CN1694441A - Method for compatible OFDM technology by TD-SCDMA system - Google Patents

Method for compatible OFDM technology by TD-SCDMA system Download PDF

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CN1694441A
CN1694441A CN 200510026171 CN200510026171A CN1694441A CN 1694441 A CN1694441 A CN 1694441A CN 200510026171 CN200510026171 CN 200510026171 CN 200510026171 A CN200510026171 A CN 200510026171A CN 1694441 A CN1694441 A CN 1694441A
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ofdm
td
scdma
scdma system
channel
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苏鹏程
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上海贝豪通讯电子有限公司
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Abstract

This invention discloses a method for TD-SCDMA compatible with OFDM technology, which carries out serial parallel conversion to the due-out high speed serial code sheet sequence and generates multiple parallel sub-sequences to be modulated to multiple sub-carriers for parallel transmission to reduce the transmit rate of each channel so as to increase the symbol period and weaken the influence of multi-channel interference, at the same time, it uses the circular prefix as the protection interval, the interference among symbols are reduced greatly and the orthogonality among channels are ensured.

Description

一种TD-SCDMA系统兼容OFDM技术的方法 TD-SCDMA system is compatible with one kind of OFDM art methods

技术领域 FIELD

:本发明涉及通信系统,特别是一种TD-SCDMA系统兼容正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)技术的方法。 : The present invention relates to communication systems, and more particularly to a TD-SCDMA system is compatible with Orthogonal Frequency Division Multiplexing (Orthogonal Frequency Division Multiplexing, OFDM) method art.

背景技术 Background technique

:IMT-2000是国际电信联盟(ITU)提出的第三代移动通信系统,而TD-SCDMA是其中的主流标准之一,是由中国无线通信标准化组织(CWTS)提出并得到ITU通过的3G无线通信标准。 : IMT-2000 is a third generation mobile communication system, the International Telecommunication Union (ITU) proposed the TD-SCDMA is one of the major standards, was proposed by the China Wireless Telecommunication Standards Organization (CWTS) and 3G wireless obtained by ITU communication standards. TD-SCDMA系统具有其突出的特点:在第三代移动通信系统的三种主流标准中唯一采用时分双工(TDD)方式,在频谱利用上具有较大的灵活性。 TD-SCDMA system has outstanding features: the three mainstream standards in the third generation mobile communication system, the only time division duplex (TDD) mode, have greater flexibility in spectrum utilization. 该系统综合采用了智能天线、同步码分多址(CDMA)、联合检测、软件无线电等无线通信中的先进技术,使系统具有较高的性能和频谱利用率。 The smart antenna system using a combination of wireless communication synchronization code division multiple access (CDMA), joint detection, and the like in the advanced software radio technology, the system has high performance and spectrum utilization.

TD-SCDMA系统由于其采用CDMA技术,必然会面临CDMA自身所引入的局限性。 TD-SCDMA system, because of its use CDMA technology, CDMA will face the limitations introduced by itself. 在CDMA系统中,采用不同的扩频码字来区分用户,这就要求各用户的扩频码具有强自相关性和弱互相关性。 In the CDMA system, different spreading codes to distinguish users words, each of which requires a user spreading code having strong autocorrelation and low cross-correlation. 但实际上各用户间的互干扰不可能完全消失,从而引起多址干扰。 But in fact mutual interference between users can not disappear completely, causing MAI.

另一方面,无线电波的传播具有自由空间传播损耗、阴影衰落以及多径衰落等特点,其中多径衰落对无线信道上传输的信号有很严重的影响。 On the other hand, propagation of radio waves having a free-space propagation loss, shadow fading and multipath fading characteristics, multipath fading which has a serious impact on the signal transmission over the wireless channel. 复杂的电波传播机制造成了无线信道的多径传播和衰落特性,这种多径衰落主要是许多由不同路径传播而来的信号的破坏性叠加而造成的,它会严重消弱接收信号的瞬时功率,显著降低无线通信系统的性能。 The radio wave propagation complicated mechanism causes multipath propagation and fading characteristics of wireless channels, such destructive multipath fading largely from many different propagation paths of a signal caused by the superposition, it will seriously impair the instantaneous received signal power, significantly reduce the performance of the wireless communication system. 多径传播结果使得接收信号产生了时延扩展、频率(Doppler)扩展和角度扩展,而这会分别引起三类选择性衰落的产生。 Result that multipath propagation delay spread reception signal generated, the frequency (Doppler) angle spread and extended, respectively, which causes three types of selective fading is generated.

(1)时延扩展假设发射信号是一个时间宽度极窄的脉冲信号,经过多径信道后,由于各信道时延的不同,接收到的信号为一串脉冲,因此接收信号的波形比原脉冲展宽了,会造成符号间干扰(ISI)。 (1) delay spread is assumed that the transmitted signal is a very narrow time width of the pulse signal after multipath channel, due to the different delay of each channel, the received signal is a train of pulses, the reception waveform of a signal than the original pulse broadening will cause inter-symbol interference (ISI). 从频域角度考虑,多径信号的时延扩展可以导致频率选择性衰落,即信号中不同的频率成分衰落特性不一样。 From the viewpoint of frequency domain, the delay spread of multipath signals may result in frequency selective fading, i.e., different frequency components of the signal fading characteristic is not the same.

(2)频率扩展由于移动用户与基站的相对运动,每条多径都会有一个明显的频率移动,在信号频域上产生多普勒扩展,引起时间选择性衰落,即在不同的时刻衰落特性不一样。 (2) Extended frequency due to relative movement of the mobile user and the base station, each multipath will have a distinct frequency shift, Doppler spread in the frequency domain signal, time selective fading caused, i.e. fading characteristics at different times Different.

(3)角度扩展角度扩展是多径信号到达天线阵列的到达角度的展宽,产生了空间选择性衰落,即在不同地点(空间)衰落特性不一样。 (3) The angular spread multipath angular spread signal show the arrival angle of the antenna array is wide, a space is generated selective fading, i.e., fading at different locations (spatial) properties are not the same.

因此,CDMA系统是干扰受限系统,其容量主要受限于多址干扰与多径干扰。 Thus, CDMA systems are interference-limited system, which is mainly limited by the capacity of multiple access interference and multipath interference. 在复杂的移动通信环境和有限的频率资源下,要达到高容量、高质量、高速率的通信,必须要克服这些因素的影响。 In a mobile communication environment complex and limited frequency resources, to achieve high communication capacity, high quality, high speed, it is necessary to overcome these factors.

目前,TD-SCDMA采用正交相移键控(QPSK)调制,对于2Mbit/s的业务,使用8PSK调制方式。 At present, TD-SCDMA uses quadrature phase shift keying (QPSK) modulation, for the 2Mbit / s service, the use of 8PSK modulation scheme. 这样的调制效率还是较低的,不能采用更高进制调制的原因是:更高效率的调制如正交幅度调制(QAM),会引入严重的干扰,这对于干扰受限的CDMA系统是极为不利的。 Such modulation efficiency is lower, a higher-ary modulation can not be used because: more efficient modulation such as quadrature amplitude modulation (the QAM), can introduce severe interference, which is extremely limited to the CDMA system interference Adverse. TD-SCDMA系统所能提供的数据传输速率仍然是有限的,对高效传输多媒体信息来说仍受到限制。 Data transmission rate TD-SCDMA system can provide is still limited, for efficient transmission of multimedia information is still limited.

虽然TD-SCDMA系统采用的诸多先进技术,如智能天线、同步CDMA、联合检测等,可以有效地抑制干扰,但难以提供更高速的数据传输速率,特别是在高速移动条件下,所造成的严重的符号间干扰难以克服。 Although the TD-SCDMA system uses many advanced technologies, such as smart antenna, a synchronous CDMA, joint detection, etc., can effectively suppress interference, but it is difficult to provide higher data transfer rates, serious especially in high-speed movement conditions, caused by inter-symbol interference difficult to overcome.

如前所述,由于信道的时变多径特征,信号多条路径上以不同的强度和延迟到达终端,会带来时延扩展,并且使得信道是频率选择性的,这会引起严重的ISI,而在高数据速率传输时减少ISI是尤为困难的。 As described above, since the time varying multipath channel characteristics, the plurality of signal paths at different intensities and delayed arrives at the terminal, will bring delay spread, and so that the channel is frequency selective, it can cause severe ISI , ISI is reduced at the high data rate transmission is particularly difficult. 一般用于对抗ISI的技术,例如最大似然序列估计(MLSE)或者线性和非线性的均衡器,MLSE在存在ISI的情况下是一种最优的检测算法,但由于计算量较大,在高数据速率无线通信中并没有太大的吸引力。 General techniques for combating ISI, such as maximum likelihood sequence estimation (the MLSE) or linear and nonlinear equalizer, the MLSE detection algorithm is an optimal in the presence of ISI, but the large amount of calculation, in high data rate wireless communications and not very attractive. 而另一方面,多载波调制对于ISI比单载波调制具有更大的抵抗能力。 On the other hand, for multi-carrier modulation ISI has a greater resistance than the single carrier modulation.

信道中多径时延功率谱的扩散区间是由信道客观特性所决定的,而决定系统传输性能的不是扩散区间的绝对值,而是扩散区间在被传送信息码元中所占的相对百分比。 Interval diffusion channel multipath delay power spectrum is determined by the channel characteristics of the objective, the transmission performance of the system is determined not the absolute value of the diffusion section, but the relative percentage of the diffusion transport section being occupied by the information symbols.

多载波传输系统的原理如图1所示,多载波技术是将高速率的信息数据流经串/并变换,分割为若干路低速数据流,增大信息码元周期,减少了多径时延扩散在接收到的信息码元中所占的相对百分比值,以削弱多径干扰对传输系统性能的影响。 Principle multicarrier transmission system shown in Figure 1, the multi-carrier technology is high rate information data stream is serial / parallel conversion, is divided into several low-speed data flow, increasing the information symbol period, reducing the multipath delay diffusion relative percentage value of the received information symbols occupied, to weaken the effects of multipath interference on the transmission performance of the system. 然后每路低速数据采用一个独立的载波调制并叠加在一起构成发送信号。 Each low-speed data and then using a separate carrier modulation and superimposed together to form the transmission signal. 在接收端用同样数量的载波对发送信号进行相干接收,获得低速率信息数据后,再经过并/串变换得到原来的高速信号。 At the receiving end with the same number of carriers of the transmission signals received coherently, to obtain a low data rate information, through the parallel / serial transform the original high-speed signal. 作为一种特殊多载波技术的OFDM技术,在频谱和计算复杂度上都是高效的。 As a special technique OFDM multicarrier technique, the computational complexity of the spectrum and it is effective. 传统的并行多载波系统把整个带宽分割后被送到子信道中,频带没有重叠,其频谱利用率很低。 Conventional parallel multicarrier system after dividing the entire bandwidth to the subchannels, the band does not overlap, the spectrum utilization is low. OFDM在频域把信道分成许多正交子信道,各子信道的载波间有1/2的重叠,但保持正交,由于频谱相互重叠,这样就提高了频谱利用率。 In the OFDM frequency domain into a plurality of orthogonal sub-channel, 1/2 overlap between each sub-channel carriers, but the orthogonality is maintained, since the spectral overlap, thus increasing the spectrum efficiency. 而且通过快速傅立叶反变换与变换(IFFT与FFT)就可实现OFDM的调制与解调,在接收端避免使用滤波器组,同时能使频谱效率提高近一倍。 And it can be achieved by inverse fast Fourier transform and the transform (IFFT and FFT) of the OFDM modulation and demodulation, avoiding at the receiving end using a filter bank, while enabling spectral efficiency nearly doubled.

