/RX(发送/接收)结构方面实现极大的改进。理想情况下，TX天线越多，从基于完美CSIT(发送端信道状态信息)的天线选择获得的益处更大，这会产生巨大的反馈开销和成本。此外，每个天线的专用RF元件，如A/D(模拟到数字)转换器、D/A(数字到模拟)转换器以及放大器等，会产生巨大成本。Multi-antenna systems, such as massive MIMO (Multiple-Input Multiple-Output), are a promising technology in future communication systems such as 5G, which can achieve extreme Big improvement. Ideally, the more TX antennas there are, the greater the benefit from antenna selection based on perfect CSIT (channel state information at the transmitter), which incurs a huge feedback overhead and cost. In addition, dedicated RF components for each antenna, such as A/D (analog to digital) converters, D/A (digital to analog) converters, and amplifiers, incur significant costs.

在具有有限数量的RF(射频)链(或称为RF硬件)的多天线系统中，用于反馈的资源是有限的。因此，有必要对具有有限反馈和RF链的实践设置进行研究。In a multi-antenna system with a limited number of RF (radio frequency) chains (or called RF hardware), resources for feedback are limited. Therefore, research into practical settings with limited feedback and RF chains is warranted.

发明内容Contents of the invention

本发明实施例涉及用于减少反馈开销的基站、移动台及其方法。Embodiments of the present invention relate to a base station, a mobile station and a method for reducing feedback overhead.

第一方面，提供了一种移动台的通信方法，所述移动台由基站服务，所述基站具有至少一个传输点，每个所述传输点配备有多个发射天线，所述方法包括：基于信道增益，从每个被选择的传输点的多个发射天线中为所述传输点确定发射天线的最佳子集；以及向所述基站报告所述最佳子集中的发射天线的量化信道状态信息CSI。In a first aspect, a communication method for a mobile station is provided, the mobile station is served by a base station, the base station has at least one transmission point, and each transmission point is equipped with a plurality of transmitting antennas, the method includes: based on channel gain, determining an optimal subset of transmit antennas for each selected transmission point from among the plurality of transmit antennas for the transmission point; and reporting quantized channel states of the transmit antennas in the optimal subset to the base station Information CSI.

在根据第一方面的方法的第一种可能的实现方式中，所述为每个传输点确定发射天线的最佳子集包括：获取所述传输点的所述多个发射天线的所述信道增益；以及选择具有最大信道增益的发射天线作为所述最佳子集。In a first possible implementation manner of the method according to the first aspect, the determining the optimal subset of transmit antennas for each transmission point includes: acquiring the channels of the multiple transmit antennas of the transmission point gain; and selecting the transmit antenna with the greatest channel gain as the best subset.

在根据第一方面或根据第一方面的任一前述实现方式的方法的第二种可能的实现方式中，所述为每个传输点确定发射天线的最佳子集包括：获取所述传输点的所述多个发射天线的所述信道增益；以及选择所述信道增益大于阈值的发射天线作为所述最佳子集。In a second possible implementation of the method according to the first aspect or any of the preceding implementations of the first aspect, the determining the optimal subset of transmit antennas for each transmission point includes: acquiring the transmission point The channel gains of the plurality of transmit antennas; and selecting transmit antennas with the channel gains greater than a threshold as the best subset.

在根据第一方面或根据第一方面的任一前述实现方式的方法的第三种可能的实现方式中，所述方法还包括：向所述基站报告所述最佳子集中的发射天线的索引。In a third possible implementation of the method according to the first aspect or any of the preceding implementations of the first aspect, the method further includes: reporting the indices of the transmit antennas in the best subset to the base station .

在根据第一方面或根据第一方面的任一前述实现方式的方法的第四种可能的实现方式中，所述为每个传输点确定发射天线的最佳子集包括：基于从所述基站接收的指示信息确定所述最佳子集，所述指示信息指示由所述基站根据信道增益选择的所述最佳子集中的发射天线的索引。In a fourth possible implementation of the method according to the first aspect or any preceding implementation of the first aspect, the determining the optimal subset of transmit antennas for each transmission point includes: based on The best subset is determined by received indication information, where the indication information indicates indexes of transmit antennas in the best subset selected by the base station according to channel gain.

在根据第一方面或根据第一方面的任一前述实现方式的方法的第五种可能的实现方式中，所述向所述基站报告所述最佳子集中的发射天线的量化信道状态信息CSI包括：利用码本报告所述量化CSI，所述码本的大小取决于所述最佳子集的大小。In a fifth possible implementation of the method according to the first aspect or any of the preceding implementations of the first aspect, the reporting the quantized channel state information (CSI) of the transmit antennas in the best subset to the base station comprising: reporting the quantized CSI using a codebook whose size depends on the size of the best subset.

在根据第一方面或根据第一方面的任一前述实现方式的方法的第六种可能的实现方式中，所述方法还包括：从所述基站接收用于指示所述最佳子集的大小的大小信息；或在所述移动台处选择所述最佳子集的大小。In a sixth possible implementation of the method according to the first aspect or any of the preceding implementations of the first aspect, the method further includes: receiving from the base station a or select the size of the best subset at the mobile station.

在根据第一方面或根据第一方面的任一前述实现方式的方法的第七种可能的实现方式中，所述方法还包括：向所述基站报告所述最佳子集中的发射天线以外的发射天线的量化CSI。In a seventh possible implementation of the method according to the first aspect or any of the preceding implementations of the first aspect, the method further includes: reporting to the base station the Quantized CSI of the transmit antenna.

第二方面，提供了一种基站的通信方法，所述基站具有至少一个传输点，每个所述传输点配备有多个发射天线，所述方法包括：从移动台接收报告，所述报告用于报告基于信道增益从每个被选择的传输点的多个发射天线中为所述传输点确定的发射天线的最佳子集的量化信道状态信息CSI；以及基于所述量化CSI发送数据。In a second aspect, a communication method for a base station is provided, the base station has at least one transmission point, and each transmission point is equipped with a plurality of transmitting antennas, the method includes: receiving a report from a mobile station, and the report uses for reporting quantized channel state information (CSI) of a best subset of transmit antennas determined for each selected transmission point from among a plurality of transmit antennas of each selected transmission point based on channel gain; and transmitting data based on the quantized CSI.

在根据第二方面的方法的第一种可能的实现形式中，所述方法还包括：获取所述传输点的所述多个发射天线的所述信道增益；以及选择具有最大信道增益的发射天线作为所述最佳子集。In a first possible implementation form of the method according to the second aspect, the method further includes: acquiring the channel gains of the multiple transmit antennas of the transmission point; and selecting the transmit antenna with the largest channel gain as the best subset.

在根据第二方面或根据第二方面的任一前述实现形式的方法的第二种可能的实现形式中，所述方法还包括：获取所述传输点的所述多个发射天线的所述信道增益；以及选择所述信道增益大于阈值的发射天线作为所述最佳子集。In a second possible implementation form of the method according to the second aspect or any preceding implementation form of the second aspect, the method further includes: acquiring the channels of the multiple transmit antennas of the transmission point gain; and selecting transmit antennas with channel gains greater than a threshold as the best subset.

在根据第二方面或根据第二方面的任一前述实现形式的方法的第三种可能的实现方式中，所述方法还包括向移动台发送指示信息，所述指示信息用于向移动台指示所述最佳子集中的发射天线的索引。In a third possible implementation of the method according to the second aspect or any of the aforementioned implementation forms of the second aspect, the method further includes sending indication information to the mobile station, the indication information is used to indicate to the mobile station Indexes of transmit antennas in the best subset.

在根据第二方面或根据第二方面的任一前述实现形式的方法的第四种可能的实现方式中，所述方法还包括从移动台接收指示信息，所述指示信息用于指示由所述移动台根据信道增益选择的所述最佳子集中的发射天线的索引。In a fourth possible implementation manner of the method according to the second aspect or any of the foregoing implementation forms of the second aspect, the method further includes receiving indication information from the mobile station, the indication information being used to indicate that the Indexes of transmit antennas in the best subset selected by the mobile station based on channel gain.

在根据第二方面或根据第二方面的任一前述实现形式的方法的第五种可能的实现方式中，所述方法还包括所述量化CSI的所述报告使用码本，所述码本的大小取决于所述最佳子集的大小。In a fifth possible implementation manner of the method according to the second aspect or any of the foregoing implementation forms of the second aspect, the method further includes that the reporting of the quantized CSI uses a codebook, and the codebook of The size depends on the size of the best subset.

在根据第二方面或根据第二方面的任一前述实现形式的方法的第六种可能的实现方式中，从所述移动台接收用于指示所述最佳子集的大小的大小信息；或在所述基站处选择所述最佳子集的大小。In a sixth possible implementation of the method according to the second aspect or according to any preceding implementation form of the second aspect, size information indicating the size of the best subset is received from the mobile station; or The size of the optimal subset is selected at the base station.

在根据第二方面或根据第二方面的任一前述实现形式的方法的第七种可能的实现方式中，所述方法还包括从移动台接收报告，所述报告用于报告所述最佳子集中的发射天线以外的发射天线的量化CSI。In a seventh possible implementation of the method according to the second aspect or any preceding implementation form of the second aspect, the method further includes receiving a report from a mobile station, the report being used to report the best sub- Quantized CSI for transmit antennas other than the concentrated transmit antenna.

第三方面，提供了一种移动台，所述移动台由基站服务，所述基站具有至少一个传输点，每个所述传输点配备有多个发射天线，所述移动台包括：确定单元，用于基于信道增益，从每个被选择的传输点的多个发射天线中为所述传输点确定发射天线的最佳子集；以及报告单元，用于向基站报告所述最佳子集中的发射天线的量化信道状态信息CSI。In a third aspect, a mobile station is provided, the mobile station is served by a base station, the base station has at least one transmission point, and each transmission point is equipped with multiple transmitting antennas, the mobile station includes: a determination unit, Determining an optimal subset of transmit antennas for each selected transmission point from multiple transmit antennas of each selected transmission point based on channel gain; and a reporting unit configured to report to the base station the optimal subset of The quantized channel state information CSI of the transmitting antenna.

在根据第三方面的移动台的第一种可能的实现形式中，所述确定单元用于获取所述传输点的所述多个发射天线的所述信道增益，并选择具有最大信道增益的发射天线作为所述最佳子集。In a first possible implementation form of the mobile station according to the third aspect, the determination unit is configured to acquire the channel gains of the multiple transmit antennas of the transmission point, and select the transmit antenna with the largest channel gain antennas as the best subset.

