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OFDM with Quadrature amplitude modulation (QAM) technique can be used for high speed optical applications. As the order of modulation increases, the bit error rate (BER) increases. Forward Error correction (FEC) coding like LDPC coding is generally used to Improve BER performance. LDPC provides large minimum distance and also the power efficiency of the LDPC code increases significantly with the code...
In this paper, a new Orthogonal Frequency Division Multiplexing (OFDM) with Permutation block spreading scheme is introduced; the transmitted stream is divided into blocks and the data symbols in each block is used to select the spreading code. Therefore, the increased frequency diversity in the system due to spreading improves bit error rate performance in the presence of frequency selective fading...
We propose two encoding strategies for a two user cooperative Orthogonal Frequency Division Multiple Access (OFDMA) system, based on block Markov superposition encoding. We obtain the expressions for the resulting achievable rate regions for both encoding strategies, and evaluate them through simulations. We show that, by allowing for re-partitioning and re-encoding of the cooperative messages across...
We study the performance of per-tone transmit antenna selection in OFDM systems with Alamouti coding. In particular, we analyse the diversity and coding gains of such systems, and compare these gains with the respective performance metrics for single-antenna selection performed on a pertone basis. Our analysis demonstrates that although the gain of single-antenna selection is superior to that of Alamouti...
One of the main disadvantages of OFDM (Orthogonal frequency-division multiplexing) is its high PAPR (Peak to Average Power Ratio). In this paper we propose a method for reducing PAPR using encoding and companding techniques. Several codes were used such as BCH, RS codes and Reed-Muller. The effect of modulation BPSK and QAM16 on the PAPR has been studied, μ-law companding has been used and the influence...
Alamouti code with differential encoding has been recently proposed for OFDM systems. It allows full-rate and full-diversity communication and can be decoded with a linear complexity when using two transmit and one receive antennas. However, these advantages assume no interbloc interference (IBI) and no intersymbol interference (ISI) which occur only if the Guard Interval (GI) size is larger than...
Cooperative orthogonal frequency division multiplexing (OFDM) systems have been shown to be fertile in both spatial and frequency diversities and can provide high transmission throughputs. In this paper, we aim at developing a cooperative space-frequency block coded (SFBC) OFDM system by using Alamouti's coding scheme. With the selective decode-and-forward relaying strategy, we first derive the equivalent...
In this paper, a new scheme that combines Orthogonal Frequency Division Multiplexing (OFDM) with parity bit selected block spreading is introduced. In this proposed method, the data symbols in each block is used to select the spreading code. Therefore, frequency diversity in the system is increased as well as improving the symbol detection due to the inherent coding in the spreading technique. Simulation...
Filter bank based multicarrier (FBMC) is an interesting alternative to OFDM especially for spectrally agile communication waveform generation and for cognitive radio scenarios. For enhanced link performance and robustness, most of the common multi-antenna schemes can be combined with FBMC equally well as with OFDM. However, one significant shortcoming of FBMC is the difficulty of combining it with...
This paper proposes a space-time-frequency coding scheme for MIMO-OFDM that achieves full rate for an arbitrary number of antennas with complex-valued information symbols. In addition, the proposed scheme provides a very high level of diversity with relatively low complexity. In the new scheme, the spatial and frequency spreading is followed by a temporal spreading that facilitates simple separation...
The performance of a wireless communication system is analyzed considering multi-carrier OFDM with Multiple- Input-Multiple-Output (MIMO) wireless channel and Space-Time Block Coding (STBC). Bit Error Rate (BER) expression for MIMO-OFDM system without and with STBC is presented considering fading and timing jitter with QPSK, DPSK and DQPSK modulation schemes. The performance results are evaluated...
In forward link multiuser space-time block coded orthogonal frequency division multiplexing (STBC-OFDM) systems, the signal-to-noise power ratio (SNR) of each user's received signal is different from those of others. Thus, when subcarriers are not properly allocated to users, intensive bit errors occur in a specific user. This causes a burst error in such a user, and the number of correctable bits...
In this paper, we implement Bose-Chaudhuri-Hocquenghen (BCH) coding to study the performance of Power Line Channel (PLC) impaired by impulsive noise and AWGN. Quadrature amplitude modulation (QAM) is employed and orthogonal frequency division multiplexing (OFDM) is used as a transmission scheme. Block truncation coding (BTC) is used for the compression of the image. A comparison is made between uncoded...
Future Communication networks are tending towards a diverse wireless networking world where the positioning information (PI) could be helpful in different techniques like the dynamic resource allocation. On the other hand, the PI could be widely used for cooperative techniques in the relay and/or routing selection process. In this paper, we propose to use the PI in the selection of the relays and...
Multiple Input Multiple Output (MIMO) is a topic of high interest for the next generation of broadcasting systems. However, their deployment in single frequency networks (SFN) becomes more critical when they are used in hybrid satellite-terrestrial transmission due to the different aspects of the respective transmission links. In this paper, we propose to apply a double layer space time block code...
The following topics are dealt with: cognitive radio; future internet research; service management; networking; source coding; network service; cooperative communication; wireless ad hoc networks; mesh networks; cryptography; ethernet; passive optical networks; MIMO systems; OFDM; OFDMA; elasticity; LDPC coding; wireless sensor networks; quality of service; random access; protocols; optical networks;...
This paper proposes a simple physical (PHY) layer design to introduce cooperation in the downlink of an infrastructure-based multicell multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) network. To improve the cell coverage, a novel PHY layer design is proposed that allows cooperation among an arbitrary and unknown number of base stations (BSs), by suitably randomizing...
Multiple frequency offsets (CFO) in cooperative communications are difficult, if not impossible, to compensate completely at the destination node. The multiple CFO make the channel time-varying, and thus the conventional space-time codes to collect diversity gain for co-located multi-input multi-output (MIMO) systems may not be applied directly. In a previous paper, we proposed a distributed space-frequency...
In this paper, we investigate distributed differential space-time block coding (STBC) for cooperative communications over frequency-selective fading channels. We carefully exploit the unitary structure of the orthogonal STBC to design a low complexity differential STBC receiver for multi-carrier broadband cooperative networks. We consider amplify-and-forward relaying and assume a single-relay scenario...
Recently, to meet higher data rate requirements, LDPC coded MIMO-OFDM systems are investigated widely. Multiple-input multiple-output (MIMO) wireless technology in combination with orthogonal frequency division multiplexing (OFDM) is an attractive solution for next-generation wireless local area networks (WLANs). Space-time block coded OFDM is capable of achieving substantial diversity gains, while...
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