OFDM把频率选择性衰落扩展到许多符号上,有效地随机化了由衰落或脉冲干扰所引起的突发错误,使得不会是几个相邻的符号遭到完全破坏,而是很多符号仅受到轻微的影响。 The OFDM frequency selective fading extend over a number of symbols, effectively randomizes burst errors caused by fading or interference caused by the pulse, so that several adjacent symbols will not have been completely destroyed, many symbols but only by the slightly affected. 由于OFDM把整个信道带宽分成许多窄的子信道,在每个单独子信道上的频率响应是相对平坦的,大大减小了符号间干扰。 Since the whole OFDM channel bandwidth into many narrow sub-channels, the frequency response over each individual sub-channel is relatively flat, significantly reduces intersymbol interference. 而且每一个子信道只占有原始带宽的一小部分,因此均衡要比串行系统简单的多。 And each sub-account for only a small portion of the original bandwidth, so balanced than serial system simpler. 一种简单的均衡算法就可以最小化每个子信道上的均方误差,而采用差分编码甚至可以完全避免采用均衡。 A simple equalization algorithm can minimize the mean square error on each sub-channel, and differential encoding a balanced or even completely avoided. OFDM适用于多径环境和频率选择性衰落信道中的高速数据传输。 OFDM for high-speed data transmission in a multipath environment and frequency selective fading channel. 由于OFDM具有抗多径能力强、频谱利用率高的优点,因此受到广泛关注。 Because OFDM has a strong resistance to multipath, high bandwidth efficiency advantages, attracted widespread attention. 人们不但认为在宽带无线接入领域采用OFDM是发展的趋势,而且它将成为未来移动通信系统的关键技术。 It is not only that the use of OFDM trend in the field of broadband wireless access, and it will become a key technology for future mobile communication systems.

为了最大限度地消除ISI,要在每个OFDM符号中插入保护间隔(guard interval),而且该保护间隔长度一般要大于无线信道的最大时延扩展,这样一个符号的多径分量就不会对下一个符号造成干扰。 To maximize the elimination of the ISI, to insert a guard interval (guard interval) in each OFDM symbol, and the guard interval length is generally greater than the maximum delay spread of the wireless channel, such a multi-path component at the symbol would not have a symbol cause interference. 在这段保护间隔内,可以不插入任何符号,即是一段空闲的传输时段。 During this guard interval may be inserted without any symbol, i.e., an idle transmit period is. 不过,一般OFDM符号需要在其保护间隔内填入循环前缀信号CP(cyclicprefix),能够消除或者至少是大大减少了ISI。 However, generally you need to fill the OFDM symbol cyclic prefix signal CP (cyclicprefix) in which a guard interval, can be eliminated or at least greatly reduced ISI. 当然,这样做的代价是降低了频谱利用率。 Of course, the cost of doing so is to reduce the spectrum efficiency. 基带OFDM系统原理如图2所示。 The OFDM baseband system shown in Fig.

与单载波系统相比,OFDM系统的主要优点有:□ OFDM系统对脉冲干扰的抵抗能力要比单载波系统大得多,这是因为OFDM信号的解调是在很多的发送信息符号周期内积分,从而使脉冲干扰的影响得以分散。 Compared with single carrier systems, the main advantage of OFDM systems are: □ OFDM system resistance to pulsed interference is much larger than the single carrier system, because the demodulation of the OFDM signal is integrated over many transmission information symbol period , so that the influence of pulsed interference is dispersed.

□ 抗多径传播与频率选择性衰落能力强,由于OFDM系统把信息分散到许多个载波上,大大降低了各子载波的信号速率,从而能减弱多径传播的影响,若再通过采用保护间隔的方法,甚至可以完全消除符号间干扰。 □ anti-multipath propagation and frequency selective fading ability, since the OFDM system information dispersed to a plurality of carriers, greatly reduces the signal rate of each subcarrier, which can weaken the influence of multipath propagation, if more by using a guard interval the method can even completely eliminate inter-symbol interference. OFDM是一种克服高速率数字通信中的符号间干扰的有效技术。 OFDM is an effective technique between the high-rate digital communications to overcome intersymbol interference.

□ 有利于采用动态比特分配技术使系统达到最大比特率。 □ facilitate dynamic bit allocation technique for maximum system bit rate. 通过选取各子信道、每个符号的比特数以及分配给各子信道的功率使总比特率最大。 By selecting sub-channels, and the number of bits assigned to each symbol so that the total power of each sub-channel bit rate is the maximum. 即要求各子信道功率分配应遵循信息论中的“注水定理”,亦即优质信道多传送,较差信道少传送,劣质信道不传送的原则。 I.e., each sub-channel power allocation required to be followed in the information theory "water theorem", i.e., high-quality multi-channel transmission, less bad channel transmission, the principles of the inferior channel is not transmitted.

□ 提高了频谱效率。 □ improve the spectrum efficiency.

正是基于OFDM系统具有如此多的优点,因此,如果在TD-SCDMA系统中提出一种与3G以后的技术(如OFDM技术)实现兼容的方法,就能更有效地抵抗多径干扰、更容易地来解决现有技术中的不足。 It is based on OFDM system with so many advantages, therefore, if the subsequent proposed a 3G technologies (e.g., OFDM techniques) in a method compatible with the TD-SCDMA system, it can be more effectively against the multipath interference, easier to address the deficiencies in the prior art.

发明内容 SUMMARY

:本发明所要解决的技术问题是提供一种TD-SCDMA兼容OFDM技术的方法,将待发送的高速串行码片序列进行串并变换,生成多路并行的子序列后,分别调制到OFDM的多个子载波上进行并行传输,虽然总的数据传输速率比较高,但降低了每一路的传输速率,从而增大码元周期,可以更有效地削弱多径干扰的影响,同时它使用循环前缀(CP)作为保护间隔,大大减少甚至消除了符号间干扰,并且保证了各信道间的正交性,从而大大减少了信道间干扰,提供更高的数据传输速率,进一步提高频谱效率,并能有效抑制高速数据传输时带来的严重的符号间干扰,同时由于3G以后的系统将主要采用OFDM作为其核心技术,本发明作为TD-SCDMA的一个备选方案可使得TD-SCDMA能够与将来的系统更好地兼容,容易实现平滑地过渡。 : The present invention is to solve the technical problem of providing a compatible OFDM technology TD-SCDMA method, a high-speed serial chip sequence to be transmitted is serial-parallel conversion to generate a sequence of multi-channel parallel after, respectively, the OFDM modulated to a plurality of sub-carriers for the parallel transmission, although the overall data transmission rate is relatively high, but reduces the transmission rate for each channel, thereby increasing the symbol period, can be more effectively weaken the influence of multipath interference, while it uses a cyclic prefix ( CP) as a guard interval, greatly reduce or even eliminate the inter-symbol interference, and to ensure orthogonality among the channels, thereby greatly reducing the inter-channel interference, to provide higher data transfer rate, to further improve spectrum efficiency, and can effectively bring high speed data transmission suppression severe inter-symbol interference, and because the system will adopt future 3G OFDM as a core technology, the present invention as an alternative may be such that TD-SCDMA TD-SCDMA system in the future can be better compatibility, easy to achieve a smooth transition.

为解决上述技术问题,本发明是这样实现的:本发明提供一种TD-SCDMA兼容OFDM技术的方法,所述TD-SCDMA系统包括4种时隙类型:DwPTS、UpPTS、GP和TS0~TS6,其中DwPTS和UpPTS分别用作上行同步和下行同步,不承载用户数据,GP用作上行同步建立过程中的传播时延保护,常规时隙TS0~TS6用作承载用户数据或控制信息,为了与OFDM技术相结合,对于不同时隙作出了相应的处理,其实现方式是:(1)对于常规时隙TS0~TS6中的用户数据或控制信息的处理(a)来源于物理信道映射的比特流在进行扩频处理之前,先要经过数据调制,可采用比TD-SCDMA中更高阶数的调制方法,以提高频谱效率和数据速率(b)数据符号序列经过常规的乘法算子加权、扩频与扰码处理后,将扰码序列分组,每组包含N个码片,将其进行串/并变换,变为一个并行的数据流,然后进行N点的快速傅立叶反变换IFFT To solve the above problems, the present invention is implemented as follows: The present invention provides a TD-SCDMA method is compatible with OFDM technology, the TD-SCDMA system includes 4 types slots: DwPTS, UpPTS, GP and TS0 ~ TS6, wherein DwPTS and UpPTS are used as the downlink synchronization and uplink synchronization, does not carry user data, the propagation delay protection process to establish uplink synchronization as GP, as a conventional time slot TS0 ~ TS6 carries user data or control information to the OFDM technology, the processing corresponding to different time slots for which implementation is: (1) a conventional process for the user data in the time slots TS0 ~ TS6 or control information (a) is derived from a physical channel mapping bitstream before spreading processing, first data after modulation, the modulation method can be of higher order than in TD-SCDMA, in order to improve spectral efficiency and data rate (b) the data symbol sequence subjected to conventional weighting multiplication operator, spreading after treatment with the scrambling code, the scrambling code sequence into groups, each containing N chips, which serial / parallel conversion, into a parallel data stream, followed by N-point inverse fast Fourier transform (IFFT) ,就将该N个码片调制到N个并行正交的子载波上,实现了OFDM的调制(c)在IFFT变换后添加一个大于信道最大延迟扩展的循环前缀CP作为保护间隔,以克服符号间干扰的影响(d)并/串变换后执行TD-SCDMA的常规处理(2)对于SYNC-DL即在DwPTS时隙中的下行同步码、SYNC-UL即在UpPTS时隙中的上行同步码和Midamble码即在常规时隙中思维训练序列的处理(a)在TD-SCDMA标准中,SYNC-DL、SYNC-UL和Midamble这几种码都是直接以码片速率的形式给出,不需要进行扩频和加扰处理,这几种码的码本都可以在3GPP的规范中直接查到,然后进行复数化处理后直接执行OFDM调制过程(b)对于SYNC-DL、SYNC-UL和Midamble,将其码片序列分别进行分组,每组包含N个码片,按照前面的OFDM调制过程,分别串/并变换后进行N点的IFFT变换,再添加CP后执行并/串变换,生成多个连续的OFDM符号(c)进一步执行TD-SCDMA的常规过程, , N chips on the modulated onto N orthogonal parallel sub-carriers, OFDM modulation achieved (c) adding a greater than the maximum channel delay spread as the CP is a guard interval after the IFFT, to overcome the symbol conventional treatment (2) sYNC-DL code in the DwPTS i.e. downlink synchronization slot, sYNC-UL i.e. uplink synchronization code in the UpPTS time slot of the TD-SCDMA is performed after (d) impact interference between the parallel / serial conversion Midamble code and training sequence that is thought process (a) in the TD-SCDMA standard, SYNC-DL, SYNC-UL code and Midamble these types are given in the form of directly in conventional chip rate timeslot, not direct performs OFDM modulation process (b) for the SYNC-DL, SYNC-UL and the rear spreading and scrambling process is required, these types of codebook code can be directly found in the 3GPP specification, and performing complex processing N-point after the Midamble, which chip sequence groups each, each set containing N chips, as previously OFDM modulation process, respectively, the serial / parallel transform (IFFT) transform, CP further added after performing parallel / serial conversion to generate a plurality of consecutive OFDM symbols (c) further performs a conventional process of TD-SCDMA, 其中Midamble码要和相应常规时隙中的扩频、加扰和OFDM调制后的数据或控制信息组合成子帧后再进一步处理(3)接收端(a)执行符号定时同步过程,即求得单个OFDM符号开始和结束的精确时刻。 Wherein Midamble codes for a conventional slot and the corresponding spread spectrum, data or control information into a combination of sub-frames and then further processing the scrambled OFDM modulation and (3) the receiving end (a) performing symbol timing synchronization process, i.e., obtain a single precise moment OFDM symbol begins and ends. 符号定时的结果将决定FFT的窗口。 Symbol timing will determine the result of the FFT window. 可以采用数据辅助、非数据辅助等方法实现符号定时。 Auxiliary data may be employed, or the like to achieve the non-data-aided symbol timing. 其中数据辅助方法可以在传输信号中周期性插入已知的训练符号作为导引符号。 The method wherein the auxiliary data may periodically insert a known training symbols as pilot symbols in the transmission signal. 非数据辅助方法采用OFDM波形的CP结构完成符号定时(b)将接收到的信号进行串/并变换并去除CP Methods NDA OFDM waveform structure completion CP symbol timing (b) the received signal serial / parallel conversion and removes a CP

