WO2017161478A1 - 一种利用无线信道互易性对多用户传输信号的方法 - Google Patents

一种利用无线信道互易性对多用户传输信号的方法 Download PDF

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WO2017161478A1
WO2017161478A1 PCT/CN2016/076829 CN2016076829W WO2017161478A1 WO 2017161478 A1 WO2017161478 A1 WO 2017161478A1 CN 2016076829 W CN2016076829 W CN 2016076829W WO 2017161478 A1 WO2017161478 A1 WO 2017161478A1
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base station
user
signal
users
noise
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PCT/CN2016/076829
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French (fr)
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张文逸
沈聪
梁宁
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中国科学技术大学
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems

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  • the invention belongs to the field of multi-user multi-antenna systems in wireless communication, and particularly relates to a method for transmitting signals to multiple users by using wireless channel reciprocity in a multi-antenna system.
  • Massive MIMO can greatly improve the spectrum efficiency and radiant energy efficiency of the cellular network.
  • large-scale antenna systems operate in Time Division Duplex (TDD) mode, so that the reciprocity of uplink and downlink channels can be utilized to obtain channel state information (CSI) through orthogonal uplink training, which is significantly reduced by channel training.
  • TDD Time Division Duplex
  • the resulting pilot overhead requires that the pilot sequences transmitted by different antennas be orthogonal to each other, so the pilot length is greater than or equal to the total number of transmit antennas).
  • the base station performs multi-user detection (uplink) or precoding (downlink) by using the estimated CSI, and obtains multiplexing gain and array gain, thereby improving the effectiveness and reliability of information transmission.
  • the present invention aims to solve the problem of excessive overhead of the conventional orthogonal pilot based downlink channel training.
  • the present invention provides a method for transmitting a signal, which is applied to a multi-user multi-antenna system, which operates in a TDD mode, including a base station and a plurality of users, and the base station configures M antennas.
  • the number of users is K, and each user has only one receiving antenna or combines multiple receiving antennas to obtain only one scalar channel output, and each user maintains ideal synchronization with the base station; discrete one downlink transmission period It is converted into T time slots, and the reciprocal uplink and downlink channels remain unchanged in the T time slots.
  • the uplink channel of the user k to the base station is recorded as h k
  • the downlink channel of the base station to the user k is recorded as symbol Having a conjugate transpose, characterized in that the method comprises:
  • the user k in the first time slot, the user k sends a constant signal to the base station, and the received signal of the base station is a simple superposition of the uplink channel of the user to the base station and the noise, that is, Where y BS [1] represents the signal received by the base station in the first time slot, and z BS [1] is the noise of the base station side;
  • the base station multiplies the signal y BS [1] received in the first time slot by a power adjustment factor a, and then broadcasts ay BS [1] to all users in a broadcast manner. Then the signal received by user j in the second time slot is Where z j [2] is the noise of the user j end, User j estimates g j based on signal y j [2] received in the second time slot, and obtains an estimate.
  • the constant signal is normalized according to the transmission power of the user.
  • the noise z BS [1] of the base station is independent and identically distributed Gaussian noise, that is, among them.
  • I M is a M-dimensional unit matrix. Indicates that the mean is 0 and the covariance matrix is The M-dimensional cyclic symmetric complex Gaussian distribution.
  • the power adjustment factor a is satisfied.
  • the noise z j [2] of the user j end is Gaussian noise, that is, among them,
  • the mean is 0
  • the variance is Cyclic symmetric complex Gaussian distribution.
  • the least squares method is used to estimate which is
  • the present invention also provides a method for transmitting a signal, which is applied to a multi-user multi-antenna system, which operates in a TDD mode, including a base station and a plurality of users, wherein the base station is configured with M antennas, and the number of users is K.