在根据第三方面或根据第三方面的任一前述实现形式的移动台的第二种可能的实现方式中，所述确定单元用于获取所述传输点的所述多个发射天线的所述信道增益，并选择所述信道增益大于阈值的发射天线作为所述最佳子集。In a second possible implementation manner of the mobile station according to the third aspect or any of the foregoing implementation forms of the third aspect, the determination unit is configured to acquire the channel gain, and selecting transmit antennas with channel gains greater than a threshold as the best subset.

在根据第三方面或根据第三方面的任一前述实现形式的移动台的第三种可能的实现方式中，所述报告单元还用于向基站报告所述最佳子集中的发射天线的索引。In a third possible implementation manner of the mobile station according to the third aspect or any of the aforementioned implementation forms of the third aspect, the reporting unit is further configured to report the index of the transmit antenna in the best subset to the base station .

在根据第三方面或根据第三方面的任一前述实现形式的移动台的第四种可能的实现方式中，所述确定单元用于基于从所述基站接收的指示信息确定所述最佳子集，所述指示信息指示由所述基站根据信道增益选择的所述最佳子集中的发射天线的索引。In a fourth possible implementation manner of the mobile station according to the third aspect or any one of the foregoing implementation forms of the third aspect, the determining unit is configured to determine the best subclass based on indication information received from the base station. set, the indication information indicates indexes of transmit antennas in the best subset selected by the base station according to channel gain.

在根据第三方面或根据第三方面的任一前述实现形式的移动台的第五种可能的实现方式中，所述报告单元用于利用码本报告量化CSI，所述码本的大小取决于所述最佳子集的大小。In a fifth possible implementation manner of the mobile station according to the third aspect or any of the aforementioned implementation forms of the third aspect, the reporting unit is configured to report quantized CSI using a codebook, the size of the codebook depends on The size of the optimal subset.

在根据第三方面或根据第三方面的任一前述实现形式的移动台的第六种可能的实现方式中，所述确定单元还用于基于从所述基站接收的大小信息确定所述最佳子集的大小，或在所述移动台处选择所述最佳子集的大小。In a sixth possible implementation manner of the mobile station according to the third aspect or any of the foregoing implementation forms of the third aspect, the determining unit is further configured to determine the optimal The size of the subset, or the size of the best subset is selected at the mobile station.

在根据第三方面或根据第三方面的任一前述实现形式的移动台的第七种可能的实现方式中，所述报告单元还用于向所述基站报告所述最佳子集中的发射天线以外的发射天线的量化CSI。In a seventh possible implementation manner of the mobile station according to the third aspect or any of the aforementioned implementation forms of the third aspect, the reporting unit is further configured to report the transmit antennas in the optimal subset to the base station Quantized CSI of other transmit antennas.

第四方面，提供了一种基站，所述基站具有至少一个传输点，每个所述传输点配备有多个发射天线，所述基站包括：接收机，用于从移动台接收报告，所述报告报告基于信道增益从每个被选择的传输点的多个发射天线中为所述传输点确定的发射天线的最佳子集的量化信道状态信息CSI；以及发射机，用于基于所述量化CSI发送数据。In a fourth aspect, a base station is provided, the base station has at least one transmission point, each of the transmission points is equipped with a plurality of transmitting antennas, the base station includes: a receiver, configured to receive a report from a mobile station, the reporting quantized channel state information CSI for each selected transmission point from a plurality of transmit antennas determined for the transmission point based on channel gain for the optimal subset of transmit antennas; CSI sends data.

在根据第四方面的基站的第一种可能的实现形式中，所述基站还包括处理器，用于获取所述传输点的所述多个发射天线的所述信道增益，并选择具有最大信道增益的发射天线作为所述最佳子集。In a first possible implementation form of the base station according to the fourth aspect, the base station further includes a processor, configured to obtain the channel gains of the multiple transmit antennas of the transmission point, and select the channel gain with the largest Gain transmit antennas as the best subset.

在根据第四方面或根据第四方面的任一前述实现形式的基站的第二种可能的实现形式中，所述基站还包括处理器，用于获取所述传输点的所述多个发射天线的所述信道增益，并选择所述信道增益大于阈值的发射天线作为所述最佳子集。In a second possible implementation form of the base station according to the fourth aspect or any of the foregoing implementation forms of the fourth aspect, the base station further includes a processor configured to acquire the multiple transmit antennas of the transmission point The channel gain of , and selecting the transmit antennas whose channel gains are greater than a threshold as the best subset.

在根据第四方面或根据第四方面的任一前述实现形式的基站的第三种可能的实现方式中，所述发射机还用于向移动台发送指示信息，所述指示信息用于向移动台指示所述最佳子集中的发射天线的索引。In a third possible implementation manner of the base station according to the fourth aspect or any of the foregoing implementation forms of the fourth aspect, the transmitter is further configured to send indication information to the mobile station, and the indication information is used to send the mobile station The station indicates the index of the transmit antenna in the best subset.

在根据第四方面或根据第四方面的任一前述实现形式的基站的第四种可能的实现方式中，所述接收机还用于从移动台接收指示信息，所述指示信息用于指示由所述移动台根据信道增益选择的所述最佳子集中的发射天线的索引。In a fourth possible implementation manner of the base station according to the fourth aspect or any of the foregoing implementation forms of the fourth aspect, the receiver is further configured to receive indication information from the mobile station, the indication information is used to indicate that the Indexes of transmit antennas in the best subset selected by the mobile station based on channel gain.

在根据第四方面或根据第四方面的任一前述实现形式的基站的第五种可能的实现方式中，所述量化CSI的所述报告使用码本，所述码本的大小取决于所述最佳子集的大小。In a fifth possible implementation manner of the base station according to the fourth aspect or any preceding implementation form of the fourth aspect, the reporting of the quantized CSI uses a codebook, and the size of the codebook depends on the The size of the optimal subset.

在根据第四方面或根据第四方面的任一前述实现形式的基站的第六种可能的实现方式中，所述接收机还用于从所述移动台接收用于指示所述最佳子集的大小的大小信息；或所述基站还包括处理器，用于在所述基站处选择所述最佳子集的大小。In a sixth possible implementation manner of the base station according to the fourth aspect or any one of the foregoing implementation forms of the fourth aspect, the receiver is further configured to receive, from the mobile station, an or the base station further includes a processor configured to select the optimal subset size at the base station.

在根据第四方面或根据第四方面的任一前述实现形式的基站的第七种可能的实现方式中，所述接收机还用于从移动台接收报告，所述报告用于报告所述最佳子集中的发射天线以外的发射天线的量化CSI。In a seventh possible implementation manner of the base station according to the fourth aspect or any preceding implementation form of the fourth aspect, the receiver is further configured to receive a report from a mobile station, the report is used to report the latest Quantized CSI for transmit antennas other than those in the best subset.

因此，本发明实施例基于信道增益选择发射天线的最佳子集，并对所选择的子集进行反馈，从而减少反馈开销。Therefore, the embodiment of the present invention selects the best subset of transmit antennas based on the channel gain, and performs feedback on the selected subset, thereby reducing feedback overhead.

附图说明Description of drawings

为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

图1示出了可应用本发明的大规模MIMO系统的例子。Fig. 1 shows an example of a massive MIMO system to which the present invention can be applied.

图2示出了本发明一个实施例的方法。Figure 2 illustrates the method of one embodiment of the invention.

图3示出了根据本发明一个实施例的天线选择的增益的例子。Fig. 3 shows an example of the gain selected by the antenna according to one embodiment of the present invention.

图4示出了根据本发明另一实施例的天线选择的增益的例子。Fig. 4 shows an example of gain selected by an antenna according to another embodiment of the present invention.

图5示出了根据本发明另一实施例的天线选择的增益的例子。Fig. 5 shows an example of the gain selected by the antenna according to another embodiment of the present invention.

图6示出了根据本发明另一实施例的天线选择的增益的例子。Fig. 6 shows an example of the gain selected by the antenna according to another embodiment of the present invention.

图7示出了本发明另一实施例的方法。Fig. 7 shows a method of another embodiment of the present invention.

图8示出了本发明一个实施例的移动台的框图。Figure 8 shows a block diagram of a mobile station according to one embodiment of the present invention.

图9示出了本发明另一实施例的移动台的框图。FIG. 9 shows a block diagram of a mobile station according to another embodiment of the present invention.

图10示出了本发明一个实施例的基站的框图。Fig. 10 shows a block diagram of a base station according to an embodiment of the present invention.

具体实施方式detailed description

下面将结合这些实施例的附图，对本发明实施例中的技术方案进行清楚、完整地描述。显然，所描述的实施例仅仅是本发明的一部分实施例，而不是全部的实施例。基于这些实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其它实施例，都属于本发明保护的范围。The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings of these embodiments. Apparently, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on these embodiments, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

将天线的子集切换到RF链可以显著提高系统的总和容量。这就表明，可用天线比RF链越多，天线子集选择增益越大。根据提出的有效搜索算法选择天线，与穷举搜索几乎实现了最优性能。然而，该搜索算法假定了完美CSIT，完美CSIT在大规模MIMO系统中尤为不可行，因为反馈开销太大，无法承担。另一方面，在有限反馈的条件下，发射天线越多，并不一定出现更好的和速率性能，因为量化质量差。随着发射天线数量的增加，量化CSI质量下降，多用户干扰就会限制系统性能。Switching a subset of antennas to the RF chain can significantly increase the aggregate capacity of the system. This shows that the more antennas than RF chains available, the greater the antenna subset selection gain. Antennas are selected according to the proposed efficient search algorithm, which almost achieves optimal performance with exhaustive search. However, this search algorithm assumes perfect CSIT, which is especially infeasible in massive MIMO systems because the feedback overhead is too large to afford. On the other hand, under the condition of limited feedback, more transmit antennas does not necessarily lead to better sum-rate performance because of poor quantization quality. As the number of transmit antennas increases, the quantized CSI quality degrades, and multi-user interference limits system performance.

图1示出了可应用本发明的大规模MIMO系统的例子，该系统包括BS(基站)，其服务于K个MS(移动台)：MS 1到MS K。Figure 1 shows an example of a Massive MIMO system to which the present invention can be applied, the system comprising a BS (Base Station) serving K MSs (Mobile Stations): MS 1 to MS K.

