Symbiotic Networks: Towards a New Level of Cooperation Between Wireless Networks

In the future, many wireless networks, serving diverse applications, will co-exist in the same environment. Today, wireless networks are mostly optimized in a rather opportunistic and/or selfish way: optimizations methods only use a local view of the network and environment, as they try to achieve the best performance within its own network. The optimizations are very often limited to a single layer and cooperation between networks is only happening through the use of gateways. In this paper, we suggest an alternative paradigm for supporting cooperation between otherwise independent networks, called ‘symbiotic networking’. This new paradigm can take many forms, such as sharing of network resources, sharing of nodes for communal routing purposes and sharing of (networking) services. Instead of optimizing network parameters within the individual networks, symbiotic networking solutions operate across network boundaries. Parameters are optimized between the networks and communal protocols are developed, leading to a more global optimization of the scarce network resources. In this paper, we describe several scenarios which can profit from symbiotic networking and illustrate a strategy for supporting networking protocols which can operate across network boundaries. Ultimately, through the disappearance of network boundaries and the introduction of cross-layer/cross-node/cross-network cooperation, symbiotic networks takes the notion of cooperation to a new level, paving the way for a true network symbiosis.

无线通信中编码协作技术研究

编码协作是无线通信中一种新的用户协作技术,它通过信道编码方式达到协作的目的。用户发送的码字被分为2部分,分别通过用户和其协作者的天线进行传输。通过协作通信中编码协作机制下的多节点协作伙伴的选择,分析了4种情况下的中断概率,并阐述了编码协作技术的研究方向。     

白适应Turbo编码调制方案设计及综合性能分析

文章提出了两种用于慢衰落信道上的较为实用化的自适应Turbo编码调制设计方案,两种方案在所有域中采用相同的Turbo编码调制器,具有较低的实现复杂度。文中对两种设计方案进行了较全面的综合性能分析,包括频谱利用率、BER性能、平均传输功率、业务中断概率、平均域持续时间等,以验证设计方案的正确性与有效性。     

一种用于无线通信的新型空时编码技术

空时编码采用多发送天线设计信道编码,联合考虑分集,编码与调制,从而提高信号在无线衰落信道中传输的可靠性,介绍了空时码的编码和译码方法,以及设计空时码的准则。     

Virtual Cellular Network: A New Wireless Communications Architecture with Multiple Access Ports

A virtual cellular network (VCN) is proposed to provide wireless random access for bursty multimedia traffic to a fixed backbone infrastructure. A VCN does not use a conventional cellular frequency reuse concept. In a VCN, each terminal sends packets using the entire system bandwidth while any nearby port can pick up the signal. Then, the ports relay the packets to the port server (PS) over a fixed (wired) network. Ports can be simple radio receivers as they do not have to support the same functionality as conventional cellular base stations. The performance is investigated in terms of probability of capture, throughput and delay. Both our analysis and simulation show that despite its simplicity this network has a larger user capacity than conventional cellular reuse patterns.     

一种基于网络编码协作的高能效无线传感器网络机制

Energy-efficient communications is crucial for wireless sensor networks (WSN) where energy consumption is constrained. The transmission and reception energy can be saved by applying network coding to many wireless communications systems. In this paper, we present a coded cooperation scheme which employs network coding to WSN. In the scheme, the partner node forwards the combination of the source data and its own data instead of sending the source data alone. Afterward, both of the system block error rates (BLERs) and energy performance are evaluated. Experiment results show that the proposed scheme has higher energy efficiency. When Noise power spectral density is -171dBm/Hz, the energy consumption of the coded cooperation scheme is 81.1% lower than that of the single-path scheme, 43.9% lower than that of the cooperation scheme to reach the target average BLER of 10-2. When the channel condition is getting worse, the energy saving effect is more obvious.     