  • each user has only one receiving antenna or combines multiple receiving antennas to obtain only one scalar channel output, and each user maintains ideal synchronization with the base station; when one downlink transmission period is discretized into T The uplink and downlink channels of the reciprocal and reciprocal remain unchanged in the T time slots, the uplink channel of the user k to the base station is recorded as h k , and the downlink channel of the base station to the user k is recorded as The method is characterized in that: the method comprises:
  • the user k in the first time slot, the user k sends a constant signal 1 to the base station, and the received signal of the base station is a simple superposition of the uplink channel of the user to the base station and the noise, that is, among them For the noise at the base station side;
  • the present invention also provides a method for transmitting a signal, which is applied to a multi-user multi-antenna system, the multi-user multi-antenna system comprising a base station and a plurality of users, characterized in that the users are divided into groups and users of different groups. Different subcarriers are occupied, and each group of users transmits signals by using the aforementioned method of transmitting signals.
  • the invention has the outstanding advantages of being easy to implement, low processing complexity, and extremely low channel training overhead, and is particularly suitable for application scenarios such as low-speed broadcast signaling transmission in a large-scale antenna system and paging of inactive users by a base station.
  • the invention provides a method for transmitting broadcast signals by using wireless channel reciprocity, which is an efficient downlink broadcast signaling transmission method, and the principle is to improve broadcast signaling by utilizing reciprocity of uplink and downlink channels in TDD mode.
  • the reliability of the transmission while significantly reducing the channel training overhead.
  • the invention is applied to a multi-user multi-antenna system, the system works in a TDD mode, the base station is configured with M antennas, the number of users is K, and each user has only one antenna or combines multiple receiving antennas to obtain only one scalar. Channel output, good synchronization between the user and the base station. Discretizing one downlink transmission period into T time slots, and the reciprocal uplink and downlink channels remain unchanged in the T time slots. If the uplink channel of user k to the base station is h k , then the base station to user k Downstream channel is (symbol Indicates conjugate transpose).
  • the signal received by the base station in the first time slot is the uplink channel of the user to the base station and a simple superposition of noise, ie among them Independently distributed Gaussian noise for the base station,
  • I M is a M-dimensional unit matrix. Indicates that the mean is 0 and the variance is The M-dimensional cyclic symmetric complex Gaussian distribution.
  • the base station multiplies the signal y BS [1] received in the first time slot by a power adjustment factor. Then ay BS [1] is broadcast back to all users, then the signal received by user j in the second time slot is among them
  • SISO single-input single-output
  • the method according to the present invention for utilizing wireless channel reciprocity for transmitting signals to multiple users is based on the following principles:
  • the downlink training needs to occupy at least M time slots; since the base station in the large-scale antenna system is generally configured with hundreds of antennas, that is, M is generally 10 2 orders of magnitude, and the typical channel coherence time is also on the order of 10 2 , so the overhead caused by this channel training method is basically unbearable.
  • the method of the present invention utilizes the reciprocity of wireless channel to transmit signals to multiple users, which can significantly improve the statistical distribution of the equivalent SISO channel between the base station and the user, thereby improving the reliability of the signaling broadcast; at the same time, due to the downlink channel
  • the training only occupies 2 transmission slots, so the overhead for channel training is also very low, which is very suitable for low-speed downlink broadcast signaling transmission.
  • the main principle is explained as follows: For the convenience of analysis, we do not lose the general assumption that the elements in h k are independent of each other and obey the cyclic symmetric complex Gaussian distribution. (ie, assume Rayleigh declines). Re-present g j as
  • the first subject is subject to a central chi-square distribution with a degree of freedom of 2M.
  • the central limit theorem and the second progressive obey the zero-mean cyclic symmetric complex Gaussian distribution.
  • M is generally on the order of 10 2 , so the first term is approximately equal to its mean. Cyclic symmetric complex Gaussian distribution
  • LOS line-of-sight component
  • This embodiment is applied to a narrowband large-scale antenna system, and only considers the case of a single cell. Accordingly, the channel hk between the user and the base station obeys flat fading, and we assume that hk obeys Rayleigh fading without loss of generality. In addition to this, it is assumed that the ideal synchronization is maintained between the user and the base station.
