Analysis of cyclic delay diversity on DVB-H systems over spatially correlated channel

The objective of this work is to research and analyze the performance of Cyclic Delay Diversity (CDD) with two transmit antenna on DVB-H systems operating in spatially correlated channel. It is shown in this paper that CDD can achieve desirable transmit diversity gain over uncorrelated channel with or without receiver diversity. However, in reality, the respective signal paths between spatially separated antennas and the mobile receiver is likely to be correlated because of insufficient antenna separation at the transmitter and the lack of scattering effect of the channel. Under this spatially correlated channel, it is apparent that CDD cannot achieve the same diversity gain as obtained under the uncorrelated channel. In this paper, a new upper bound on the pairwise error probability (PEP) of the CDD with spatial correlation of two transmit antennas is derived. The upper bound is used to study the CDD theoretical error performance and diversity gain losses over a generalized spatially correlated Rayleigh channel. This theoretical analysis is validated by the simulation of DVB-H systems with two transmit antennas and the CDD scheme. Both the theoretical and simulated results give the valuable insight that the CDD ability to perform well with a certain amount of channel correlation

Generation of correlated Rayleigh fading channels for accurate simulationof promising wireless communication systems

In this paper, a generalized method is proposed for the accurate simulation of equal/ unequal power correlated Rayleigh fading channels to overcome the shortcomings of existing methods. Spatial and spectral correlations are also considered in this technique for different transmission conditions. It employs successive coloring for the inphase and quadrature components of successive signals using real correlation vector of successive signal envelopes rather than complex covariance matrix of the Gaussian signals which is utilized in conventional methods. Any number of fading signals with any desired correlations of successive envelope pairs in the interval [0, 1] can be generated with high accuracy. Moreover, factorization of the desired covariance matrix is avoided to overcome the shortcomings and high computational complexity of conventional methods. Extensive simulations of different representative scenarios demonstrate the effectiveness of the proposedtechnique. The simplicity and accuracy of this method will help the researchers to study and simulate the impact of fading correlation on the performance evaluation of various multi-antenna and multicarrier communication systems. Moreover, it enables the engineers for efficient design and deployment of new schemes for feasible wireless application

Equivalent-Capacity-Based Design of Space-Time Block-Coded Sphere-Packing-Aided Multilevel Coding

A multilevel coding (MLC) scheme invoking sphere packing (SP) modulation combined with space time block coding (STBC) is designed. The coding rates of each of the MLC component codes are determined using the so-called equivalent capacity based constituent-code rate-calculation procedure invoking a 4-dimensional (4D) sphere packing bit-to-symbol mapping scheme. Four different-rate Low-Density Parity Check (LDPC) constituent-codes are used by the MLC scheme. The performance of the resultant equivalent capacity based design is characterized using simulation results. Our results demonstrate an approximately 3.5dB gain over an identical scheme dispensing with SP modulation. Furthermore although a similar performance gain is attained by both the proposed MLC scheme and its benchmarker, which uses a single-class LDPC code, the MLC scheme is preferred, since it benefits from the new classic philosophy of using low-memory, low-complexity component codes as well as providing an unequal error protection capability

Precoder design for space-time coded systems over correlated Rayleigh fading channels using convex optimization

A class of computationally efficient linear precoders for space-time block coded multiple-input multiple-output wireless systems is derived based on the minimization of the exact symbol error rate (SER) and its upper bound. Both correlations at the transmitter and receiver are assumed to be present, and only statistical channel state information in the form of the transmit and receive correlation matrices is assumed to be available at the transmitter. The convexity of the design based on SER minimization is established and exploited. The advantage of the developed technique is its low complexity. We also find various relationships of the proposed designs to the existing precoding techniques, and derive very simple closed-form precoders for special cases such as two or three receive antennas and constant receive correlation. The numerical simulations illustrate the excellent SER performance of the proposed precoders