该BS配备有大型天线(N_T)和数量有限的RF链(N_RF)，即N_T>＝N_RF。为了充分了解系统性能是如何与RF链的数量相关的，将考虑两种不同的情况(N_T>N_RF或N_T＝N_RF)。为了最大化系统(速率)性能，选择发射天线的子集，并将其切换到RF链。选择过程可以在接收机侧进行，并通过有限的回程资源来报告相应的CSI。我们假设为独立同分布(i.i.d.)瑞利信道。The BS is equipped with a large antenna (N_T ) and a limited number of RF chains (N_RF ), ie N_T >= N_RF . In order to fully understand how the system performance is related to the number of RF chains, two different cases (_NT > N_RF or_NT = N_RF ) will be considered. To maximize system (rate) performance, a subset of transmit antennas is selected and switched to the RF chain. The selection process can be performed at the receiver side, and the corresponding CSI is reported through limited backhaul resources. We assume an independent identically distributed (iid) Rayleigh channel.

对于SU MISO(单用户，多输入单输出)的情况，用以最大化速率的优化波束赋形策略是需要准确CSIT的匹配波束赋形(MBF)。然而，以有限的反馈来报告所有CSI会导致大的量化损失。另一方面，可通过仅反馈部分CSI来实现较高的准确性。自然地，该想法是选择和报告最强信道(具有最大幅值)。由于波束赋形增益与所选择的天线的数量成正比，所以这必然会打破量化质量和波束赋形增益之间的优化权衡。实际上，该方法可以被解释为利用有限反馈的混合选择/MBF。For the case of SU MISO (Single User, Multiple Input Single Output), the optimal beamforming strategy to maximize the rate is Matched Beamforming (MBF) which requires accurate CSIT. However, reporting all CSI with limited feedback results in a large quantification loss. On the other hand, higher accuracy can be achieved by feeding back only part of the CSI. Naturally, the idea is to select and report the strongest channel (with the largest magnitude). Since beamforming gain is proportional to the number of antennas selected, this necessarily breaks the optimal trade-off between quantization quality and beamforming gain. In fact, the method can be interpreted as hybrid selection/MBF with limited feedback.

对于MU MISO(多用户，多输入单输出)的情况，每个MS报告最重要的CSI(具有最大信道增益)，发射机将未报告的CSI视为零。基于部分信道信息考虑迫零(ZF)波束赋形策略。利用大规模发射天线，MS报告互相非重叠天线子集的概率就会高。然后，用于取消多用户干扰的ZF波束赋形器也是期望信号的匹配的波束赋形。的确，由于已报告的CSI的不完美性和未报告的CSI，还有残余的多用户干扰。但是，如果可用反馈比特能担负所选择的天线子集的大小，第一个因素可以克服。由于未报告信道的信道增益很小，所以第二个因素可以忽略。总之，当我们获得的增益超过传统的MU MISO系统，多路复用增益就能实现。For the MU MISO (Multiple User, Multiple Input Single Output) case, each MS reports the most significant CSI (with maximum channel gain), and the transmitter treats unreported CSI as zero. A zero-forcing (ZF) beamforming strategy is considered based on partial channel information. With a large number of transmit antennas, the probability of an MS reporting mutually non-overlapping antenna subsets is high. Then, the ZF beamformer used to cancel the multi-user interference is also the matched beamforming of the desired signal. Indeed, there is residual multi-user interference due to the imperfection of reported CSI and unreported CSI. However, the first factor can be overcome if the available feedback bits can afford the size of the selected antenna subset. Since the channel gain of the unreported channel is small, the second factor can be neglected. In conclusion, multiplexing gain can be achieved when we obtain gain over traditional MU MISO system.

此外，如果我们能消除天线选择开销，系统性能就可以得到进一步提升。由于MS需要向BS通知所选择的天线子集，所以在大规模MIMO系统中导致的开销会非常大。在文献中，已对FDD系统中从下行(上行)链路到上行(下行)链路的可预测性进行了研究。这表明，在某种程度上，信道排序信息(COI)对于BS而言是已知的。在这种模式下，所有的反馈比特可用于量化信道。为了揭示潜在的增益，我们将对有/无天线选择开销的情况进行研究。Furthermore, if we can eliminate the antenna selection overhead, the system performance can be further improved. Since the MS needs to inform the BS of the selected antenna subset, the overhead incurred in massive MIMO systems can be very large. In the literature, the predictability from downlink (uplink) to uplink (downlink) in FDD systems has been studied. This suggests that, to some extent, the channel ordering information (COI) is known to the BS. In this mode, all feedback bits are available for quantizing the channel. In order to reveal the potential gain, we will study with/without antenna selection overhead.

假定为接收机处优选CSI(CSIR)，每个MS处有“B”个反馈比特可用。在每个时刻，MS的接收机首先基于瞬时CSI选择具有最大幅值的最强信道，并利用随机向量量化(RVQ)向BS的发射机报告选择组合的索引和对应的CSI。对于“B”个反馈比特，传统/参考方案被定义为N_T＝N_RF。本发明试图研究所提方案何时会优于参考方案，以及增益如何随着NT和B成比例变化。即，本发明提出如何通过动态天线选择在实际设置(有限的反馈和RF链)下最大限度地获取天线选择增益。Assuming preferred CSI at the receiver (CSIR), there are "B" feedback bits available at each MS. At each moment, the receiver of the MS first selects the strongest channel with the largest magnitude based on the instantaneous CSI, and reports the index of the selected combination and the corresponding CSI to the transmitter of the BS using Random Vector Quantization (RVQ). For "B" feedback bits, the legacy/reference scheme is defined as N_T =N_RF . The present invention attempts to investigate when the proposed scheme outperforms the reference scheme and how the gain scales with NT and B. That is, the present invention proposes how to maximize antenna selection gain under practical settings (limited feedback and RF chain) through dynamic antenna selection.

图2示出了本发明一个实施例的通信方法。图2的方法由MS执行，例如，如图1所示的MS 1到MS K中的一个，该MS由BS服务，该BS具有至少一个传输点，每个传输点配备有多个发射天线。Fig. 2 shows a communication method of an embodiment of the present invention. The method in FIG. 2 is performed by MSs, for example, one of MS 1 to MS K shown in FIG. 1 , the MS is served by a BS having at least one transmission point each equipped with multiple transmit antennas.

201、该MS基于信道增益，从每个被选择的传输点的多个发射天线中为该传输点确定发射天线的最佳子集。201. The MS determines an optimal subset of transmit antennas for each selected transmission point from multiple transmit antennas of each selected transmission point based on channel gain.

BS可包括一个或多个传输点，如天线阵列、天线组、DA(分布式天线)元件等。如图1所示，每个传输点配备有多个(N_T)发射天线，其中，对于不同的传输点，N_T可以不同或固定。A BS may include one or more transmission points, such as antenna arrays, antenna groups, DA (distributed antenna) elements, and the like. As shown in FIG. 1 , each transmission point is equipped with multiple (_NT ) transmitting antennas, where_NT may be different or fixed for different transmission points.

202、该MS向该BS报告该最佳子集中的发射天线的量化CSI。202. The MS reports the quantized CSI of the transmit antennas in the best subset to the BS.

具体地，最佳子集具有所有发射天线中最显著的CSI。最佳子集之外的其他发射天线的CSI可以不报告，这样反馈开销就会减少，同时这类非完美CSI报告引起的负面影响也能控制在一个可接受的范围。Specifically, the best subset has the most significant CSI among all transmit antennas. The CSI of other transmitting antennas outside the optimal subset may not be reported, so that the feedback overhead will be reduced, and at the same time, the negative impact caused by such non-perfect CSI reporting can also be controlled within an acceptable range.

子集选择可以在MS处执行。作为提出的非限制方案，在步骤201中，MS可以获取传输点的所有多个发射天线的信道增益，并选择具有最大信道增益的发射天线作为该最佳子集。Subset selection can be performed at the MS. As a proposed non-limiting solution, in step 201, the MS can obtain channel gains of all multiple transmit antennas of a transmission point, and select the transmit antenna with the largest channel gain as the best subset.

下面将所提方案与参考方案进行比较，其中，随机选择N_T个天线中的N_RF个进行发送。In the following, the proposed scheme is compared with the reference scheme, in which N_RF antennas among_NT antennas are randomly selected for transmission.

SU情况1：无RF链约束，有选择开销SU case 1: No RF chain constraint, with selection overhead

考虑所提方案，其中从N_T个天线中选出M个，平均输出SNR表示为：Considering the proposed scheme, where M antennas are selected from_NT antennas, the average output SNR is expressed as:

其中，in,

且输入SNR＝P/σ²通过波束赋形来增强，通过量化来减弱。波束赋形增益由两项组成：前一项表示阵列增益，后一项代表天线选择增益。为了向发射机(BS)通知选择了哪些天线，使用有效比特对选择的CSI进行量化的同时，接收机(MS)使用某些比特(选择开销)来发送天线子集的索引。And the input SNR=P/σ² is enhanced by beamforming and weakened by quantization. The beamforming gain consists of two terms: the former represents the array gain and the latter represents the antenna selection gain. In order to inform the transmitter (BS) which antennas are selected, while the selected CSI is quantized using effective bits, the receiver (MS) uses some bits (selection overhead) to transmit the index of the antenna subset.

利用N_T个天线的参考方案的平均输出SNR表示为：The average output SNR of the reference scheme using_NT antennas is expressed as:

${SNR SNR}_{r r e e f f} = = \frac{P P}{{σ σ}^{22}} \cdot &Center Dot; {N N}_{T T} \cdot &Center Dot; ((11 - - 22^{- - \frac{B B}{{N N}_{T T} - - 11}})) - - - - - - ((33))$

可以看出，(1)<＝(3)，这表明该情况下所提方案不提供增益。利用所有N_T个天线是较好的选择。It can be seen that (1)<=(3), which indicates that the proposed scheme provides no gain in this case. Utilizing all N_T antennas is a better choice.

