Spatially Coupled Protograph-Based LDPC Codes for Decode-and-Forward in Erasure Relay Channel

In this work, we present a framework analysis of a millimeter wave (mmWave) vehicular communications systems. Communications between vehicles take place through a cooperative relay which acts as an intermediary base station (BS). The relay is equipped with multiple transmit and receive antennas and it employs decode-and-forward (DF) to process the signal. Also, the relay applies maximal ratio combining (MRC), and maximal ratio transmission (MRT), respectively, to receive and forward the signal.As the vehicles' speeds are relative high, the channel experiences a fast fading and this time variation is modeled following the Jake's autocorrelation model. We also assume narrowband fading channel. Closed-form expressions of the reliability metrics such as the outage probability and the mean rate are derived. Capitalizing on these performances, we derive the high signal-to-noise-ratio (SNR) asymptotes to get full insights into the system gains such as the diversity and coding gains.

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AWGN and Rayleigh Fading Behavior of the Wireless Decode-and-Forward Relay Channel with Arbitrary Time and Power Allocation

Indonesian Journal of Electrical Engineering and Computer Science ◽

10.11591/ijeecs.v10.i1.pp248-257 ◽

2018 ◽

Vol 10 (1) ◽

pp. 248

Author(s):

Muhammad Zarol Fitri Khairol Fauz ◽

Elsheikh Mohamed Ahmed Elsheikh

Keyword(s):

Mutual Information ◽

Power Allocation ◽

Fading Channels ◽

Time Allocation ◽

Rayleigh Fading ◽

Cellular Systems ◽

Base Stations ◽

Relay Channel ◽

Decode And Forward ◽

Half Duplex

Relying has in use for decades to tackle some of the challenges of wireless communication such as extending transmitting distance, transmitting over rough terrains. Diversity achieved through relaying is also a means to combat the random behavior of fading channels. In this work, effect of time and power allocation on relay performance is studied. The channel considered is the three-node channel with half-duplex constraint on the relay. The relaying technique assumed is decode-and-forward. Mutual information is used as the criteria to measure channel performance. There is half-duplex constraint and a total transmission power constraint on the relay source node and the relay node. A model is established to analyze the mutual information as a function of time allocation and power allocation in the case of AWGN regime. The model is extended to the Rayleigh fading scenario. In both AWGN and Rayleigh fading, results showed that the importance of relaying is more apparent when more resources are allocated to the relay. It was also shown that quality of the source to destination link has direct impact on the decision to relay or not to relay. Relatively good source to destination channel makes relaying less useful. The opposite is true for the other two links, namely the source to relay channel and the relay to destination channel. When these two channels are good, relaying becomes advantageous. When applied to cellular systems, we concluded that relaying is more beneficial to battery-operated mobile nodes than to base stations.

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Energy Efficiency of a Decode-and-Forward Multiple-Relay Network with Rate Adaptive LDPC Codes

Sensors ◽

10.3390/s19214793 ◽

2019 ◽

Vol 19 (21) ◽

pp. 4793 ◽

Cited By ~ 2

Author(s):

Bushra Bashir Chaoudhry ◽

Syed Ali Hassan ◽

Joachim Speidel ◽

Haejoon Jung

Keyword(s):

Energy Efficiency ◽

Channel Coding ◽

Forward Error Correction ◽

Ldpc Codes ◽

Maximum Energy ◽

Cooperative Transmission ◽

Relay Network ◽

Decode And Forward ◽

Forward Error ◽

Multiple Relay

This paper presents cooperative transmission (CT), where multiple relays are used to achieve array and diversity gains, as an enabling technology for Internet of Things (IoT) networks with hardware-limited devices. We investigate a channel coding aided decode-and-forward (DF) relaying network, considering a two-hop multiple-relay network, where the data transmission between the source and the destination is realized with the help of DF relays. Low density parity check (LDPC) codes are adopted as forward error correction (FEC) codes to encode and decode the data both at the source and relays. We consider both fixed and variable code rates depending upon the quality-of-service (QoS) provisioning such as spectral efficiency and maximum energy efficiency. Furthermore, an optimal power allocation scheme is studied for the cooperative system under the energy efficiency constraint. We present the simulation results of our proposed scheme, compared with conventional methods, which show that if decoupled code rates are used on both hops then a trade-off has to be maintained between system complexity, transmission delay, and bit error rate (BER).

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