2008 Information Theory and Applications Workshop最新文献_第5页

Buffering requirements for variable-iterations LDPC decoders 可变迭代LDPC解码器的缓冲要求

2008 Information Theory and Applications Workshop Pub Date : 2008-08-15 DOI: 10.1109/ITA.2008.4601025

S. L. Sweatlock, S. Dolinar, K. Andrews

{"title":"Buffering requirements for variable-iterations LDPC decoders","authors":"S. L. Sweatlock, S. Dolinar, K. Andrews","doi":"10.1109/ITA.2008.4601025","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601025","url":null,"abstract":"Low-density parity-check (LDPC) decoders, like iterative decoders for other block codes, can be designed to stop after a variable number of iterations, dependent on the difficulty of decoding particular noisy received words, also called frames. The number of iterations the decoder spends on a given frame determines both the probability of successful decoding, and the time expended. But whereas the speed of an LDPC decoder without a buffer is determined by its most difficult frames, the speed of a variable-iterations decoder with sufficient buffering approaches that determined by frames of average difficulty. It is relatively straightforward to analyze this as a D/G/1 queuing problem combined with empirically measured probability distributions of iteration counts for specific LDPC codes. Our analysis parallels that of other researchers, e.g., (J. Vogt and A. Finger, 2001), (G. Bosco et al., 2005), (M. Rovini and A. Martinez, 2007), and examines the resulting implications on LDPC decoder design choices. We find that a buffer large enough to hold only B = 2 or 3 additional frames is sufficient to achieve near optimal performance. We prove a strong monotonicity condition: not only does a variable-iterations decoder with buffer size B +1 frames outperform one with buffer size B in terms of average error rate, every single frame is guaranteed to receive at least as many iterations from the decoder with the larger buffer, if needed. Significantly, at low error rates, a variable-iterations decoder with buffer size B can keep pace with an input data rate B +1 times faster than a fixed-iterations decoder with the same processing speed.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125325848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

Adaptive rateless coding under partial information 部分信息下的自适应无速率编码

2008 Information Theory and Applications Workshop Pub Date : 2008-08-15 DOI: 10.1109/ITA.2008.4601012

S. Agarwal, A. Hagedorn, A. Trachtenberg

引用次数: 12

The application of distributed spectrum sensing and available resource maps to cognitive radio systems 分布式频谱感知和可用资源图在认知无线电系统中的应用

2008 Information Theory and Applications Workshop Pub Date : 2008-08-15 DOI: 10.1109/ITA.2008.4601095

C. da Silva, W. Headley, J. Reed, Youping Zhao

引用次数: 18

Layered source-channel coding: A distortion-diversity perspective 分层源信道编码:失真分集的观点

2008 Information Theory and Applications Workshop Pub Date : 2008-08-15 DOI: 10.1109/ITA.2008.4601050

Sheng Jing, Lizhong Zheng, M. Médard

引用次数: 1

Joint multi-cell processing for downlink channels with limited-capacity backhaul 有限容量回程下行信道的联合多小区处理

2008 Information Theory and Applications Workshop Pub Date : 2008-08-15 DOI: 10.1109/ITA.2008.4601071

S. Shamai, O. Simeone, O. Somekh, H. Poor

{"title":"Joint multi-cell processing for downlink channels with limited-capacity backhaul","authors":"S. Shamai, O. Simeone, O. Somekh, H. Poor","doi":"10.1109/ITA.2008.4601071","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601071","url":null,"abstract":"Multicell processing in the form of joint encoding for the downlink of a cellular system is studied under the realistic assumption that the base stations (BSs) are connected to a central unit via finite-capacity links (finite-capacity backhaul). Three scenarios are considered that present different trade-offs between global processing at the central unit and local processing at the base stations and different requirements in terms of codebook information (CI) at the BSs: 1) local encoding with CI limited to a subset of nearby BSs; 2) mixed local and central encoding with only local CI; 3) central encoding with oblivious cells (no CI). Three transmission strategies are proposed that provide achievable rates for the considered scenarios. Performance is evaluated in asymptotic regimes of interest (high backhaul capacity and extreme signal-to-noise ratio, SNR) and further corroborated by numerical results. The major finding of this work is that central encoding with oblivious cells is a very attractive option for both ease of implementation and performance, unless the application of interest requires high data rate (i.e., high SNR) and the backhaul capacity is not allowed to increase with the SNR. In this latter cases, some form of CI at the BSs becomes necessary.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123749941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 28

On the Gaussian K-description problem under symmetric distortion constraints 对称畸变约束下的高斯k -描述问题

2008 Information Theory and Applications Workshop Pub Date : 2008-08-15 DOI: 10.1109/ITA.2008.4601081

C. Tian, S. Mohajer, S. Diggavi

{"title":"On the Gaussian K-description problem under symmetric distortion constraints","authors":"C. Tian, S. Mohajer, S. Diggavi","doi":"10.1109/ITA.2008.4601081","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601081","url":null,"abstract":"We consider multiple description (MD) coding for the Gaussian source under the symmetric mean squared error distortion constraints. With focus on the three description problem, we provide inner and outer bounds for the rate region, between which the gap can be bounded by some small constants. At the heart of this result is a novel lower bound for the sum rate, which is derived through generalization of the well-known bounding technique by Ozarow. In contrast to the original method, we expand the probability space by more than one (instead of only one) random variable, and further impose a particular Markov structure on them. The outer bound is then established by applying this technique to several bounding planes of the rate region. For the inner bound, we consider a simple scheme of combining successive refinement coding and lossless multilevel diversity coding (MLD). Both the inner and outer bounds can be written as the intersection of ten half spaces with matching normal directions, and thus can be easily compared. The small gap between them, where the boundary of the MD rate region clearly resides, suggests the surprising competitiveness of this simple achievability scheme. The geometric structure of the MLD rate region provides important guidelines as to the normal directions of the outer bound hyperplanes, which demonstrates an intimate connection between MD and MLD coding. These results can be generalized and improved in various ways which are also discussed.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131719673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The marginal utility of cooperation in sensor networks 传感器网络中合作的边际效用