SU情况2：有RF链约束，有选择开销SU case 2: with RF chain constraints, with selection overhead

考虑所提方案，其中从N_T个天线中选出N_RF个，平均输出SNR表示为：Considering the proposed scheme, where N_RF antennas are selected from_NT antennas, the average output SNR is expressed as:

$S S N N R R__c c a a n no d d = = \frac{P P}{{σ σ}^{22}} \cdot &Center Dot; (({N N}_{R R F f} + + {N N}_{R R F f} \cdot &Center Dot; {Σ Σ}_{n no = = {N N}_{R R F f} + + 11}^{{N N}_{T T}} \frac{11}{n no})) \cdot &Center Dot; ((11 - - 22^{- - \frac{{B B}_{e e f f f f}}{{N N}_{R R F f} - - 11}})) - - - - - - ((44))$

其中，in,

而从N_T个天线中随机选择N_RF个的参考方案的平均输出SNR表示为：And the average output SNR of the reference scheme with randomly selected N_RF antennas from_NT antennas is expressed as:

$S S N N R R__r r e e f f = = \frac{P P}{{σ σ}^{22}} \cdot \cdot {N N}_{R R F f} \cdot \cdot ((11 - - 22^{- - \frac{B B}{{N N}_{R R F f} - - 11}})) - - - - - - ((66))$

应注意，(6)是一个相对于N_RF的单调递增函数，最终在下面一个固定点达到饱和：It should be noted that (6) is a monotonically increasing function with respect to_NRF , eventually saturating at a fixed point as follows:

$\underset{{N N}_{R R F f} &RightArrow; &Right Arrow; ∞ ∞}{lim lim} {SNR SNR}_{r r e e f f} = = \frac{P P}{{σ σ}^{22}} \cdot &Center Dot; B B \cdot \cdot l l n no ((22)) - - - - - - ((77))$

这仅是输入SNR和B的函数，它表明在有限反馈的条件下，我们宁可利用尽可能多的RF链。然而，由RF链增加而获得的边际增益却变得越来越小。另一方面，对于固定数量的RF链，识别出所提方案比参考方案具有增益的B和N_T的临界点，同时也对增益随着B和N_T发生的变化进行了研究。This is only a function of the input SNR and B, and it shows that under the condition of limited feedback, we would rather utilize as much RF chain as possible. However, the marginal gain obtained by increasing the RF chain becomes smaller and smaller. On the other hand, for a fixed number of RF chains, the critical points of B and_NT where the proposed scheme has gain over the reference scheme are identified, and the variation of the gain with B and_NT is also studied.

a)固定N_RF和N_Ta) Fixed N_RF and_NT

借助于调和级数(harmonic series)和二项式系数，With the help of harmonic series and binomial coefficients,

$\begin{matrix} S S N N R R__c c a a n no d d &GreaterEqual; &Greater Equal; S S N N R R__r r e e f f,, λ λ = = {log log}_{22} (((\begin{matrix} {N N}_{T T} \\ {N N}_{R R F f} \end{matrix}))) / / (({N N}_{R R F f} - - 11)) \\ &DoubleRightArrow; &DoubleRightArrow; B B &GreaterEqual; &Greater Equal; (({N N}_{B B F f} - - 11)) {log log}_{22} {{[[((11 + + log log ((\frac{{N N}_{T T}}{{N N}_{R R F f}})))) 22^{λ λ} - - 11]] / / log log ((\frac{{N N}_{T T}}{{N N}_{R R F f}}))}} \end{matrix} - - - - - - ((88))$

为了实现一些增益，反馈比特的数量应满足(4)。增益ΔSNR＝In order to achieve some gain, the number of feedback bits should satisfy (4). Gain ΔSNR =

SNR_cand-SNR_ref如下成比例变化SNR_cand-SNR_ref changes proportionally as follows

$ΔSNR ΔSNR ~ ~ ((α α - - 22^{{- - γ γ}^{B B}})) - - - - - - ((99))$

其中，α和γ是独立于B的常数。当B趋于无限大时，where α and γ are constants independent of B. When B tends to infinity,

${ΔSNR ΔSNR}_{d d B B} = = 1010 {log log}_{1010} \frac{((44))}{((66))} = = 1010 {log log}_{1010} [[11 + + l l o o g g ((\frac{{N N}_{T T}}{{N N}_{R R F f}}))]] - - - - - - ((1010))$

例如N_T/N_RF＝50,ΔSNR_dB＝7dB。增益随log(N_T)成比例变化。For example, N_T /N_RF =50, ΔSNR_dB =7dB. Gain varies proportionally with log(N_T ).

b)固定N_RF和Bb) Fixed N_RF and B

$S S N N R R__c c a a n no d d &GreaterEqual; &Greater Equal; S S N N R R__r r e e f f &DoubleRightArrow; &DoubleRightArrow; x x &GreaterEqual; &Greater Equal; 22^{\frac{- - B B}{{N N}_{R R F f} - - 11}} ((((11 + + x x)) 22^{\frac{{N N}_{R R F f}}{(({N N}_{R R F f} - - 11)) l l o o g g ((22))} \cdot &Center Dot; x x + + μ μ} - - 11)) - - - - - - ((1111))$

假设N_T/N_RF≥e, Assuming N_T /N_RF ≥ e,

应注意，(8)是(7)的充分条件。然后，我们得到N_T的临界点It should be noted that (8) is a sufficient condition for (7). Then, we get the critical point of N_T

$&DoubleRightArrow; &DoubleRightArrow; {N N}_{R R F f} \leq \leq {N N}_{T T} \leq \leq {N N}_{R R F f} \cdot &Center Dot; exp exp [[\frac{l l o o g g ((22)) ((B B - - ((μ μ + + 11)) (({N N}_{R R F f} - - 11))))}{{N N}_{R R F f}}]] - - - - - - ((1313))$

$μ μ = = \frac{{N N}_{R R F f}}{{N N}_{R R F f} - - 11} {log log}_{22} ((e e)) - - \frac{{N N}_{R R F f}}{22 (({N N}_{R R F f} - - 11))} {log log}_{22} ((22 {πN πN}_{R R F f})) - - - - - - ((1414))$

这表明比率是有界的，即，为了从有限B的所提方案实现增益，N_T/N_RF≤ρ(B,N_RF)。随着N_T增加，选择开销接近/超过可用比特的数量，且有效/残余比特的数量太小，无法准确地量化信道。与现有技术相比，增加TX天线的数量并不总是对我们有利。当B很小或N_T很大时，所提方案还不及参考方案。我们可以通过增加B或减小N_T来获得增益。This suggests that the ratio is bounded, ie,_NT /N_RF ≤ ρ(B, N_RF ) in order to achieve gain from the proposed scheme with finite B. As_NT increases, the selection overhead approaches/exceeds the number of available bits, and the number of effective/residual bits is too small to accurately quantize the channel. Increasing the number of TX antennas is not always in our favor compared to existing technologies. When B is small or_NT is large, the proposed scheme is not as good as the reference scheme. We can gain gain by increasing B or decreasing_NT .

c)固定N_RF、N_T和Bc) Fix N_RF ,_NT and B

在这种情况下，所提方案可能不及参考方案。可以通过利用部分RF链获得增益。通过这种方式，选择开销会减少，更多反馈比特会使量化准确性更高。同时，发射阵列增益变得更低，应采取优化过程来实现使用部分RF链的优缺点之间的最佳平衡。In this case, the proposed solution may be inferior to the reference solution. Gain can be obtained by utilizing part of the RF chain. In this way, selection overhead is reduced and more feedback bits lead to higher quantization accuracy. At the same time, the transmit array gain becomes lower and an optimization process should be taken to achieve the best balance between the advantages and disadvantages of using part of the RF chain.

将M表示为所用RF链的数量，找到最优M<＝N_RF以最大化平均输出SNR，并反馈相应的CSI子集。将通用优化函数定义为如下：Denoting M as the number of RF chains used, find the optimal M <= N_RF to maximize the average output SNR, and feed back the corresponding CSI subset. Define the generic optimization function as follows:

${S S}_{M m} = = arg arg \underset{M m &Element; &Element; [[11,, {N N}_{R R F f}]]}{max max} \underset{{S S}_{M m} &Subset; &Subset; {{(\begin{matrix} {N N}_{T T} \\ M m \end{matrix})}}}{max max} f f ((S S N N R R)) - - - - - - ((1515))$

这需要复杂的穷举搜索算法来实现最优解。幸好，我们的情况中用低复杂度选择方法来最大化SNR。更具体地，通过幅值对信道进行排序，并报告最大的那些。This requires complex exhaustive search algorithms to achieve the optimal solution. Fortunately, in our case a low-complexity selection method is used to maximize the SNR. More specifically, the channels are sorted by magnitude and the largest ones are reported.

该情况下平均输出SNR表示为：The average output SNR in this case is expressed as:

$S S N N R R__c c a a n no d d ((M m)) = = \frac{P P}{{σ σ}^{22}} \cdot \cdot ((M m + + M m \cdot \cdot {Σ Σ}_{n no = = M m + + 11}^{{N N}_{T T}} \frac{11}{n no})) \cdot &Center Dot; ((11 - - 22^{- - \frac{{B B}_{e e f f f f}}{M m - - 11}})),, 11 \leq \leq M m \leq \leq {N N}_{R R F f} - - - - - - ((1616))$

由于耦合性质，很难获得使所提方案优于参考方案的M的闭式解。需要1<M<＝N_RF的数值优化过程。这表明所提方案至少提供了增益的下界。当B很大时，利用所有RF链是最优的，(16)归结为(4)。否则，数值优化(16)，并将其与参考方案对比，然后确定要增加B还是减小N_T。Due to the coupled nature, it is difficult to obtain a closed-form solution of M that makes the proposed scheme better than the reference scheme. A numerical optimization process of 1<M<=N_RF is required. This shows that the proposed scheme at least provides a lower bound on the gain. When B is large, utilizing all RF chains is optimal, and (16) boils down to (4). Otherwise, optimize numerically (16), compare it to a reference solution, and decide whether to increase B or decrease N_T .

假设发射机已经预先知道信道排序信息(COI)，则可以进一步改进所提方案。对于FDD系统，我们可以根据下行链路信道预测上行链路信道，反之亦然。简言之，就是可以使用有限阶自回归(AR)过程来对上行/下行链路上的频率选择性衰落(能量)进行建模。当上/下行载波频率的相对偏差很小时，表明两个链路共享共同的AR系数。因此，两个链路经受相似的变化趋势。为此，发射机处COI的假设是有效的，并且选择开销也消除了。为了揭示潜在的增益，我们再次考虑上面两种无选择开销的情况。Assuming that the transmitter already knows the channel ordering information (COI) in advance, the proposed scheme can be further improved. For FDD systems, we can predict the uplink channel from the downlink channel and vice versa. In short, it is possible to model frequency-selective fading (energy) on the uplink/downlink using a finite-order autoregressive (AR) process. When the relative deviation of the uplink/downlink carrier frequency is small, it indicates that the two links share a common AR coefficient. Therefore, both links undergo similar trends. For this, the assumption of COI at the transmitter is valid and the selection overhead is eliminated. To reveal the potential gain, we again consider the above two cases with no selection overhead.