  • the base station-to-user equivalent SISO channel has a strong LOS component, which makes the downlink broadcast signaling transmission at this time highly reliable. , can also achieve a higher transmission rate.
  • the method of the present invention not only occupies very low slot resources in the channel training phase (only 2 slots), but also can be used when the M/K is large. Significantly improve the statistical distribution of the equivalent SISO channel between the base station and the user, thereby greatly improving the reliability of the broadcast signal transmission.
  • the number of users that the base station can simultaneously serve is not limited by the number of base station antennas. Increasing the number of users only weakens the LOS component of the equivalent SISO channel between the base station and the user to some extent.
  • the inventive method has a low processing complexity at the base station side. Therefore, the method of the present invention is particularly suitable for scenarios such as low-speed downlink broadcast signaling transmission or base station paging for inactive users.

Abstract

本发明提出了一种利用无线信道互易性由基站向多用户传输信号的方法，该方法利用信道反馈将基站到每个用户间的向量信道转化为带较强视距分量(LOS)的等效单入单出(SISO)信道，从而在几乎不需要信道训练开销的情况下，达到可靠的多用户信号传输。本发明具有容易实现、处理复杂度低、信道训练开销极低等突出优势，特别适用于大规模天线系统中的低速广播信令传输以及基站寻呼非活跃用户等应用场景。

Description

一种利用无线信道互易性对多用户传输信号的方法 技术领域
本发明属于无线通信中的多用户多天线系统领域，特别涉及多天线系统中利用无线信道互易性对多用户传输信号的方法。
背景技术
据《国际电子电气工程师协会无线通信会刊》(IEEE Trans.Wireless Commun.，vol.9，no.11，pp.3590-3600，2010.)介绍，通过在基站配置数百根天线，并在相同的时频资源块上同时服务数十个用户，大规模天线系统(massive MIMO)可极大地提升蜂窝网的频谱效率和辐射能量效率。一般而言，大规模天线系统工作于时分双工(TDD)模式，从而可利用上下行信道的互易性，通过正交的上行训练来获取信道状态信息(CSI)，显著降低由信道训练所带来的导频开销(最优的基于导频的信道训练要求不同天线发送的导频序列相互正交，因此导频长度要大于或等于发送天线总数)。基站利用估计到的CSI进行多用户检测(上行)或预编码(下行)，获取复用增益和阵列增益，提升信息传输的有效性和可靠性。然而，当基站要广播控制信令或要寻呼非活跃用户时，由于基站没有这些用户的CSI，复用增益和阵列增益均无法获得；另一方面，在这种情况下正交的上行信道训练不再适用(用户自主选择导频序列无法保证不同用户的导频序列相互正交)，正交的下行信道训练带来的导频和反馈开销非常高昂以至于难以承受，因此广播信令的传输面临巨大挑战。
发明内容