(c)执行严格的载波频率偏移误差估计,进行频率校正。 (C) strict carrier frequency offset estimation error, correct the frequency. 频率偏移误差估计可以基于传输信号中的特定训练信息进行,也可以对频域内的接收信号进行分析得到。 Frequency offset error estimation may be based on the particular training information in the transmitted signal, or may be obtained by analyzing the received signal in the frequency domain. 在OFDM系统中面临的一个主要问题是对频偏误差的敏感性。 One of the major issues facing the OFDM system is sensitive to offset errors. 因此,在TD-SCDMA系统中引入OFDM技术时,则对载波频率准确度要求比在原来的TD-SCDMA系统中更加重要(d)执行N点的FFT变换,把信号从时域变回频域,以实现OFDM解调(e)采用一定的信道估计算法估计出OFDM各个子载波上的信道系数(f)然后对于OFDM解调后的信号再执行单用户或多用户检测,以判决出发送的数据。 Therefore, the introduction of OFDM technology in the TD-SCDMA system, the carrier frequency accuracy than the more important in the original TD-SCDMA system, (d) Implementation N point FFT is required, the signal from the time domain back to the frequency domain to achieve OFDM demodulation (e) using a certain algorithm to estimate the channel estimates channel coefficients (f) on each OFDM subcarrier and OFDM demodulation for the signal and then perform a single or multi-user detection, the decision to send the data.

在TD-SCDMA与OFDM相结合时,采用简单的均衡就可以实现OFDM的解调,与瑞克(RAKE)接收的思路不同,不必再采用RAKE接收技术,原来的TD-SCDMA接收机采用RAKE分集接收技术来区分和绑定多路信号能量,能够提供一定的分集增益,然而由于多路信号能量不相等,如果路径数较多,这种信号能量的分散将使得信道估计精确度降低,RAKE的接收性能下降就会很快。 When TD-SCDMA and combining OFDM, equalization simple OFDM demodulation can be achieved, with the rake (RAKE) reception of different ideas, without having to use RAKE receiver techniques, previous TD-SCDMA receiver uses diversity RAKE reception techniques to distinguish between multiple binding and signal energy, can provide some diversity gain, however, due to multipath signal energy are not equal, if the large number of paths, the dispersed signal energy so that the channel estimating accuracy, of the RAKE receiving performance will quickly decline.

在接收端进行信道估计时,可以利用DwPTS时隙中发送SYNC-DL的多个连续OFDM符号、UpPTS时隙中发送SYNC-UL的多个连续OFDM符号,以及每个常规时隙中发送Midamble码的多个连续OFDM符号作为导频符号,或者也可以在发送端的突发中插入特定的导频符号,执行信道估计。 When the receiving side performs channel estimation may be utilized DwPTS transmits SYNC-DL time slot of a plurality of consecutive OFDM symbols, transmitted in the UpPTS time slot of a plurality of consecutive SYNC-UL OFDM symbols, and each of conventional slot Midamble code transmitted a plurality of consecutive OFDM symbols as pilot symbols, or may insert specific pilot symbols at the transmitting end bursts, perform channel estimation.

在接收端单用户检测方案中,根据估计出的OFDM各个子载波上的信道系数,执行简单的均衡,可以采用最大比合并(MRC)、廹零均衡(ZF)和最小均方误差均衡(MMSE)等信道均衡算法,对于均衡器的输出再进行解扰和解扩操作,得到最终的检测结果,另外,在接收端均衡和解扰解扩也可以合并执行,以估计发送数据。 At the receiving end the single user detection scheme, based on the estimated OFDM channel coefficients on the carrier each sub perform simple equalization, maximum ratio combining (MRC) may be employed, Po Equalization (ZF) and minimum mean square error equalizer (MMSE ) and other channel equalization algorithm, the output of the equalizer and then descrambles and despreads the operation to obtain the final detection result, further, at the receiving end equalization despreading and descrambling can be performed combined to estimate the transmission data.

在接收端多用户检测方案中,可以采用连续干扰抵消(SIC)、并行干扰抵消(PIC)和联合检测(Joint Detection,JD)等方法,将它们原来应用于单载波系统中的算法修改后可应用于该TD-SCDMA与OFDM结合的系统中,可以有效地抑制多址干扰的影响,进一步提高系统的性能。 After the receiving end multiuser detection scheme may be employed a successive interference cancellation (the SIC), Parallel Interference Cancellation (PIC) and detection of the joint (Joint Detection, JD) or the like, they are originally applied to the modified algorithm may be a single-carrier system applied to the OFDM combined with TD-SCDMA system, can effectively suppress the influence of multiple access interference, to further improve the performance of the system.

在接收端仅需要单个FFT就可以处理多个用户的信号了,TD-SCDMA是一个同步系统,尽管不可能保证完全精确的同步,然而在OFDM调制中,为了对抗符号间干扰而插入的保护间隔可以容许用户间有小的时间偏移,这种情况下对于信号可以逐符号地进行处理,而不会受到相邻符号的干扰。 At the receiving end, only a single FFT plurality of user signals can be processed, TD-SCDMA is a synchronous system, although the precise synchronization can not completely guarantee, however, in the OFDM modulation in order to combat inter-symbol interference and a guard interval inserted can allow a small time offset between the user, in this case for the signal processing can be performed symbol by symbol, without interference from adjacent symbols.

在TD-SCDMA与OFDM相结合的系统中可以很方便地实现自适应传输技术,在该系统中可以利用多载波结构的特点,使用信道状态信息(CSI),根据信道状态不同用户在每个子载波分配不同的信息比特数目,发送功率,编码速率或它们的组合以获得自适应,由于自适应传输需要获得小区中每个用户的信道估计信息,这个先决条件使得自适应传输更适合于在下行链路中进行,在TD-SCDMA系统中,由于采用TDD模式,上行链路和下行链路使用同样的频带但是不同的时隙,这样上下行链路信道经历相似的衰落,自适应传输可以很容易实现而只需要很少的额外信令开销,而对于其它3G标准所采用的频分双工(FDD)模式,由于上下行链路信道使用不同的频率,则需要附加的信令开销以交换当前的自适应参数和信道状态,从而在TD-SCDMA与OFDM相结合的系统中更易于采用自适应传输技 Can easily implement adaptive transmission technique in systems TD-SCDMA and OFDM combined in the system may utilize the characteristics of a multi-carrier structure, the use of channel state information (CSI), according to a channel state of different users in each sub-carrier assign different number of information bits, transmission power, coding rate, or a combination thereof to obtain the adaptation, since each user need to obtain adaptive transmission channel estimation information in the cell, such that this precondition is more suited to adaptive transmission in the downlink path for the same frequency bands but different time slots so that uplink and downlink channel experiencing a similar decline in the adaptive transmission can easily TD-SCDMA system, since a TDD mode, uplink and downlink use but only to achieve very little additional signaling overhead, while for other 3G standards employed frequency division duplex (FDD) mode, since the uplink and downlink channel use different frequencies, an additional signaling overhead is required to exchange the current adaptive parameters and channel state, and thus more easily adaptive transmission technology in the OFDM system, TD-SCDMA combines the .

不必过多考虑采取很复杂的降低峰值平均功率比的措施,OFDM系统存在的一个不利方面是具有较高的峰值平均功率比,当TD-SCDMA系统中引入OFDM技术时也会存在这个问题,但影响程度要低得多,在OFDM系统中,最坏的情况通常发生在所有的载波都用同样的符号进行调制,但是在TD-SCDMA和OFDM结合的系统中,这种情况是很容易避免的,每个用户的数据经过扩频和扰码后得到的伪随机序列调制在OFDM的各个子载波上,多个用户相叠加的结果使得在每个子载波上的信号值是随机分布的双极性信号的和,则其倾向于服从高斯(Gaussian)分布,这样多个用户相叠加的效果有效地降低了峰值平均功率比。 Not too much to consider measures to reduce the complex peak to average power ratio, there is a downside of the OFDM system is a high peak to average power ratio, when the TD-SCDMA system, the introduction of OFDM technology will have this problem, but Effect much lower extent, in the OFDM system, usually it occurs in the worst case all the carriers are modulated with the same reference numerals, but in the TD-SCDMA system and a combination of OFDM, this situation is easily avoided each user data after the spreading and scrambling code to obtain the pseudo-random sequence modulated on respective subcarriers of the OFDM, the result of superposition of a plurality of users so that the signal phase values ​​on each sub-carrier is randomly distributed bipolar and signals, it tends to Gaussian (Gaussian) distribution, so that a plurality of superposed users effect effectively reduces the peak to average power ratio.

本发明具有的优点是:□ 在TD-SCDMA中结合OFDM技术可以有效地对抗多径干扰的影响。 The invention has the advantage that: □ can effectively combat the effects of multipath interference of OFDM incorporated in TD-SCDMA technology.

□ 在移动通信系统中需要支持多个用户,码分多址CDMA是支持多用户通信的有效手段,而采用OFDM又可达到较理想的频率分集的效果。 □ In the mobile communication system needs to support multiple users, Code Division Multiple Access CDMA is an effective means of supporting communication with multiple users, but also to achieve the effect of use of OFDM ideal frequency diversity.

□ TD-SCDMA采用了同步CDMA技术,使得上行信道各移动终端发出的信号在基站处保持同步,而多用户OFDM对于定时同步的要求非常严格,这样在TD-SCDMA系统中就易于与OFDM技术相结合。 □ TD-SCDMA uses a synchronous CDMA technology, so that the uplink channel of each mobile signal sent from the terminal to maintain synchronization at the base station, the multi-user OFDM for timing synchronization requirements are very strict, so that the TD-SCDMA system is liable to the OFDM technology combined.

□ TD-SCDMA是一个同步系统,尽管不可能保证完全精确的同步,然而在OFDM调制中,为了对抗符号间干扰而插入的保护间隔可以容许用户间有小的时间偏移。 □ TD-SCDMA is a synchronous system, although the precise synchronization can not completely guarantee, however, in the OFDM modulation in order to combat inter-symbol interference can be tolerated guard interval is inserted with a small time offset between users. 这种情况下对于信号可以逐符号地进行处理,而不会受到相邻符号的干扰。 The signal may be processed symbol by symbol in this case, without interference from adjacent symbols. 这还有一个附加的好处是仅需要单个FFT就可以处理多个用户的信号了。 It has an additional benefit is that users need only a single FFT multiple signals can be processed.

