Generalizing the Sampling Property of the Q-function for Error Rate Analysis of Cooperative Communication in Fading Channels

This paper extends some approximation methods that are used to identify closed form Bit Error Rate (BER) expressions which are frequently utilized in investigation and comparison of performance for wireless communication systems in the literature. By using this group of approximation methods, some expectation integrals, which are complicated to analyze and have high computational complexity to evaluate through Monte Carlo simulations, are computed. For these integrals, by using the sampling property of the integrand functions of one or more arguments, reliable BER expressions revealing the diversity and coding gains are derived. Although the methods we present are valid for a larger class of integration problems, in this work we show the step by step derivation of the BER expressions for a canonical cooperative communication scenario in addition to a network coded system starting from basic building blocks. The derived expressions agree with the simulation results for a very wide range of signal-to-noise ratio (SNR) values.Comment: 5 pages, 5 figures, Submitted to IEEE International Symposium on Information Theory, ISIT 2013, Istanbul, Turke

A Low-Complexity Graph-Based LMMSE Receiver Designed for Colored Noise Induced by FTN-Signaling

We propose a low complexity graph-based linear minimum mean square error (LMMSE) equalizer which considers both the intersymbol interference (ISI) and the effect of non-white noise inherent in Faster-than-Nyquist (FTN) signaling. In order to incorporate the statistics of noise signal into the factor graph over which the LMMSE algorithm is implemented, we suggest a method that models it as an autoregressive (AR) process. Furthermore, we develop a new mechanism for exchange of information between the proposed equalizer and the channel decoder through turbo iterations. Based on these improvements, we show that the proposed low complexity receiver structure performs close to the optimal decoder operating in ISI-free ideal scenario without FTN signaling through simulations.Comment: 6 pages, 6 figures, IEEE Wireless Communications and Networking Conference 2014, Istanbul, Turke

Practical Wireless Network Coding and Decoding Methods for Multiple Unicast Transmissions

We propose a simple yet effective wireless network coding and decoding technique. It utilizes spatial diversity through cooperation between nodes which carry out distributed encoding operations dictated by generator matrices of linear block codes. For this purpose, we make use of greedy codes over the binary field and show that desired diversity orders can be flexibly assigned to nodes in a multiple unicast network, contrary to the previous findings in the literature. Furthermore, we present the optimal detection rule for the given model that accounts for intermediate node errors and suggest a network decoder using the sum-product algorithm. The proposed sum-product detector exhibits near optimal performance.Comment: 6 pages, 5 figures, Submitted to WCNC 2012, IEEE Wireless Communication and Networking Conferenc

Practical Methods for Wireless Network Coding With Multiple Unicast Transmissions

We propose a simple yet effective wireless network coding and decoding technique for a multiple unicast network. It utilizes spatial diversity through cooperation between nodes which carry out distributed encoding operations dictated by generator matrices of linear block codes. In order to exemplify the technique, we make use of greedy codes over the binary field and show that the arbitrary diversity orders can be flexibly assigned to nodes. Furthermore, we present the optimal detection rule for the given model that accounts for intermediate node errors and suggest a low-complexity network decoder using the sum-product (SP) algorithm. The proposed SP detector exhibits near optimal performance. We also show asymptotic superiority of network coding over a method that utilizes the wireless channel in a repetitive manner without network coding (NC) and give related rate-diversity trade-off curves. Finally, we extend the given encoding method through selective encoding in order to obtain extra coding gains

ISI channel equalizers based on the factor graphs for M-QAM signalling M-QAM kipleme icin garpan gizge temelli ISI kanal denklestiriciler

In this work, we consider two methods especially for high order modulation types, namely the sum-product (SP) and linear minimum mean square error (LMMSE) algorithms, which were previously utilized to equalize the inter-symbol interference (ISI) channel. Techniques for reducing the computational complexity are proposed for the SP-based method. In addition, a new technique for the calculation of the extrinsic information is proposed, which significantly improves the performance in the LMMSE equalizer. The comparison of these proposed techniques is made through simulations carried out under the fading channel assumptio

A Wireless Vehicle-based mobile network infrastructure designed for smarter cities

The evolution of smart city services and applications requires a more efficient wireless infrastructure to provide the needed data rate to users in a high-density environment with high mobility, satisfying at the same time the request for high-connectivity and low-energy consumption. To address the challenges in this new network scenario, we propose to opportunistically rely on the increasing number of connected vehicles in densely populated urban areas. The idea is to support the macro base station (BS) with a secondary communication tier composed of a set of smart and connected vehicles that are in movement in the urban area. As a first step towards a comprehensive cost-benefit analysis of this architecture, this paper considers the case where these vehicles are equipped with femto-mobile access points (fmAPs) and constitute a mobile out-of-band relay infrastructure. We first study this network system with a continuous time model, in which three techniques to select an fmAP (if more than one is available) are proposed and the maximal feasible gain in the data rate is characterized as a function of the vehicle density, average vehicle speeds, handoff overhead cost, as well as physical layer parameters. We then introduce a time slotted model, in which we consider a more realistic communication channel, with an exponential path loss model, and we investigate the tradeoff between energy consumption and expected data rate, as a function of the system parameters. The analytical and simulation results, with both the continuous and time slotted models, provide a first benchmark characterizing this architecture and the definition of guidelines for its future realistic study and implementation