CN101764643A

Movatterモバイル変換

Info

Publication number: CN101764643A
Application number: CN200910244602A
Authority: CN
Inventors: 李旭; 张学臻
Original assignee: Beijing Jiaotong University
Current assignee: Beijing Jiaotong University
Priority date: 2009-12-31
Filing date: 2009-12-31
Publication date: 2010-06-30

Abstract

本发明公开了一种基于物理层Mesh模式联合前导和导频的信道均衡方法及系统。该方法包括：提取接收的数据帧的第一个OFDM符号，获取接收的前导序列；依据所述接收前导序列，计算前导信道估计；提取接收的数据帧中的数据符号，确定所述数据符号导频位置处的复数元素，获取接收的数据符号导频序列；依据所述接收的数据符号导频序列，计算相位估计；将所述前导信号估计的幅度与所述相位估计值的相位的联合起来，确定信道估计补偿值，以补偿后续的OFDM符号数据。本发明使用前导的幅度加上导频的相位确定补偿值，来估计下一部分OFDM符号的相位偏移，以较为精确的信道估计对信道进行均衡，提高了无线通信系统的整体性能。

The invention discloses a channel equalization method and system based on a physical layer Mesh mode joint preamble and pilot frequency. The method includes: extracting the first OFDM symbol of the received data frame, and obtaining the received preamble sequence; calculating the preamble channel estimation according to the received preamble sequence; extracting the data symbols in the received data frame, and determining the leading sequence of the data symbols The complex number element at the frequency position is obtained to obtain the received data symbol pilot sequence; according to the received data symbol pilot sequence, the phase estimate is calculated; the amplitude of the preamble signal estimate is combined with the phase of the phase estimate value , to determine a channel estimation compensation value to compensate subsequent OFDM symbol data. The present invention uses the amplitude of the preamble plus the phase of the pilot to determine the compensation value to estimate the phase offset of the next part of OFDM symbols, equalize the channel with relatively accurate channel estimation, and improve the overall performance of the wireless communication system.

Description

Translated fromChinese

基于物理层Mesh模式联合前导和导频的信道均衡方法及系统Channel equalization method and system based on joint preamble and pilot in physical layer Mesh mode

技术领域technical field

本发明涉及无线通信领域，尤其涉及一种基于物理层Mesh模式联合前导和导频的信道均衡方法及系统。The invention relates to the field of wireless communication, in particular to a channel equalization method and system based on a physical layer Mesh mode joint preamble and pilot frequency.

背景技术Background technique

在诸多的宽带无线通信技术中，Orthogonal Frequency DivisionMultiplexing(OFDM)无疑是最具有应用前景的技术之一。在信道的衰落特性中，对宽带无线移动业务影响最大的是多径衰落和多普勒频移。而OFDM不但可以通过插入循环前缀(CP)的方法，有效地抑止多径带来的符号间干扰，还可以通过对信道时变特性的合理估计，灵活地设计系统的符号长度，减轻信道时变特性对系统性能的影响。由于OFDM的这些技术特点，避免了在接收机中采用复杂的时域均衡器和自适应跟踪算法。并且，通过使用快速傅立叶变换(FFT)，可以保证在相对简单的系统硬件结构下，提供可靠、稳定的通信质量。正是因为这些优势，OFDM技术已经被各种无线通信标准所广泛采用。Among many broadband wireless communication technologies, Orthogonal Frequency Division Multiplexing (OFDM) is undoubtedly one of the most promising technologies. Among the fading characteristics of the channel, multipath fading and Doppler frequency shift have the greatest impact on broadband wireless mobile services. OFDM can not only effectively suppress the inter-symbol interference caused by multipath by inserting a cyclic prefix (CP), but also flexibly design the symbol length of the system by reasonably estimating the time-varying characteristics of the channel to reduce the time-varying channel. Effect of characteristics on system performance. Due to these technical characteristics of OFDM, complex time-domain equalizers and adaptive tracking algorithms are avoided in the receiver. In addition, by using Fast Fourier Transform (FFT), reliable and stable communication quality can be guaranteed under a relatively simple system hardware structure. Because of these advantages, OFDM technology has been widely adopted by various wireless communication standards.

虽然系统结构可以消除符号间干扰，OFDM系统仍然需要精确的信道信息来进行信道均衡，从而完全补偿多径衰落。Although the system structure can eliminate inter-symbol interference, OFDM system still needs accurate channel information for channel equalization, so as to fully compensate for multipath fading.

