Adaptive transmission with discrete code rates and power levels

Throughput maximization of an adaptive transmission system with a finite number of transmission power levels and code rates for communication over slow fading channels is analyzed, based on the concept of information outage. Properties of throughput maximizing policies lead to an iterative algorithm that yields good system designs. Numerical results show that carefully designed discrete adaptive transmission systems with a small number of power levels and code rates can achieve throughput values close to ergodic capacity.     

Optimal transmission ranges and code rates for frequency-hop packetradio networks

We consider a frequency-hopping multihop packet radio network using M-ary frequency-shift keying modulation in a Rayleigh fading environment. Each node transmits packets using an extended (n, k) Reed-Solomon code and the slotted ALOHA channel access protocol. For this network, we determine the optimum transmission range, optimum code rate, and optimum slotted ALOHA transmission probability to be used by each node in the network. Tradeoffs in choosing the transmission range and code rate, and the spectral efficiency of the network are captured in a new performance measure, information efficiency, which is analogous to expected forward progress. Maximizing the information efficiency yields the optimum desired network parameters     

Adaptive space-time transmission with side information

In this letter, a simple adaptive transmit diversity technique with side information is presented. The proposed scheme has a number of attractive characteristics. First, it is simple to implement. Second, it is efficient in terms of bandwidth requirements for side information feedback. Finally, it adapts to the quality of the side information to accordingly configure the space-time signal set to be transmitted so that additional gain in signal-to-noise ratio can be achieved at the receiver. In effect, it can be viewed as a flexible combination of suboptimal beamforming and space-time block coding.     

Adaptive code excited predictive coding

A novel way to use the code excited linear prediction (CELP) concept that decreases the processing load while keeping the same speech quality is discussed. Rather than performing individual weighting of each candidate sequence, a global implementation of the perceptual weighting function at the codebook level is proposed. As a result, the analysis-by-synthesis procedure does not require the processing of all the candidate sequences through the synthesis and weighting filters; the complexity requirement of the algorithm is therefore much reduced. The concept is carried out with an adaptive codebook. Two fixed-point implementations of the adaptive CELP (ACELP) algorithm are reported: a 7.2 kb/s block coder (7 MIPS), and a 12 kb/s low-delay coder (11 MIPS). Both coders have been rated to provide the same quality as the 13 kb/s block coder adopted by the GSM for the European cellular telephone     

Multilevel code for high information rates

A multilevel line code (4L7-4) suitable for transmission on a 1.2/4.4 mm coaxial cable at information rates in excess of 140 Mb/s is presented. 4L7-4 is a transparent code with bounded digital sum variation and provides adequate timing information and good monitoring capabilities.     

Error-correcting code for optical-fibre transmission systems

A simple error-correcting code for optical-fibre transmission systems is proposed, and its correcting principle is explained. This code offers the same advantages as the CMI code, which is widely used in optical-fibre transmission systems. Moreover it has the ability to correct a single error in a block. Owing to this ability, the maximum repeater space can be increased.     

Binary code suitable for line transmission

A practical method is described for encoding an unrestricted binary signal into a form suitable for transmission through a binary regenerated signal path while incurring only a small increase in modulation rate.     

基于准正交空时分组码的高速率码字设计

为了适应通信系统对高速率大容量的需求,设计了码率为2及1.5的非正交空时分组码。在此基础上,采用简化了的条件最大似然译码方法,可以大大降低译码复杂度。仿真结果表明,该编码设计具有接近实际信道容量的特点,并且其误比特率性能优于正交及准正交编码设计。     

New transmission code for digital optical communications

A new code with the aim of facilitating realisation of a simple repeater is presented and compared to the other codes with similar properties. Its spectrum is calculated and a simple coder and decoder are proposea.     

Turbo码在无线传输中的应用

简介Turbo码的结构和实现，系统分析了其关键技术，重点讨论了Turbo码技术在无线传输中的应用．阐述了Turbo码在实际系统中的l立用进展，并展望了Turbo码的应用前景。     

应用于无人机测控传输系统的多元LDPC码

针对无人机巡查区域地理环境复杂、信道特性多变、突发衰减严重的问题,设计了一种基于多元低密度奇偶校验( Q-LDPC)码的无人机测控传输系统。为减小置信传播( BP)类译码算法中振荡变量节点引入的错误传播,采用加权因子校正迭代前后的变量信息,从而减小短环对遥测、遥控等中短码字译码性能的影响,提高无人机测控传输系统可靠性。基于突发衰减信道建立系统仿真模型,仿真结果表明,所提方案通过将连续的突发比特错误转换为数量较小的符号错误,能够有效抵御快速衰落,降低误码率,为无人机对地观测提供安全保障。     

Easily trimmed third-order RC-active-filter section with finite transmission zeros

A third-order single-amplifier RC-active-filter section with finite transmission zeros is described. The poles and zeros of the network can be adjusted with little interaction by varying resistances in a suitable sequence, so that the section can be economically constructed with wide tolerance capacitors and trimmed to specification. A design for a ninth-order audio bandpass filter is included as an example.     

