In this chapter, we introduce a novel code-based index modulation technique for orthogonal frequency division multiplexing (OFDM), named index modulated OFDM spread spectrum (IM-OFDM-SS), which utilizes the indices of spreading codes to convey information in addition to conventional constellation ...
In this paper, we have proposed a new adaptive modulation scheme for DM-OFDM-IM to enhance the average BER performance and SE according the channel condition. The proposed scheme divides the overall subcarrier into subgroups, and then each subgroup can be modulated by a different modulation schem...
This paper proposes a novel spread spectrum and sub-carrier index modulation (SS-SIM) scheme, which is integrated to orthogonal frequency division multiplexing (OFDM) framework to enhance the diversity over the conventional IM schemes. Particularly, the resulting scheme, called SS-SIM-OFDM, jointly ...
Like SM/GSM, in OFDM-IM only a portion of subcarriers are activated according to their indices, and only those convey M-ary modulated signals [13]. Various authors have modified and improved the basic OFDM-IM scheme. An example is using precoding techniques to improve further the ...