【作者】 张英海；

【导师】 宋俊德； 胡健栋；

【作者基本信息】 北京邮电大学 ， 电路与系统， 2007， 博士

【摘要】 随着通信技术的发展，移动通信网络与其它网络，特别是互联网的结合日益紧密，提高了用户对下行的数据传输的需求，导致了上下行链路传输速率的非对称特性。不仅如此，在电磁辐射限制的约束下，上下行的传输速率也具有显著的非对称特性，通过上下行链路电磁辐射对人体SAR值的计算对比表明：在电磁辐射影响的限制下，上行链路的传输速率是受限的，而下行链路的传输速率远远大于上行链路。因此，考虑电磁环境与健康的限制条件的单用户的上下行链路容量的非对称性也将成为未来移动通信系统的显著特点。自适应技术可以根据信道、业务要求的变化改变系统中的某些参数，进而提高频谱利用率。目前的自适应技术主要是指链路自适应，系统根据单条链路的信道的传输环境以及剩余资源，通过自适应技术来提高单用户的吞吐量。本文提出了双工自适应的概念，双工自适应就是指移动通信系统根据不同方向链路的业务种类、总量、长期统计以及瞬态特性，而动态调节上下行链路的资源分配，以适应未来移动通信系统的非对称特性。目前人们只是在TDD模式下研究双工自适应技术，TDD自适应技术是指时分双工系统中的上下行时隙切换点是可变的，可以根据业务的情况动态的调整上下行时隙的分配，从而灵活的为上下行分配资源。由于可变切换点会带来交叉时隙干扰，因此解决可变切换点中的交叉时隙干扰问题成为TDD自适应技术的关键。本文提出了一种基于隔离区域的移动台间干扰解决方案—IRIM(Isolated-Region Interference Mitigation)，在该方案中隔离区域是由移动台接收到的导频信号差值来确定。在论文中对该方案进行了仿真验证，仿真结果表明该方案可以很可靠地实现移动台之间的交叉时隙干扰的隔离，而且隔离区域比其它方法的要小，对交叉时隙的覆盖影响小。本文认为在FDD模式下同样可以实现双工自适应技术，但是FDD模式下的双工自适应技术有其特有的设计方法，诸如带宽的非对称性、业务的非对称性以及传输能力的级联问题等等。文中提出了一种新型的自适应非对称频分双工技术——AFDD(Asymmetric Frequency Division Duplex)。AFDD系统根据业务的实际情况确定上行(下行)单位带宽，将上行(下行)频率按上行(下行)单位带宽分成多个频点，所有上行(下行)频点组成上行(下行)频率池，每个小区根据业务的实际情况，动态使用频率池中的频点。AFDD兼具TDD与对称型FDD的优点，能够灵活的为上、下行链路分配资源，更好的适应未来移动通信系统的非对称特性，同时它又具有鲁棒性好，覆盖面积广等优点。结合CDMA技术，本文分析了AFDD＼CDMA在系统容量和覆盖等性能上的提高，并分析了其无线资源管理算法，得出了适应AFDD＼CDMA系统的接入控制算法-最优信噪比接入，并在文中对其进行了仿真验证。OFDM技术被认为是未来移动通信的核心技术，本文结合OFDMA技术，分析了AFDD＼OFDMA相对于FDD＼OFDMA提高了系统容量，降低了阻塞率。论文中对系统容量和阻塞率进行了合理的数学推导，证明了系统容量和阻塞率都有性能的提高。更多还原

【Abstract】 With the development of communications techniques, the relationship between communications networks and other networks especially Internet has become more and more compact, which enhance the user’s demand of downlink transmission data and make rate of the uplink and downlink become asymmetric. Besides that, under the restriction of electromagnetic radiation, the rate of uplink and downlink are also asymmetric. By the calculation of human’s SAR which is caused by uplink and downlink electromagnetic radiation, it shows that: under the restriction of electromagnetic radiation, the uplink transmission rate is limited; the downlink rate is much higher than that of uplink. So, the asymmetric characteristic between uplink and downlink for one user which take restriction of electromagnetic surrounding and human health into account will be very important in the future communication system.Adaptive technique change the system’s parameter according to the channel condition and service demand to improve the efficiency of frequency usage. Nowadays, adaptive technique mainly concerns about link adaptive, in which the system adopt the adaptive technique according to the channel condition and resource of single transmission link to improve the throughput of single user. Duplex adaptive is introduced in this article, it is means that the system allocates the resource to uplink and downlink dynamically according to the characteristic of downlink and uplink to suit the asymmetric characteristic of future mobile communication system.Nowadays people mainly concern about duplex adaptive technique of TDD, the switch point of TDD adaptive technique is variable, the TDD adaptive technique can allocate the slot of uplink and downlink dynamically according to traffic conditions. But the variable switch point may cause crossed slot interfere, so how to avoid the crossed slot interfere is the key technique of TDD adaptive technique. This article introduce a scheme -- IRIM(Isolated-Region Interference Mitigation)to solve the crossed slot interference based on isolated area, the isolated area is determined by difference of pilot signal. In this article, simulation is done to prove this scheme, the simulation results shows that it can avoid the crossed slot interference of mobile stations efficiently and the isolated area is smaller than other schemes. What’s more, it causes little infections to coverage of crossed slot.Besides TDD adaptive technique, the FDD adaptive technique is also reasonable, but the FDD adaptive has its special design method such as asymmetric bandwidth, asymmetric characteristics of service. This article introduces a novel adaptive asymmetric frequency division duplex. AFDD allocate the uplink (downlink) bandwidth according to the service circumstance, it divide the uplink (downlink) frequency into several frequency points, all the uplink (downlink) frequency points make up uplink (downlink) frequency pool, each cell use the frequency points dynamically according to the actual service circumstance. AFDD has the advantages of TDD and FDD, it can allocate the uplink and downlink frequency resource flexibly to suit the asymmetric characteristic of the future mobile communications system, it also has the advantages such as strong robustness, wide coverage.Combining with CDMA, this article analyze the improvement of AFDD\CDMA to FDD\CDMA in the area of system capability and coverage. We also analyze the radio resource management of AFDD\CDMA, and prove the call access control method—SNR based access control is most suitable to AFDD\CDMA system by simulation. As the OFDM is the core technique of future mobile communication system, this article also analyzes improvement of AFDD\OFDMA to FDD\OFDMA in the area of system capability, AFDD\OFDMA reduce the block rate compare to FDD\OFDMA and it is proved by mathematics analysis.更多还原