动态TDD技术HARQ时序冲突的解决方案

动态TDD技术的引入不仅能够很好地解决突发性业务需求增长较快的问题,还能提升小区通信系统的服务质量.在动态TDD系统中,无线帧配置可以通过系统中的负载量来改变.但是一些子帧可能会在重配后改变传输方向,导致一些HARQ进程出现时序冲突,影响系统性能.为了解决动态TDD系统中的HARQ时序冲突问题,提出了一种基于过渡无线帧的混合自动重传方案.当重配周期到来时,在重配点后增加一个过渡无线帧,使得HARQ时序以一种较简单、时序冲突较少的方式过渡到重配后的无线帧.在LTE系统仿真平台上建立HARQ模型进行性能验证,仿真结果表明,所提方案能有效地提升系统资源利用率,并给系统平均吞吐量带来增益.     

TDD CDMA系统无线资源管理真法的建模与仿真

无线资源管理是第三代移动通信系统中的重要组成部分，用于对业务需求、资源分配、系统容量和稳定性进行控制，而TDD CDMA系统特性及其中引入的智能天线技术使得无线资源管理算法需重新建模设计。本文利用OPNET仿真软件对TDD CDMA系统进行了建模，并且对我们提出的几种适用于TDD CDMA系统的新无线资源管理算法进行了仿真，与传统算法获得的仿真结果对比，验证了其性能增益。     

Multiuser MIMO OFDM Based TDD/TDMA for Next Generation Wireless Communication Systems

Multiple-input multiple-output (MIMO) wireless technology in combination with orthogonal frequency division multiplexing (MIMO OFDM) is an attractive air-interface solution for next-generation wireless local area networks (WLANs), wireless metropolitan area networks (WMANs), and fourth-generation mobile cellular wireless systems. In this paper, one multiuser MIMO OFDM systems with TDD/TDMA was proposed for next-generation wireless mobile communications, i.e., TDD/TDMA 4G, which can avoid or alleviate the specific limitations of existing techniques designed for multiuser MIMO OFDM systems in broadband wireless mobile channel scenarios, i.e., bad performance and extreme complexity of multiuser detectors for rank-deficient multiuser MIMO OFDM systems with CDMA as access modes, extreme challenges of spatial MIMO channel estimators in rank-deficient MIMO OFDM systems, and exponential growth complexity of optimal sub-carrier allocations for OFDMA-based MIMO OFDM systems. Furthermore, inspired from the Steiner channel estimation method in multi-user CDMA uplink wireless channels, we proposed a new design scheme of training sequence in time domain to conduct channel estimation. Training sequences of different transmit antennas can be simply obtained by truncating the circular extension of one basic training sequence, and the pilot matrix assembled by these training sequences is one circular matrix with good reversibility. A novel eigenmode transmission was also given in this paper, and data symbols encoded by space–time codes can be steered to these eigenmodes similar to MIMO wireless communication systems with single-carrier transmission. At the same time,, an improved water-filling scheme was also described for determining the optimal transmit powers for orthogonal eigenmodes. The classical water-filling strategy is firstly adopted to determine the optimal power allocation and correspondent bit numbers for every eigenmode, followed by a residual power reallocation to further determine the additional bit numbers carried by every eigenmode. Compared with classical water-filling schemes, it can also obtain larger throughputs via residual power allocation. At last, three typical implementation schemes of multiuser MIMO OFDM with TDMA, CDMA and OFDMA, i.e., TDD/TDMA 4G, VSF-OFCDM and FuTURE B3G TDD, were tested by numerical simulations. Results indicated that the proposed multiuser MIMO OFDM system schemes with TDD/TDMA, i.e., TDD/TDMA 4G, can achieve comparable system performance and throughputs with low complexity and radio resource overhead to that of DoCoMo MIMO VSF-OFCDM and FuTURE B3G TDD.     