本发明旨在解决传统的基于正交导频的下行信道训练的开销过大的问题。
为解决上述技术问题，本发明提出一种传输信号的方法，应用于多用户多天线系统，所述多用户多天线系统工作于TDD模式，包括基站和多个用户，所述基站配置M根天线，用户数为K，且每个用户均只有一根接收天线或者对多根接收天线进行信号合并后只获得一个标量信道输出，各用户与所述基站间保持理想同步；将一个下行传输周期离散化为T个时隙，且互易的上下行信道在这T个时隙内保持不变，用户k到基站的上行信道记为hk，基站到用户k的下行信道记为
Figure PCTCN2016076829-appb-000001
符号
Figure PCTCN2016076829-appb-000002
表示共轭转置，其特征在于，所述方法包括：
S1、在第1个时隙，用户k向基站发送一个常数信号，所述基站的接收信号为用户到基站的上行信道以及噪声的简单叠加，即
Figure PCTCN2016076829-appb-000003
其中yBS[1]表示所述基站在第1个时隙接收到的信号，zBS[1]为基站端的噪声；
S2、在第2个时隙，基站将所述第1个时隙接收到的信号yBS[1]乘以一个功率调整因子a，然后将ayBS[1]以广播方式反馈给所有用户，则用户j在第2个时隙接收到的信号为
Figure PCTCN2016076829-appb-000004
其中zj[2]为用户j端的噪声，
Figure PCTCN2016076829-appb-000005
用户j根据在第2个时隙接收到的信号yj[2]对gj进行估计，得到估计量
Figure PCTCN2016076829-appb-000006
S3、在第t个时隙，t＝3，…，T，基站利用ayBS[1]对要在第t个时隙广播给用户的信号xBS[t]进行预编码，并将axBS[t]yBS[1]广播给所有用户，则用户j在第t个时隙接收到的信号为yi[t]＝gixBS[t]+zj[t]，其中zj[t]为用户j端的噪声，用户j利用所述
Figure PCTCN2016076829-appb-000007
来解调所述xBS[t]。
根据本发明的具体实施方式，在所述步骤S1中，所述常数信号按照用户的发送功率进行归一化。
根据本发明的具体实施方式，在所述步骤S1中，基站端的噪声zBS[1]为独立同分布的高斯噪声，即
Figure PCTCN2016076829-appb-000008
其中，
Figure PCTCN2016076829-appb-000009
为基站端的噪声功率，IM为M维单位矩阵，
Figure PCTCN2016076829-appb-000010
表示均值为0，协方差矩阵为
Figure PCTCN2016076829-appb-000011
的M维循环对称复高斯分布。
根据本发明的具体实施方式，在所述步骤S2中，所述功率调整因子a满足
Figure PCTCN2016076829-appb-000012
根据本发明的具体实施方式，在所述步骤S2中，用户j端的噪声zj[2]为高斯噪声，即
Figure PCTCN2016076829-appb-000013
其中，
Figure PCTCN2016076829-appb-000014
为用户端的噪声功率，
Figure PCTCN2016076829-appb-000015
表示均值为0，方差为
Figure PCTCN2016076829-appb-000016
的循环对称复高斯分布。
根据本发明的具体实施方式，在所述步骤S2中，以最小二乘法估计
Figure PCTCN2016076829-appb-000017
即
Figure PCTCN2016076829-appb-000018
本发明还提出一种传输信号的方法，应用于多用户多天线系统，所述多用户多天线系统工作于TDD模式，包括基站和多个用户，所述基站配置M根天线，用户数为K，且每个用户均只有一根接收天线或者对多根接收天线进行信号合并后只获得一个标量信道输出，各用户与所述基站间保持理想同步；将一个下行传输周期离散化为T个时隙，且互易的上下行信道在这T个时隙内保持不变，用户k到基站的上行信道记为hk，基站到用户k的下行信道记为
Figure PCTCN2016076829-appb-000019
其特征在于，所述方法包括：
S1、在第1个时隙，用户k向基站发送一个常数信号1，所述基站的接收信号为用户到基站的上行信道以及噪声的简单叠加，即
Figure PCTCN2016076829-appb-000020
其中
Figure PCTCN2016076829-appb-000021
