A Reliable Approach for Modeling the Actual Antenna Pattern in Millimeter-Wave Communication

This letter presents a mathematical framework for evaluating the link capacity of an interfered communication link in a millimeter-wave mobile scenario, accounting in detail for the shape of the antenna pattern and for the statistic of the direction of arrivals. The developed approach, whose accuracy is verified by Monte Carlo validations in 2D and 3D wireless environments, does not require simplified antenna models, thus enabling to maintain the actual pattern during the analysis

Recent Results on the Implementation of a Burst Error and Burst Erasure Channel Emulator Using an FPGA Architecture

The behaviour of a transmission channel may be simulated using the performance abilities of current generation multiprocessing hardware, namely, a multicore Central Processing Unit (CPU), a general purpose Graphics Processing Unit (GPU), or a Field Programmable Gate Array (FPGA). These were investigated by Cullinan et al. in a recent paper (published in 2012) where these three devices capabilities were compared to determine which device would be best suited towards which specific task. In particular, it was shown that, for the application which is objective of our work (i.e., for a transmission channel simulation), the FPGA is 26.67 times faster than the GPU and 10.76 times faster than the CPU. Motivated by these results, in this paper we propose and present a direct hardware emulation. In particular, a Cyclone II FPGA architecture is implemented to simulate a burst error channel behaviour, in which errors are clustered together, and a burst erasure channel behaviour, in which the erasures are clustered together. The results presented in the paper are valid for any FPGA architecture that may be considered for this scope

Useful Mathematical Tools for Capacity Approaching Codes Design

Focus of this letter is the oldest class of codes that can approach the Shannon limit quite closely, i.e., lowdensity parity-check (LDPC) codes, and two mathematical tools that can make their design an easier job under appropriate assumptions. In particular, we present a simple algorithmic method to estimate the threshold for regular and irregular LDPC codes on memoryless binary-input continuous-output AWGN channels with sum-product decoding, and, to determine how close are the obtained thresholds to the theoretical maximum, i.e., to the Shannon limit, we give a simple and invertible expression of the AWGN channel capacity in the binary input - soft output case. For these codes, the thresholds are defined as the maximum noise level such that an arbitrarily small bit-error probability can be achieved as the block length tends to infinity. We assume a Gaussian approximation for message densities under density evolution, a widely used simplification of the decoding algorithm

More Accurate Analysis of Sum-Product Decoding of LDPC codes Using a Gaussian Approximation

This letter presents a more accurate mathematical analysis, with respect to the one performed in Chung et al.\u2019s 2001 paper, of belief-propagation decoding for Low-Density Parity- Check (LDPC) codes on memoryless Binary Input - Additive White Gaussian Noise (BI-AWGN) channels, when considering a Gaussian Approximation (GA) for message densities under density evolution. The recurrent sequence, defined in Chung et al.\u2019s 2001 paper, describing the message passing between variable and check nodes, follows from the GA approach and involves the function \u3c6(x), therein defined, and its inverse. The analysis of this function is here resumed and studied in depth, to obtain tighter upper and lower bounds on it. Moreover, unlike the upper bound given in the above cited paper, the tighter upper bound on \u3c6(x) is invertible. This allows a more accurate evaluation of the asymptotical performance of sum-product decoding of LDPC codes when a GA is assumed

On rate-compatible punctured turbo codes design

We propose and compare some design criteria for the search of good systematic rate-compatible punctured turbo code (RCPTC) families. The considerations presented by S. Benedetto et al. (1998) to find the "best" component encoders for turbo code construction are extended to find good rate-compatible puncturing patterns for a given interleaver length . This approach is shown to lead to codes that improve over previous ones, both in the maximum-likelihood sense (using transfer function bounds) and in the iterative decoding sense (through simulation results). To find simulation and analytical results, the coded bits are transmitted over an additive white Gaussian noise (AWGN) channel using an antipodal binary modulation. The two main applications of this technique are its use in hybrid incremental ARQ/FEC schemes and its use to achieve unequal error protection of an information sequence

Wireless Video

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Joint Voice/Video Retry Limit Adaptation for On-Demand Streaming over WiFi Networks

This letter proposes a fast retry limit adaptation algorithm for the 802.11e distributed networks. Different from existing solutions, which manage a unique access category, the presented method jointly estimates the retry limits associated with both voice and video packets. The algorithm that operates in saturated and non-saturated traffic conditions is validated adopting an 802.11n physical layer and comparing its performance with a proper extension of an existing solution

Performance analysis of time of arrival estimation on OFDM signals

This letter characterizes the error performance of realistically modelled orthogonal frequency division multiplexing (OFDM) signals, when their time of arrival has to be estimated in an additive white Gaussian noise channel. In particular, different power distributions on the available sub-carriers of the OFDM signal are considered, and bounds on the corresponding root mean square estimation error (RMSEE) are evaluated. The tools used for such purpose are the widely adopted Cram\ue9r-Rao bound and the Ziv-Zakai bound, which is tight in a wide range of signal-to-noise ratio (SNR) values. The presented analysis reveals that, for a given signal bandwidth, a proper power distribution on the OFDM sub-carriers is crucial for achieving a good performance in the low to medium SNR region, where the RMSEE curve exhibits the typical threshold behavior. Moreover, a trade-off between asymptotic and threshold performance is identified, thanks to the adoption of a novel performance figure, which directly describes the threshold RMSEE behavior

Limiting Performance of Millimeter-Wave Communications in the Presence of a 3D Random Waypoint Mobility Model

This paper proposes a mathematical framework for evaluating the limiting capacity of a millimeter-wave (mmWave) communication involving a mobile user (MU) and a cellular base station. The investigation is realized considering a threedimensional (3D) space in which the random waypoint mobility model is used to probabilistically identify the location of the MUs. Besides, the analysis is developed accounting for path-loss attenuation, directional antenna gains, shadowing, and modulation scheme. Closed-form formulas for the received signal power, the Shannon capacity, and the bit error rate (BER) are obtained for both line-of-sight (LoS) and non-LoS scenarios in the presence of a noise-limited operating regime. The conceived theoretical model is firstly checked by Monte Carlo validations, and then employed to explore the influence of the antenna gain and of the cell radius on the capacity and on the BER of a fifth-generation (5G) link in a 3D environment, taking into account both the 28 and 73 GHz mmWave bands

Low Complexity Rate Compatible Puncturing Patterns Design for LDPC Codes

In contemporary digital communications design, two major challenges should be addressed: adaptability and flexibility. The system should be capable of flexible and efficient use of all available spectrums and should be adaptable to provide efficient support for the diverse set of service characteristics. These needs imply the necessity of limit-achieving and flexible channel coding techniques, to improve system reliability. Low Density Parity Check (LDPC) codes fit such requirements well, since they are capacity-achieving. Moreover, through puncturing, allowing the adaption of the coding rate to different channel conditions with a single encoder/decoder pair, adaptability and flexibility can be obtained at a low computational cost.In this paper, the design of rate-compatible puncturing patterns for LDPCs is addressed. We use a previously defined formal analysis of a class of punctured LDPC codes through their equivalent parity check matrices. We address a new design criterion for the puncturing patterns using a simplified analysis of the decoding belief propagation algorithm, i.e., considering a Gaussian approximation for message densities under density evolution, and a simple algorithmic method, recently defined by the Authors, to estimate the threshold for regular and irregular LDPC codes on memoryless binary-input continuous-output Additive White Gaussian Noise (AWGN) channels