Multi-symbol Encapsulated Orthogonal Frequency Division Multiplexing Research Articles

Performance Analysis of MSE-OFDM System

In this paper we analyze the effects of interchannel interference (ICI) and intersymbol interference (ISI) on the performance of a Multi-Symbol Encapsulated Orthogonal Frequency Division Multiplexing (MSE-OFDM) system. MSE-OFDM is a bandwidth efficient OFDM scheme, where a number of OFDM symbols are grouped together as a frame and protected by one single cyclic prefix. This reduces the extent of redundancy caused by the CP and increases the bandwidth efficiency of the system. We have derived expressions for probability of error for MSE-OFDM in presence of ICI and ISI, which result from the time variation and delay spread of mobile channels. Both analysis and simulation results are presented for the MSE-OFDM system and are found to be almost identical.

Multiple Access Scheme for Multi-Symbol Encapsulated Orthogonal Frequency Division Multiplexing

A new multiple access scheme using Multi-Symbol Encapsulated Orthogonal Frequency Division Multiplexing (MSE-OFDM) is proposed. This is basically a time division multiple access (TDMA) technique utilizing the MSE-OFDM. The Bit Error Rate (BER) performance of the TDMA system using conventional OFDM is slightly better than that of the proposed system. This weakness is compensated as the proposed technique exhibits an improvement in bandwidth efficiency compared to the TDMA using conventional OFDM.

A Time Slicing Adaptive OFDM System for Mobile Multimedia Communications

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Multi-Symbol Encapsulated-Orthogonal Frequency Division Multiplexing (MSE-OFDM) is an adaptive OFDM system which was proposed earlier to meet the overwhelming needs of spectrum-efficient wireless communication systems. In this technique, one cyclic prefix (CP) is used for multiple OFDM symbols. The motivation for MSE-OFDM is to mitigate two major inherited disadvantages of OFDM system at the same time i.e., the sensitivity to carrier frequency offset (CFO) and high peak to average power ratio (PAPR). In this paper, we propose a new time slicing technique where the cyclic prefix is replaced with the precoded pseudo-random sequence for MSE-OFDM system. Therefore it is possible to multiplex multiple data streams using this technique with dynamic data rates for mobile multimedia communications. It also overcomes disadvantages with other techniques such as high sensitivity to frequency offset inherited with Orthogonal Frequency Division Multiple Access (OFDMA) system and complex equalization problem with conventional Single Carrier-Frequency Division Multiple Access (SC-FDMA). Therefore this technique can be used for both uplink and downlink transmissions of mobile multimedia communications with variable data rates. With those inherent advantages of proposed time slicing technique which is compatible to DVB-H standard, power saving for mobile receivers is enabled and therefore extended battery life can be guaranteed which is very important for the mobile users. </para>

Frequency offset mitigation of cooperative ofdm system in wireless digital broadcasting

Mobile digital broadcasting is expected to become a promising application in future wireless communication. To improve the system performance in limitation of size and cost, the OFDM and MIMO techniques are adopted. Recently, cooperative diversity techniques are developed to be a solution. In this paper, we propose the carrier frequency offset mitigation scheme in cooperative communication using multi-symbol encapsulated orthogonal frequency division multiplexing (MSE-OFDM), in which one cyclic prefix (CP) is used for multiple OFDM symbols. We use the FFT size-reduced MSE-OFDM system which can be used to reduce the peak-to-average power ratio (PAPR) and improve the robustness to carrier frequency offset. The cooperative communication uses not only direct path from source to destination but also indirect path via relay station. Each different relays require more precise frequency synchronization and lower PAPR, so we adopt the MSEOFDM to increase the system performance. The performance analysis of cooperative MSE-OFDM in multipath fading channels has been done and the effect of carrier frequency offset and PAPR have been studied.

On the Design and Performance Analysis of Multisymbol Encapsulated OFDM Systems

A new multicarrier system, termed multisymbol encapsulated orthogonal frequency division multiplexing (MSE-OFDM), is proposed, in which one cyclic prefix (CP) is used for multiple OFDM symbols. The original motivation for the MSE-OFDM proposal is to reduce the redundancy due to the CP in static-channel environments. The authors then found that an alternative implementation of the system can be used to improve the robustness to frequency offset and reduce the peak-to-average power ratio (PAPR). Equalization and demodulation algorithms for the MSE-OFDM system are proposed. A new preamble and the corresponding frequency-offset and channel estimation techniques are studied for the MSE-OFDM system. Using the proposed MSE-OFDM preamble, the joint maximum likelihood (ML) estimation of the frequency offset and the channel impulse response (CIR) is investigated in this paper. Possible ways to reduce the joint estimation complexity, including exploitation of the preamble structure, approximation of the joint ML estimator, and fast Fourier transform (FFT) pruning, are discussed. The performance of the proposed MSE-OFDM systems and channel estimators are analyzed and verified through numerical simulations. An analysis on the bandwidth efficiency, the performance with frequency offset, and the PAPR of the MSE-OFDM system are also presented