Abstract
A novel transmission scheme is introduced for efficient data transmission by conveying additional information bits through jointly changing the index and number of active subcarriers within each orthogonal frequency division multiplexing (OFDM) subblock. The proposed scheme is different from the conventional OFDM-subcarrier number modulation (OFDM-SNM) and OFDM-index modulation (OFDM-IM), in which data bits are transmitted using either number or index of active subcarriers. The proposed modulation technique offers superior spectral and energy efficiency compared to its counterparts OFDM-SNM and OFDM-IM, especially at low modulation orders such as binary phase shift keying (BPSK) that can provide high reliability and low complexity, making it suitable for Internet of Things (IoT) applications that require better spectral and energy efficiency while enjoying high reliability and low complexity. Bit error rate (BER) performance analysis is provided for the proposed scheme, and Monte Carlo simulations are presented to prove the consistency of simulated BER with the analyzed one.
Highlights
5G envisions supporting a wide variety of use cases and related requirements [1], [2]
We focus on the basic idea and system model of the proposed orthogonal frequency division multiplexing (OFDM)-HNIM, whereas employing the novel design in [28] to the proposed scheme could be considered as a future work for improving the OFDM-HNIM system
We assume that the number of allowed active subcarriers of the OFDM-GIM is one, two, or three out of four available subcarriers in each subblock [21]
Summary
It should be noted that there would be similar SAP when g = 13, 14, 15, 16 as expected from their SNM mapping, due to setting a fixed length of p2 data code To solve this ambiguity in mapping, extra bits could be transmitted to a receiver to differentiate between these exceptional cases. To avoid ambiguity and extra bits signaling at the ML detector as well as satisfying the equiprobable subcarrier activation (ESA) requirement [26], the aforementioned exceptional cases are assigned unique SAPs where their corresponding I (g) values are mostly different from their expected SNM mapping. The bits conveyed by the index and number of activated subcarriers for each subblock are estimated based on the obtained SAP using the hybrid demapper. PERFORMANCE EVALUATION OF THE PROPOSED HYBRID SCHEME Here, the evaluation of the hybrid system performance is performed based on key metrics such as spectral efficiency, average bit error probability, energy efficiency, and computational complexity
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