SU情况3：无RF链约束，无选择开销SU case 3: No RF chain constraint, no selection overhead

假设选择了M个天线，所提方案的平均输出SNR表示为：Assuming that M antennas are selected, the average output SNR of the proposed scheme is expressed as:

$\begin{matrix} {SNR SNR}_{c c a a n no d d} = = \frac{P P}{{σ σ}^{22}} \cdot \cdot ((M m + + M m \cdot &Center Dot; {Σ Σ}_{n no = = M m + + 11}^{{N N}_{T T}} \frac{11}{n no})) \cdot \cdot ((11 - - 22^{- - \frac{B B}{M m - - 11}})) & M m &Element; &Element; [[11,, {N N}_{T T}]] \end{matrix} - - - - - - ((1717))$

而参考方案利用所有的N_T个天线：Whereas the reference scheme utilizes all_NT antennas:

${SNR SNR}_{r r e e f f} = = \frac{P P}{{σ σ}^{22}} \cdot &Center Dot; {N N}_{T T} \cdot \cdot ((11 - - 22^{- - \frac{B B}{{N N}_{T T} - - 11}})) - - - - - - ((1818))$

很难导出使所提方案优于参考方案，即(17)>(18)，的M的闭合表达式。然而，通过蒙特卡罗(Monte-Carlo)仿真很容易看出，通过选择部分发射天线，增益就能实现。该增益取决于NT、NRF和B。图3给出的例子中，存在所提方案优于参考方案的下界。通过CSI准确性与波束赋形增益之间的折中，在中间区域实现最大增益。It is difficult to derive a closed expression for M that makes the proposed scheme better than the reference scheme, ie (17) > (18). However, it is easy to see through Monte-Carlo simulations that by selecting a fraction of the transmit antennas, the gain can be achieved. This gain depends on NT, NRF and B. In the example given in Fig. 3, there is a lower bound that the proposed scheme is better than the reference scheme. Through the trade-off between CSI accuracy and beamforming gain, the maximum gain is achieved in the middle region.

SU情况4：有RF链约束，无选择开销SU Case 4: With RF chain constraints, no selection overhead

$\begin{matrix} {SNR SNR}_{c c a a n no d d} = = \frac{P P}{{σ σ}^{22}} \cdot \cdot ((M m + + M m \cdot \cdot {Σ Σ}_{n no = = M m + + 11}^{{N N}_{T T}} \frac{11}{n no})) \cdot &Center Dot; ((11 - - 22^{- - \frac{B B}{M m - - 11}})) & M m &Element; &Element; [[11,, {N N}_{R R F f}]] \end{matrix} - - - - - - ((1919))$

而参考方案从N_T个天线中随机选出N_RF个：The reference scheme randomly selects N_RF antennas from_NT antennas:

${SNR SNR}_{r r e e f f} = = \frac{P P}{{σ σ}^{22}} \cdot \cdot {N N}_{R R F f} \cdot \cdot ((11 - - 22^{- - \frac{B B}{{N N}_{R R F f} - - 11}})) - - - - - - ((2020))$

由于参考方案的性能因有限的RF链而变差，所以与SU情况3相比，获得的增益会更多，如图3所示，其中曲线“Pro”和“Ref”分别对应所提方案和参考方案。Since the performance of the reference scheme is degraded by the limited RF chain, more gains are obtained compared to SU case 3, as shown in Fig. 3, where the curves “Pro” and “Ref” correspond to the proposed scheme and Reference plan.

接下来，考虑多用户MISO广播信道(BC)，采用迫零波束赋形策略获取多路复用增益。非完美报告的CSI以及未报告的CSI会导致残余多用户干扰的存在。所提方案与上述SU情况相同，同时提供了两个参考方案。Next, considering the multi-user MISO broadcast channel (BC), a zero-forcing beamforming strategy is adopted to obtain the multiplexing gain. Imperfectly reported CSI as well as unreported CSI will lead to the existence of residual multi-user interference. The proposed scheme is the same as the case of SU mentioned above, and two reference schemes are provided at the same time.

所提方案：对信道增益进行排序，选择最大的M，并报告所选子集的索引和该子集相应的CSIProposed scheme : sort the channel gains, select the largest M, and report the index of the selected subset and the corresponding CSI of the subset

参考方案1：固定MS的数量为Nu，并报告用于发送的前M个天线(等价地，随机从N_T个天线中选出M个)的CSIReference scheme 1 : the number of fixed MSs is Nu, and the CSI of the first M antennas (equivalently, randomly selected from_NT antennas) for transmission is reported

参考方案2：固定MS的数量，等于所报告的天线的数量(Nu＝M)，并报告用于发送的前M个天线(等价地，随机从N_T个天线中选出M个)的CSIReference solution 2 : The number of fixed MSs is equal to the number of reported antennas (Nu=M), and the number of the first M antennas used for transmission (equivalently, M antennas are randomly selected from_NT antennas) is reported. CSI

MU情况1：无RF链约束，有选择开销MU case 1: No RF chain constraints, with selection overhead

所提方案的平均速率表示为：The average rate of the proposed scheme is expressed as:

${R R}_{c c a a n no d d} = = M m \cdot &Center Dot; {E E.}_{H h,, W W} [[log log ((11 + + \frac{P P / / M m \cdot &Center Dot; | | {h h}_{i i}^{H h} {v v}_{max max,, i i} {| |}^{22}}{11 + + P P / / M m \cdot &Center Dot; \underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} | | {h h}_{i i}^{H h} {v v}_{max max,, j j} {| |}^{22}}))]] - - - - - - ((21 twenty one))$

其中，信道和RVQ码本上采用了期望值。V_max,i表示将未报告CSI视为零，用部分(最大信道增益)CSI计算出的波束赋形向量。同时，两个参考方案的平均速率表达为Among them, the expected value is adopted on the channel and the RVQ codebook. V_max,i represents the beamforming vector calculated with partial (maximum channel gain) CSI, considering unreported CSI as zero. Meanwhile, the average rate of the two reference schemes is expressed as

${R R}_{r r e e f f 11} = = {N N}_{u u} \cdot &Center Dot; {E E.}_{H h,, W W} [[log log ((11 + + \frac{P P / / {N N}_{u u} \cdot &Center Dot; | | {h h}_{i i}^{H h} {v v}_{i i} {| |}^{22}}{11 + + P P / / {N N}_{u u} \cdot &Center Dot; \underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} | | {h h}_{i i}^{H h} {v v}_{j j} {| |}^{22}}))]] - - - - - - ((22 twenty two))$

${R R}_{r r e e f f 22} = = M m \cdot \cdot {E E.}_{H h,, W W} [[l l o o g g ((11 + + \frac{P P / / M m \cdot &Center Dot; | | {h h}_{i i}^{H h} {v v}_{i i} {| |}^{22}}{11 + + P P / / M m \cdot &Center Dot; \underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} | | {h h}_{i i}^{H h} {v v}_{j j} {| |}^{22}}))]] - - - - - - ((23 twenty three))$

随后可以导出(22)和(23)的闭式近似值，而闭式表达式仍然是开放的。然而，通过图4中的模拟(如曲线401至403所示)，我们可以看出，由于选择开销较大，所提方案无法提供优于参考方案的增益，尤其在大规模发射天线系统中。同样，我们可以在发射机处用COI消除此开销。Closed-form approximations to (22) and (23) can subsequently be derived, while the closed-form expressions remain open. However, through the simulation in Fig. 4 (shown by curves 401 to 403), we can see that the proposed scheme cannot provide better gain than the reference scheme due to the large selection overhead, especially in large-scale transmit antenna systems. Again, we can remove this overhead with COI at the transmitter.

MU情况2：无RF链约束，无选择开销MU case 2: No RF chain constraint, no selection overhead

该情况中，所提方案与两个参考方案相比，实际上实现了增益，因为In this case, the proposed scheme actually achieves a gain compared to the two reference schemes because

1)它忽略了选择开销，并获得与参考方案1和2相同的CSI质量；1) It ignores the selection overhead and achieves the same CSI quality as reference schemes 1 and 2;

2)它通过报告最显著的信道而保持了大部分信道信息；以及2) It preserves most of the channel information by reporting the most significant channel; and

3)如果MS选择互相非重叠子集，在已报告的子集上的简单匹配的波束赋形也是其他MS的ZFBF；由于其源于未报告的信道(具有相对较小的信道增益)，所以多用户干扰很小。3) If MSs choose mutually non-overlapping subsets, simple matched beamforming on the reported subset is also ZFBF for other MSs; since it originates from an unreported channel (with relatively small channel gain), so Multi-user interference is minimal.

图5示出了所提方案获得的增益超过两个参考方案的模拟结果。Fig. 5 shows the simulation results of the gain obtained by the proposed scheme over two reference schemes.

从曲线501至503可以看出，中间的M实现了最大增益。原因如下：对于小的M，CSI的量化具有高质量，同时高概率的非重叠子集带来高波束赋形增益。但是，由于存在很多未报告的CSI，这就对应于低多路复用增益和大的多用户干扰。另一方面，大的M(接近N_T)正好与此相反。因此，中间的M实现了这些因素之间的最佳平衡。It can be seen from the curves 501 to 503 that M in the middle achieves the maximum gain. The reason is as follows: for small M, the quantization of CSI is of high quality, while high probability of non-overlapping subsets leads to high beamforming gain. However, since there is a lot of unreported CSI, this corresponds to low multiplexing gain and large multi-user interference. On the other hand, large M (near_NT ) is just the opposite. Therefore, the M in the middle achieves the best balance between these factors.

应注意，增益很大程度上取决于非重叠子集，这同时有利于ZF和匹配的波束赋形。已报告的部分CSI的数量必须可比于N_T，否则多用户干扰会降低系统性能。另一方面，如果Nu的数量固定，Nt的数量增加，我们最终会得到非重叠子集。但是由于未报告CSI的数量更大，多用户干扰会占优势。It should be noted that the gain strongly depends on the non-overlapping subsets, which favors both ZF and matched beamforming. The number of reported fractional CSIs must be comparable to N_T , otherwise multi-user interference will degrade system performance. On the other hand, if the number of Nu is fixed and the number of Nt is increased, we end up with non-overlapping subsets. But due to the larger amount of unreported CSI, multi-user interference will dominate.