□ TD-SCDMA系统所能提供的数据传输速率还是比较有限的(最高2Mbit/s),所采用的调制方式(QPSK或8-PSK)的阶数还是比较低的。 Data transmission rate □ TD-SCDMA system can provide is relatively limited (up to 2Mbit / s), the modulation scheme (QPSK or 8-PSK) is used in the order is relatively low. 而OFDM是一种宽带传输技术,能够有效地对抗符号间干扰的影响,可以采用较高的调制阶数(如16-QAM等)以提高调制效率,可以提供更高的数据传输速率。 And a broadband OFDM transmission technology, it is possible to effectively combat the effects of intersymbol interference may be the higher modulation order (e.g., 16-QAM, etc.) to improve modulation efficiency, it can provide a higher data transfer rate employed.

□ OFDM的多载波结构使得在TD-SCDMA系统中可以很方便地实现自适应传输技术。 □ OFDM multi-carrier structure makes it possible to easily implement adaptive transmission technique in TD-SCDMA systems. 在TD-SCDMA系统中,由于采用TDD模式,上行链路和下行链路使用同样的频带但是不同的时隙,这样上下行链路信道经历相似的衰落,自适应传输可以很容易实现而只需要很少的额外信令开销。 In the TD-SCDMA system, since a TDD mode, uplink and downlink use the same frequency bands but different time slots so that uplink and downlink channel experiencing a similar decline, adaptive transmission can be easily achieved but only very little additional signaling overhead.

□ OFDM系统存在的一个不利方面是具有较高的峰值平均功率比。 One disadvantage of existing □ OFDM systems having high peak to average power ratio. 当TD-SCDMA系统中引入OFDM技术时也会存在这个问题,但影响程度要低得多。 When the TD-SCDMA system will have this problem when the introduction of OFDM technology, but the effect is much lower. 每个用户的数据经过扩频和扰码后得到的伪随机序列调制在OFDM的各个子载波上,多个用户相叠加的结果使得在每个子载波上的信号值是随机分布的双极性信号的和,则其倾向于服从Gaussian分布,这样多个用户相叠加的效果有效地降低了峰值平均功率比。 Each user data after the spreading and scrambling code to obtain the pseudo-random sequence modulated on respective subcarriers of the OFDM, the result of superposition of a plurality of users so that the signal phase values ​​on each sub-carrier is randomly distributed bipolar signals and, it tends to obey the Gaussian distribution, so that a plurality of superposed users effect effectively reduces the peak to average power ratio.

□ TD-SCDMA与OFDM结合起来作为TD-SCDMA的一个备选方案,将使得TD-SCDMA系统与3G以后的技术(将主要采用OFDM作为其核心技术)能够实现更好的兼容,实现平滑过渡。 □ TD-SCDMA combines the OFDM As an alternative TD-SCDMA, and TD-SCDMA system will be such that with future 3G technology (mainly the OFDM as a core technology) enables better compatibility, smooth transition.

附图说明 BRIEF DESCRIPTION

:图1是现有技术多载波传输系统原理框图。 : FIG. 1 is a schematic block diagram of a prior art multicarrier transmission system.

图2是现有技术基带OFDM系统原理框图。 FIG 2 is a prior art schematic block diagram of a baseband OFDM system.

图3是本发明TD-SCDMA子帧的结构示意图。 3 is a schematic structural diagram of TD-SCDMA sub-frame of the present invention.

图4是本发明TD-SCDMA系统DwPTS的突发结构示意图。 FIG 4 is a schematic structural diagram of a burst of TD-SCDMA the DwPTS according to the present invention.

图5是本发明TD-SCDMA系统UpPTS的突发结构示意图。 FIG 5 is a schematic structural diagram of a burst TD-SCDMA system of the present invention the UpPTS.

图6是本发明TD-SCDMA系统的常规时隙结构示意图。 FIG 6 is a schematic view of a conventional slot structure of the TD-SCDMA system according to the present invention.

图7是本发明TD-SCDMA系统的16-QAM星座图。 FIG 7 is a 16-QAM constellation TD-SCDMA system according to the present invention.

图8是本发明的发射端基带部分的示意图。 8 is a schematic of the baseband transmitter portion of the present invention.

图9是本发明数据符号的扩频、加扰和OFDM调制过程的示意图。 9 is a schematic of the present invention, the data symbol spreading, scrambling, and OFDM modulation process.

图10是本发明的接收端基带部分的示意图。 FIG 10 is a schematic diagram of the baseband section of the receiver of the present invention.

图11是本发明单用户检测方案的示意图。 FIG 11 is a schematic view of a single-user detection scheme of the present invention.

具体实施方式 Detailed ways

:本发明提供一种TD-SCDMA兼容OFDM技术的方法,具体方案如下:在TD-SCDMA系统中,为了保证数据在无线链路上的可靠传输,物理层首先需要对来自MAC和高层的数据流进行编码/复用,然后经过物理信道映射之后,信道上的数据将进行扩频和扰码处理。 : The present invention provides a TD-SCDMA method is compatible with OFDM technology, specific programs as follows: In the TD-SCDMA system, in order to ensure reliable transmission of data over a wireless link, a physical layer data from the first MAC and the need for high flow encoding / multiplexing, and after physical channel mapping, the data channel is spread and scrambled. 扩频用高于数据比特速率的数字序列与信道数据相乘,相乘的结果扩展了信号的带宽,将比特速率的数据流转换成了具有码片速率的数据流。 Digital spread channel data sequence with a data bit rate higher than a multiplication result of the expanded bandwidth of the signal, the bit rate of the data stream into a data flow became chip rate. 扩频处理通常也叫做信道化操作,所使用的数字序列称为信道化码,这是一组长度可以不同但仍相互的码组。 Spreading processing is often called channelization operation, called number sequence used channelization code, which is one of length may be different from each other but still codes. 扰码与扩频类似,也是用一个数字序列与扩频处理后的数据相乘。 Similarly spreading and scrambling, the data is a sequence of numbers multiplied spread spectrum processing. 与扩频不同的是,扰码用的数字序列与扩频后的信号序列具有相同的码片速率,所作的乘法运算是一种逐码片相乘的运算。 The difference is that the spread spectrum digital signal sequence with a spreading sequence having the same scrambling code, the chip rate, a multiplication done chip by chip multiplication operation. 扰码的目的是为了标识数据的小区属性。 Scrambling code object is to identify the cell attribute data.

TD-SCDMA扩频后的码片速率为1.28Mc/s,扩频因子的范围为1~16,调制符号的速率为80.0k符号/s~1.28M符号/s。 Chip rate after spreading for the TD-SCDMA 1.28Mc / s, the spreading factor ranges from 1 to 16, symbol rate modulation symbol is 80.0k /s~1.28M symbols / s.

□ TD-SCDMA系统的帧结构与突发结构TD-SCDMA帧长度为10ms,并且将其分成两个结构完全相同的5ms子帧。 A frame structure with TD-SCDMA frame length burst structure □ TD-SCDMA system is 10ms, and divided into two 5ms sub-frame exactly the same structure. 子帧结构如图3所示。 Subframe structure as shown in FIG. 每个子帧由3个特殊时隙和7个常规时隙组成(TS0~TS6)。 Each subframe consists of three special time slots 7 and conventional slots (TS0 ~ TS6).

TD-SCDMA采用TDD模式,在物理信道上是将一个突发(Burst)在所分配的无线帧的特定时隙发射。 TD-SCDMA uses a TDD mode, a physical channel is one burst (Burst) emission in the particular time slot of a radio frame allocated. 时隙结构也就是突发的结构。 Slot structure is burst structure. 由图3,TD-SCDMA系统共定义了4种时隙类型:DwPTS、UpPTS、GP和TS0~TS6。 FIG 3, TD-SCDMA system are defined for four types of slots: DwPTS, UpPTS, GP and TS0 ~ TS6. 其中DwPTS和UpPTS分别用作上行同步和下行同步,不承载用户数据,GP用作上行同步建立过程中的传播时延保护,常规时隙(TS0~TS6)用作承载用户数据或控制信息。 Wherein DwPTS and UpPTS are used as the downlink synchronization and uplink synchronization, does not carry user data, GP propagation delay as the uplink synchronization establishment process of protection, the conventional slot (TS0 ~ TS6) used to carry user data or control information.

DwPTS时隙用来发送下行同步码(SYNC-DL),其结构如图4所示。 DwPTS time slot for transmitting downlink synchronization code (SYNC-DL), the structure shown in FIG.

UpPTS时隙被UE用来发送上行同步码(SYNC-UL),其结构如图5所示。 UpPTS time slot by the UE for transmitting an uplink synchronization code (SYNC-UL), the structure shown in FIG.

TS0~TS6共7个常规时隙用作用户数据或控制信息的传输,它们具有完全相同的时隙结构,其结构如图6所示。 TS0 ~ TS6 total of seven regular time slots transmitted as user data or control information, they have exactly the same slot structure, the structure shown in Fig.

下面分别阐述常规时隙、DwPTS时隙和UpPTS时隙的处理过程。 Conventional processes are set forth below slot, DwPTS and UpPTS time slot of the slot.

□ 常规时隙中用户数据或控制信息的处理a.数据调制如图6所示,每一个常规时隙都是由两个数据域构成,这两个域分别位于训练序列(Midamble)之前和之后。 □ before processing a conventional time slot user data or control information. FIG modulated data, each of a conventional slot configuration is composed of two data fields, the two fields are located in the training sequence 6 (the Midamble) and after . 来源于物理信道映射的比特流在进行扩频处理之前,先要经过数据调制。 Prior to physical channel mapping from the bit stream during the spreading process, first through data modulation. 数据调制把连续的多个比特映射为一个复数值的数据符号。 Modulating the plurality of consecutive data bits of a data symbol mapped to complex-valued. 在TD-SCDMA系统中一般采用的数据调制技术是QPSK,而对于2Mbit/s的业务,使用8PSK调制方式。 In the TD-SCDMA system typically uses data modulation technique is QPSK, and for the 2Mbit / s service, the use of 8PSK modulation scheme. 这些调制方式的效率还是比较低的,为了进一步提高频谱效率,本发明采用16-QAM调制。 These modulation efficiency is still relatively low, in order to further improve spectral efficiency, the present invention uses 16-QAM modulation. 由于采用了可以有效对抗符号间干扰的OFDM传输技术,所以可以适当地提高调制的阶数。 As a result of OFDM transmission technology can effectively combat inter-symbol interference, it is possible to suitably increase the modulation order. 16-QAM把连续的4个比特映射为一个复数值的数据符号,其星座图如图7所示。 The 16-QAM four consecutive bits are mapped to complex-valued data symbol a which constellation diagram shown in Fig. 为了减少接收机中相邻点间的误码率,比特模式采用Gray编码方案。 In order to reduce the error rate in the receiver between adjacent points using Gray coding scheme bit pattern.