一种单载波频域均衡方案及性能仿真

参考IEEE802.16标准建议的单载波频域均衡的方法,提出了一种适合时变深衰落信道的单载波均衡方案。该方案采用了基于分集合并的判决反馈均衡结构,不但具有较好的抗符号间干扰能力,而且可以显著改善无线通信系统的抗衰落性能。对该方案的抗符号间干扰能力进行了软件仿真。     

Performance Analysis of Wireless Multimedia DS/CDMA Communications with Power Control and Hybrid ARQ

In this paper, we present aperformance analysis of a wireless multimedia direct-sequence code-divisionmultiple-access(DS/CDMA) system based on different error control schemes and an optimal power control algorithm over multipath Rayleigh fading channels.The error control schemes consist of Forward Error Correction (FEC), diversity, and Automatic Repeat reQuest (ARQ). The concatenated codes with a Reed–Solomon outer code andconvolutional inner code are used as FEC. Since a multimedia system is required to support services with different rates and Quality of Services (QoS), different error control schemes are used to satisfy the requirements of different media. In particular, a power control algorithm which can optimize the capacityperformance of the integrated system is presented. Numerical results will show that power optimization can increase the capacity and decrease the total transmission power. By incorporating diversity and hybrid ARQ along with appropriate code ratesin the optimal power controlled system, dramatic increase in system capacitycan also be achieved.     

无线传感网物理层协作分集的性能分析

该文针对无线传感网中的远距传输问题,研究了一种无需网络同步和正交信道的协作分集方法的性能,给出了在两种典型信道中当解码转发存在误差传播时远程目的节点的误码率及分集指数;分析了当转发节点间为白高斯信道时增加协作节点数能够提高目的节点性能的条件。研究结果表明,当转发节点间为白高斯信道时,只要转发节点处于正常工作点,增加节点数就能提高目的节点的性能;当转发节点间为瑞利平衰落信道时,只有当转发节点处于一定位置时,协作分集相对于直接发送或传统空间分集才有性能增益;当转发节点间为瑞利平衰落信道时增加跳数性能更好,为白高斯信道时增加分支数更有效;当转发节点间为瑞利平衰落信道时,误差传播将使目的节点的分集指数为1,但在较低信噪比条件下对分集性能影响很小。     

基于差分调制的编码协作方案

通常的编码协作采用相干检测方式,要求精确的信道估计,从而增加了系统实现复杂度。考虑采用非相干检测,提出了一种基于差分调制的编码协作方案,并分析了该方案下系统协作与非协作的误码率性能,并在目的端引入CRC校验方法进一步提高用户上行信道不对称时的系统性能。仿真表明:进行协作后系统可以达到完全分集。当源端用户比协作用户上行信道信噪比高时,提出的方案可使系统性能改善0.2~1.2 dB。     

A Combined Interleaving Technique for Trellis Coded MPSK Systems in Rayleigh Fading Channels

Freedom of mobility is the latesttrend in the evolution of digital communicationsystems. In these systems bandwidth and powerconstraints limit the mobility of the users. TCM(trellis coded modulation) is a combined coding andmodulation scheme which increases the productivity ofa digital communication system without increasing thetransmitted power or the required bandwidth. A mobilecommunication channel is affected from noise andfading because of the multipath propagation. On aRayleigh fading channel, coding should be used withtechniques which uncorrelate the received energy ofeach consecutive coded symbol. Interleaving is one ofthese techniques and used to make burst errors intorandom errors which can be corrected by errorcorrecting codes. In this paper, the trellis codingsystem which combines a regular convolutional encoder,bit interleaver, coordinate interleaver, and anappropriate decoder is considered. The analytical biterror probability upper bounds are derived for the8-PSK TCM system whose diversity is increased by usinga regular 2/3 rate convolutional code followed bythree bit interleavers and a 8-PSK signal mapperfollowed by two coordinate interleavers. Theanalytical and simulation results show that toincrease the diversity of the trellis coded M-PSKsystems in Rayleigh fading channels is the primary keyfor reliable transmission of high quality voice anddigital data.     

比特交织编码协同方案及性能分析

在慢衰落信道条件下,为提高误码率性能,提出一种比特交织编码协同方案,用户或协同伙伴的编码数据,相邻两帧的打孔或者未打孔部分分别通过比特交织器进行交织,然后通过BPSK调制并按发送方案和划分时隙进行发送。推导了比特交织编码协同方案在慢衰落信道条件下的成对错误概率,仿真证明,此方案能够获得三阶完全分集。     

一种改善Turbo乘积编码OFDM系统性能的新方法

本文提出一种利用对译码器软信息限幅来改善多径衰落信道中Turbo乘积编码OFDM(TPC-OFDM)系统性能的新方法。通过对不同多径衰落信道中QPSK映射和16QAM映射的TPC-OFDM系统性能的数值仿真，结果表明在10^-5误比特率下，这种新方法比传统的迭代译码大约有6～10dB的改进，对严重多径环境下TPC-OFDM系统的错误平底也有明显的改进。     

