Self-concatenated code design and its application in power-efficient cooperative communications

In this tutorial, we have focused on the design of binary self-concatenated coding schemes with the help of EXtrinsic Information Transfer (EXIT) charts and Union bound analysis. The design methodology of future iteratively decoded self-concatenated aided cooperative communication schemes is presented. In doing so, we will identify the most important milestones in the area of channel coding, concatenated coding schemes and cooperative communication systems till date and suggest future research directions

Turbo trellis-coded hierarchical modulation assisted decode-and-forward cooperation

Hierarchical modulation, which is also known as layered modulation, has been widely adopted across the telecommunication industry. Its strict backward compatibility with single-layer modems and its low complexity facilitate the seamless upgrading of wireless communication services. The potential employment of hierarchical modulation in cooperative communications has the promise of increasing the achievable throughput at a low power consumption. In this paper, we propose a single-relay aided hierarchical modulation based cooperative communication system. The source employs a pair of Turbo Trellis-Coded Modulation schemes relying on specially designed hierarchical modulation, while the relay invokes the Decode-and-Forward protocol. We have analysed the system’s achievable rate as well as its bit error ratio using Monte-Carlo simulations. The results demonstrate that the power consumption of the entire system is reduced to 3.62 dB per time slot by our scheme

Distributed convolutional-coded differential space-time block coding for cooperative communications

A low complexity distributed coding scheme is proposed for communications over Rayleigh fading channels. Convolutional Coding (CC) assisted Differential Phase-Shift Keying (DPSK) modulation is employed at the source node for conveying the source signals to two relay nodes as well as to the destination node during the first transmission period. Iterative detection exchanging extrinsic information between the DPSK demapper and CC decoder is carried out at each relay node in order to recover the source signals. Then, the CC-encoded bits are re-encoded by the two relays to generate Differential Space-Time Block Coding (DSTBC) symbols for transmission to the destination node during the second transmission period. At the destination node, iterative decoding exchanging extrinsic information is invoked between the DPSK demapper and the concatenated CC-DSTBC decoder, where the later is viewed as a single amalgamated decoder. The relay and destination nodes do not have to estimate the channel’s fading coefficients due to the employment of DPSK and DSTBC schemes. Our design requires only two decoding iterations between the DPSK and CC decoders at each relay in order to further reduce the complexity of the relay nodes. Our distributed coding scheme assisted by two low-complexity relay nodes outperforms the non-cooperative benchmarker scheme by about 8 dBs, when aiming for a bit error ratio of 10-5

Relay-Induced Error Propagation Reduction for Decode-and-Forward Cooperative Communications

An attractive hybrid method of mitigating the effects of error propagation that may be imposed by the relay node (RN) on the destination node (DN) is proposed. We selected the most appropriate relay location for achieving a specific target Bit Error Ratio (BER) at the relay and signalled the RN-BER to the DN. The knowledge of this BER was then exploited by the decoder at the destination. Our simulation results show that when the BER at the RN is low, we do not have to activate the RN-BER aided decoder at the DN. However, when the RN-BER is high, significant system performance improvements may be achieved by activating the proposed RN-BER based decoding technique at the DN. For example, a power-reduction of up to about 19dB was recorded at a DN BER of 10-4

Design guidelines for spatial modulation

A new class of low-complexity, yet energyefficient Multiple-Input Multiple-Output (MIMO) transmission techniques, namely the family of Spatial Modulation (SM) aided MIMOs (SM-MIMO) has emerged. These systems are capable of exploiting the spatial dimensions (i.e. the antenna indices) as an additional dimension invoked for transmitting information, apart from the traditional Amplitude and Phase Modulation (APM). SM is capable of efficiently operating in diverse MIMO configurations in the context of future communication systems. It constitutes a promising transmission candidate for large-scale MIMO design and for the indoor optical wireless communication whilst relying on a single-Radio Frequency (RF) chain. Moreover, SM may also be viewed as an entirely new hybrid modulation scheme, which is still in its infancy. This paper aims for providing a general survey of the SM design framework as well as of its intrinsic limits. In particular, we focus our attention on the associated transceiver design, on spatial constellation optimization, on link adaptation techniques, on distributed/ cooperative protocol design issues, and on their meritorious variants