输入比特序列经过映射以后,输出序列可以表示为:d‾(k,i)=(d‾1(k,1),d‾2(k,i)‾,Λ,d‾Nk(k,i))T,i=1,2;k=1,Λ,K]]>式中,k是一个时隙中的用户数,最大为16,Nk是第k个用户在一个数据域中的符号数,其值与使用的扩频因子Qk有关。 The input bit sequence after after mapping, the output sequence may be expressed as: d & OverBar; (k, i) = (d & OverBar; 1 (k, 1), d & OverBar; 2 (k, i) & OverBar;, & Lambda;, d & OverBar; Nk (k , i)) T, i = 1,2; k = 1, & Lambda;, K]]> where, k is the number of users in one slot, a maximum of 16, Nk is the k th user in a data field the number of symbols, spreading factor Qk value and its related use. 数据块d(k,1)在训练序列的前面发送,而数据块d(k,2)在训练序列的后面发送。 Data block d (k, 1) in front of the training sequence transmission, and the data block d (k, 2) after the transmission of the training sequence.

b.扩频经过复值映射后,复值数据符号dn(k,i)将被扩频。 B. After spreading the mapped complex values, complex valued data symbols dn (k, i) will be spread. 在TD-SCDMA系统中,上行方向的扩频使用长度为Qk∈{1,2,4,8,16)的实值信道化码序列,而在下行方向,Qk∈{1,16}。 In the TD-SCDMA system, using spread spectrum upstream longitudinal direction of Qk∈ {1,2,4,8,16) of real-valued channelization code sequence in the downlink direction, Qk∈ {1,16}. 实值信道化码序列可表示为:c(k)=(c1(k),c2(k),Λ,cQk(k)),k=1,Λ,K]]>序列中的元素cq(k)∈{1,-1};k=1,Λ,K。 Real-valued channelization code sequence can be expressed as: c (k) = (c1 (k), c2 (k), & Lambda;, cQk (k)), k = 1, & Lambda;, K]]> sequence element cq (k) ∈ {1, -1}; k = 1, Λ, K. c(k)也叫做正交可变扩频因子(OVSF)码。 c (k) also known as (OVSF) codes orthogonal variable spreading factor.

为了降低多码传输时的峰均值比,与信道化码相伴的还有一个信道化特征乘法算子wQk(k)∈{ejπ/2pk},pk∈{0,Λ,Qk-1}]]>,Qk是扩频因子。 To reduce the peak to average ratio of the multi-code transmission, accompanying with a channelization code and a channelization characterized multiplication operator wQk (k) & Element; {ej & pi; / 2pk}, pk & Element; {0, & Lambda;, Qk-1 }]]>, Qk is the spreading factor. 乘法算子通常在扩频之前与经过复值映射的每一数据符号相乘(也可扩频之后进行),因而wQk(k)通常也叫做加权因子。 Typically multiplication operator (may be performed after spreading) before and after spreading by multiplying each data symbol mapped complex values, and thus wQk (k) also commonly referred to weighting factors.

c.扰码数据符号经过扩频处理后,还要进行扰码处理。 C. scrambled data symbols after spreading processing, but also a scrambled. 如果说信道化处理标识了用户(码分信道),那么对数据进行扰码处理则是为了标识小区。 If the channel processing user identification (code channel), then the data is scrambled in order to identify the cell. 在TD-SCDMA系统中,采用短的复扰码来对数据符号进行加扰处理。 In the TD-SCDMA system, the complex scrambling code using short scrambling process is performed on the data symbols. 扰码序列的长度固定为16,可以表示为:v=(v1,v2,Λ,v16)。 Scrambling sequence length is fixed to 16, may be expressed as: v = (v1, v2, Λ, v16). 复序列中的元素vi(i=1,Λ,16)取值范围为{1,j,-1,-j}。 Complex sequences of elements vi (i = 1, Λ, 16) in the range {1, j, -1, -j}. 复扰码是由一个长度为16的二进制实数扰码序列v=(v1,v2,Λ,v16)产生的。 Complex is a real number binary scrambling code of length 16 by the scrambling sequence v = (v1, v2, Λ, v16) produced. TD-SCDMA系统共定义了128个这样的实数序列,每个小区配置4个。 TD-SCDMA system 128 are defined for such a sequence of real numbers per cell configuration 4. 复扰码序列v和实扰码序列v中各元素的关系为:vi=(j)i·vivi∈{1,-1};i=1,Λ,16则复序列v中的各元素vi是虚实交替的。 Relationship complex scrambling sequence v and the elements of the real scrambling sequence v as: vi = (j) i · vivi∈ {1, -1}; i = 1, Λ, 16 then the complex elements in the sequence v vi alternate is the actual situation.

d.串/并变换与OFDM调制用户k经过扩频和加扰后的数据以每Qmax个码片分为一组。 D. serial / parallel conversion and OFDM modulation through user k spread and scrambled data chips per Qmax grouped. 该组中用户k的扩频码和小区的扰码结合起来可以看作是用户k和小区特定的扩频码s(k)=(sp(k)),]]>其中:sp(k)=c1+[(p-1)modQk](k)v‾p,p=1,2,...,Qmax]]>则该组码片序列中第p个码片up(k,i)可以表示为:up(k,i)=d‾1+[(p-1)modQk](k,i)wQk(k)sp(k),p=1,2,...,Qmax]]>将该组序列的Qmax个码片进行串/并变换,变为一个并行的数据流,然后通过OFDM调制后传送出去。 The group spreading code of user k and cell scrambling code combination can be seen as a cell-specific and user k spreading codes s (k) = (sp (k)),]]> wherein: sp (k) = c1 + [(p-1) modQk] (k) v & OverBar; p, p = 1,2, ..., Qmax]]> is the set of the first chip sequence p chips of up (k, i) can be expressed as: up (k, i) = d & OverBar; 1 + [(p-1) modQk] (k, i) wQk (k) sp (k), p = 1,2, ..., Qmax]]> the chips Qmax genomic sequence is serial / parallel conversion, into a parallel data stream and then transmitted via the OFDM modulation. 这里OFDM采用的子载波数N=Qmax。 The number of subcarriers used in OFDM here N = Qmax. 如图8所示。 As shown in FIG. 该组码片序列经过OFDM调制所发送的基带信号为:xn(k,i)=Σp=1Qmaxexp(j2πpn/Qmax)up(k,i),n=1,...,Qmax]]>即OFDM调制可以通过将串/并变换后的数据执行Qmax点的IFFT变换来有效地实现。 The set of chip sequence after baseband signal OFDM modulated transmitted as: xn (k, i) = & Sigma; p = 1Qmaxexp (j2 & pi; pn / Qmax) up (k, i), n = 1, ..., Qmax ]]> i.e., OFDM modulation can be performed IFFT transformation data points Qmax serial / parallel converted efficiently achieved.

为了克服符号间干扰的影响,在IFFT变换后要添加一个大于信道最大延迟扩展的CP作为保护间隔。 In order to overcome the effects of intersymbol interference, after the IFFT to add a channel greater than the maximum channel delay spread as a guard interval CP. 通过使用这个保护间隔,接收端可以取出不受符号间干扰的信号部分,以实现无符号间干扰的传输。 By using the guard interval, the receiver can not remove the intersymbol interference signal portions in order to achieve transmission without intersymbol interference.

综上所述,对于常规时隙中发送的用户数据或控制信息扩频、扰码和OFDM调制的一般过程如图9所示。 In summary, user data or control information for a conventional slot in the transmitted spread spectrum, scrambling and general process OFDM modulation as shown in FIG. k表示用户号,i∈{1,2}代表常规突发中的数据块号,Qk为时隙中当前使用的扩频因子,Qmax=16为时隙内使用的最大扩频因子,同时也是扰码序列的长度,nk=Qmax/Qk。 k represents the user number, i∈ {1,2} represent the data block number in the normal burst, Qk is the slot currently used spreading factor, Qmax = 16 is the maximum spreading factor used in the slot, but also the length of the scrambling sequence, nk = Qmax / Qk.

③对于SYNC-DL、SYNC-UL和Midamble码的处理在3GPP的规范中,SYNC-DL、SYNC-UL和Midamble这几种码都是直接以码片速率的形式给出,不需要进行扩频,它们分别是在DwPTS时隙(参阅图4)、UpPTS时隙(参阅图5)和常规时隙(参阅图6)中发送的。 ③ for the SYNC-DL, SYNC-UL and processing of Midamble codes in 3GPP specifications, SYNC-DL, SYNC-UL and these types Midamble codes are directly given as the chip rate does not need spreading , they are in the DwPTS time slot (see FIG. 4), UpPTS time slot (see FIG. 5) and a conventional time slot (see FIG. 6) is transmitted. 此外,这几种码在不同的临近小区有不同的配置,因而也不需要进行加扰处理。 In addition, these types of codes have different configurations in different adjacent cells, and therefore not require scrambling process. 所有这几种码的码本都可以在3GPP的规范中直接查到,不需任何生成过程(Midamble需通过循环移位来区分用户)。 All these types of codebook code can be directly found in the 3GPP specification, without any generation process (need to distinguish users by the Midamble cyclic shift). 所需的处理只是这几种码都是以实数值的形式给出的,需要进行复数化处理。 This process required several codes are given only in the form of real-valued, complex processing is required.

设这几种码的实值序列为:u=(u1,u2,Λ,ui,Λ,uk),K=64SYNC-DL128SYNC-UL144Midamble]]>复数化处理使用下面的关系式作用于实值序列u中的每一位元素。 Real-valued sequence set these types of code is: u = (u1, u2, & Lambda;, ui, & Lambda;, uk), K = 64SYNC-DL128SYNC-UL144Midamble]]> complex process using the following relation acting to the real u sequence of values ​​of every element.

ui=(j)i·uiui∈{1,-1} i=1,2,Λ,K经过复数化处理后,复值序列u=(u1,u2,Λ,ui,Λ,uK)中的元素是虚实交替的,然后对其再进行OFDM调制。 ui = (j) i · uiui∈ {1, -1} i = 1,2, Λ, K, after a plurality of treatment, the complex value sequence u = (u1, u2, Λ, ui, Λ, uK) of element is the actual situation alternating, and its further performs OFDM modulation. 对于SYNC-DL,其64个码片分成4组,每组按照前面的OFDM调制过程(参阅图8),分别进行Qmax点的IFFT变换,生成4个连续的OFDM符号发送出去。 For the SYNC-DL, which is 64 chips divided into four groups according to the preceding OFDM modulation process (see FIG. 8), respectively, each point IFFT transformation Qmax, generates four consecutive OFDM symbols transmitted. 对于SYNC-UL,其128个码片分成8组,每组分别进行Qmax点的IFFT变换,生成8个连续的OFDM符号发送出去。 For the SYNC-UL, which is 128 chips divided into eight groups, respectively, each point IFFT transformation Qmax, generates 8 consecutive OFDM symbols transmitted. 对于Midamble,其144个码片分成9组,每组分别进行Qmax点的IFFT变换,生成9个连续的OFDM符号发送出去。 For the Midamble, which chip 144 yards divided into 9 groups, respectively, each point IFFT transformation Qmax, generates nine consecutive OFDM symbols transmitted.

④接收机方案在接收端要执行符号定时过程,即求得单个OFDM符号开始和结束的精确时刻。 ④ scheme at the receiving end the receiver symbol timing to perform the process, i.e., a single OFDM symbol to obtain the exact start and end time. 符号定时的结果将决定FFT的窗口。 Symbol timing will determine the result of the FFT window. 可以采用数据辅助和非数据辅助两种方法实现符号定时。 And auxiliary data may be employed two methods assist in achieving non-data symbol timing. 数据辅助方法可以在传输信号中周期性插入已知的训练符号作为导引符号。 The method of auxiliary data may periodically insert a known training symbols as pilot symbols in the transmission signal. 非数据辅助方法采用OFDM波形的循环前缀结构完成符号定时。 Methods NDA Cyclic Prefix OFDM waveform of the symbol timing to complete the structure. 而且,在OFDM系统中面临的一个主要问题是对频偏误差的敏感性。 Moreover, a major problem faced in the OFDM system is sensitive to offset errors. 因此,在TD-SCDMA系统中引入OFDM技术时,对于载波频率估计的准确度比在原来的TD-SCDMA系统中更加重要,要执行严格的载波频率偏移误差估计,进行频率校正。 Thus, the OFDM technology is introduced in the TD-SCDMA system, for a carrier frequency estimation accuracy is more important than in the original TD-SCDMA systems, a strict carrier frequency offset estimation error, correct the frequency. 频率偏移误差估计可以基于传输信号中的特定训练信息进行,也可以对频域内的接收信号进行分析得到。 Frequency offset error estimation may be based on the particular training information in the transmitted signal, or may be obtained by analyzing the received signal in the frequency domain.

