【作者】 徐心毅；

【导师】 朱秋萍；

【作者基本信息】 武汉大学 ， 通信与信息系统， 2014， 博士

【摘要】 本论文联合分布式天线(DAS)技术与分数频率复用(FFR)技术提出一种更优越的通信网络结构,DAS/FFR网络结构。DAS/FFR网络结构可以有效降低小区边缘区域的同信道干扰(CCI)。 DAS/FFR系统具有低复杂性：远端天线(RA)采用简单的全向天线,移动终端(MS)采用单天线系统,但可以整体建模为一个虚拟多入多出(MIMO)系统以进行中央信号处理。本论文采用更为贴近实际的多小区多用户模型,计算出小区内任意点的信号干扰噪声比(SINR)。这一方法有助于研究实际中整个小区覆盖范围内的SINR,吞吐量以及误码率(BER)分布。DAS/FFR网路结构中上行链路与下行链路的主要干扰来自小区内干扰(ICI),尤其是在相邻两个RA的半角方向上,即本论文所提出的“最差方向”问题。为了降低ICI,在下行链路(DL)采用传输预处理(TPP)技术来增加整个小区边缘区域的吞吐量。上行链路引入移动中继(MR),采用多点协作技术(COMP),即基于“信息共享与数据融合”的联合概率数据关联(PDA)多用户检测器,这一方法可以大幅度降低小区边缘区域的BER。因此DAS/FFR网络结构在DL与UL存在的“最差方向”问题都得以解决。当然无论TPP技术还是COMP技术都需要准确的信道信息(CSI),而准确的CSI在实际应用中难以获得,因此进一步研究了下行链路与上行链路的多用户功率控制(PC)技术,以提高小区边缘区域的SINR。本论文考虑了非理想光纤信道模型,并将BS-RA-MS链路联合建模为复合式信道,以观察光纤产生的色散与非线性影响对无线信道吞吐量和BER性能的影响。并将这一模型应用在多用户多小区网络模型。在下行链路,即便计算了非理想光纤信道,采用TPP技术也可以在整个小区覆盖范围达到吞吐量5bits/s/Hz。在上行链路,通过有效的选择MR,联合PDA多用户检测算法可以使整个小区边缘80%的覆盖范围获得低于10-4的BER值,20%的覆盖范围BER值介于[10-410-2]。因为需要为移动中继分配一个额外的时隙,因此BER性能的提高以吞吐量的降低为代价。当采用PC技术时,不依赖CSI,没有MR协助传输时,整个小区的BER都可以到达低于10-3,当有MR协助传输时,整个小区的BER极小。更多还原

【Abstract】 In this thesis, we design an superior architecture of communication network by combing the techniques of distributed antennas (DAS) and fractional frequency reuse (FFR), where the cell-edge area is additionally relies on FFR for the reason of reducing co-channel interference (CCI). Furthermore, the proposed pervasive DAS/FFR scheme has a low complexity by employing a single omni-directional transmit antenna at each remote antenna (RA) and a single receive antenna at each mobile station (MS), but jointly modelling them as a virtual multiple-input and multi-output (MIMO). Hence, the jointly designing the transmit pre-processing (TPP) matrix of all the cooperative RAs in case of downlink (DL) and multiuser detection (MUD) techniques for all the active MSs in the case of uplink (UL) are capable of being invoked for central processing at the base station (BS). We consider a more practical multiuser, multicell scenario with practical cellular parameters, where any particular user’s position is mapped to a specific Signal-to-Interference-plus-Noise-Ratio (SINR). This method is capable of demonstrating distribution characters of SINR of the entire cellular area.The dominant interference of our DAS/FFR scheme is caused by the intra-cell interference (ICI) for both cases of DL and UL, especially in the’worst-case direction’ when the MS is roaming near the angle halfway between two adjacent RAs. In order to mitigate the ICI, the TPP matrix is designed for all the cooperative RAs is capable of achieving an increased throughput for the entire cell-edge area in DL, regardless of the specific geographic distribution of the users. Our novel combined probabilistic data association (PDA) multiuser detector is invoked by the mobile relays (MR) aided pervasive DAS/FFR architecture, which is capable of substantially reducing the bit-error ratio (BER) for the MS roaming at arbitrary positions, especially in the’ worst-case direction’. Practically, the generation of perfect Channel State Information (CSI) is difficult to achieve, whilst having an imperfect CSI obviously leads to a reduced performance. Hence, we introduce power control (PC) for improving the SINR of the MSs roaming in the cell-edge area for both DL and UL scenario.We consider a more realistic optical fibre backhaul, where the BS-RA-MS link will be treated as a composite channel. Hence, the effects of the fibre-induced imperfections on the attainable throughput and the BER performance of the wireless channel can be calculated, especially when applying different wireless transmissioin strategies, such as the modulation scheme, non-cooperative and cooperative processing techniques. This method allows us to portray the geographic of the SINR across the entire cellular area. In the DL of the cooperative DAS aided FFR scheme, a throughput of h=5bits/s/Hz may be maintained for an imperfect optical fibre backhaul, regardless of the specific geographic distribution of the users roaming in the cell edge area. Provided that an idle MR may be activated in the vicinity of the optimum relay position, in the UL of the cooperative DAS aided FFR scheme,80%of the cell-edge area exhibits a BER, which is better than10-4, while the remaining20%has a BER value of [10-410-2]. Naturally, this BER performance improvement is achieved at the cost of potentially halving the throughput, because the MR has to receive and retransmit its information in different time-slots. When applying power control (PC), the BER recorded across the entire cellular area may be reduced, below10-3even without the assistance of MRs.更多还原