2008 Information Theory and Applications Workshop Pub Date : 2008-08-15 DOI: 10.1109/ITA.2008.4601058

Yu-Ching Tong, G. Pottie

{"title":"The marginal utility of cooperation in sensor networks","authors":"Yu-Ching Tong, G. Pottie","doi":"10.1109/ITA.2008.4601058","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601058","url":null,"abstract":"We present arguments that a small number of sensors within the network provide most of the utility. That is, cooperation of more than a small number of nodes has little benefit. We present two scenarios. In the first scenario, all sensors provide identical utility, and their utilities are aggregated sequentially. The second scenario is sensor fusion with signal strength decreasing with distance. In that scenario the source is at the origin and the sensors are distributed, either uniformly or according to a planar standard normal distribution. We also vary the total number of sensors distributed in both scenarios to observe the utility/density trade off. Localization using the Fisher information as the utility metric is used to demonstrate that few sensors are sufficient to derive most of the utility out of the sensor network. Simulation results back up an order statistics analysis of the behavior. The implication is that while co-operation is useful for some objectives such as combating fading and uncertainty of individual sensors, it is inefficient as a mean to increase the utility of a sensor network if the best sensorpsilas utility is significantly short of the desired utility.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"71 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128005333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Dynamic rate allocation in fading multiple access channels 衰落多址信道中的动态速率分配

2008 Information Theory and Applications Workshop Pub Date : 2008-08-15 DOI: 10.1109/ITA.2008.4601054

Ali ParandehGheibi, A. Eryilmaz, A. Ozdaglar, M. Médard

{"title":"Dynamic rate allocation in fading multiple access channels","authors":"Ali ParandehGheibi, A. Eryilmaz, A. Ozdaglar, M. Médard","doi":"10.1109/ITA.2008.4601054","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601054","url":null,"abstract":"We consider the problem of rate allocation in a fading Gaussian multiple-access channel (MAC) with fixed transmission powers. Our goal is to maximize a general concave utility function of transmission rates over the throughput capacity region. In contrast to earlier works in this context that propose solutions where a potentially complex optimization problem must be solved in every decision instant, we propose a low-complexity approximate rate allocation policy and analyze the effect of temporal channel variations on its utility performance. To the best of our knowledge, this is the first work that studies the tracking capabilities of an approximate rate allocation scheme under fading channel conditions. We build on an earlier work to present a new rate allocation policy for a fading MAC that implements a low-complexity approximate gradient projection iteration for each channel measurement, and explicitly characterize the effect of the speed of temporal channel variations on the tracking neighborhood of our policy. We further improve our results by proposing an alternative rate allocation policy for which tighter bounds on the size of the tracking neighborhood are derived. These proposed rate allocation policies are computationally efficient in our setting since they implement a single gradient projection iteration per channel measurement and each such iteration relies on approximate projections which has polynomial-complexity in the number of users.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129482769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Capacity limits and performance results for frequency-hop transmission over partial-band noise channels 部分频带噪声信道上跳频传输的容量限制和性能结果

2008 Information Theory and Applications Workshop Pub Date : 2008-08-15 DOI: 10.1109/ITA.2008.4601060

M. Pursley, T. Royster

引用次数: 0

Beamforming in wireless relay networks 无线中继网络中的波束形成

2008 Information Theory and Applications Workshop Pub Date : 2008-08-15 DOI: 10.1109/ITA.2008.4601040

Yindi Jing, H. Jafarkhani

{"title":"Beamforming in wireless relay networks","authors":"Yindi Jing, H. Jafarkhani","doi":"10.1109/ITA.2008.4601040","DOIUrl":"https://doi.org/10.1109/ITA.2008.4601040","url":null,"abstract":"This paper is on relay beamforming in wireless networks, in which the receiver has perfect information of all channels and each relay knows its own channels. Instead of the commonly used total power constraint on relays and the transmitter, we use a more practical assumption that every node in the network has its own power constraint. A two-step amplify-and-forward protocol with beamforming is used, in which the transmitter and relays are allowed to adaptively adjust their transmit power and directions according to available channel information. The optimal beamforming problem is solved analytically. The complexity of finding the exact solution is linear in the number of relays. Our results show that the transmitter should always use its maximal power and the optimal power used at a relay is not a binary function. It can take any value between zero and its maximum transmit power. Also, interestingly, this value depends on the quality of all other channels in addition to the relaypsilas own ones. Despite this coupling fact, distributive strategies are proposed in which, with the aid of a low-rate broadcast from the receiver, a relay needs only its own channel information to implement the optimal power control. Simulated performance shows that network beamforming achieves full diversity and outperforms other existing schemes.","PeriodicalId":345196,"journal":{"name":"2008 Information Theory and Applications Workshop","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127584650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 10