发明内容Contents of the invention

本发明的目的在于提供一种基于物理层Mesh模式联合前导和导频的信道均衡方法及系统。基于本发明，可以获取相对精确信道信息对信道进行均衡，以提高无线系统的性能。The purpose of the present invention is to provide a channel equalization method and system based on the joint preamble and pilot in the Mesh mode of the physical layer. Based on the present invention, relatively accurate channel information can be obtained to equalize the channel, so as to improve the performance of the wireless system.

本发明一种基于物理层Mesh模式联合前导和导频的信道均衡方法，包括如下步骤：前导信道估计获取步骤，提取接收的数据帧的第一个OFDM符号，获取接收的前导序列；依据所述接收前导序列，计算前导信道估计；相位估计获取步骤，提取接收的数据帧中的数据符号，确定所述数据符号导频位置处的复数元素，获取接收的数据符号导频序列；依据所述接收的数据符号导频序列，计算相位估计；信道估计补偿值计算步骤，将所述前导信号估计的幅度与所述相位估计值的相位的联合起来，确定信道估计补偿值，以补偿后续的OFDM符号数据。A channel equalization method based on the joint preamble and pilot of the physical layer Mesh mode of the present invention includes the following steps: the preamble channel estimation acquisition step, extracting the first OFDM symbol of the received data frame, and obtaining the received preamble sequence; according to the Receive the preamble sequence, calculate the preamble channel estimate; The phase estimation acquisition step extracts the data symbol in the received data frame, determines the complex number element at the pilot position of the data symbol, and obtains the received data symbol pilot sequence; according to the received The pilot sequence of the data symbol calculates the phase estimation; the channel estimation compensation value calculation step combines the magnitude of the preamble signal estimation with the phase of the phase estimation value to determine the channel estimation compensation value to compensate for subsequent OFDM symbols data.

上述信道均衡方法，优选所述前导信道估计获取步骤中，依据所述接收前导序列，计算前导信道估计具体为：依据所述接收的前导序列和本地前导序列按照LS方法确定所述前导信道估计。In the above channel equalization method, preferably in the step of obtaining the leading channel estimate, calculating the leading channel estimate according to the received preamble sequence specifically includes: determining the leading channel estimate according to the LS method according to the received preamble sequence and the local preamble sequence.

上述信道均衡方法，优选所述相位估计获取步骤中，依据所述接收数据符号导频序列，计算相位估计包括：In the above channel equalization method, preferably in the phase estimation obtaining step, calculating the phase estimation according to the received data symbol pilot sequence includes:

相位估计步骤，依据所述接收数据符号导频序列，计算所述相位估计，并将所述相位插值至一个OFDM符号长度，获取插值后的相位估计值。The phase estimation step is to calculate the phase estimation according to the received data symbol pilot sequence, and interpolate the phase to a length of one OFDM symbol, and obtain an interpolated phase estimation value.

上述信道均衡方法，优选所述信道估计补偿值计算步骤中，依据：H_est＝|H_estimate_preamble|*ej*Phase_est获取所述信道估计补偿值；In the above-mentioned channel equalization method, preferably in the step of calculating the channel estimation compensation value, the channel estimation compensation value is obtained according to: H_est=|H_estimate_preamble|*ej*Phase_est;

其中，H_est为信道估计补偿值，H_estimate_preamble为所述前导信道估计，|H_estimate_preamble|为所述前导信道估计的幅值；Phase_est为所述插值后的相位估计值。Wherein, H_est is the channel estimation compensation value, H_estimate_preamble is the preamble channel estimate, |H_estimate_preamble| is the magnitude of the preamble channel estimate; Phase_est is the phase estimation value after the interpolation.

另一方面，本发明还提供了一种基于物理层Mesh模式联合前导和导频的信道均衡系统，包括：前导信道估计获取模块，用于提取接收数据帧的第一个OFDM符号，获取接收的前导序列；依据所述接收前导序列，计算前导信道估计；相位估计获取模块，用于提取所述接收数据帧中的数据符号，确定所述数据符号导频位置处的复数元素，获取接收数据符号导频序列；依据所述接收的数据符号导频序列，计算相位估计；信道估计补偿值计算模块，用于将所述前导信号估计的幅度与所述相位估计值的相位的联合起来，确定信道估计补偿值，以补偿后续的OFDM符号数据。On the other hand, the present invention also provides a channel equalization system based on the joint preamble and pilot of the physical layer Mesh mode, including: a preamble channel estimation acquisition module, which is used to extract the first OFDM symbol of the received data frame, and obtain the received Preamble sequence; Calculate the preamble channel estimate according to the received preamble sequence; The phase estimation acquisition module is used to extract the data symbols in the received data frame, determine the complex elements at the pilot positions of the data symbols, and obtain the received data symbols Pilot sequence; calculate phase estimation according to the received data symbol pilot sequence; channel estimation compensation value calculation module, used to combine the amplitude of the preamble signal estimation and the phase of the phase estimation value to determine the channel The compensation value is estimated to compensate subsequent OFDM symbol data.