为基站端的噪声；
S2、在第t个时隙，t＝2，…，T，基站先对要在第t个时隙广播给用户的数据进行差分调制，得到调制后的信号xBS[t]，再利用
Figure PCTCN2016076829-appb-000022
对所述xBS[t]进行预编码，并将
Figure PCTCN2016076829-appb-000023
广播给所有用户，则用户j在第t个时隙接收到的信号为
Figure PCTCN2016076829-appb-000024
其中
Figure PCTCN2016076829-appb-000025
Figure PCTCN2016076829-appb-000026
为用户j端的噪声，用户j不进行显式的信道估计，而对所述基站的广播信号进行非相干的差分解调。
本发明还提出一种传输信号的方法，应用于多用户多天线系统，所述多用户多天线系统包括基站和多个用户，其特征在于，将所述用户分为若干组，不同组的用户占用不同的子载波，每组用户均采用前述的传输信号的方法传输信号。
本发明具有容易实现、处理复杂度低、信道训练开销极低等突出优势，特别适用于大规模天线系统中的低速广播信令传输以及基站寻呼非活跃用户等应用场景。
附图说明
图1是M＝100，K＝5时，基站与用户之间等效SISO信道gj的实部与虚部的经验累积密度函数，以及与渐进分布
Figure PCTCN2016076829-appb-000027
的对比。
图2是M＝100，K＝50时，gj的实部与虚部的经验累积密度函数，以及与渐进分布
Figure PCTCN2016076829-appb-000028
的对比。
图3是M＝100，K＝500时，gj的实部与虚部的经验累积密度函数，以及与渐进分布
Figure PCTCN2016076829-appb-000029
的对比。
具体实施方式
本发明提出一种利用无线信道互易性传输广播信号的方法，该方法是一种高效的下行广播信令传输方法，其原理是利用TDD模式下上下行信道的互易性来提升广播信令传输的可靠性，同时显著降低信道训练开销。
本发明应用于多用户多天线系统，系统工作于TDD模式，基站配置M根天线，用户数为K，且每个用户均只有一根天线或者对多根接收 天线进行信号合并后只获得一个标量信道输出，用户与基站间保持良好同步。将一个下行传输周期离散化为T个时隙，且互易的上下行信道在这T个时隙内保持不变，如果记用户k到基站的上行信道为hk，则基站到用户k的下行信道为
Figure PCTCN2016076829-appb-000030
(符号
Figure PCTCN2016076829-appb-000031
表示共轭转置)。
S1、在第1个时隙，所有用户均发送一个相同的常数(由于用户没有CSI，无法进行上行功率控制；不失一般性，该常数可归一化为1，通过调整噪声功率来反映用户发送功率的变化)，则基站在第1个时隙接收到的信号为用户到基站的上行信道以及噪声的简单叠加，即
Figure PCTCN2016076829-appb-000032
其中
Figure PCTCN2016076829-appb-000033
为基站端独立同分布的高斯噪声，
Figure PCTCN2016076829-appb-000034
为基站端的噪声功率，IM为M维单位矩阵，
Figure PCTCN2016076829-appb-000035
表示均值为0，方差为
Figure PCTCN2016076829-appb-000036
的M维循环对称复高斯分布。
S2、在第2个时隙，基站将所述第1个时隙接收到的信号yBS[1]乘以一个功率调整因子
Figure PCTCN2016076829-appb-000037
然后将ayBS[1]以广播方式反馈给所有用户，则用户j在第2个时隙接收到的信号为
Figure PCTCN2016076829-appb-000038
其中
Figure PCTCN2016076829-appb-000039
为用户端的高斯噪声，
Figure PCTCN2016076829-appb-000040
可视为基站到用户j的等效单入单出(SISO)信道，用户根据接收到的信号yj[2]对等效信道gj做出某种估计，得到估计量
Figure PCTCN2016076829-appb-000041
(以最小二乘估计为例，
Figure PCTCN2016076829-appb-000042
)；
S3、在第t个时隙，t＝3，…，T，基站同样利用ayBS[1]对要广播给用户的信号xBS[t]进行预编码，并将axBS[t]yBS[1]广播给所有用户，则用户j在第t个时隙接收到的信号可以表示为yj[t]＝gjxBS[t]+zj[t]，用户j利用第2个时隙所估计的