本发明的基带接收机结构如图10所示。 The baseband receiver architecture of the present invention as shown in Fig. 在接收端执行与发送端相反的过程,对接收到的信号进行符号定时同步、串/并变换并去除CP后,根据估计出的频率偏移进行频率校正,再执行Qmax点的FFT变换,把信号从时域变回频域,以实现OFDM解调。 After the end opposite the receiving side performs the transmission process, the received signal symbol timing synchronization, serial / parallel conversion and the CP is removed, based on the estimated frequency offset frequency correction, and then performs the FFT transformation point Qmax, the signal from the time domain back to the frequency domain to realize OFDM demodulation. 同时,采用一定的信道估计算法估计出OFDM各个子载波上的信道系数。 At the same time, using a certain algorithm to estimate the channel estimation on the channel coefficient of each subcarrier OFDM. 可以利用DwPTS时隙中发送SYNC-DL的4个连续OFDM符号、UpPTS时隙中发送SYNC-UL的8个连续OFDM符号,以及每个常规时隙中发送Midamble码的9个连续OFDM符号作为导频符号,执行信道估计。 DwPTS timeslot may be utilized in the transmission of four SYNC-DL consecutive OFDM symbols in the UpPTS time slot transmits SYNC-UL 8 consecutive OFDM symbols, and transmitting each code Midamble conventional slot 9 consecutive OFDM symbols as pilot pilot symbols, performs channel estimation. 然后对于OFDM解调后的信号再执行单用户或多用户检测,以判决出发送的数据。 Then for the OFDM demodulated signal and then perform a single or multi-user detection to the judgment of the data transmission.

第k个用户的单用户检测器如图11所示。 K-th user's single-user detector as shown in FIG. 在OFDM的每个子信道上可认为是窄带平坦衰落的,信道估计模块所估计出的第p个子信道的信道系数为H(p)。 On each OFDM subchannel may be considered narrowband flat fading, the channel estimation module estimates the p-th sub-channel coefficients of H (p). 执行OFDM模块后接收信号向量为Y=(Y(1),Y(2),...,Y(Qmax))T,其元素Y(p)为在第p个子载波上的接收信号。 After the module performs OFDM reception signal vector is Y = (Y (1), Y (2), ..., Y (Qmax)) T, whose elements are the Y (p) of the received signal at the p-th subcarrier. G为单抽头Qmax×Qmax的均衡器,且G=G(1)G(2)OG(Qmax)]]>为一对角线矩阵,复数G(p)(p=1,2,...,Qmax)表示第p个子载波的均衡系数。 G is a one-tap equalizer Qmax × Qmax, and G = G (1) G (2) OG (Qmax)]]> is a diagonal matrix, a plurality of G (p) (p = 1,2, .. ., Qmax) represents equalization coefficient p of subcarriers. 均衡器的输出结果为:R=G·Y。 The output of the equalizer is: R = G · Y.

在本发明中,通过简单地改变系数G(p)可以很容易地实现均衡。 In the present invention, it can easily be achieved by simply changing the equalization coefficients G (p). 这里以几种简单的均衡算法为例:(a)最大比合并(MRC):把均衡系数G(p)设置为与信道相匹配,即G(p)=H*(p),则它可用来实现一个频域RAKE接收机。 Here in several simple equalization algorithm as an example: (a) maximum ratio combining (MRC): the equalization coefficients G (p) to match the channel, i.e., G (p) = H * (p), then it is available to implement a RAKE receiver frequency domain.

(b)廹零均衡(ZF):均衡系数G(p)=H*(p)/|H(p)|2。 (B) Po Equalization (ZF): the equalizer coefficients G (p) = H * (p) / | H (p) | 2. 对于同步CDMA,它能重建不同用户之间的正交性,以消除多址干扰MAI的影响。 For synchronous CDMA, it can rebuild orthogonality between different users, in order to eliminate the influence of MAI MAI. 这种接收机的缺点是在某些子信道深度衰落时受到限制,此时这些子信道上的噪声会被放大到降低接收机性能的地步。 The disadvantage of this receiver is limited at certain deep fading subchannels, the subchannels at this time the noise will be amplified to the point of reduced receiver performance. 不过这个问题可以通过使用下面的最小均方误差(MMSE)均衡方法很容易解决。 But this can be solved by using the following minimum mean square error (MMSE) equalization method is very easy to solve.

(c)最小均方误差均衡(MMSE):均衡系数G(p)=H*(p)/(|H(p)|2+λ)。 (C) equalization minimum mean square error (MMSE): equalization coefficients G (p) = H * (p) / (| H (p) | 2 + λ). 它与廹零均衡的主要区别在于调整因子λ,它用来在遭受深度衰落的子信道上限制任何可能的噪声放大。 It is the main difference with the zero balance Po that the adjustment factor λ, which is used to limit any possible noise amplification on subchannel suffering deep fading.

在下行链路中,对于要解码的用户,干扰用户的数据从同一个基站发送过来,估计这些信道系数是相对简单的。 In the downlink, for the user to be decoded, the interference from the user data sent from the same base station, the channel estimate these coefficients is relatively simple.

对于均衡器的输出再进行解扰和解扩操作,得到最终的检测结果。 The output of the equalizer and then descrambles and despreads the operation to obtain the final detection result. 另外,在接收端均衡和解扰解扩也可以合并执行,以估计发送数据。 Further, descrambling and equalization at the receiving end can also be combined despread performed to estimate the transmission data.

在TD-SCDMA系统中结合OFDM技术可以有效地抵抗多径干扰的影响,而另一方面,多址干扰又是影响其性能的主要因素。 OFDM technology incorporated in the TD-SCDMA system can effectively resist the effects of multipath interference, on the other hand, the multiple access interference is the main factor affecting the performance thereof. 针对于此,采用多用户检测可以有效地提高系统的性能,其中干扰抵消(IC)是比较常用的方法,并且可以应用到TD-SCDMA与OFDM相结合的系统中。 In light of this, the use of multi-user detection can improve the performance of the system in which interference cancellation (IC) methods are commonly used, and may be applied to the TD-SCDMA system and the OFDM combined.

比较简单的非线性接收机是连续干扰抵消(SIC)。 The receiver is relatively simple nonlinear successive interference cancellation (SIC). 在这个算法中,首先检测具有最高功率的用户。 In this algorithm, first detects the user with the highest power. 然后利用检测结果重构该用户的信号,并将它从接收机输入信号中去除。 And then reconstructed using the detection result of the user signal, and it is removed from the receiver input signal. 接着对剩下的用户重复该操作直到所有的用户都检测出来。 The user then repeated for the remaining operations until all users are detected. 另外还可以采用并行干扰抵消(PIC),处理速度相对快一些。 May additionally also be employed parallel interference cancellation (PIC), the processing speed is relatively faster. 首先使用信道匹配滤波器输出对所有用户的数据进行估计,然后,对于每一个用户,从信号中去除其他用户造成的干扰后得到一个新的估计。 First, using a channel matched filter outputs to estimate the data for all users, and then, for each user, is removed from the signal obtained in a new estimate of the interference to other users caused. 这个过程可以重复多次。 This process can be repeated many times.

联合检测技术是在多用户检测技术基础上提出的。 Joint detection technique is proposed in the multi-user detection technology basis. 该技术是减弱或消除多址干扰、多径干扰和远近效应的有效手段,能够简化功率控制,降低功率控制精度,弥补正交扩频码互相关性不理想所带来的消极影响,从而改善系统性能、提高系统容量、增大小区覆盖范围。 This technique is reduce or eliminate multiple access interference, multipath interference and near-far effect of the effective means, power control can be simplified, reducing the power control precision, to compensate the negative effects of orthogonal spreading codes over the cross-correlation is not brought about, thereby improving system performance, improve system capacity, the cell coverage increases. 联合检测技术同样也可应用于TD-SCDMA与OFDM相结合的系统中。 Joint detection technique is also applicable to TD-SCDMA system and the OFDM combined.

对于TD-SCDMA与OFDM相结合的系统,在下行链路的接收中,干扰抵消主要由于其复杂度一般不会考虑采用。 For OFDM systems TD-SCDMA and combining the received downlink interference cancellation due primarily to their complexity is generally not considered. 而且,这样的接收机需要系统中所有用户的重要信息,例如它们的扩频码、功率等。 Moreover, important information for all users in the system such receivers require, for example, their spreading codes, power, etc. 因此在下行链路采用单用户检测方案。 Thus a single user detection scheme in downlink.

在上行链路中,设计基站时,干扰抵消以及联合检测都可以采用。 In the uplink, the design of the base station, the joint detection and interference cancellation may be employed. TD-SCDMA是一个同步系统,尽管不可能保证完全精确的同步,然而在OFDM调制中,为了对抗符号间干扰而插入的保护间隔可以容许用户间有小的时间偏移。 TD-SCDMA is a synchronous system, although the precise synchronization can not completely guarantee, however, in the OFDM modulation in order to combat inter-symbol interference can be tolerated guard interval is inserted with a small time offset between users. 这种情况下对于信号可以逐符号地进行处理,而不会受到相邻符号的干扰。 The signal may be processed symbol by symbol in this case, without interference from adjacent symbols. 这还有一个附加的好处是仅需要单个FFT就可以处理多个用户的信号了。 It has an additional benefit is that users need only a single FFT multiple signals can be processed. 而在其它非同步系统中,对每个用户就需要有一个单独的FFT操作。 In other asynchronous system, you need to have a separate FFT operation for each user.

因此,TD-SCDMA与OFDM相结合的优势与必要性如下:□ TD-SCDMA是一个干扰(或信噪比)受限系统,其容量主要受限于移动信道的主要干扰:多径干扰与多址干扰,而OFDM是克服多径干扰最为有效的手段。 Thus, the necessity and advantages of TD-SCDMA and OFDM combined as follows: □ TD-SCDMA is an interference (or SNR) limited system, the capacity is mainly limited by interference from mobile main channel: multi-path interference and multi MAI, and OFDM to overcome multipath interference, the most effective means. 为了对抗多径干扰,TD-SCDMA接收机采用RAKE分集接收技术来区分和绑定多路信号能量,能够提供一定的分集增益。 To combat multipath interference, TD-SCDMA receiver uses RAKE diversity reception to distinguish and bind multiple signal energy, it is possible to provide some diversity gain. 然而由于多路信号能量不相等,试验证明,如果路径数超过7或8条,这种信号能量的分散将使得信道估计精确度降低,RAKE的接收性能下降就会很快。 However, due to multipath signal energy are not equal, the test proved that, if the path exceeds 7 or 8, the dispersion of this signal energy that would reduce the accuracy of channel estimation, RAKE reception performance will decline rapidly. 而OFDM技术与RAKE接收的思路不同,它是将待发送的信息码元通过串并变换,降低速率,从而增大码元周期,以更有效地削弱多径干扰的影响。 OFDM technology and the different RAKE reception idea, which is the information symbol to be transmitted by the serial-parallel conversion, the rate of reduction, thereby increasing the symbol period, to more effectively weaken the influence of multipath interference. 同时它使用CP作为保护间隔,大大减少甚至消除了码间干扰,并且保证了各信道间的正交性,从而大大减少了信道间干扰。 It uses the same time as a guard interval CP, greatly reduce or even eliminate the inter-symbol interference, and to ensure orthogonality among the channels, thereby greatly reducing the inter-channel interference.