含山广播电视台全台网系统设计与实现

介绍了含山广播电视台全台网系统设计,详细地阐述了设计方案、实现方法、技术特点和网络安全措施等.该系统以媒体资产管理子系统为核心,充分考虑广播和电视的资源整合,实现了全台网络化、无带化和文件化.     

TD-SCDMA移动通信系统无线干扰分析

在简要介绍无线干扰产生的根源的基础上,首先分析了TDD系统中的典型干扰：小区内的干扰、小区间的干扰、TDD系统与FDD系统的干扰等,然后特别研究和总结了建设基于TD-SCDMA标准的3G移动通信系统存在的无线干扰基本情形,主要有：TD-SCDMA技术内的干扰、WCDMA与TD-SCDMA的干扰、cdma2000与TD-SCDMA的干扰、TD-SCDMA与GSM/GPRS的干扰、TD-SCDMA与PHS的干扰等,并从系统工程设计和技术方案设计以及政府频率规划等角度简要指出了降低和消除干扰的方法.     

B3G系统中一种新的无线资源分配策略

如何合理地利用有限的无线资源,保证链路里传输的各种业务的QoS,同时提供较低的操作和管理开销,从而保证实现B3G系统中的新业务的发展,是无线资源分配策略设计的重点。提供了B3G系统中一种新的无线资源分配策略,并利用OPNET Modeler建立了一个仿真平台对协议算法进行了验证。仿真结果显示,该策略具有很高的资源分配效率,并能针对不同业务的不同需求提供不同的时延保障,对B3G系统QoS框架中的3种业务都能提供良好的支持,并已应用于B3G原型系统。     

Evolution map from TD-SCDMA to FuTURE B3G TDD

The rapid growth of mobile applications in recent years has created a need for wideband wireless communication. The only predictable trend is that data-rate and QoS requirements will increase rapidly. This demand is pushing time-division-synchronous code-division multiple access (TD-SCDMA) to evolve in order to provide higher and higher data rates. This article presents the evolution map from TD-SCDMA to future terrestrial universal radio environment (FuTURE) TDD in China. The evolution includes four phases: low chip rate (LCR), high-speed downlink/uplink packet access (HSxPA)/TD-SCDMA EV 1x, long-term evolution (LTE) TDD, and FuTURE beyond 3G TDD. The main features of each phase are described in detail. By introducing the new technologies into the system step by step, for example, multiple input and multiple output (MIMO), orthogonal frequency-division multiplexing (OFDM), TD-SCDMA system can evolve to FuTURE B3G TDD smoothly, and provide high-data-rate services with low cost, low latency, and improved coverage and capacity.     

后3G无线接入系统的软硬件平台研究和设计

本文分析了后3G移动通信系统的业务特征和网络发展趋势,研究了后3G空中接口技术和无线接入系统平台设计需求,探讨了后3G无线接入系统的软硬件平台设计方法,并将之应用于后3G实验验证系统的实现.     

Investigation of radio resource scheduling in WLANs coupled with 3G cellular network

In this article, based on the overview of network coupling structure between radio access technologies, the concept of joint radio resource management built onto the reference structure is introduced. In order to optimize usage of radio resource and jointly designed from the user perspective, a joint scheduling mechanism allowing traffic to be split over a tightly coupled radio network supported by an adaptive radio multihoming approach is deliberately discussed. With respect to the time-division access scheme in HIPERLAN/2, which is selected as one example of WLAN, algorithms and performance of traffic scheduling in such a radio access technology are given. The required synchronization scheme supporting traffic splitting is also introduced.     

HSDPA系统无线资源管理策略

HSDPA是WCDMA 3GPP Release-5规范中引入的新技术,无线资源管理策略是影响HSDPA性能的主要因素之一.介绍了HSDPA系统中无线资源管理的功率和码资源分配,调度算法,切换过程等,主要比较了HSDPA与3GPP Release-99规范的无线资源管理策略的不同.