Figure PCTCN2016076829-appb-000043
来解调基站广播信号xBS[t]。
本发明利用无线信道互易性对多用户传输信号的方法所依据的原理是：
为获取用户的CSI，若采用传统的基于正交导频的下行信道训练，则下行训练至少要占用M个时隙；由于大规模天线系统中的基站一般配 置数百根天线，即M一般在102量级，而典型的信道相干时间一般也在102这一量级，因此这种信道训练方式所带来的开销基本上是难以承受的。
为了降低下行信道训练的开销，可以考虑在下行信道训练阶段和数据传输阶段均采用相同的重复编码策略，以重复因子r＝M为例，所有的基站天线均发送相同的导频(下行信道训练阶段)或数据信号(下行数据传输阶段)。具体来说，在第一个传输时隙让所有的基站天线均发送相同的导频(不失一般性可假设为常数
Figure PCTCN2016076829-appb-000044
)，则用户j接收到的信号为
Figure PCTCN2016076829-appb-000045
表示hjm的共轭，这相当于把基站到用户j之间的向量信道折叠为一个等效的SISO信道。虽然这种重复编码策略可以显著降低下行信道训练的开销，但问题在于，该等效SISO信道与基站仅配置单天线时的SISO信道同分布(不失一般性，可假设hjm，m∈{1，2，…，M}独立同分布)，因此重复因子r＝M时的重复编码策略不能获取任何的分集增益。当重复因子r减小时，重复编码策略可获取一定的分集增益，但下行信道训练开销也随之增大；对于低速的广播信令传输而言，为此付出的信道训练开销应尽可能小，因此基于重复编码策略的下行信道训练与信令广播仍有其局限性。
另一方面，本发明利用无线信道互易性对多用户传输信号的方法可显著改善基站与用户间等效SISO信道的统计分布，从而提升信令广播的可靠性；与此同时，由于下行信道训练仅占用2个传输时隙，因此用于信道训练的开销也非常低，非常适合用于低速的下行广播信令传输。主要原理解释如下：为了分析的方便，我们不失一般性地假设hk中的元素相互独立且均服从循环对称复高斯分布
Figure PCTCN2016076829-appb-000046
(即假设瑞利衰落)。将gj重新表示为
Figure PCTCN2016076829-appb-000047
易知第一项服从自由度为2M的中心卡方分布，另外由中心极限定理，第二项渐进服从零均值循环对称复高斯分布。更进一步地，如前所 述M一般在102量级，因此第一项近似等于其均值
Figure PCTCN2016076829-appb-000048
而第二项近似为循环对称复高斯分布
Figure PCTCN2016076829-appb-000049
综上所述，通过本发明的两步信道训练与估计，基站到用户的向量信道可近似等效为服从分布
Figure PCTCN2016076829-appb-000050
的莱斯衰落信道；与重复因子r＝M时的基于重复编码的信道训练与信号广播相比，本发明所诱导出的等效SISO信道有一个视距分量(LOS)，且当比值M/K较大时(值得一提的是，一般而言大规模天线系统中的M比K高一个量级)，该视距分量较强，从而能显著提升信号广播的可靠性，降低中断概率。
以下结合附图说明本发明的实施例。
本实施例应用于窄带大规模天线系统，且只考虑单小区的情形，相应地，用户与基站之间的信道hk服从平坦衰落，我们不失一般性地假设hk服从瑞利衰落
Figure PCTCN2016076829-appb-000051
除此之外，假设用户与基站之间保持理想同步。
图1是M＝100，K＝5时，基站与用户之间等效SISO信道gj的实部与虚部的经验累积密度函数，以及与渐进分布
Figure PCTCN2016076829-appb-000052
的对比。
观察图1，我们发现当基站天线数远大于所服务的用户数时，基站到用户的等效SISO信道具有很强的LOS分量，从而使得此时的下行广播信令传输具有很高的可靠性，也可以达到较高的传输速率。
图2是M＝100，K＝50时，gj的实部与虚部的经验累积密度函数，以及与渐进分布
Figure PCTCN2016076829-appb-000053
的对比。图3是M＝100，K＝500时，gj的实部与虚部的经验累积密度函数，以及与渐进分布
Figure PCTCN2016076829-appb-000054
的对比。对比图1到图3，我们发现即便基站仅配置100根天线，gj的经验分布与其渐进分布依然
