Wimax系统双二进制Turbo码的译码算法及VLSI实现

设计了一款应用于World Interoperability for Microwave Access (Wimax)系统的双二进制Turbo码译码器.该译码器对传统Max-log-MAP译码算法进行改进,在增加很少计算复杂度下有效地补偿了传统算法中max计算带来的误差.此外,提出了一种低复杂度,适用于Wimax系统中所有Turbo码码长的通用交织器结构.仿真结果表明,改进的Max-log-MAP译码算法在误码率10-4下相对于传统算法获得了约0.35~0.4 dB的译码增益;提出的通用交织器结构明显降低了译码器的计算复杂度和面积,提高了系统的吞吐率.该译码器可以在200 MHz工作频率下得到20.91 Mb/s的吞吐率,完全满足Wimax系统数据率的要求.     

一种OFDM系统利用预编码进行峰均比降低的算法

为了降低OFDM系统峰均比,本文提出了一种低复杂度的预编码方案.该方案利用快速傅立叶变换取代原始方案中的乘法操作,极大地降低了计算复杂度.在此低复杂度方案的基础上,给出了一个基于通用平方根升余弦的预编码矩阵.理论分析和计算机仿真结果表明,与原始预编码算法相比,本文提出的方案具有更好的峰均比降低性能,同时计算复杂度有极大的降低.     

改进型高吞吐率QC-LDPC码解码器设计

通过对LDPC码解码算法及解码器结构的研究,本文提出一种改进型高吞吐率QC-LDPC码解码器设计方案.综合考虑硬件复杂度和解码吞吐率,该方案利用分层解码算法和部分并行结构进行设计,并采用提前检测技术,消除冗余的迭代,实现高吞吐率.然后通过ModelSim SE6.0对该解码器进行仿真测试,验证了其功能的正确性,最后采用...     

MB-OFDM UWB系统中高吞吐率Viterbi译码器的实现

提出了一种用于MB-OFDM UWB系统的高吞吐率低功耗Viterbi译码器结构.该结构利用基4蝶形单元的对称性,降低了Viterbi译码器的实现复杂度.采用SMIC 0.131μm CMOS工艺设计并实现了该译码器,在时钟频率为240MHz时,它的最大数据吞吐率为480Mb/s,功耗为135mW.在加性高斯白噪声信道下,它的误码率十分接近理论仿真值.该译码器可用于MB-OFDM UWB系统以及其他高吞吐率低功耗的通信系统中.     

一种低延迟极化码串行抵消译码器设计

为了克服5G移动通信系统中极化码串行抵消(SC)译码算法延迟高、计算复杂度高、硬件结构复杂度高等问题,基于冻结比特、冻结比特对和冻结区间等方式,提出了冻结比特设计模式。该设计模式包含基于冻结比特对的译码延迟和计算复杂度的分析方法。通过优先剪枝冻结比特结点的方式,进一步化简SC译码树,提高了搜索译码树的速度。码长为1 024的改进流水线树型SC译码器基于FPGA平台实现。实验结果表明,译码延迟为2.35μs,数据吞吐率为435 Mbit/s。与现有译码器相比,该译码器的译码延迟、数据吞吐率分别优化了9.6%、10.4%。     

一种QC_LDPC码译码器的设计

根据BP译码算法,设计了一种高速部分并行QC_LDPC码译码器结构,该结构适用于所有其校验矩阵具有准循环特性的LDPC码.针对传统BP译码器的结构复杂度高,系统运行频率低和吞吐率小等特点,本设计将BP译码算法中大量的复杂函数运算通过查找表的方法来实现;校验节点和变量节点的处理均采用5级流水线的方式;采用提前终止迭代译码策略.本设计能有效地减少译码器硬件实现复杂度,同时提高系统运行地频率和数据吞吐率.     

基于信息位编码的自适应搜索RFID防碰撞算法研究

无线射频识别（RFID）技术可实现对目标物体的自动识别.为了减少对物体标签识别时间,提出一种基于信息位编码的自适应搜索的防碰撞（AS）算法.读写器充分利用碰撞位信息,要求标签返回碰撞位编码信息,进而自适应地生成有效查询前缀,对标签进行无空闲时隙识别,以减少查询次数,提高算法的性能.此外,AS算法也解决了读写器与标签通信中传输信息冗余等问题.本文通过理论分析证明了该算法的有效性,其中吞吐率的理论值与实验值的误差不超过5%,还从时间复杂度和通信复杂度对该算法进行了详细地分析.仿真结果表明：AS算法不仅提高了系统的性能,而且还降低了标签能量的消耗.特别是当标签数为1000时,该算法的吞吐率仍保持在61%左右,比查询树算法和自适应多叉树算法的系统效率分别提高了72%和20.1%左右.     