效率感知的无线网络编码机制

网络编码在无线网络中的应用可以显著提高无线网络的吞吐量和容量。然而,当前大多数的无线网络编码机制在进行编码操作时,都没有考虑将不同长度的报文编码在一起时的效率问题。该文研究了在进行网络编码操作时如何获得最优的每字节编码效率,并设计了编码效率感知的无线网络编码机制(coDing Efficiency awarE Network coding, DEEN),以提升每字节的编码效率。模拟结果表明,DEEN协议能够有效地提升无线网络的容量。     

大气无线光通信调制方式性能分析

在对三种典型大气无线光通信调制方式--OOK、PPM和DPIM的调制结构进行分析的基础上,结合大气无线光信道特点,分析比较了这三种调制方式的带宽需求、传输容量、功率需求和差错性能.理论分析与仿真结果表明,OOK方式实现简单,不需要符号同步,带宽需求最小,但功率利用率太低;PPM方式大大提高了功率利用率,但带宽利用率最低,而且需要符号同步;DPIM相比于OOK具有更高的功率利用率,相比于PPM具有更高的带宽利用率,而且不需要符号同步,应用于无线光通信系统具有显著的优势.     

Performance of Coded Cooperative Diversity with Interference in Nakagami Fading Environments

Diversity is an effective technique in enhancing the link quality and increasing network capacity. When multiple antennas can not be used in mobile units, user cooperation can be employed to provide transmit diversity. In this paper, we analyze the error performance of coded cooperative diversity with multiple cooperating users over Nakagami fading channels under interference conditions. We derive the end-to-end bit error probability of coded cooperation (averaged over all cooperation scenarios). Results show that allowing more cooperating users improves the performance of the network under low loads, where two cooperating users suffice for highly loaded networks. Furthermore, the gains obtained by increasing the number of cooperating users decreases with increasing the network load.      

B3G无线通信中合作网络的一种新型无线接入方案

The paper discusses the signifi cance and development foreground of co-operation among heterogeneous networks in composite radio context for B3G wireless communications. The concept of composite reconfigurable wireless network is introduced in the paper, and the development of future wireless communication systems is also discussed. The basic confi guration framework of the network interoperation is given, and the functions of important parts are analyzed. A management platform for co-operation between WLAN...     

A New Anonymous Channel Protocol in Wireless Communications

In this paper, the authors shall propose a new anonymous channel protocol for wireless communications. Compared with Juang et al.'s protocol and Jan et al.'s protocol, our protocol is more efficient. In addition, our protocol saves the trouble of employing public key cryptography in the anonymous channel ticket authentication phase just as Jan et al.'s protocol.     

Decision fusion for Wireless Sensor Networks under Nakagami fading channels

Decision fusion rules for Wireless Sensor Networks (WSNs) under Nakagami fading channels are investigated in this paper. Considering the application limitation of Likelihood Ratio Test fusion rule based on information of Channel Statistics using Series expansion (LRT-CSS), and the detection performance limitation of the Censoring based Mixed Fusion rule (CMF), a new LRT fusion rule based on information of channel statistics has been presented using Laplace approximation (LRT-CSL). Theoretical analysis and simulations show that the proposed fusion rule provides better detection performance than the Censoring based Mixed Fusion (CMF) and LRT-CSS fusion rules. Furthermore, compared with LRT-CSS fusion rule, the proposed fusion rule expands the application range of likelihood ratio test fusion rule.     

Diversity Combining and Equalization with TCM for Wireless Communications

This paper presents an equalization structure in which antennadiversity, adaptive decision feedback equalization (DFE), interleavingand trellis-coded modulation (TCM) can be effectively combined to combatboth ISI and cochannel interference in cellular mobile radioenvironments. The feedback filter of the DFE can use either tentative orfinal decision symbols of the TCM Viterbi decoding to cancel tail ISIwith the square root Kalman algorithm. A performance bound on theaverage pairwise error probability for TCM under perfect interleavingand equalization is obtained by analysis. Some simulation results whichillustrate the potential of the proposed system will also be given. Inparticular, a performance comparison between the proposed method anduncoded QPSK modulation will be undertaken.