然而，随着N_T增加，并且如果发射机可以动态地决定MS的数量，MS的最佳数量也会增加。通过这种方式，用户间干扰可以较小(我们反馈足够数量的显著CSI)。然后，我们等价地使得Nu与SU-MISO情况相当。对于每个MS，我们已经表示出，当N_T逐渐增大时，边际增益变小。这从图6可以看出。However, as_NT increases, and if the transmitter can dynamically decide the number of MSs, the optimal number of MSs also increases. In this way, inter-user interference can be small (we feed back a sufficient amount of significant CSI). We then equivalently make Nu comparable to the SU-MISO case. For each MS, we have shown that the marginal gain becomes smaller as_NT increases gradually. This can be seen from Figure 6.

当MS的数量非常大时，所提方案易于与多用户分集相结合，即，选择具有非重叠子集的MS进行发送。MS的数量和每个MS的所报告CSI的数量应由发射机基于总速率的闭式/近似值来确定。给定N_T和B，通过最大化总速率表达式来完成，该总速率表达式是N_T、B和M的函数。也需要MS选择算法。When the number of MSs is very large, the proposed scheme is easy to combine with multi-user diversity, ie select MSs with non-overlapping subsets for transmission. The number of MSs and the number of reported CSI per MS shall be determined by the transmitter based on a close-form/approximation of the aggregate rate. Given_NT and B, this is done by maximizing the overall rate expression as a function of_NT , B and M. The MS selection algorithm is also required.

虽然通过仿真看出所提方案的增益大于参考方案的增益，但是分析结果仍将有助于了解这些系统参数对速率性能的影响。此处我们给出(22)和(23)的闭式近似值，并对计算封闭表达式(21)提供指导。Although the gain of the proposed scheme is greater than that of the reference scheme through simulation, the analysis results will still help to understand the influence of these system parameters on the rate performance. Here we give closed-form approximations to (22) and (23), and provide guidance for computing the closed expression (21).

$\begin{matrix} {R R}_{r r e e f f 11} = = N N u u \cdot &Center Dot; {E E.}_{H h,, W W} [[log log ((11 + + \frac{P P / / N N u u \cdot &Center Dot; | | {H h}_{i i}^{H h} {v v}_{i i} {| |}^{22}}{11 + + P P / / N N u u \cdot \cdot \underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} | | {h h}_{i i}^{H h} {v v}_{j j} {| |}^{22}}))]] \approx \approx N N u u \cdot \cdot log log ((11 + + \frac{P P / / N N u u \cdot \cdot {E E.}_{H h,, W W} {{| | {h h}_{i i}^{H h} {v v}_{i i} {| |}^{22}}}}{11 + + P P / / N N u u \cdot &Center Dot; \underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} {E E.}_{H h,, W W} {{| | {h h}_{i i}^{H h} {v v}_{j j} {| |}^{22}}}})) \\ = = N N u u \cdot &Center Dot; log log ((11 + + \frac{\frac{P P}{N N u u} \cdot &Center Dot; ((M m - - N N u u + + 11))}{11 + + \frac{P P}{N N u u} \cdot &Center Dot; M m \cdot &Center Dot; \underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} \frac{11}{M m - - 11} 22^{\frac{- - B B}{M m - - 11}}})) = = N N u u \cdot &Center Dot; log log ((11 + + \frac{P P \cdot &Center Dot; ((M m - - N N u u + + 11)) / / N N u u}{11 + + P P \cdot \cdot \frac{N N u u - - 11}{N N u u} \cdot \cdot \frac{M m}{M m - - 11} \cdot \cdot 22^{\frac{- - B B}{M m - - 11}}})) \end{matrix} - - - - - - ((24 twenty four))$

$\begin{matrix} {R R}_{r r e e f f 22} = = M m \cdot \cdot {E E.}_{H h,, W W} [[log log ((11 + + \frac{P P / / M m \cdot \cdot | | {h h}_{i i}^{H h} {v v}_{i i} {| |}^{22}}{11 + + P P / / M m \cdot \cdot \underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} | | {h h}_{i i}^{H h} {v v}_{j j} {| |}^{22}}))]] \approx \approx M m \cdot &Center Dot; log log ((11 + + \frac{P P / / M m \cdot &Center Dot; {E E.}_{H h,, W W} {{| | {h h}_{i i}^{H h} {v v}_{i i} {| |}^{22}}}}{11 + + P P / / M m \cdot &Center Dot; \underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} {E E.}_{H h,, W W} {{| | {h h}_{i i}^{H h} {v v}_{j j} {| |}^{22}}}})) \\ = = M m \cdot &Center Dot; log log ((11 + + \frac{\frac{P P}{M m} \cdot &Center Dot; M m \cdot &Center Dot; \frac{11}{M m}}{11 + + \frac{P P}{M m} \cdot \cdot M m \cdot \cdot \underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} \frac{11}{M m - - 11} 22^{\frac{- - B B}{M m - - 11}}})) = = M m \cdot \cdot log log ((11 + + \frac{P P / / M m}{11 + + P P \cdot &Center Dot; 22^{\frac{- - B B}{M m - - 11}}})) \end{matrix} - - - - - - ((2525))$

$\begin{matrix} {R R}_{c c a a n no d d} = = M m \cdot \cdot {E E.}_{H h,, W W} [[log log ((11 + + \frac{P P / / M m \cdot &Center Dot; | | {h h}_{i i}^{H h} {v v}_{max max,, i i} {| |}^{22}}{11 + + P P / / M m \cdot \cdot \underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} | | {h h}_{i i}^{H h} {v v}_{max max,, j j} {| |}^{22}}))]] \\ \approx \approx M m \cdot &Center Dot; log log ((11 + + \frac{P P / / M m \cdot &Center Dot; {E E.}_{H h,, W W} {{| | {h h}_{i i}^{H h} {v v}_{max max,, i i} {| |}^{22}}}}{11 + + P P / / M m \cdot &Center Dot; {E E.}_{H h,, W W} {{\underset{j j &NotEqual; &NotEqual; i i}{Σ Σ} | | {h h}_{i i}^{H h} {v v}_{max max,, j j} {| |}^{22}}}})) \end{matrix} - - - - - - ((2626))$

为了计算(26)的分子和分母中的期望值，我们需要建立概率模型来表示平均波束赋形增益(主要是由来自非重叠子集的匹配波束赋形增益来确定)。To compute the expected value in the numerator and denominator of (26), we need to build a probabilistic model representing the average beamforming gain (mainly determined by the matched beamforming gains from non-overlapping subsets).

MU情况3：有RF链约束，无选择开销MU case 3: with RF chain constraints, no selection overhead

在该情况中，非常重要的是如何将RF链切换到部分发射天线。RF切换需要通过穷举搜索在发射机处进行优化。应注意，MU情况3给出了MU情况2的下界。仿真结果表明，所提方案不及MU情况2，但其增益仍然大于参考方案的增益。In this case, it is very important how the RF chain is switched to part of the transmit antenna. RF switching needs to be optimized at the transmitter by exhaustive search. It should be noted that MU case 3 gives a lower bound for MU case 2. Simulation results show that the proposed scheme is inferior to MU case 2, but its gain is still greater than that of the reference scheme.

可替换地，作为另一实施例，替代或除基于增益排序的选择外，子集选择可以基于由通信系统的控制器(如基站中的控制功能)决定和配置的阈值。Alternatively, as another embodiment, instead of or in addition to the selection based on gain ranking, the subset selection may be based on a threshold decided and configured by a controller of the communication system (such as a control function in a base station).

具体地，在步骤201中，MS可以获取该传输点的多个发射天线的信道增益，并选择该信道增益大于阈值的发射天线作为最佳子集。Specifically, in step 201, the MS may acquire channel gains of multiple transmit antennas of the transmission point, and select transmit antennas whose channel gains are greater than a threshold as the best subset.

可选地，作为另一实施例，最佳子集以外的发射天线的CSI可以进一步报告给BS。即，最佳子集以外的部分或全部发射天线可以组成一个较弱子集，MS可以为该较弱子集报告CSI。该较弱子集的选择可以与最佳子集的选择相似，例如，基于信道增益的排序并选择信道增益最小者，或基于另一阈值，以选择信道增益低于该阈值的发射天线。作为另一实施例，该较弱子集可以简单地是选择最佳子集后的剩余天线。Optionally, as another embodiment, the CSI of transmit antennas other than the optimal subset may be further reported to the BS. That is, some or all transmit antennas other than the best subset may form a weaker subset, and the MS may report CSI for the weaker subset. The selection of the weaker subset may be similar to the selection of the best subset, for example, based on ranking of channel gains and selecting the one with the smallest channel gain, or based on another threshold to select transmit antennas with channel gains lower than the threshold. As another example, the weaker subset may simply be the remaining antennas after selecting the best subset.

可替换地，子集选择可以在BS侧执行，执行方式类似于上述在MS侧的执行方式，此情况中，在步骤201中，MS可以基于从基站接收的指示信息确定最佳子集，该指示信息指示由该基站根据信道增益选择的该最佳子集中的发射天线的索引。Alternatively, the subset selection may be performed on the BS side in a manner similar to the above-mentioned execution manner on the MS side. In this case, in step 201, the MS may determine the best subset based on the indication information received from the base station, the The indication information indicates indexes of transmit antennas in the best subset selected by the base station according to channel gain.

进一步，当MS确定最佳子集和/或较弱子集时，MS可以向BS报告这些子集中的发射天线的索引。另一方面，当BS确定最佳子集和/或较弱子集时，BS可以向MS指示这些子集中的发射天线的索引。Further, when the MS determines the best subset and/or the weaker subset, the MS may report the indices of the transmit antennas in these subsets to the BS. On the other hand, when the BS determines the best subset and/or the weaker subset, the BS may indicate to the MS the indices of the transmit antennas in these subsets.

可选地，MS可以利用码本报告所述量化CSI，该码本的大小取决于该最佳子集的大小。Alternatively, the MS may report the quantized CSI using a codebook whose size depends on the size of the best subset.

最佳子集的大小可以由BS确定，该情况中，MS可以从基站接收用于指示该最佳子集的大小的大小信息。或者该最佳子集的大小可以由MS本身决定，例如，MS可以选择该最佳子集的大小。The size of the best subset may be determined by the BS, in which case the MS may receive size information indicating the size of the best subset from the base station. Or the size of the optimal subset can be determined by the MS itself, for example, the MS can select the size of the optimal subset.