SIFT描述子高效扫描控制电路结构设计

尺度不变特征变化(SIFT)算法是目前在图像配准领域最为活跃的算法之一,但描述子特征向量描述部分的计算复杂度特别高,现有硬件实现方法的数据吞吐率仅为50%.为了克服该瓶颈,提出了一种新型的描述子特征向量扫描控制机制,占用硬件资源少,显著提高有效像素点的采样率.在硬件耗用仅提高1.16%的情况下,平均吞吐率达到77%,与传统方法相比吞吐率提高了54%.     

TD-LTE中下行MIMO技术QRM-MLD信号检测算法

MIMO技术是LTE系统中的一个关键技术,在实际应用中,下行MIMO信号检测算法的选用需要在计算复杂度和系统性能之间取得合理折中.主要对QRM-MLD检测算法及其优化方案进行了分析与研究,同时结合ML算法仿真比较.结果表明,对于QRM-MLD算法,随M的增大,检测性能提高,同时计算复杂度也增大.在相同计算复杂度下,QRM-MLD优化方案的性能明显优于一般方案,是一种有效的MIMO检测算法.     

TD-SCDMA随机接入信道的分析

给出了TD-SCDMA(时分双工同步码分多址)系统中一种新的随机接入方案,对该方案进行了理论分析 和计算机仿真,得到了随机接入信道吞吐率和时延公式,并将其数值计算结果与计算机仿真结果以及原方案计算 机仿真结果进行了对比。     

TDD慢衰落系统中的预重传GBN-ARQ性能分析

该文提出一种新的适于TDD时变慢衰落系统的预重传GBN-ARQ算法,并与Nakamura Osamu提出的预重传方案分析比较。比较的结果认为:吞吐率较低时该文提出的预重传方案改善明显,吞吐率较高时Nakamura Osamu方案增益较大,且该文算法对预测准确率的稳健性明显高于Nakamura Osamu预重传方案。仿真结果表明归一化吞吐率为0.6附近,该文预重传方案吞吐率相对于普通GBN提高大约4dB。     

射频供能无线传感器网络高能效数据收集方案

在射频供能无线传感器网络中,提高网络能效和吞吐率是一个重要的研究问题.该文统筹考虑信道分配、节点的能量阈值以及MAC（Medium Access Control）帧分块重传机制,提出高能效和高吞吐率的数据收集方案;推导了节点的充电时间、节点传输一个MAC帧的平均能耗和平均时延、网络能效和吞吐率,定义了网络效用函数,形成了最大化网络效用的优化问题.通过调整效用系数并求解优化问题,可以获得使网络能效和吞吐率最大化的最优能量阈值和MAC帧最优分块个数.仿真结果表明,所提方案的能效和吞吐率高于已有方案.     

一种新颖的TD-LTE系统上行小区间干扰管理方法

For OFDM based system with Single-Frequency Networking (SFN), ICI (inter-cell interference), especially uplink ICI, becomes a bottleneck to improve system performance. Since the conventional interference management scheme with OI (overload indicator) can not show the instantaneous ICI, this paper proposes a method to reduce ICI by utilizing channel reciprocity of TD-LTE system. In the proposed scheme, UE shall make a decision whether to reduce its power or not after predicting the instantaneous ICI level according to the scheduling results. The system simulation results show that the proposed scheme can reduce the uplink ICI effectively and improve the system performance such as system spectrum efficiency, 10% user throughput, 50% user throughput, packet drop rate etc. significantly while keep 5% cell edge user throughput loss less than 5%. For example, the proposed scheme improved system spectrum efficiency about 50% and 50% user throughput gain is larger than 140%. Meanwhile, the proposed scheme controls the system ICI level and variance effectively. The mean system ICI level and variance are reduced by 4.5dB and 18dB respectively. The proposed scheme can be joint implemented with those existing ICI mitigation methods such as (soft) frequency reuse, power control etc. to further improve the system performance.     

自适应调制混合ARQ系统中低时延冗余递增策略的研究

冗余递增混合ARQ能提供较高的数据通过率,但也带来了较大的传输时延。该文提出一种具备低时延冗余递增策略的混合ARQ系统并与自适应调制系统相结合,不但根据不同的接收信噪比,选取不同的调制方式,而且还选择不同的冗余递增策略。仿真和计算结果表明,与采用固定冗余递增策略的自适应调制混合ARQ系统相比,该系统在保证较高的数据通过率的前提下,大大降低了系统传输时延。     

一种基于交织重组和星座重组的Type-II型混合ARQ方案

为提高系统的通过率及译码效率,高速可靠数据传输系统采用混合ARQ方案。本文提出了一种基于交织重组和星座重组的混合ARQ方案,分析了系统的通过率、误帧率及重传时延。通过仿真说明本方案可获得较大的通过率增益,减小重传延时,提高了系统的传输可靠性。     

