OFDM With Index Modulation Assisted by Multiple Amplify-and-Forward Relays

Abstract

A multi-relay assisted orthogonal frequency division multiplexing (OFDM) system with index modulation (OFDM-IM) is proposed in this letter, assuming that amplify-and-forward (AF) relaying protocol is adopted at relays. Two commonly used AF protocols are considered: fixed-gain (FG) AF and variable-gain (VG) AF relaying protocols. To utilize relays in an efficient manner, we also employ two multi-carrier relay selection schemes termed bulk and per-subcarrier (PS) relay selection in the proposed system. We analyze the outage performance of the proposed system and derive closed-form expressions of the average outage probabilities (AOPs) for all cases with different AF relaying protocols and multi-carrier relay selection schemes. In addition, we obtain the asymptotic expressions of AOPs in the high signal-to-noise ratio (SNR) region, by which it is proven that the full diversity gain equaling the number of relays is attainable.

Opportunistic Spectrum Sharing Based on OFDM With Index Modulation

“…where P I refers to the error probability of the SAP detection; ζ = 1 for n = 2, while ζ = 1/2 for n > 2; P sb denotes the BEP of M -ary PSK/QAM demodulation in dualhop AF relaying over Rayleigh fading channels. In (26), the approximation results from the first term on the right-hand side, which describes the BEP for the case where the SAP is detected erroneously. In this case, errors occur in both the IM bits and the constellation bits.…”

“…Finally, substituting (53) and (59) (or (60)) into (26) yields the upper bound on the BER of the PU. Remark 3: Similar to OFDM-IM, in OFDM-IM-CR with ϕ 2 e = 0, the IM bits have higher protection due to second order diversity, while the ordinary modulation bits have only one-diversity-order protection [22].…”

“…In [23], adaptive mapping schemes between IM bits and SAPs are presented for dual-hop OFDM-IM DF relaying networks. To enhance the system reliability, in [24]- [26], multiple relays with relay selection are employed for dual-hop OFDM-IM. In contrast to the dual-hop schemes in [23]- [26], multi-hop DF relaying is developed for OFDM-IM in [27], further enlarging the communication coverage.…”

“…To enhance the system reliability, in [24]- [26], multiple relays with relay selection are employed for dual-hop OFDM-IM. In contrast to the dual-hop schemes in [23]- [26], multi-hop DF relaying is developed for OFDM-IM in [27], further enlarging the communication coverage. In view of two information-carrying units, the potential of OFDM-IM is investigated in overlay OFDM-based CR networks, where the PU transmits classical OFDM signals, and the SU employs OFDM-IM to forward the PU's information via M -ary symbols and convey its own information through SAPs [28].…”

Toward Spectral and Energy Efficient 5G Networks Using Relayed OFDM with Index Modulation

“…To mitigate the disadvantages of cooperative multi-hop structure with relays in series and provide a higher degree of network design flexibility, the cooperative dual-hop structure with T relays in parallel is in use, when the distance between source and destination is moderate [11]- [14]. Another benefit of the cooperative dual-hop structure with relays in parallel is that a variety of RS schemes can be performed to harvest a coding gain and/or even a diversity gain.…”