总之，MS可以遵循以下行为：In summary, MS can follow the following behavior:

1)如果BS或传输点的RF链的数量等于发射天线的数量，则MS报告所有发射天线的量化CSI，即，最佳子集等于整个可用天线组。1) If the number of RF chains of the BS or transmission point is equal to the number of transmit antennas, the MS reports the quantized CSI for all transmit antennas, i.e. the best subset is equal to the entire set of available antennas.

2)如果BS或传输点的RF链的数量少于发射天线的数量，且如果请求MS报告大小等于RF链的数量的天线子集，则只要可用反馈比特的数量大于一定阈值(为发射天线的数量与RF链的数量的函数)，MS选择和报告最佳天线子集和该子集的量化CSI，否则，该MS报告预定义的天线组(其数量等于RF链的数量)的量化CSI。2) If the number of RF chains of the BS or transmission point is less than the number of transmit antennas, and if the MS is requested to report a subset of antennas whose size is equal to the number of RF chains, then as long as the number of available feedback bits is greater than a certain threshold (for the number of transmit antennas function of the number of antennas and the number of RF chains), the MS selects and reports the best antenna subset and the quantized CSI of the subset, otherwise, the MS reports the quantized CSI of the predefined antenna group (the number of which is equal to the number of RF chains).

3)如果BS或传输点的RF链的数量少于发射天线的数量，且如果对于给定数量的反馈比特，请求MS报告大小等于RF链的数量的天线子集，则只要发射天线的数量小于一定阈值(为反馈比特的数量与RF链的数量的函数)，则MS报告最佳天线子集和该子集的量化CSI，否则，该MS报告预定义天线组(其数量等于RF链的数量)的量化CSI。3) If the number of RF chains of the BS or transmission point is less than the number of transmit antennas, and if, for a given number of feedback bits, the MS is requested to report a subset of antennas whose size is equal to the number of RF chains, then as long as the number of transmit antennas is less than A certain threshold (a function of the number of feedback bits and the number of RF chains), the MS reports the best antenna subset and the quantized CSI of the subset, otherwise, the MS reports a predefined antenna group (the number of which is equal to the number of RF chains ) quantified CSI.

4)如果BS或传输点的RF链的数量少于发射天线的数量，且如果MS不限于报告任一特定天线子集大小，则MS选择最佳天线子集并报告其索引和相应的量化CSI。该情况中，天线子集大小可以严格小于RF链的数量。4) If the number of RF chains of the BS or transmission point is less than the number of transmit antennas, and if the MS is not limited to reporting any particular antenna subset size, the MS selects the best antenna subset and reports its index and corresponding quantized CSI . In this case, the antenna subset size can be strictly smaller than the number of RF chains.

总之，在有限的反馈和/或RF链约束下，通过动态的和用户特定的天线选择，增加TX天线的数量在SU/MU MISO场景中是有益的。In summary, increasing the number of TX antennas is beneficial in SU/MU MISO scenarios with dynamic and user-specific antenna selection under limited feedback and/or RF chain constraints.

图7示出了本发明另一实施例的通信方法。图7的方法由BS执行，如图1所示的BS，该BS具有至少一个传输点，每个传输点配备有多个发射天线。Fig. 7 shows a communication method according to another embodiment of the present invention. The method in FIG. 7 is executed by a BS, such as the BS shown in FIG. 1 , the BS has at least one transmission point, and each transmission point is equipped with multiple transmitting antennas.

701、该BS从MS接收报告，该报告用于报告基于信道增益从每个被选择的传输点的多个发射天线中为该传输点确定的发射天线的最佳子集的量化信道状态信息CSI。701. The BS receives a report from the MS, and the report is used to report the quantized channel state information (CSI) of the best subset of transmit antennas determined for the transmission point from the plurality of transmit antennas of each selected transmission point based on the channel gain .

702、该BS基于该量化CSI发送数据。702. The BS sends data based on the quantized CSI.

图7的方法过程与图2的方法过程对应或相似，因此，此处不再详述。The method process in FIG. 7 corresponds to or is similar to the method process in FIG. 2 , and therefore, will not be described in detail here.

可选地，子集选择可以在BS处执行，在此情况下，在步骤701中，该BS可以获取传输点的多个发射天线的信道增益，并选择具有最大信道增益的发射天线作为该最佳子集。Optionally, the subset selection may be performed at the BS. In this case, in step 701, the BS may obtain the channel gains of multiple transmit antennas of the transmission point, and select the transmit antenna with the largest channel gain as the optimal channel gain. Jiaziji.

可替换地，在步骤701中，该BS可以获取传输点的多个发射天线的信道增益，并选择该信道增益大于阈值的发射天线作为该最佳子集。可替换地，作为另一实施例，子集选择可以在MS处执行，在此情况下，在步骤701中，该BS可以从移动台接收指示信息，该指示信息用于指示由该移动台根据信道增益选择的最佳子集中的发射天线的索引。Alternatively, in step 701, the BS may obtain channel gains of multiple transmit antennas of a transmission point, and select transmit antennas whose channel gains are greater than a threshold as the optimal subset. Alternatively, as another embodiment, subset selection may be performed at the MS, in this case, in step 701, the BS may receive indication information from the mobile station, the indication information is used to indicate that the mobile station selects the subset according to The index of the transmit antenna in the best subset for channel gain selection.

可选地，作为另一实施例，最佳子集以外的发射天线的CSI可以进一步报告给BS。即，最佳子集以外的部分或全部发射天线可以组成一个较弱子集，MS可以为该较弱子集报告CSI。该较弱子集的选择可以与最佳子集的选择相似，例如，可以基于信道增益的排序并选择信道增益最小者，或基于另一阈值，以选择信道增益小于该阈值的发射天线。作为另一实施例，较弱子集可以简单地是选择最佳子集后的剩余天线。Optionally, as another embodiment, the CSI of transmit antennas other than the optimal subset may be further reported to the BS. That is, some or all transmit antennas other than the best subset may form a weaker subset, and the MS may report CSI for the weaker subset. The selection of the weaker subset may be similar to the selection of the best subset, for example, it may be based on sorting of channel gains and selecting the one with the smallest channel gain, or based on another threshold, so as to select transmit antennas with channel gains smaller than the threshold. As another example, the weaker subset may simply be the remaining antennas after selecting the best subset.

进一步地，当MS确定最佳子集和/或较弱子集时，MS可以向BS报告这些子集中发射天线的索引。另一方面，当BS确定最佳子集和/或较弱子集时，BS可以向MS指示这些子集中发射天线的索引，例如，通过向MS发送相应的指示信息。Further, when the MS determines the best subset and/or the weaker subset, the MS may report to the BS the indices of the transmit antennas in these subsets. On the other hand, when the BS determines the best subset and/or the weaker subset, the BS may indicate to the MS the indices of the transmit antennas in these subsets, for example, by sending corresponding indication information to the MS.

可选地，MS可以使用码本报告量化CSI，该码本的大小取决于最佳子集的大小。Alternatively, the MS can report quantized CSI using a codebook whose size depends on the size of the best subset.

最佳子集的大小可以由BS决定，该情况中，MS可以从该基站接收用于指示该最佳子集的大小的大小信息；或该最佳子集的大小可以由MS本身来决定，例如，该MS可以选择该最佳子集的大小。The size of the optimal subset may be determined by the BS, and in this case, the MS may receive size information indicating the size of the optimal subset from the base station; or the size of the optimal subset may be determined by the MS itself, For example, the MS can choose the size of the best subset.

图8示出了本发明一实施例中的移动台的框图。移动台80由基站服务，该基站具有至少一个传输点，每个该传输点配备有多个发射天线。如图8所示，该移动台包括确定单元81和报告单元82。Fig. 8 shows a block diagram of a mobile station in an embodiment of the present invention. The mobile station 80 is served by a base station having at least one transmission point each equipped with a plurality of transmitting antennas. As shown in FIG. 8 , the mobile station includes a determining unit 81 and a reporting unit 82 .

确定单元81，用于基于信道增益，从每个被选择的传输点的多个发射天线中为该传输点确定发射天线的最佳子集。The determining unit 81 is configured to determine an optimal subset of transmitting antennas for each selected transmission point from the multiple transmitting antennas of the selected transmission point based on the channel gain.

报告单元82，用于向基站报告该最佳子集中的发射天线的量化信道状态信息CSI。The reporting unit 82 is configured to report the quantized channel state information CSI of the transmit antennas in the best subset to the base station.

移动台80的部件可以实现基于图1至图6的实施例中所述的MS相关的相应过程，为简便起见，此处不再赘述。The components of the mobile station 80 can implement the corresponding procedures related to the MS described in the embodiments based on FIG. 1 to FIG.

可选地，作为一实施例，确定单元81用于获取传输点的多个发射天线的信道增益，并选择具有最大信道增益的发射天线作为该最佳子集。Optionally, as an embodiment, the determining unit 81 is configured to acquire channel gains of multiple transmit antennas of the transmission point, and select a transmit antenna with a maximum channel gain as the optimal subset.

可选地，作为另一实施例，确定单元81用于获取传输点的多个发射天线的信道增益，并选择该信道增益大于阈值的发射天线作为最佳子集。Optionally, as another embodiment, the determining unit 81 is configured to obtain channel gains of multiple transmit antennas of the transmission point, and select transmit antennas whose channel gains are greater than a threshold as an optimal subset.

可选地，作为另一实施例，报告单元82还用于向基站报告该最佳子集中的发射天线的索引。Optionally, as another embodiment, the reporting unit 82 is further configured to report the index of the transmit antenna in the best subset to the base station.

可选地，作为另一实施例，确定单元81用于基于从基站接收的指示信息确定最佳子集，该指示信息指示由该基站根据信道增益选择的最佳子集中的发射天线的索引。Optionally, as another embodiment, the determining unit 81 is configured to determine the best subset based on indication information received from the base station, where the indication information indicates indices of transmit antennas in the best subset selected by the base station according to channel gain.

可选地，作为另一实施例，报告单元82用于利用码本报告量化CSI，该码本的大小取决于该最佳子集的大小。Optionally, as another embodiment, the reporting unit 82 is configured to use a codebook to report the quantized CSI, and the size of the codebook depends on the size of the optimal subset.

可选地，作为另一实施例，确定单元81还用于基于从该基站接收的大小信息确定该最佳子集的大小，或在该移动台处选择该最佳子集的大小。Optionally, as another embodiment, the determining unit 81 is further configured to determine the size of the optimal subset based on the size information received from the base station, or select the size of the optimal subset at the mobile station.