Figure PCTCN2016076829-appb-000055
高度吻合。除此之外，当基站天线数与所服务的用户数的比值减小时，基站到用户的等效SISO信道的LOS分量不断削弱，但依然优于重复因子r＝M时的基于重复编码的信道训练与信令广播。
由于更好地利用了TDD模式下上下行信道的互易性，本发明方法不仅在信道训练阶段占用的时隙资源很低(仅为2个时隙)，而且在M/K较大时能够显著改善基站与用户之间等效SISO信道的统计分布，从而大幅提升广播信号传输的可靠性。理论上而言，基站能够同时服务的用户数不受基站天线数目的限制，增加用户数仅在一定程度上削弱基站与用户间等效SISO信道的LOS分量。除此之外，该发明方法在基站端的处理复杂度低。因此，本发明方法特别适用于低速的下行广播信令传输或基站对非活跃用户的寻呼等场景。
以上所述的具体实施例，对本发明的目的、技术方案和有益效果进行了进一步详细说明，应理解的是，以上所述仅为本发明的具体实施例而已，并不用于限制本发明，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (13)

  1. 一种传输信号的方法，应用于多用户多天线系统，所述多用户多天线系统工作于TDD模式，包括基站和多个用户，所述基站配置M根天线，用户数为K，且每个用户均只有一根接收天线或者对多根接收天线进行信号合并后只获得一个标量信道输出，各用户与所述基站间保持理想同步；
    将一个下行传输周期离散化为T个时隙，且互易的上下行信道在这T个时隙内保持不变，用户k到基站的上行信道记为hk，基站到用户k的下行信道记为
    Figure PCTCN2016076829-appb-100001
    符号
    Figure PCTCN2016076829-appb-100002
    表示共轭转置，所述方法包括：
    S1、在第1个时隙，用户k向基站发送一个常数信号，所述基站的接收信号为用户到基站的上行信道以及噪声的简单叠加，即
    Figure PCTCN2016076829-appb-100003
    其中yBS[1]表示所述基站在第1个时隙接收到的信号，zBS[1]为基站端的噪声；
    S2、在第2个时隙，基站将所述第1个时隙接收到的信号yBS[1]乘以一个功率调整因子a，然后将ayBS[1]以广播方式反馈给所有用户，则用户j在第2个时隙接收到的信号为
    Figure PCTCN2016076829-appb-100004
    其中zj[2]为用户j端的噪声，
    Figure PCTCN2016076829-appb-100005
    用户j根据在第2个时隙接收到的信号yj[2]对gj进行估计，得到估计量
    Figure PCTCN2016076829-appb-100006
    S3、在第t个时隙，t＝3，...，T，基站利用ayBS[1]对要在第t个时隙广播给用户的信号xBS[t]进行预编码，并将axBS[t]yBS[1]广播给所有用户，则用户j在第t个时隙接收到的信号为yj[t]＝gjxBS[t]+zj[t]，其中zj[t]为用户j端的噪声，用户j利用所述
    Figure PCTCN2016076829-appb-100007
    来解调所述xBS[t]。
  2. 根据权利要求1所述的传输信号的方法，在所述步骤S1中，所述常数信号按照用户的发送功率进行归一化。
  3. 根据权利要求1所述的传输信号的方法，在所述步骤S1中，基站端的噪声zBS[1]为独立同分布的高斯噪声，即
    Figure PCTCN2016076829-appb-100008
    其中，
    Figure PCTCN2016076829-appb-100009
    为基站端的噪声功率，IM为M维单位矩阵，
    Figure PCTCN2016076829-appb-100010
    表示均值为0，协方差矩阵为
    Figure PCTCN2016076829-appb-100011
    的M维循环对称复高斯分布。
  4. 根据权利要求1所述的传输信号的方法，在所述步骤S2中，所述功率调整因子a满足
    Figure PCTCN2016076829-appb-100012
  5. 根据权利要求1所述的传输信号的方法，在所述步骤S2中，用户j端的噪声zj[2]为高斯噪声，即
    Figure PCTCN2016076829-appb-100013
    其中，