上述信道均衡系统，优选所述幅度补偿因子获取模块中，依据所述接收前导序列，计算前导信道估计具体为：依据所述接收的前导序列和本地前导序列按照LS(最小平方差)方法确定所述前导信道估计。In the above channel equalization system, preferably in the amplitude compensation factor acquisition module, the calculation of the leading channel estimation according to the received preamble sequence is specifically: according to the received preamble sequence and the local preamble sequence according to the LS (least square difference) method to determine the The above-mentioned preamble channel estimation.

上述信道均衡系统，优选所述相位估计获取模块中，依据所述接收数据符号导频序列，计算相位估计包括：相位估计单元，用于依据所述接收数据符号导频序列，计算所述相位估计，并将所述相位插值至一个OFDM符号长度，获取插值后的相位估计值。In the above channel equalization system, preferably in the phase estimation acquisition module, calculating the phase estimation according to the received data symbol pilot sequence includes: a phase estimation unit, configured to calculate the phase estimation according to the received data symbol pilot sequence , and interpolating the phase to a length of one OFDM symbol to obtain an estimated value of the interpolated phase.

上述信道均衡系统，优选所述信道估计补偿值计算模块中，依据：H_est＝|H_estimate_preamble|*ej*Phase_est获取所述信道估计补偿值；In the above channel equalization system, preferably, in the channel estimation compensation value calculation module, the channel estimation compensation value is obtained according to: H_est=|H_estimate_preamble|*ej*Phase_est;

本发明在OFDM调制过程中插入的前导及导频，利用前导幅度的稳定性以及导频相位的准确性，使用前导的幅度加上导频的相位来估计下一部分OFDM符号的相位偏移，以较为精确的信道信息对信道进行均衡，提高了无线通信系统的整体性能。The preamble and pilot inserted in the OFDM modulation process of the present invention utilize the stability of the preamble amplitude and the accuracy of the pilot phase, use the preamble amplitude plus the phase of the pilot to estimate the phase offset of the next part of OFDM symbols, and More accurate channel information equalizes the channel and improves the overall performance of the wireless communication system.

附图说明Description of drawings

图1为本发明基于物理层导频的信道均衡方法实施例的步骤流程图；Fig. 1 is the flow chart of the steps of the channel equalization method embodiment based on the physical layer pilot of the present invention;

参照图2，图2为发明基于物理层导频的信道均衡方法实施例中的信号处理示意图；Referring to FIG. 2, FIG. 2 is a schematic diagram of signal processing in an embodiment of a channel equalization method based on a physical layer pilot;

图3为IEEE 802.16e物理层帧结构图；Fig. 3 is IEEE 802.16e physical layer frame structure diagram;

图4为OFDM数据符号导频位置图；Figure 4 is a diagram of OFDM data symbol pilot positions;

图5为接收机结构框图；Fig. 5 is a structural block diagram of the receiver;

图6为本发明基于物理层导频的信道均衡系统实施例的结构示意图。FIG. 6 is a schematic structural diagram of an embodiment of a channel equalization system based on physical layer pilots according to the present invention.

具体实施方式Detailed ways

为使本发明的上述目的、特征和优点能够更加明显易懂，下面结合附图和具体实施方式对本发明作进一步详细的说明。In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

参照图1，图1为本发明基于物理层导频的信道均衡方法实施例的步骤流程图。包括如下步骤：Referring to FIG. 1 , FIG. 1 is a flow chart of steps of an embodiment of a channel equalization method based on physical layer pilots according to the present invention. Including the following steps:

前导信道估计获取步骤110，提取接收的数据帧的第一个OFDM符号，获取接收前导序列；依据所述接收的前导序列，计算前导信道估计。The leading channelestimation obtaining step 110 is to extract the first OFDM symbol of the received data frame to obtain the received preamble; and calculate the leading channel estimate according to the received preamble.

