A joint channel estimation and channel coding scheme is presented for channels with memory using polar codes. Unlike the conventional approach of first estimating all channel parameters and then performing channel decoding separately, the proposed scheme incorporates a subset of reliable estimates of channel parameters into the decoding procedure and computes decoding metrics averaged over the statistical behavior of the channel. Specifically, decoding algorithms for finite-state Markov channels of any order, for the Gauss-Markov channel and for flat-fading channels are presented. Further, by adapting list decoding to identify reliably-decoded bits within a codeword, channel estimation and decoding steps are performed iteratively to boost the reliability of channel estimation as well as error correction. In order to improve the performance even further, a new pilot arrangement scheme is developed that utilizes the structure of polar codes and sends pilot symbols embedded within the polar codewords. This construction can be viewed as a new family of shortened polar codes that can be of independent interest. Simulation results demonstrate the benefit of the proposed approach compared to existing solutions.

A joint channel estimation and channel coding scheme is presented for finite-state Markov channels using polar codes. Unlike the conventional approach of first estimating all channel parameters and then performing channel decoding separately, the proposed scheme incorporates a subset of reliable estimates of channel parameters into the decoding algorithm and computes decoding metrics averaged over the statistical behavior of the Markov channel. By adapting list decoding (without any inner code), channel estimation and decoding steps can be performed iteratively to boost the reliability of channel estimation as well as error correction. In order to improve the performance even further, a new pilot transmission scheme is developed that utilizes the structure of polar codes and sends pilot symbols along with code symbols. This construction can be viewed as a new family of shortened polar codes that can be of independent interest. Simulation results demonstrate the benefit of the proposed approach compared to existing solutions.

Interference cancellation is one major multiuser detection strategy for suppressing interference effects and improving system performance. In this paper, a novel blind decision-feedback interference cancellation framework and its implementations with least squares, maximum likelihood and minimum mean squared error criteria are proposed and analyzed. Compared with existing blind multiuser receivers, the proposed framework and schemes require a small number of previous received signals and no subspace separation or sequence estimation. The detection complexity and delay can therefore be low. The proposed schemes can also be implemented in an adaptive fashion. Theoretical analysis as well as computer simulations is provided to demonstrate the performance of the proposed schemes.

Though hierarchical modulation offers an important coverage and throughput tradeoff for wireless communications, it has received relatively little attention to date. Traditional hierarchical modulation suffers from the interference between layers, which results in both capacity loss and bit-error rate increasing. In this paper, an enhanced hierarchical modulation technique along with four optimization criteria are discussed. The proposed hierarchical modulation enhancement, where the enhancement-layer signal constellation is intentionally rotated, helps achieve better performance with little complexity increase. The first criterion is to maximize the achievable spectral efficiency with optimizing the Euclidean distance profile. The second criterion is to lower demodulation error rate with maximizing the modulation efficiency, a concept suggested for quantizing inter- layer interference. The third criterion is proposed to maximize the demodulation robustness when the imperfect channel estimation happens. The last approach is suggested for maximizing the RF power amplifier efficiency at the transmitter side with reducing the peak-to-average-power ratio of modulated signals when multi-carrier transmission is applied. All proposed schemes are simple and efficient. They can help recover the performance loss by regular hierarchical modulations with little complexity increase. Computer simulation is provided to support our conclusions.

The cellular relay network can provide both coverage extension and capacity enhancement. However, the network in nature requires more complex operation for maintaining each connection because of an increase dimension of node mobility that affects the signal-to-noise ratio (SNR) at each receiver node in the respective link in the relay architecture. As the outage ratio depends on the SNR statistics and the number of connections admitted in the system, admission capacity planning needs to take into account the SNR fluctuations. In this paper, we propose a new method for admission capacity planning in a cellular network using a cooperative relaying mechanism called decode-and- forward. Our approach is based on a new consideration of the randomness of the channel gain in our formulation of the outage ratio. Admission capacity planning is mathematically formulated as an optimization problem that maximizes the accommodation capacity (in number of connections) subject to a constraint that the outage ratio is upper-bounded by a certain threshold value. The simplicity of the problem formulation facilitates its solution in real-time. The proposed planning method provides an attractive means for dimensioning a cellular relay network with cooperative relay nodes.

The question on how much feedback we need for MIMO beamforming is addressed in terms of the distortion and reliability of MIMO beamforming feedback in this paper. We model MIMO beamforming feedback with noisy Gaussian binary erasure feedback channel, in which the MIMO forward link is modelled as a Gaussian channel and the reverse link is simplified as a Gaussian binary erasure channel. For the forward link channel quantization, an information-theoretic lower bound and a heuristic sphere-packing upper bound for the achievable rate- distortion region are given. For the reverse link channel feedback, the rate-reliability region is analyzed with Shannon bounds. Though a large codebook design with high-rate feedback is generally desired for less distortion, it may be unnecessary due to the limitation of channel estimation and feedback channel. Tradeoffs between codebook design and channel state information feedback are therefore revealed.