□ 在移动通信系统中需要支持多个用户,CDMA是支持多用户通信的有效手段,而采用OFDM又可达到较理想的频率分集的效果。 □ In the mobile communication system needs to support multiple users, CDMA is an effective means of supporting communication with multiple users, but also to achieve the effect of use of OFDM ideal frequency diversity.

□ TD-SCDMA采用了同步CDMA技术,使得上行信道各移动终端发出的信号在基站处保持同步,而多用户OFDM对于定时同步的要求非常严格,这样在TD-SCDMA系统中就易于与OFDM技术相结合。 □ TD-SCDMA uses a synchronous CDMA technology, so that the uplink channel of each mobile signal sent from the terminal to maintain synchronization at the base station, the multi-user OFDM for timing synchronization requirements are very strict, so that the TD-SCDMA system is liable to the OFDM technology combined.

□ TD-SCDMA是一个同步系统,尽管不可能保证完全精确的同步,然而在OFDM调制中,为了对抗符号间干扰而插入的保护间隔可以容许用户间有小的时间偏移。 □ TD-SCDMA is a synchronous system, although the precise synchronization can not completely guarantee, however, in the OFDM modulation in order to combat inter-symbol interference can be tolerated guard interval is inserted with a small time offset between users. 这种情况下对于信号可以逐符号地进行处理,而不会受到相邻符号的干扰。 The signal may be processed symbol by symbol in this case, without interference from adjacent symbols. 这还有一个附加的好处是仅需要单个FFT就可以处理多个用户的信号了。 It has an additional benefit is that users need only a single FFT multiple signals can be processed.

□ TD-SCDMA系统所能提供的数据传输速率还是比较有限的(最高2Mbit/s),所采用的调制方式(QPSK或8-PSK)的阶数还是比较低的。 Data transmission rate □ TD-SCDMA system can provide is relatively limited (up to 2Mbit / s), the modulation scheme (QPSK or 8-PSK) is used in the order is relatively low. 而OFDM是一种宽带传输技术,能够有效地对抗符号间干扰的影响,可以采用较高的调制阶数(如16-QAM等)以提高调制效率,可以提供更高的数据传输速率。 And a broadband OFDM transmission technology, it is possible to effectively combat the effects of intersymbol interference may be the higher modulation order (e.g., 16-QAM, etc.) to improve modulation efficiency, it can provide a higher data transfer rate employed.

□ OFDM的多载波结构使得在TD-SCDMA系统中可以很方便地实现自适应传输技术。 □ OFDM multi-carrier structure makes it possible to easily implement adaptive transmission technique in TD-SCDMA systems. 在一般的OFDM系统中,使用CSI,根据信道状态不同用户在每个子载波分配不同的信息比特数目,星座大小,发送功率,编码速率或它们的组合以获得自适应。 In a typical OFDM system, using the CSI, a channel state according to different users in each subcarrier allocation different number of information bits, the constellation size, transmission power, coding rate, or a combination thereof to obtain the adaptation. 另一方面,在TD-SCDMA与OFDM相结合的系统中可以考虑利用多载波结构的特点采用自适应传输技术以获得系统性能的提高。 On the other hand, in the TD-SCDMA system and the OFDM combined use of the characteristics may be considered a multi-carrier transmission technique adaptive structure to obtain improved system performance. 由于自适应传输需要获得小区中每个用户的信道估计信息,这个先决条件使得自适应传输更适合于在下行链路中进行。 Since the need to obtain adaptive transmission channel estimation of each user in the cell information, such that this precondition is more suitable for adaptive transmission in the downlink. 在TD-SCDMA系统中,由于采用TDD模式,上行链路和下行链路使用同样的频带但是不同的时隙,这样上下行链路信道经历相似的衰落,自适应传输可以很容易实现而只需要很少的额外信令开销。 In the TD-SCDMA system, since a TDD mode, uplink and downlink use the same frequency bands but different time slots so that uplink and downlink channel experiencing a similar decline, adaptive transmission can be easily achieved but only very little additional signaling overhead. 而对于其它3G标准所采用的FDD模式,由于上下行链路信道使用不同的频率,则需要附加的信令开销以交换当前的自适应参数和信道状态。 For the FDD mode other 3G standards adopted, since the uplink and downlink channel use different frequencies, an additional signaling overhead is required to exchange the current status and channel adaptation parameters. 因此,在TD-SCDMA与OFDM相结合的系统中更易于采用自适应传输技术。 Accordingly, the TD-SCDMA system and the OFDM combined more easily adaptive transmission technique.

□ OFDM系统存在的一个不利方面是具有较高的峰值平均功率比。 One disadvantage of existing □ OFDM systems having high peak to average power ratio. 当TD-SCDMA系统中引入OFDM技术时也会存在这个问题,但影响程度要低得多。 When the TD-SCDMA system will have this problem when the introduction of OFDM technology, but the effect is much lower. 在OFDM系统中,最坏的情况通常发生在所有的载波都用同样的符号进行调制。 In an OFDM system, generally occurs in the worst case all the carriers are modulated with the same reference numerals. 但是在TD-SCDMA和OFDM结合的系统中,这种情况是很容易避免的。 However, TD-SCDMA, and OFDM system, in conjunction with, this situation is easily avoided. 每个用户的数据经过扩频和扰码后得到的伪随机序列调制在OFDM的各个子载波上,多个用户相叠加的结果使得在每个子载波上的信号值是随机分布的双极性信号的和,则其倾向于服从Gaussian分布,这样多个用户相叠加的效果有效地降低了峰值平均功率比。 Each user data after the spreading and scrambling code to obtain the pseudo-random sequence modulated on respective subcarriers of the OFDM, the result of superposition of a plurality of users so that the signal phase values ​​on each sub-carrier is randomly distributed bipolar signals and, it tends to obey the Gaussian distribution, so that a plurality of superposed users effect effectively reduces the peak to average power ratio.

□ TD-SCDMA与OFDM结合起来作为TD-SCDMA的一个备选方案,将使得TD-SCDMA系统与3G以后的技术(将主要采用OFDM作为其核心技术)能够实现更好的兼容,实现平滑过渡。 □ TD-SCDMA combines the OFDM As an alternative TD-SCDMA, and TD-SCDMA system will be such that with future 3G technology (mainly the OFDM as a core technology) enables better compatibility, smooth transition.

因而,在TD-SCDMA系统中,可以将同步CDMA与OFDM结合起来,作为TD-SCDMA的一个备选方案,充分利用二者相结合的优势,以更好地克服多径干扰并提供更高业务质量和数据传输速率的多媒体业务。 Accordingly, the TD-SCDMA systems, synchronization may combine CDMA and OFDM, as an alternative of TD-SCDMA, full use of the advantages of a combination of both, in order to better overcome multipath interference and provide higher service quality and data rate multimedia services.

总之,本发明充分利用同步CDMA和OFDM相结合的优势,可以弥补TD-SCDMA系统的不足,更好地克服多径干扰,有效地消除高速数据传输时的符号间干扰,提供更高数据传输速率和业务质量的多媒体业务。 In summary, the present invention fully utilizes synchronous CDMA and OFDM combined advantages, can make up the TD-SCDMA system, better overcome multipath interference effectively eliminates inter-symbol interference at the time of high speed data transmission, to provide higher data transfer rates and service quality multimedia services. 也可使得TD-SCDMA系统与3G以后的技术(将主要采用OFDM作为其核心技术)能够实现更好的兼容,可以平滑过渡到将来的系统。 It may also be such that TD-SCDMA system with future 3G technology (mainly the OFDM as a core technology) enables better compatibility can be a smooth transition to future systems.

综上所述仅为本发明的较佳实施例而已,并非用来限定本发明的实施范围。 As described above merely preferred embodiments of the present invention only, not intended to limit the scope of embodiments of the present invention. 即凡依本发明申请专利范围的内容所作的等效变化与修饰,都应为本发明的技术范畴。 I.e. all such modifications and equivalent applications under this invention, the scope of the patent made by the technical scope of the present invention should be.

Claims (18)