相位估计获取步骤120，提取所述接收的数据帧中的数据符号，确定所述数据符号导频位置处的复数元素，获取接收数据符号导频序列；依据所述接收的数据符号导频序列，计算相位估计。The phaseestimation acquisition step 120 is to extract the data symbols in the received data frame, determine the complex elements at the pilot positions of the data symbols, and obtain the received data symbol pilot sequence; according to the received data symbol pilot sequence, Compute the phase estimate.

信道估计补偿值计算步骤130，将所述前导信号估计的幅度与所述相位估计值的相位的联合起来，确定信道估计补偿值，以补偿后续的OFDM符号数据。In the channel estimation compensationvalue calculation step 130, the estimated amplitude of the preamble signal is combined with the phase of the phase estimation value to determine a channel estimation compensation value to compensate subsequent OFDM symbol data.

参照图2，图2为发明基于物理层导频的信道均衡方法实施例中的信号处理示意图。对接收的数据帧分别进行导频提取和前导提取后，基于导频提取，生成相位估计；基于前导提取，生成前导信道估计。依据生成的相位估计与前导信道估计，对接收到的数据进行补偿。Referring to FIG. 2 , FIG. 2 is a schematic diagram of signal processing in an embodiment of the method for channel equalization based on physical layer pilots. After performing pilot extraction and preamble extraction on the received data frame respectively, based on the pilot extraction, a phase estimate is generated; based on the preamble extraction, a preamble channel estimate is generated. Based on the generated phase estimate and leading channel estimate, the received data is compensated.

本实施例充分利用OFDM调制过程中插入的前导及导频的估计值，利用前导幅度的稳定性以及导频相位的准确性，使用前导的幅度加上导频的相位来估计下一部分OFDM符号的相位偏移，从而起到优化OFDM系统的作用。This embodiment makes full use of the preamble and the estimated value of the pilot inserted in the OFDM modulation process, utilizes the stability of the preamble amplitude and the accuracy of the pilot phase, and uses the amplitude of the preamble plus the phase of the pilot to estimate the next part of OFDM symbols. Phase offset, thereby playing a role in optimizing the OFDM system.

上述实施例中，依据无线信道的传输特性，将信道对信号作用的影响分为幅度影响和相位影响，分别将前导的幅度影响估计和导频的相位影响估计作用于数据OFDM符号进行均衡。幅度影响由LS算法的结果得出，相位影响也利用相似的处理方法。In the above embodiment, according to the transmission characteristics of the wireless channel, the influence of the channel on the signal is divided into amplitude influence and phase influence, and the amplitude influence estimation of the preamble and the phase influence estimation of the pilot frequency are respectively applied to the data OFDM symbols for equalization. Amplitude effects are derived from the results of the LS algorithm, and phase effects are treated similarly.

下面结合图3至图5，对上述实施例做进一步的说明。其中，图3为IEEE 802.16e物理层帧结构图，从图中可以看到，IEEE802.16e物理层的帧结构分为1个前导、4个数据符号、以及1个保护符号，导频均插在数据符号之中。图4为OFDM数据符号导频位置图，图中a为数据，b为数据中插入的导频，c为0频。图5为接收机结构框图，通过图5可以看出，接收机分为同步模块、OFDM解调模块、均衡模块、数据解调模块以及同步模块五个部分，本专利所提出的信道估计思是在均衡模块中得以实现的。The above embodiment will be further described below with reference to FIG. 3 to FIG. 5 . Among them, Figure 3 is a frame structure diagram of the IEEE 802.16e physical layer. It can be seen from the figure that the frame structure of the IEEE802.16e physical layer is divided into 1 preamble, 4 data symbols, and 1 protection symbol. in data symbols. Figure 4 is a diagram of OFDM data symbol pilot positions, in which a is data, b is the pilot inserted in the data, and c is zero frequency. Fig. 5 is a structural block diagram of the receiver. As can be seen from Fig. 5, the receiver is divided into five parts: a synchronization module, an OFDM demodulation module, an equalization module, a data demodulation module and a synchronization module. The channel estimation idea proposed in this patent is implemented in the equalization module.

步骤(1)，初始化。按照IEEE 802.16e设帧结构频域前导序列为H_preamble，由201点复数序列构成，数据符号导频为H_pilot，8点实数序列。经信道传输后，OFDM解调输出端前导符号序列为H_preamble_receive，由200点复数序列构成，接收导频序列为H_pilot_receive，8点的复数序列。接收到的数据为Data，200点的复数序列。Step (1), initialization. According to IEEE 802.16e, the preamble sequence in the frequency domain of the frame structure is H_preamble, which is composed of 201-point complex sequence, and the data symbol pilot is H_pilot, which is an 8-point real sequence. After channel transmission, the leading symbol sequence at the OFDM demodulation output end is H_preamble_receive, which is composed of a 200-point complex sequence, and the receiving pilot sequence is H_pilot_receive, an 8-point complex sequence. The received data is Data, a complex sequence of 200 points.