可选地，作为另一实施例，报告单元82还用于向该基站报告该最佳子集中的发射天线以外的发射天线的量化CSI。Optionally, as another embodiment, the reporting unit 82 is further configured to report the quantized CSI of the transmitting antennas other than the transmitting antennas in the optimal subset to the base station.

图9示出了本发明另一实施例中的移动台的框图。Fig. 9 shows a block diagram of a mobile station in another embodiment of the present invention.

如图9所示，移动台90包括处理器91，发射机92和接收机93。As shown in FIG. 9 , a mobile station 90 includes a processor 91 , a transmitter 92 and a receiver 93 .

处理器91用于基于信道增益，从每个被选择的传输点的多个发射天线中为该传输点确定发射天线的最佳子集。The processor 91 is configured to determine an optimal subset of transmit antennas for each selected transmission point from the plurality of transmit antennas for the transmission point based on the channel gain.

发射机92用于向该基站报告该最佳子集中的发射天线的量化信道状态信息CSI。The transmitter 92 is configured to report the quantized channel state information CSI of the transmit antennas in the best subset to the base station.

移动台90的部件可以实现基于图1至图6的实施例中所述的MS相关的相应过程，为简便起见，此处不再赘述。The components of the mobile station 90 can implement the corresponding procedures related to the MS described in the embodiments based on FIG. 1 to FIG.

可选地，作为一实施例，处理器91用于获取传输点的多个发射天线的信道增益，并选择具有最大信道增益的发射天线作为该最佳子集。Optionally, as an embodiment, the processor 91 is configured to obtain channel gains of multiple transmit antennas of the transmission point, and select a transmit antenna with a maximum channel gain as the optimal subset.

可选地，作为另一实施例，处理器91用于获取传输点的多个发射天线的信道增益，并选择信道增益大于阈值的发射天线作为该最佳子集。Optionally, as another embodiment, the processor 91 is configured to obtain channel gains of multiple transmit antennas of the transmission point, and select transmit antennas with channel gains greater than a threshold as the optimal subset.

可选地，作为另一实施例，发射机92还用于向该基站报告该最佳子集中的发射天线的索引。Optionally, as another embodiment, the transmitter 92 is further configured to report the indices of the transmit antennas in the best subset to the base station.

可选地，作为另一实施例，处理器91用于基于由接收机93从基站接收的指示信息确定最佳子集，该指示信息用于指示由该基站根据信道增益选择的该最佳子集中的发射天线的索引。Optionally, as another embodiment, the processor 91 is configured to determine the best subset based on indication information received by the receiver 93 from the base station, where the indication information is used to indicate the best subset selected by the base station according to the channel gain Index of the concentrated transmit antenna.

可选地，作为另一实施例，发射机92用于利用码本报告量化CSI，该码本的大小取决于该最佳子集的大小。Optionally, as another embodiment, the transmitter 92 is configured to use a codebook to report the quantized CSI, and the size of the codebook depends on the size of the optimal subset.

可选地，作为另一实施例，处理器91还用于基于从该基站接收的大小信息确定该最佳子集的大小，或在该移动台处选择该最佳子集的大小。Optionally, as another embodiment, the processor 91 is further configured to determine the size of the optimal subset based on the size information received from the base station, or select the size of the optimal subset at the mobile station.

可选地，作为另一实施例，发射机92还用于向该基站报告该最佳子集中的发射天线以外的发射天线的量化CSI。Optionally, as another embodiment, the transmitter 92 is further configured to report the quantized CSI of the transmitting antennas other than the transmitting antennas in the optimal subset to the base station.

图10示出了本发明一实施例中的基站的框图。基站100可以具有至少一个传输点，每个传输点配备有多个发射天线。如图10所示，基站100包括接收机101和发射机102。Fig. 10 shows a block diagram of a base station in an embodiment of the present invention. The base station 100 may have at least one transmission point, and each transmission point is equipped with multiple transmit antennas. As shown in FIG. 10 , a base station 100 includes a receiver 101 and a transmitter 102 .

接收机101用于从移动台接收报告，该报告报告基于信道增益从每个被选择的传输点的多个发射天线中为该传输点确定的发射天线的最佳子集的量化信道状态信息CSI。The receiver 101 is adapted to receive a report from a mobile station reporting quantized channel state information CSI for each selected transmission point based on channel gain for the optimal subset of transmit antennas determined for that transmission point out of a plurality of transmit antennas .

发射机102用于基于该量化CSI发送数据。The transmitter 102 is configured to transmit data based on the quantized CSI.

基站100的部件可以实现基于图1至图6的实施例中所述的BS相关的相应过程，为简便起见，此处不再赘述。Components of the base station 100 may implement corresponding processes related to the BS described in the embodiments based on FIG. 1 to FIG. 6 , and details are not repeated here for simplicity.

可选地，作为一实施例，基站100还可以包括处理器103，用于获取传输点的多个发射天线的信道增益，并选择具有最大信道增益的发射天线作为最佳子集。Optionally, as an embodiment, the base station 100 may further include a processor 103, configured to obtain channel gains of multiple transmit antennas of a transmission point, and select a transmit antenna with a maximum channel gain as an optimal subset.

可选地，作为另一实施例，基站100还可以包括处理器103，用于获取该传输点的多个发射天线的信道增益，并选择该信道增益大于阈值的发射天线作为最佳子集。Optionally, as another embodiment, the base station 100 may further include a processor 103, configured to obtain channel gains of multiple transmit antennas of the transmission point, and select transmit antennas whose channel gains are greater than a threshold as an optimal subset.

可选地，作为另一实施例，发射机102还用于向移动台发送指示信息，该指示信息用于向移动台指示该最佳子集中的发射天线的索引。Optionally, as another embodiment, the transmitter 102 is further configured to send indication information to the mobile station, where the indication information is used to indicate to the mobile station indexes of transmit antennas in the best subset.

可选地，作为另一实施例，接收机101还用于从移动台接收指示信息，该指示信息用于指示由该移动台根据信道增益选择的该最佳子集中的发射天线的索引。Optionally, as another embodiment, the receiver 101 is further configured to receive indication information from the mobile station, where the indication information is used to indicate indexes of transmit antennas in the best subset selected by the mobile station according to channel gain.

可选地，作为另一实施例，量化CSI的报告使用码本，该码本的大小取决于最佳子集的大小。Optionally, as another embodiment, the report of the quantized CSI uses a codebook, and the size of the codebook depends on the size of the optimal subset.

可选地，作为另一实施例，接收机101还用于从移动台接收用于指示该最佳子集的大小的大小信息。Optionally, as another embodiment, the receiver 101 is further configured to receive size information indicating the size of the optimal subset from the mobile station.

可选地，作为另一实施例，基站100还可以包括处理器103，用于在该基站处选择该最佳子集的大小。Optionally, as another embodiment, the base station 100 may further include a processor 103, configured to select a size of the optimal subset at the base station.

可选地，作为另一实施例，接收机101还用于从移动台接收报告，该报告用于报告该最佳子集中的发射天线以外的发射天线的量化CSI。Optionally, as another embodiment, the receiver 101 is further configured to receive a report from the mobile station, where the report is used to report the quantized CSI of the transmit antennas other than the transmit antennas in the best subset.

在本发明实施例中，MS可以是如下任何一种，可以是固定或移动的，并且固定MS的例子可以包括用户设备、终端、移动台、用户单元或站点等。移动MS的例子可包括蜂窝电话、个人数字助手(PDA)、无线调制解调器、无线通信装置、手持装置、膝上型计算机、无绳电话或无线本地环路(WLL)站点等。In the embodiment of the present invention, the MS may be any of the following, which may be fixed or mobile, and examples of the fixed MS may include user equipment, terminal, mobile station, subscriber unit or station, etc. Examples of a mobile MS may include a cellular telephone, a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless telephone, or a wireless local loop (WLL) station, among others.

应注意，在上下文中使用的诸如“第一、第二等”的术语仅用于将一个实体或操作与另一实体或操作区分开，而不意图表示这些实体或操作之间的实际关系或顺序。另外，术语“包括”、“包含”或其变型意图以包括性的方式进行包括，而不是以排除性的方式，因此包括某元素的过程、方法、对象或设备将不仅仅包括该元素，也可以包括没有明确列出的其他元素，或者进一步包括该过程、方法、对象或设备固有的元素。除非另外定义，术语“包括一个…”所定义的元素将不排除包括所述元素的过程、方法、对象或设备排除其他相同元素的存在。It should be noted that terms such as "first, second, etc." used in this context are only used to distinguish one entity or operation from another entity or operation, and are not intended to indicate an actual relationship or relationship between these entities or operations. order. In addition, the terms "comprising", "comprising" or variations thereof are intended to be inclusive, not exclusive, such that a process, method, object, or device that includes an element will not only include that element, but also Other elements not explicitly listed may be included, or further elements inherent to the process, method, object, or device may be included. Unless otherwise defined, an element defined by the term "comprising a..." shall not exclude the process, method, object or apparatus comprising said element excluding the presence of other identical elements.

根据本发明实施例的描述，本领域技术人员将清楚地理解，本发明可由软件结合必要的通用硬件实现，当然也可以仅仅由硬件实现，但前者是优选的。基于该理解，本发明的解决方案本身或本发明对现有技术作出贡献的部分可以以软件产品的形式实现，并且软件产品可以存储在存储介质中，如ROM/RAM、硬盘、紧致盘等，包含能够使得计算机装置(个人计算机、服务器或网络装置等)执行实施例或部分实施例中所描述的方法。According to the description of the embodiments of the present invention, those skilled in the art will clearly understand that the present invention can be implemented by software combined with necessary general-purpose hardware, of course, it can also be implemented only by hardware, but the former is preferred. Based on this understanding, the solution of the present invention itself or the part of the present invention that contributes to the prior art can be implemented in the form of software products, and the software products can be stored in storage media, such as ROM/RAM, hard disk, compact disk, etc. , including enabling a computer device (personal computer, server, or network device, etc.) to execute the methods described in the embodiments or some of the embodiments.

尽管通过优选实施例的方式描述了本发明，但应注意，本领域技术人员可对实施例进行多种修改或变形，而这些修改或变形应落入本发明的保护范围内。Although the present invention has been described by means of preferred embodiments, it should be noted that those skilled in the art can make various modifications or variations to the embodiments, and these modifications or variations should fall within the protection scope of the present invention.