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The WiMAX technology has drawn enormous attentions from wireless communication industry in recent years. Its sophisticated physical layer (PHY) adopts such techniques as multiple-input and multiple-output (MIMO) and orthogonal frequency division multiplexing (OFDM), which are fundamentally different techniques from the previous 3G mobile system. To help the readers gain the knowledge of some key components...
An efficient anti-jamming piecewise coding based on cognitive OFDM modulation in cognitive radio network (CRN) is proposed in this paper. The optimal design methods of building piecewise code with low redundancy are presented. In cognitive OFDM, anti-jamming piecewise coding could recover the lost packets in parallel interference channels by implementing different number of parity check blocks, thus...
MB-OFDM UWB technology has attracted much attention in high speed wireless communications. A UWB communication system with channel coding is noticing for avoiding the performance degradation due to adverse channel propagation conditions. In this paper, we propose a novel Euclidean Geometry low-density parity-check (LDPC) coding scheme for MB-OFDM UWB systems. We emphasized on the construction of Euclidean...
In this paper, we employ to provide a method which combines Turbo codes and Low-Density Parity-Check (LDPC) codes based on Orthogonal Frequency Division Multiplexing (OFDM) system by adaptive encoding. The technique of channel estimation is used. The code rate and encoding scheme are all adaptive selection in the light of different channel conditions, so that we can make good use of these two types...
In this paper, in order to achieve the available spatial, temporal and frequency diversities, and also make the system implementation feasible for high speed orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) multiplexing, a novel LSTF transmitter architecture with multiple channel encoders is proposed with each independently coded information sub-stream being...
This paper is focused on the study of layered space-time-frequency (LSTF) architectures with channel coding for orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) multiplexing systems for high speed wireless communications over a frequency-selective fading channel. In order to achieve the available spatial, temporal and frequency diversities, and also make the...
Orthogonal frequency division multiplexing (OFDM) and interleave-division multiple-access (IDMA) are both attractive technique in modern wireless communication. In this paper, we study a multi-user system, which combines OFDM and IDMA, and fortunately, inherits many advantages. In order to improve system performance, low-density parity-check (LDPC) coding is further applied. And moreover, a turbo-type...
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...
Irregular low-density parity-check (LDPC) code design for parallel sub-channels with different qualities is investigated. Such channels appear in many communication systems, e.g., orthogonal frequency-division multiplexing systems. When channel knowledge is available at both the transmitter and receiver, following the literature, we consider allotted LDPC codes which carefully assign different parts...
In wireless OFDM-based systems, coding jointly over all the sub-carriers simultaneously performs better than coding separately per sub-carrier. However, the joint coding is not always optimal. In this paper, we propose a novel coding scheme based on fountain codes, which combines the separate coding and the joint coding over all the sub-carriers. The key element in the new proposed system is that...
In this paper, a new distributed LDPC coder is developed in the cooperative relay networks. Although the proposed scheme requires to use the same bandwidth as the conventional approach over OFDM based transmission, the use of the hybrid ARQ can be reduced. In addition, the overall performance can be improved using the proposed approach.
This paper considers MIMO-OFDM transmission with low density parity check (LDPC) codes. We employ a low complexity minimum mean-square-error (MMSE) soft-interference-cancelation (SIC) based double iterative receiver (DIR). Results are presented for a real system implementation at 5.2 GHz. We achieve zero packet errors at 90% of the measured indoor locations, when transmitting at 600 Mbit/s, with 15...
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;...
Forward error correction (FEC) coding in conjunction with M-ary hyper phase-shift keying (MHPSK) is considered in order to improve the robustness of a high spectral efficiency, non-linear satellite communications link. MHPSK is a spectrally efficient modulation technique that uses four orthonormal basis functions to increase the Euclidean distance between different symbols in the signal space. The...
This paper presents a joint adaptive modulation and coding (AMC) scheme, which exploits the coherence bandwidth of the wireless channel to divide the transmitted frame into independent sub-channels that correspond to the channel coherence bandwidth. This strategy is implemented for orthogonal frequency division multiplexing (OFDM) systems with channel state information (CSI) feedback. Low density...
This paper proposes a novel orthogonal frequency- division multiplexing (OFDM)-based iterative channel estimation and irregular repeat-accumulate (IRA) decoding scheme where the pilot symbols are encoded along with the input data and are used for both channel estimation and decoding. To achieve the objective of minimizing the bit error rate, this paper employs systematic IRA codes so that pilot symbols...
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...
An accurate and simple link quality model is of utmost importance in link adaptation (LA) design. Our previous work in has verified the good accuracy of the mutual information (MI) model for rate compatible (RC) LDPC coded OFDM system. In this paper, the MI model is used to predict the retransmission length T of two hybrid ARQ schemes, partial chase combining (PCC) and incremental redundancy (IR)...
An precise but simple link quality model is crucial to improve the accuracy and flexibility of link adaptation design of LDPC coded OFDM system, because it acts as a link-to-system interface which provides system simulator immediately the BLER performance of a certain modulation and coding scheme corresponding to the current SINR states, which is an instantaneous vector. This contribution extends...
High PAPR of the transmitted signal is a major drawback in the OFDM systems. In this paper, coding schemes are proposed to reduce high PAPR One is using parity check coding scheme, and the other is using selected mapping (SLM) applied scheme. With parity check coding scheme, the parity information is used to expand the signal space. Mapping from original source information to the corresponding message...
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