步骤(2)，由接收前导符号序列与本地前导序列按照LS方法得到前导信道估计值H_estimate_preambleStep (2), the preamble channel estimate value H_estimate_preamble is obtained from the received preamble symbol sequence and the local preamble sequence according to the LS method

步骤(3)，生成相位补偿因子Phase_compensate_pilot和幅度补偿因子Amplitude_compensate_preamble。其中相位补偿因子是由各个符号中的导频进行信道估计后再进过插值至一个OFDM符号长度取其相位得到Phase_est，幅度补偿因子是由步骤二的H_estimate_preamble取幅值得到。Step (3), generating a phase compensation factor Phase_compensate_pilot and an amplitude compensation factor Amplitude_compensate_preamble. Among them, the phase compensation factor is obtained from the channel estimation of the pilot frequency in each symbol and then interpolated to the length of one OFDM symbol to obtain Phase_est, and the amplitude compensation factor is obtained from the amplitude value of H_estimate_preamble in step 2.

步骤(4)，将前导信号估计值的幅度与每一段OFDM符号导频信号相位估计值的相位联合起来，形成最终的信道估计补偿值H_est，并利用这一估计值补偿接下来的OFDM符号。其中补偿式H_est＝|H_estimate_preamble|*ej*Phase_est。In step (4), the magnitude of the preamble signal estimate is combined with the phase of the pilot signal phase estimate of each OFDM symbol to form the final channel estimation compensation value H_est, and this estimate is used to compensate the next OFDM symbol. Wherein the compensation formula H_est=|H_estimate_preamble|*ej*Phase_est.

其中，H_est为信道估计补偿值，H_estimate_preamble为所述前导信道估计，|H_estimate_preamble|为所述前导信道估计的幅值；Phase_est为所述插值后的相位估计。Wherein, H_est is the channel estimation compensation value, H_estimate_preamble is the preamble channel estimate, |H_estimate_preamble| is the magnitude of the preamble channel estimate; Phase_est is the interpolated phase estimate.

参照图6，图6为本发明基于物理层导频的信道均衡系统实施例的结构示意图。包括：Referring to FIG. 6 , FIG. 6 is a schematic structural diagram of an embodiment of a channel equalization system based on physical layer pilots according to the present invention. include:

前导信道估计获取模块62，用于提取接收的数据帧的第一个OFDM符号，获取接收前导序列；依据所述接收的前导序列，计算前导信道估计。The preamble channel estimation acquisition module 62 is configured to extract the first OFDM symbol of the received data frame, and acquire the received preamble sequence; and calculate the preamble channel estimate according to the received preamble sequence.

相位估计获取模块64，用于提取所述接收的数据帧中的数据符号，确定所述数据符号导频位置处的复数元素，获取接收的数据符号导频序列；依据所述接收数据符号导频序列，计算相位估计。The phase estimation acquisition module 64 is used to extract the data symbols in the received data frame, determine the complex elements at the pilot positions of the data symbols, and obtain the received data symbol pilot sequence; according to the received data symbol pilot sequence, computing the phase estimate.

信道估计补偿值计算模块66，用于将所述前导信号估计的幅度与所述相位估计值的相位的联合起来，确定信道估计补偿值，以补偿后续的OFDM符号数据。The channel estimation compensation value calculation module 66 is configured to combine the estimated magnitude of the preamble signal and the phase of the phase estimation value to determine a channel estimation compensation value to compensate subsequent OFDM symbol data.

上述各个模块的工作原理与方法实施例中相类似，在此不再赘述，相关之处互相参照即可。The working principles of the above-mentioned modules are similar to those in the method embodiments, and will not be repeated here, and the relevant parts can be referred to each other.

以上对本发明所提供的一种基于物理层Mesh模式联合前导和导频的信道均衡方法及系统进行了详细介绍，本文中应用了具体个例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处，综上所述，本说明书内容不应理解为对本发明的限制。A channel equalization method and system based on the physical layer Mesh mode joint preamble and pilot provided by the present invention has been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present invention. The above embodiments The description is only used to help understand the method of the present invention and its core idea; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation and scope of application. In summary, As stated above, the content of this specification should not be construed as limiting the present invention.