Multicarrier transmission peak-to-average power reduction usingsimple block code

A simple added-bit block code suitable for transmission in multicarrier systems is presented. It is applied across the carriers and offers a reduction in peak-to-average power ratio, without significantly reducing overall efficiency or increasing complexity     

Multicarrier transmission peak-to-average power reduction usingsimple block code

The author comments on the coding scheme system proposed by S. Fragiacomo et al. (ibid., vol. 34, pp. 953-4, 1998) and concludes that it is ineffective for multicarrier transmission systems with a large number of carriers     

A novel concatenated code based on the improved SCG-LDPC code for optical transmission systems

Based on the optimization and improvement for the construction method of systematically constructed Gallager (SCG) (4, k) code, a novel SCG low density parity check (SCG-LDPC)(3969, 3720) code to be suitable for optical transmission systems is constructed. The novel SCG-LDPC (6561,6240) code with code rate of 95.1% is constructed by increasing the length of SCG-LDPC (3969,3720) code, and in a way, the code rate of LDPC codes can better meet the high requirements of optical transmission systems. And then the novel concatenated code is constructed by concatenating SCG-LDPC(6561,6240) code and BCH(127,120) code with code rate of 94.5%. The simulation results and analyses show that the net coding gain (NCG) of BCH(127,120)+SCG-LDPC(6561,6240) concatenated code is respectively 2.28 dB and 0.48 dB more than those of the classic RS(255,239) code and SCG-LDPC(6561,6240) code at the bit error rate (BER) of 10 -7 .     

Numerical modeling of generalized millimeter-wave transmission media with finite element and transmission line matrix methods

In this paper, a general finite element method as well as a graded-mesh TLM procedure for determining the dispersion characteristics, field distribution, pseudo-impedance and losses of generalized millimeter-wave transmission media are described. These methods cover arbitrary cross-sections and account for realistic features (finite metallization thickness, substrate mounting grooves etc.) that are often neglected in theoretical analysis. Dispersion characteristics and characteristic impedances obtained for dielectrically loaded ridged wave-guides compare well with the available data. Conductor and dielectric losses are also computed for these structures. A modified finline structure called “ridged finline” is also analysed. The main advantages of this structure are its large monomode bandwidth and reduced dispersion. The cutoff frequencies of bilateral finlines in circular waveguides are also computed.     

Lossless chain code compression with an improved Binary Adaptive Sequential Coding of zero-runs

A new method for encoding a sequence of integers, named Binary Adaptive Sequential Coding with Return to Bias, is proposed in this paper. It extends the compressing pipeline for chain codes’ compression consisting of Burrows Wheeler Transform, Move-To-Front Transform, and Adaptive Arithmetic Coding. We also explain when to include the Zero-Run Transform into the above-mentioned pipeline. The Zero-Run Transform generates a sequence of integers corresponding to the number of zero-runs. This sequence is encoded by Golomb coding, Binary Adaptive Sequential Coding, and the new Binary Adaptive Sequential Coding with Return to Bias. Finally, a comparison is performed with the two state-of-the-art methods. The proposed method achieved similar compression efficiency for the Freeman chain code in eight directions. However, for the chain codes with shorter alphabets (Freeman chain code in four directions, Vertex Chain Code, and Three-OrThogonal chain code), the introduced method outperforms the referenced ones.     

Adaptive STBC-VBLAST transmission for mobile WiMAX

Multiple-input multiple-output (MIMO) technology can provide high data rate and substantial diversity. Space time block code (STBC) provides diversity gain and obtains signal of better quality even under bad channel conditions. However, it has no contribution to system average throughput. Vertical-bell laboratory layered space-time (VBLAST) improves peak data rate but leads to higher packet error rate (PER) at cell edge when the channel condition is poor. To get both higher system average throughput and cell edge throughput, an adaptive STBC-VBLAST transmission for downlink mobile WiMAX system is proposed and analyzed through system-level simulation in this article. The proposed approach compares the effective capacity of two candidate MIMO modes (STBC or VBLAST) and reports its decision to the base station with only one extra signaling bit. The simulation results show that the proposed approach can attain a balance between STBC and VBLAST. Besides, the cell throughput approximates that of pure VBLAST and the cell edge throughput is close to that of pure STBC.     

Adaptive type II hybrid ARQ scheme using zigzag code

The authors propose a new hybrid type II ARQ scheme based on the simple multidimensional concatenated zigzag code. Owing to the fact that the error-correcting capability of zigzag codes is far better than that of conventional convolutional codes, the throughput of our scheme is better than existing hybrid ARQ schemes     

Method of aligning code translators used in digital transmission

A method is proposed for establishing quickly and reliably whether word misalignment of a triple ternary (4B3T) decoder exists and for its rapid realignment. The method does not refer to any frame structure present in the original binary signal.