1.一种TD-SCDMA系统兼容OFDM技术的方法,其特征在于包括以下步骤:在发射端,对TD-SCDMA系统提供的码片进行分组,并对每组码片执行OFDM的调制处理,然后执行TD-SCDMA的常规处理;在接收端,包括:执行符号定时同步过程;执行载波频率偏移误差估计并进行频率校正;执行OFDM解调过程;执行信道估计过程,从而估计出OFDM各个子载波上的信道系数;以及对OFDM解调后的信号执行单用户或多用户检测,以判决发送的数据。 A TD-SCDMA system methods compatible with OFDM technology, comprising the steps of: at the transmitting side, the chip of TD-SCDMA system provided by the packet, modulation processing and performs OFDM chips of each group, then conventional processing execution of TD-SCDMA; at a receiving end, comprising: performing symbol timing synchronization procedure; perform carrier frequency offset estimation error and frequency correction; performs OFDM demodulation; perform channel estimation process to estimate an individual OFDM subcarriers on channel coefficients; and a data signal performs single user or multiuser detection after OFDM demodulation is performed to determine the transmission.
2.根据权利要求1所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于,所述TD-SCDMA系统包括4种时隙类型:DwPTS、UpPTS、GP和TS0~TS6,其中DwPTS和UpPTS分别用作上行同步和下行同步,不承载用户数据,GP用作上行同步建立过程中的传播时延保护,常规时隙TS0~TS6用作承载用户数据或控制信息,在所述发射端,是对TD-SCDMA系统不同时隙作出了相应的处理以便更好的与OFDM技术相结合。 2. The method of claim compatible OFDM technique. 1 TD-SCDMA system as claimed in claim, characterized in that the TD-SCDMA system includes 4 types slots: DwPTS, UpPTS, GP and TS0 ~ TS6, wherein DwPTS and UpPTS were used as the downlink synchronization and uplink synchronization, does not carry user data, GP propagation delay as the uplink synchronization establishment process of protection, as a conventional time slot TS0 ~ TS6 carries user data or control information at the transmitting end, it is the corresponding process made in order to better combine the OFDM technique different slots TD-SCDMA system.
3.根据权利要求2所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:在对所述码片分组之前,对于所述常规时隙TS0~TS6中的用户数据或控制信息的处理,对来源于物理信道映射的比特流,进行数据调制以及常规的乘法算子加权、扩频与扰码处理后,将扰码序列分组。 The method is compatible OFDM technology of the TD-SCDMA system as claimed in claim 2, wherein: prior to said chip packet, user data or control information in TS0 ~ TS6 to the conventional processing slot , the bit stream derived from a physical channel mapping, data modulation and a conventional weighted multiplication operator, after the spreading with scrambling, the scrambling sequence packets.
4.根据权利要求3所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于,所述执行数据调制的步骤可采用比TD-SCDMA中更高阶数的调制方法,以提高频谱效率和数据速率。 According to the TD-SCDMA system is compatible. 3 OFDM art method as claimed in claim, wherein the step of performing data modulation method may be employed higher order modulation than in TD-SCDMA, and in order to improve spectral efficiency data rate.
5.根据权利要求2所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:对于SYNC-DL即在DwPTS时隙中的下行同步码、SYNC-UL即在UpPTS时隙中的上行同步码和Midamble码即在常规时隙中的训练序列,这几种码在TD-SCDMA标准中,都是直接以码片速率的形式给出,不需要进行扩频和加扰处理,对这几种码的码本都可以在3GPP的规范中直接查到,然后进行复数化处理后直接执行OFDM调制过程。 According to claim 2 TD-SCDMA system is compatible OFDM art method as claimed in claim, wherein: i.e. for downlink synchronization SYNC-DL code in the DwPTS time slot, SYNC-UL i.e. UpPTS timeslot in the uplink synchronization Midamble code and training sequence code i.e. in a conventional slot, these types of codes in the TD-SCDMA standard, are directly given as the chip rate, spreading, and scrambling process is not required, few of these direct performs OFDM modulation process codebook code seed can be directly found in the 3GPP specification, and then after performing complex processing.
6.根据权利要求2至5项任一项所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:所述执行OFDM调制的过程包括以下步骤:在对不同时隙的码片进行分组时,即对常规时隙TS0~TS6中的扰码序列进行分组,对于SYNC-DL、SYNC-UL和Midamble,将其码片序列分别进行分组,使每组包含N个码片;对每组码片进行串/并变换,变为一并行数据流;进行N点的快速傅立叶反变换IFFT,将该N个码片调制到N个并行正交的子载波上;在IFFT变换后,添加一大于信道最大延迟扩展的循环前缀CP作为保护间隔,以克服符号间干扰的影响;执行并/串变换,生成多个连续的OFDM符号。 From 6.2 to 5 according to any one of the TD-SCDMA system is compatible with OFDM technology method according to claim, wherein: the process performs OFDM modulation comprises the steps of: grouping chips different time slots when, that is scrambling sequence regular time slots TS0 ~ TS6 group, for SYNC-DL, SYNC-UL and the Midamble, each sequence of chips which are grouped so that each group contains N chips; each group chip serial / parallel conversion, becomes a parallel data stream; performing inverse fast Fourier transform IFFT point N, the N chip is modulated onto N parallel sub-carriers orthogonal; after the IFFT, adding a is greater than the maximum channel delay spread as the CP is a guard interval, to overcome the effects of intersymbol interference; performing parallel / serial conversion to generate a plurality of consecutive OFDM symbols.
7.根据权利要求6所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:在执行TD-SCDMA的常规处理之前,还包括使Midamble码和其相应常规时隙中的扩频、加扰和OFDM调制后的数据或控制信息组合成子帧的步骤。 The TD-SCDMA system of claim 6 OFDM technology compatible method as claimed in claim, characterized in that: prior to performing the normal processing of TD-SCDMA, Midamble code further comprises a conventional time slot and its corresponding spreading, plus data or control information into a combination of sub-frame after the step of scrambling and OFDM modulation.
8.根据权利要求2所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:在接收端进行信道估计时,可以利用DwPTS时隙中发送SYNC-DL的多个连续OFDM符号、UpPTS时隙中发送SYNC-UL的多个连续OFDM符号,以及每个常规时隙中发送Midamble码的多个连续OFDM符号作为导频符号,或者也可以在发送端的突发中插入特定的导频符号,执行信道估计。 According to claim 2 TD-SCDMA system is compatible with the method of claim OFDM technique, wherein: at the receiving end to perform channel estimation may be utilized DwPTS transmits SYNC-DL time slot of a plurality of consecutive OFDM symbols, while the UpPTS SYNC-UL transmission slot a plurality of consecutive OFDM symbols and a plurality of consecutive OFDM symbols Midamble code transmitted each time slot as a conventional pilot symbols or pilot symbols may be inserted in the burst specific on the transmitting side, performing channel estimation.
9.根据权利要求1所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:所述执行符号定时同步过程可采用数据辅助方法实现符号定时,所述数据辅助方法可在传输信号中周期性插入已知的训练符号作为导引符号。 TD-SCDMA system according to claim 1 OFDM technology compatible method as claimed in claim, wherein: said performing symbol timing synchronization process can be implemented method of symbol timing auxiliary data, the auxiliary data may periodically method in the transmitted signal insertion of the known training symbols as pilot symbols.
10.根据权利要求1所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:所述执行符号定时同步过程可采用非数据辅助方法实现符号定时,所述非数据辅助方法采用OFDM波形的CP结构完成符号定时。 TD-SCDMA system according to claim 1 OFDM technology compatible method as claimed in claim, wherein: said performing symbol timing synchronization process can be implemented method NDA symbol timing, the non-data-aided OFDM waveform Methods CP symbol timing to complete the structure.
11.根据权利要求1所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:所述在接收端执行OFDM解调的过程包括,在基带部分,对接收到的信号进行符号定时同步,串/并变换,并去除CP后,根据载波频率偏移估计的结果进行频率校正,再执行N点的FFT变换,把信号从时域变回频域。 TD-SCDMA system according to claim 1 OFDM technology compatible method as claimed in claim, wherein: said receiving end during performs OFDM demodulation includes, in the baseband part, the received signal symbol timing synchronization, serial / parallel conversion, and the CP is removed, correct the frequency offset estimation according to the result of the carrier frequency, and then performs N-point FFT transform of the signal from the frequency domain back to the time domain.
12.根据权利要求1所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:在TD-SCDMA与OFDM相结合时,采用简单的均衡就可以实现OFDM的解调,与RAKE接收的思路不同,不必再采用RAKE接收技术,原来的TD-SCDMA接收机采用RAKE分集接收技术来区分和绑定多路信号能量,能够提供一定的分集增益,然而由于多路信号能量不相等,如果路径数较多,这种信号能量的分散将使得信道估计精确度降低,RAKE的接收性能下降就会很快。 TD-SCDMA system according to claim 1 compatible with OFDM technology, characterized in that: when the TD-SCDMA and combining OFDM, equalization simple OFDM demodulation can be achieved, and RAKE receiving ideas different, no longer use RAKE receiver techniques, previous TD-SCDMA receiver uses RAKE diversity reception to distinguish and bind multiple signal energy, it is possible to provide some diversity gain, however, due to multipath signal energy are not equal, if the number of paths more, the dispersion of this signal energy that would reduce the accuracy of channel estimation, RAKE reception performance will decline rapidly.
13.根据权利要求1所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:在接收端单用户检测方案中,根据估计出的OFDM各个子载波上的信道系数,执行简单的均衡,可以采用最大比合并MRC、廹零均衡ZF和最小均方误差均衡MMSE等信道均衡算法,对于均衡器的输出再进行解扰和解扩操作,得到最终的检测结果。 TD-SCDMA system according to claim 1 OFDM technology compatible method as claimed in claim, wherein: the receiving end the single user detection scheme, the channel coefficients based on the estimated individual OFDM subcarriers, perform simple equalization, the maximum ratio combining the MRC can be employed, Po equalization ZF equalization and minimum mean square error MMSE channel equalization algorithm and the like, then the output of the equalizer descrambling and despreading operations, to obtain the final detection result.
14.根据权利要求1所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于,在接收端单用户检测方案中,执行均衡、解扰以及解扩的操作,该三种操作可以合并执行,以估计发送数据。 TD-SCDMA system according to claim 1 compatible to the OFDM technique, characterized in that, at the receiving end the single user detection scheme, perform equalization, despreading and descrambling operation, the three kinds of operation may be executed concurrently to estimate transmit data.
15.根据权利要求13或14所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于所述均衡操作可采用最大比合并MRC、廹零均衡ZF和最小均方误差均衡MMSE等信道均衡算法。 15. The TD-SCDMA system as claimed in claim 13 or 14 OFDM technology compatible method, characterized in that the equalization operation may employ a maximum ratio combining the MRC, ZF Po Equalization and MMSE equalization MMSE channel equalization algorithm, etc. .
16.根据权利要求1所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:在接收端多用户检测方案中,可以采用连续干扰抵消SIC、并行干扰抵消PIC和联合检测JD等方法,将它们原来应用于单载波系统中的算法修改后可应用于该TD-SCDMA与OFDM结合的系统中,可以有效地抑制多址干扰的影响,进一步提高系统的性能。 16. The TD-SCDMA system according to an OFDM technology compatible method as claimed in claim, wherein: the receiving end multiuser detection scheme may be employed a successive interference cancellation the SIC, PIC parallel interference cancellation method and the joint detection JD et al, after their original modification algorithm is applied to a single carrier system may be applied to the TD-SCDMA system the OFDM bonding, can effectively suppress the influence of multiple access interference, to further improve the performance of the system.
17.根据权利要求1所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:在接收端仅需要单个FFT就可以处理多个用户的信号了,TD-SCDMA是一个同步系统,尽管不可能保证完全精确的同步,然而在OFDM调制中,为了对抗符号间干扰而插入的保护间隔可以容许用户间有小的时间偏移,这种情况下对于信号可以逐符号地进行处理,而不会受到相邻符号的干扰。 TD-SCDMA system according to claim 1 compatible to the OFDM technique, characterized in that: the receiver needs only a single FFT plurality of user signals can be processed, TD-SCDMA system is a synchronous, while not possible to ensure completely accurate synchronization, however, in the OFDM modulation in order to combat inter-symbol interference can be tolerated guard interval is inserted with a small time offset between the user, the signal may be processed in this case symbol by symbol, without subject to interference from adjacent symbols.
18.根据权利要求1所述的TD-SCDMA系统兼容OFDM技术的方法,其特征在于:在TD-SCDMA与OFDM相结合的系统中可以很方便地实现自适应传输技术,在该系统中可以利用多载波结构的特点,使用信道状态信息CSI,根据信道状态不同用户在每个子载波分配不同的信息比特数目,发送功率,编码速率或它们的组合以获得自适应,由于自适应传输需要获得小区中每个用户的信道估计信息,这个先决条件使得自适应传输更适合于在下行链路中进行,在TD-SCDMA系统中,由于采用TDD模式,上行链路和下行链路使用同样的频带但是不同的时隙,这样上下行链路信道经历相似的衰落,自适应传输可以很容易实现而只需要很少的额外信令开销,而对于其它3G标准所采用的FDD模式,由于上下行链路信道使用不同的频率,则需要附加的信令开销以交换当前的自适应参数和信道状态,从 TD-SCDMA system compatible OFDM technique 18. The method of claim 1, wherein: it is easy to implement adaptive transmission technique in OFDM systems TD-SCDMA and combining may be utilized in the system characteristics of the multi-carrier structure, the use of channel state information of the CSI, channel state different users at different each subcarrier allocation number of information bits, transmission power, coding rate, or a combination thereof to obtain an adaptive, since the adaptive transmission need to obtain a cell each user channel estimation information, so that this precondition is more suitable for adaptive transmission in the downlink, the TD-SCDMA system, since a TDD mode, uplink and downlink use the same frequency band but with different slot, so that the uplink and downlink channel experiencing a similar decline, adaptive transmission can be easily achieved and requires very little additional signaling overhead, while for other 3G FDD mode adopted standards, since the uplink and downlink channel using different frequencies, an additional signaling overhead is required to exchange the current state and the channel adaptation parameters, from 在TD-SCDMA与OFDM相结合的系统中更易于采用自适应传输技术。 More easily adaptive transmission technique in the TD-SCDMA system in the combination of OFDM.
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