The density of radio access points in currently deployed cellular networks increases in order to improve the reuse of available resources and to serve more user terminals at high data rates. This implies higher deployment costs, which demands low-cost and flexible alternatives. However, this ambitious goal cannot be accomplished with conventional cellular systems but requires new technologies s...

With the advent of 5G and need for energy-efficient massively connected wireless networks, in this work, we consider an energy harvesting (EH) based multi-relay downlink cooperative non-orthogonal multiple access (NOMA) system with practical constraints. The base station serves NOMA users help decode-and-forward EH relays, where relays harvest from station's radio frequency. A relay is selected...

In recent years, there has been considerable interest in the use of CDMA in mobile communications. Bit error rate is one of the most important parameters in the evaluation of CDMA systems. In this paper, we develop a technique to find an accurate approximation to the probability of bit error for asynchronous direct–sequence code division multiple–access (DS/CDMA) systems by modeling the multipl...

The employment of the network coding (NC) combined with distributed FEC, in cooperative transmission schemes leads to a more efficient use of the additional time-frequency resources required by cooperation, i.e. by allowing a single relay node to serve two or more user terminals (Multiple Access Relay Channel). This paper proposes a low complexity cooperation algorithm which employs network and...

This paper proposes cooperative coding using an interference cancellation technique to improve the performance of the PB/MC-CDMA system. The cooperation of multiple relay nodes which help to advance the source signal are considered to be the multiple transmit antennas within this system. However, if errors occur at relay nodes due to the frequency selective fading channel, then error propagatio...

Abstract— In this paper, we propose a direct/cooperative amplify-and-forward relay (D/AR) switching using a spectrum division/adaptive subcarrier allocation (SDASA) for increasing the uplink capacity of single carrier-frequency division multiple access (SC-FDMA). In the D/AR switching, switching between direct communication and cooperative AF relay is done so that the channel capacity is maximi...

In a relay channel, between the sender X and the the receiver Y lies at least one relay. Generally, the relay can both transmit its own information and help forwarding other sources’ information. This summary considers the latter case, i.e., the relay intends solely to help the receiver. The relay and the transmitter cooperate to resolve the receiver’s uncertainty. Due to the presence of relay,...

For the high end-to-end channel capacity, the amplify-and-forward scheme multiple-hop MIMO relays system is considered. The distance between each transceiver is optimized to prevent some relays from being the bottleneck and guarantee the high end-to-end channel capacity. However, in some cases, the location of relays can’t be set at the desired location, the transmit power of each relay should ...

We propose novel cooperative protocols for various coherent flat-fading channels composed of half-duplex nodes. We consider relay, cooperative broadcast (CB), multiple-access relay (MAR) and cooperative multiple-access (CMA) channels and devise efficient protocols for them. We also present automatic repeat request (ARQ) variants of these protocols. We evaluate the proposed protocols using the d...

User cooperation is a communication strategy where transmitting users share their resources to help each others’ transmission for reliable delivery of their message at destination. Multiple-access-channel with Dedicated-relay (MAC-DR) is a MAC channel, where there are more than one transmitters, single receiver, and a fixed or dedicated node which act as a relay for transmitting users. In this ...