We propose a decentralized random parity forwarding technique in large-scale wireless networks composed of multiple sources, multiple relays, and single destination to enhance the reliability of decoding. The parity bits are generated independently and randomly at the relays and forwarded to the destination. This makes the protocol overhead minimal in coordinating the relay nodes and enables a decentralized network operation. Also, it allows relay nodes to be easily added with little overhead as the network scale increases. The presented model incorporates random distribution of nodes in the network as well as random mobility of nodes that results in a random number of cooperating relay nodes. We analyze the probability of decoding error, and the normalized throughput. We also analyze the outage probability that a selected encoding rule produces an error probability greater than a threshold. We present the energy saving and the coverage area extension provided by the random parity forwarding technique. The effect of multiple antennas at the destination and forward error correcting code at the source are analyzed.

We investigate how finite-rate feedback and imperfect channel estimation impact MIMO relay network throughput and design in this paper. We start from multi-antenna transceiver with random beamforming and formulate the SNR and capacity loss due to channel estimation and quantization errors. We thereafter extend the analysis to multi-antenna relay network with multiple MIMO relay hops and discuss how the end-to-end throughput is scaled by MIMO pilot size, codebook size, relay network size and inter-beam interference. Some tradeoffs for MIMO relay network design are revealed. Computer simulations are provided to demonstrate our results.

Most previous work on cooperative cellular networks has considered homogeneous relaying architectures where all nodes act as both sources and relays or considered heterogeneous relaying architecture where relays are fixed. In this paper, we examine the power consumption performance of heterogeneous cooperative cellular networks with two classes of nodes: source nodes (subscriber stations, SS's) that do not act as relays, and relaying agents (relays station, RS) that are dedicated to relaying functions with little concern about power consumption. In this architecture, source nodes are able to reap the benefits of cooperative communication, such as improvements in the achievable data rate and reductions in the transmit power, while reducing the overall power consumption since they do not act as a relay. We consider a geometry of a cell. Then we consider random locations of SS and RS, respectively, to analyze the average power consumption over the region of interest under the assumption that the SS and RS are distributed uniformly over the cell region.

Present (predominant) modes of video delivery – broadcast, cable, and satellite – are inflexible in terms of program times, viewing locations, and viewing devices. With increased mobility of users, together with the availability of a variety of viewing devices, the need for video consumption ‘anytime’, ‘anywhere’, ‘anyhow’ has been growing. This paper presents a model to support the above needs using entities called virtual content container (VCCs). The VCCs facilitate the selection of video content of interest, and subsequent consumption in time/space delayed manner, and provide flexibilities of viewing times, locations, and devices.

At present most of the personal entertainment content (audio and video) is consumed primarily via three modes – broadcast (broadcast, cable, satellite networks), packaged on CDs and DVDs, or stored on personal storage on PCs or media players (hard disks, flash memories, etc). These modes of content consumption have drawbacks such as inflexibility of having access to any desired content at any time, from anywhere, and consuming on any device. This paper proposes a content management system model which uses entities called personal content portfolios (PCPs) based on concepts from financial systems. Using aggregates of PCPs, the content management system manages large pools of content in an optimal manner and offers content and a variety of services in a cost-effective manner to consumers. Some major benefits and issues to be addressed in the design and use of PCPs are also discussed.

We present a bandwidth-efficient coded cooperative relaying technique that provides a significant coding gain without requiring an increase in bandwidth relative to uncoded cooperative relaying system. The key to the technique is that the redundant bits introduced by the code are accommodated by expanding the relay set, rather than expanding the signal set as in traditional trellis coded modulation. An increase in the number of relays produces additional interference, but its effect can be suppressed by signal processing (decorrelation) and channel coding techniques to produce a positive coding gain without sacrificing data rate or expanding bandwidth. We present the optimum number of relays and the optimal code rate that minimize the end-to-end bit error probability. Additional increase in coding gain by allowing the relay nodes to decode and re-encode is analyzed.

We propose a new blind multiuser signal model and detection framework for solving the near-far problem in synchronous CDMA in this paper. Compared with existing blind detectors, the proposed framework requires a minimum number of previously received signals, which is about the number of interfering users, and no sub-space separation or sequence estimation. Hence its computation complexity and detection delay are much reduced. Following this framework, several blind multiuser detectors are developed using least squares (LS) estimation, best least unbiased (BLU) estimation and minimum mean-square error (MMSE) estimation criteria and a recursively adaptive procedure is developed for further decreasing the complexity. All these can be easily extended for asynchronous CDMA. The near-far performance of this framework and the trade-off between the complexity and performance are discussed. Computer simulations are provided to demonstrate the performance of the proposed schemes too.