Cooperative communication is an emerging paradigm where multiple mobiles share their resources (bandwidth and power) to achieve better overall performance. Coded cooperation is a mechanism where cooperation is combined with-and operates through-channel coding, as opposed to the repetition-based methods. This work develops expressions for outage probability of coded cooperation. In this work, each node acts as both a data source as well as a relay, i.e., only active (transmitting) nodes are available to assist other nodes, and each node operates under overall (source + relay) power and bandwidth constraints. Outage expressions confirm that full diversity is achieved by coded cooperation. This shows that despite superficial similarities, coded cooperation is distinct from decode-and-forward, which has been shown to have diversity one. The outage probability expressions developed in this work characterize coded performance at various rates. Furthermore, outage probabilities yield bounds that are arguably more insightful than the bit-error rate (BER) results previously available for coded cooperation. Numerical comparisons shed light on the relative merits of coded cooperation and various repetition-based methods, under various inter-user and uplink channel conditions.

Motivated by the recent works on the relay channel and cooperative diversity, this letter introduces coded cooperation, where cooperation is achieved through channel coding methods instead of a direct relay or repetition. Each codeword is partitioned into two subsets that are transmitted from the user's and partner's antennas, respectively. Coded cooperation achieves impressive gains compared to a non-cooperative system while maintaining the same information rate, transmit power, and bandwidth. We develop bounds on BER and FER and illustrate the advantage of coded cooperation under a number of different scenarios.

When mobiles cannot support multiple antennas due to size or other constraints, conventional space-time coding cannot be used to provide uplink transmit diversity. To address this limitation, the concept of cooperation diversity has been introduced, where mobiles achieve uplink transmit diversity by relaying each other's messages. A particularly powerful variation of this principle is coded cooperation. Instead of a simple repetition relay, coded cooperation partitions the codewords of each mobile and transmits portions of each codeword through independent fading channels. This paper presents two extensions to the coded cooperation framework. First, we increase the diversity of coded cooperation in the fast-fading scenario via ideas borrowed from space-time codes. We calculate bounds for the bit- and block-error rates to demonstrate the resulting gains. Second, since cooperative coding contains two code components, it is natural to apply turbo codes to this framework. We investigate the application of turbo codes in coded cooperation and demonstrate the resulting gains via error bounds and simulations.

Coded cooperation is a new framework recently proposed for cooperative communication. In this work, we present outage probability results for coded cooperation, and demonstrate that full diversity is achieved. In addition, we compare the outage behavior of coded cooperation with other repetition-based cooperative schemes.

Transmit diversity generally requires more than one antenna at the transmitter. However, many wireless devices are limited by size or hardware complexity to one antenna. Recently, a new class of methods called cooperative communication has been proposed that enables single-antenna mobiles in a multi-user environment to share their antennas and generate a virtual multiple-antenna transmitter that allows them to achieve transmit diversity. This article presents an overview of the developments in this burgeoning field.

Cooperative communication has recently emerged as an effective form of signaling in wireless fading channels. This work examines cooperative communication in multi-user networks, where the geometry of information flow becomes an issue, i.e., who should cooperate with whom? In particular, one is interested in algorithms that do not require global network information, which is often unavailable due to latency, limited memory, or other constraints. In this work we propose and study distributed protocols for partner selection in cooperative networks. In this class of protocols, wireless users act individually and independently in establishing cooperative communication, without the aid of a central authority. Such a setup is especially of interest in ad-hoc networks, or networks of wireless sensors. We perform outage analysis for the proposed protocols, showing that full diversity in the number of cooperating users is achieved. The cooperative network with the proposed protocols performs significantly better than the non-cooperative counterpart.

In a multi-user environment, coded cooperation creates transmit diversity for small mobiles (e.g. handsets) that cannot support more than one antenna. Coded cooperation allows these mobiles to share their antennas via a simple and effective coding method. In this work we present an analytical methodology for evaluating the performance of coded cooperation. We develop tight bounds for bit and block error capabilities, showing in the process that coded cooperation achieves maximal diversity. We demonstrate the validity of these bounds via simulations.

We propose a new user cooperation scheme for wireless communications in which we combine cooperation with existing channel coding methods. Simulation results show a significant improvement in the BER for both users, even when the channel between them is poor, or when they have significantly different channel qualities to the base station.

User cooperation provides uplink transmit diversity even when mobile units cannot accommodate multiple antennas due to size constraints. Recently, a versatile user cooperation method called coded cooperation diversity was introduced, in which standard channel coding methods are used to implement cooperation. This method achieves remarkable gains compared to a conventional (non-cooperative) system while maintaining the same information rate and transmit power. In this work, we investigate the performance of coded cooperation under a variety of conditions. We investigate slow Rayleigh fading scenarios where the users have either similar or significantly different quality channels to the base station. We compare coded cooperation with the amplify-and-forward protocol proposed by Laneman, Wornell, and Tse. Furthermore, we consider the effects of conventional power control on cooperating users for the slow fading case. Finally, we present some results for the case of fast Rayleigh fading.

Linebarger et al. (see Proceedings of Thirty-First Asilomar Conference on Signals, Systems & Computers, Pacific Grove, California, USA, vol.1, p.123-27, 1997) introduced a new, optimal approach to low rank transform domain adaptive filtering is , using a least squares, matrix based framework. Further, Raghothaman (see Proceedings of 8th IEEE DSP Workshop, Utah, USA, 1998) provides a computationally efficient algorithm to solve the formulation of the problem proposed by Linebarger. In this paper, we examine an alternative method for applying an optimal low rank transform, within the framework derived by Linebarger, to convert an overdetermined, full rank system into a low rank system. In addition, we propose a computationally efficient algorithm for the implementation of our method, using the DCT as the unitary transformation. Finally, we evaluate the performance of our algorithm via simulation in an acoustic echo canceller application, and show that the performance of our method is superior to existing low rank methods, NLMS and affine projection