    Figure PCTCN2016076829-appb-100014
    为用户端的噪声功率，
    Figure PCTCN2016076829-appb-100015
    表示均值为0，方差为
    Figure PCTCN2016076829-appb-100016
    的循环对称复高斯分布。
  6. 根据权利要求1所述的传输信号的方法，在所述步骤S2中，以最小二乘法估计
    Figure PCTCN2016076829-appb-100017
    即
    Figure PCTCN2016076829-appb-100018
  7. 一种传输信号的方法，应用于多用户多天线系统，所述多用户多天线系统包括基站和多个用户，该方法将所述用户分为若干组，不同组的用户占用不同的子载波，每组用户均采用权利要求1至6中任一项所述的传输信号的方法传输信号。
  8. 一种传输信号的方法，应用于多用户多天线系统，所述多用户多天线系统工作于TDD模式，包括基站和多个用户，所述基站配置M根天线，用户数为K，且每个用户均只有一根接收天线或者对多根接收天线进行信号合并后只获得一个标量信道输出，各用户与所述基站间保持理想同步；
    将一个下行传输周期离散化为T个时隙，且互易的上下行信道在这T个时隙内保持不变，用户k到基站的上行信道记为hk，基站到用户k的下行信道记为
    Figure PCTCN2016076829-appb-100019
    其特征在于，所述方法包括：
    S1、在第1个时隙，用户k向基站发送一个常数信号，所述基站的接收信号为用户到基站的上行信道以及噪声的简单叠加，即
    Figure PCTCN2016076829-appb-100020
    其中yBS[1]表示所述基站在第1个时隙接收到的信号，zBS[1]为基站端的噪声；
    S2、在第t个时隙，t＝2，...，T，基站先对要在第t个时隙广播给用户的数据进行差分调制，得到调制后的信号xBS[t]，然后将所述第1个时隙接收到的信号yBS[1]乘以一个功率调整因子a，利用ayBS[1]对所述xBS[t]进行预编码，再将ayBS[1]xBS[t]广播给所有用户，则用户j在第t个时隙接收到的信号为
    Figure PCTCN2016076829-appb-100021
    其中zj[t]为用户j端的噪声，
    Figure PCTCN2016076829-appb-100022
    用户j不进行显式的信道估计，而对所述基站的广播信号进行非相干的差分解调。
  9. 根据权利要求8所述的传输信号的方法，在所述步骤S1中，所述常数信号按照用户的发送功率进行归一化。
  10. 根据权利要求8所述的传输信号的方法，在所述步骤S1中，基站端的噪声zBS[1]为独立同分布的高斯噪声，即
    Figure PCTCN2016076829-appb-100023
    其中，
    Figure PCTCN2016076829-appb-100024
    为基站端的噪声功率，IM为M维单位矩阵，
    Figure PCTCN2016076829-appb-100025
    表示均值为0，协方差矩阵为
    Figure PCTCN2016076829-appb-100026
    的M维循环对称复高斯分布。
  11. 根据权利要求8所述的传输信号的方法，在所述步骤S2中，所述功率调整因子a满足
    Figure PCTCN2016076829-appb-100027
  12. 根据权利要求8所述的传输信号的方法，在所述步骤S2中，用户j端的噪声zj[t]为高斯噪声，即
    Figure PCTCN2016076829-appb-100028
    其中，
    Figure PCTCN2016076829-appb-100029
    为用户端的噪声功率，
    Figure PCTCN2016076829-appb-100030
    表示均值为0，方差为
    Figure PCTCN2016076829-appb-100031
    的循环对称复高斯分布。
  13. 一种传输信号的方法，应用于多用户多天线系统，所述多用户多天线系统包括基站和多个用户，该方法将所述用户分为若干组，不同组的用户占用不同的子载波，每组用户均采用权利要求8至12中任一项所述的传输信号的方法传输信号。
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