Abstract
In this paper, a novel interference free dual-hop device-to-device (D2D) aided cooperative relaying strategy (CRS) based on spatial modulation (SM) (termed D2D-CRS-SM) is proposed. In D2D-CRS-SM, two cellular users (e.g., a near user (NU) and a relay-aided far user (FU)) and a pair of D2D transmitter (D)-receivers (D) are served in two time-slots. Two different scenarios are investigated considering information reception criteria at the NU. Irrespective of the scenarios, the base station (BS) exploits SM to map information bits into two sets: modulation bits and antenna index, in phase-1. In the first scenario, the BS maps FU information as the modulation bits and NU information as antenna index, whereas modulation bits correspond to NU information and the antenna index carries FU’s information in scenario-2. The iterative-maximum ratio combining (i-MRC) technique is then used by NU and D to de-map their desired information bits. During phase-2, D also exploits SM to forward FU’s information received from BS and its own information bits to the D2D receiver D. Then, FU and D retrieve their desired information by using i-MRC. Due to exploiting SM in both phases, interference free information reception is possible at each receiving node without allocating any fixed transmit power. The performance of D2D-CRS-SM is studied in terms of bit-error rate and spectral efficiency considering M-ary phase shift keying and quadrature amplitude modulation. Finally, the efficiency of D2D-CRS-SM is demonstrated via the Monte Carlo simulation.
Highlights
As mentioned in the previous section, D1 forwards the signal of far user (FU) during P2, only if the received signal from base station (BS) is correctly estimated during P1, otherwise D1 remains silent during P2
Considering similar antenna configurations at the nodes involved in transmission, it is noticed that BER of NU is lower than other two users (D2 and FU) while BER of FU is higher than others for the transmission of same number of data bits
We observed that NU achieves higher SE performance than other two users (D1 and FU) while SE of FU is lower than others for the transmission of equal number of data bits with a similar antenna configuration at the nodes involved in transmission
Summary
Cellular communication is an essential part of the daily activities of billions of people. The performance of MIMO communications largely depend on antenna spacing of transmission and reception [20,21] It depends on antenna synchronization among the transmit antennas and the interference cancellation techniques used to reduce the inter-channel interference (ICI) at the receiver [22,23]. Unlike MIMO, SM allows only one antenna to transmit at a particular time instant while other antennas remain silent This in turn avoids ICI and interference cancellation techniques are not required at the receiver. SM-MIMO offers reduced receiver complexity [12,13,14,15,16,17,18] Conventional modulation techniques such as M-ary phase shift keying (M-PSK) and M-ary quadrature amplitude modulation (M-QAM) map a certain number of information bits into a symbol. Efficient power control, selection of communication mode, and efficient resource allocation are important issues for interference management in cellular network with D2D communications [30,31]
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