Superposition Coding Aided Bi-directional Relay Transmission Employing Iteratively Decoded Self-Concatenated Convolutional Codes

In this paper, we consider coding schemes designed for two nodes communicating with each other with the aid of a relay node, which receives information from the two nodes in the first time slot. At the relay node we combine a powerful Superposition Coding (SPC) scheme with Iteratively Decoded Self-Concatenated Convolutional Codes (SECCC-ID), which exchange mutual information between each other. It is assumed that decoding errors may be encountered at the relay node. The relay node then broadcasts this information in the second time slot after re-encoding it, again, using a SECCC encoder. At the destination, an amalgamated SPC-SECCC block then detects and decodes the signal either with or without the aid of a priori information. Our simulation results demonstrate that the proposed scheme is capable of reliably operating at a low BER for transmission over both AWGN and uncorrelated Rayleigh fading channels. We compare the proposed scheme’s performance to a direct transmission link between the two sources having the same throughput. Additionally, the SPC-SECCC system achieves a low BER even for realistic error-infested relaying

Network Coded Modulation for Two Way Relay Networks

Modern wireless networks use cooperative relaying to expand its coverage area. Wireless relaying allows mobile terminals toparticipate in transmission even when these terminals are not being the initial source or final destination. This can be achieved in differentways ranging from simple conventional relaying to more sophisticated coding at terminal and relay nodes to improve transmissionperformance. The proposed work here studied such system by simulating different coding techniques to be used in two way relay networkcoding (TWRC). Some of these techniques were previously proposed to improve transmission performance in conventional datacommunication systems. BER performance of different arrangements of coding and relaying schemes are evaluated using computersimulation tests. Ideal AWGN channel model and standard wireless channel models for wireless networks are considered in the simulationtests. The results have been shown that coding schemes such as Trellis Coded Modulation (TCM) and Repeat Accumulate (RA) codes aremore suitable in two way relaying networks. Over AWGN, TCM-8PSK improves BER performance by at least 2 dB at high SNR fordifferent relaying arrangements. For fading channels, this advantage is slightly reduced. Regenerative repeating at relay node seems to be apromising arrangement. It seems that there is no sense in using RA codes over fading channels due to its poor performance and relativelylower speed caused by repetitions

Soft information based protocols in network coded relay networks

Future wireless networks aim at providing higher quality of service (QoS) to mobile users. The emergence of relay technologies has shed light on new methodologies through which the system capacity can be dramatically increased with low deployment cost. In this thesis, novel relay technologies have been proposed in two practical scenarios: wireless sensor networks (WSN) and cellular networks. In practical WSN designs, energy conservation is the single most important requirement. This thesis draws attention to a multiple access relay channels model in the WSN. The network coded symbol for the received signals from correlated sources has been derived; the network coded symbol vector is then converted into a sparse vector, after which a compressive sensing (CS) technique is applied over the sparse signals. A theoretical proof analysis is derived regarding the reliability of the network coded symbol formed in the proposed protocol. The proposed protocol results in a better bit error rate (BER) performance in comparison to the direct implementation of CS on the EF protocol. Simulation results validate our analyses. Another hot topic is the application of relay technologies to the cellular networks. In this thesis, a practical two-way transmission scheme is proposed based on the EF protocol and the network coding technique. A trellis coded quantization/modulation (TCQ/M) scheme is used in the network coding process. The soft network coded symbols are quantized into only one bit thus requiring the same transmission bandwidth as the simplest decode-and-forward protocol. The probability density function of the network coded symbol is derived to help to form the quantization codebook for the TCQ. Simulations show that the proposed soft forwarding protocol can achieve full diversity with only a transmission rate of 1, and its BER performance is equivalent to that of an unquantized EF protocol