Multilevel-coded QAM with MIMO turbo-equalization in broadband single-carrier signaling

A new scheme employing multilevel coded bit-interleaved transmission allowing for efficient turbo-equalization is proposed for multiple-input-multiple-output (MIMO) broadband single-carrier signaling. The proposed scheme is based on block-partitioned hierarchical constellations and offers robustness in data throughput efficiency against varying spatio-temporal characteristics of fading channels. The proposed scheme is compared to a standard bit-interleaved-coded-modulation (BICM) system in frequency-selective channels, and found to offer better overall throughput. It is also shown that level-wise retransmission control with the proposed multilevel single-carrier signaling scheme can offer further throughput improvement. Channel measurement-based simulations are used to evaluate performances of both schemes in real fields. Channel parameter analysis using a superresolution technique is performed to clarify the underlying reasons for the performance characteristics of the systems.     

A Modified Selective-Repeat Type-II Hybrid ARQ System and Its Performance Analysis

The hybrid ARQ scheme with parity retransmission for error control, recently proposed by Lin and Yu [1], [2], is quite robust. This scheme provides both high system throughput and high system reliability. In this paper, a modified Lin-Yu hybrid ARQ scheme is presented. The modified scheme provides a slightly better throughput performance than the original Lin-Yu scheme; however, it is more flexible in utilizing the error-correction power of a code. The modified scheme can be incorporated with a rate 1/2 convolutional code using Viterbi decoding. Furthermore, the pure selectiverepeat ARQ is a degenerated case of the modified scheme in selective mode. Lin and Yu analyzed their scheme only for a receiver buffer of sizeNwhereNis the number of data blocks that can be transmitted in a round-trip delay interval. No analysis for other buffer sizes was given. In this paper, the throughput performance of the modified Lin-Yu scheme is analyzed for any size of receiver buffer. Consequently, the throughput efficiency of the pure selective-repeat ARQ for any receiver buffer size can be obtained. We also show that the modified scheme achieves the same order of reliability as a pure ARQ scheme.     

时变信道中自适应VR-HARQ研究

为了更好地解决时变信道中可靠性与吞吐率这一对矛盾,本文提出一种基于线性预测的自适应冗余可变混合ARQ(VR-HARQ)方案.在该方案中,由于时变信道的慢衰落特性,时变信道被等效为有限状态的Markov过程,每个Markov状态对应信道的不同信噪比,同时,文章详细地描述了信道吞吐率与误码率之间的数学关系,推导了每个Markov状态的最佳编码方案,然后系统采用自适应线性预测算法,根据当前个时段的信道状态,估计下一个时段信道的信噪比以及其所对应的Markov状态,最后根据吞吐率最大原则选择合适的纠错编码方案.仿真结果表明:自适应线性预测VR-HARQ方案的性能明显优于传统VR-HARQ方案.     

TD LTE-A系统下的中继规划技术

LTE-A通过使用中继技术达到提升小区边缘用户吞吐量、拓展小区覆盖和提升小区频谱效率等效果。文中针对中继在小区中配置和使用的问题,在TD LTE-A系统下提出了一种中继规划方案。结合中继位置选择和中继服务基站选择两种方法得到中继规划方法;考虑两跳中继场景下的链路信干燥比,并得到最优频率效率的中继选择算法;结合两者得到中继规划方案并进行仿真。仿真结果显示,采用了中继规划方案的回溯链路的信干燥比得到平均约2 dB的提升,且使小区吞吐量提升了约13%。     

Toward the Energy Efficiency of Resource Allocation Algorithms for OFDMA Downlink MIMO Systems

The problem of the simultaneous multi-user resource allocation algorithm in orthogonal frequency division multiple access (OFDMA) based systems has recently attracted significant interest. However, most studies focus on maximizing the system throughput and spectral efficiency. As the green radio is essential in 5G and future networks, the energy efficiency becomes the major concern. In this paper, we develop four resource allocation schemes in the downlink OFDMA network and the main focus is on analyzing the energy efficiency of these schemes. Specifically, we employ the advanced multi-antenna technology in a multiple input-multiple output (MIMO) system. The first scheme is based on transmit spatial diversity (TSD), in which the vector channel with the highest gain between the base station (BTS) and specific antenna at the remote terminal (RT) is chosen for transmission. The second scheme further employs spatial multiplexing on the MIMO system to enhance the throughput. The space-division multiple-access (SDMA) scheme assigns single subcarrier simultaneously to RTs with pairwise “nearly orthogonal” spatial signatures. In the fourth scheme, we propose to design the transmit beamformers based on the zero-forcing (ZF) criterion such that the multi-user interference (MUI) is completely removed. We analyze the tradeoff between the throughput and power consumption and compare the performance of these schemes in terms of the energy efficiency.