A new carrier index differential chaos shift keying (DCSK) modulation method combining index modulation (IM) with multicarrier DCSK (MC-DCSK) is proposed. Two schemes employing two different index selectors and detectors to implement IM and demodulation are introduced. The new designed index selectors are one-to-one mappings between the index symbols and the carrier activation patterns, which can avoid the disaster caused by the previous designed selectors. Analytical bit error rate expressions of the two systems are derived over the additive white Gaussian noise as well as multipath Rayleigh fading channels. Simulation results verify the superiority of one scheme in energy efficiency and another scheme in spectral efficiency, respectively, compared with MC-DCSK.

A carrier index differential chaos shift keying (CI-DCSK) modulation has been proposed to improve BER performance, spectral efficiency (SE) and energy efficiency (EE) compared to traditional DCSK. CI-DCSK employs a one-to-one mapping between the index symbols and the carrier activation patterns, which limits the numbers of both index carriers and index bits. In this letter, a generalized carrier index differential chaos shift keying (GCI-DCSK) modulation is proposed, which extends the aforementioned CI-DCSK by employing the combinatorial method to index selector and index demapper, where the numbers of both index carriers and index bits are arbitrarily adjustable. Theoretical bit error rate (BER) expressions over both additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels are derived. It is shown that GCI-DCSK can flexibly provide red the desired performance, EE, and SE compared to CI-DCSK, commutation code index DCSK (CCI-DCSK) and permutation index DCSK (PI-DCSK). Besides, in some cases, GCI-DCSK can provide higher SE, larger EE and better error performance than multicarrier DCSK (MC-DCSK) with the same bandwidth.

In this paper, two carrier index differential chaos shift keying with simultaneous wireless information and power transfer (CI-DCSK SWIPT) schemes, which integrate carrier index differential chaos shift keying (CI-DCSK) modulation with wireless power transfer, are proposed. In the proposed schemes, based on the transmission characteristics of index modulation (IM), the inactive carriers of CI-DCSK are exploited to delivery energy by transmitting random noise-like signals subjected to normal distribution. By applying time switching (TS) at the receiver, each frame time of the proposed schemes is divided into two intervals. Unlike usual TS-based systems, two intervals of the proposed schemes are related, where energy harvesting and decoding of the modulated bits are both operated in the second interval. Analytical bit error rate (BER) expressions over additive white Gaussian noise (AWGN) and multipath Rayleigh fading channels of the two schemes are derived. The expression for the parameter $\xi$ is also derived, which measures the probability of self-sufficiency of these schemes. The impact of the dividing point of two intervals on BER performance of systems is also analysed and optimized. Since the energy on the inactive carriers is adjustable, the schemes are always self-sustainable in energy supply. To provide the best performance, the ratio of energy on the inactive carriers to that on the active carriers is optimized. Simulation results show that though performances of the proposed schemes are a little worse than CI-DCSK with the same spectral efficiency (SE), the proposed schemes are all self-sustainable.

Conventional routing protocols proposed for Vehicular Ad-hoc Network (VANET) are usually inefficient and vulnerable for multi-hop data forwarding due to the unavailability of global information and inefficiencies in their route discovering schemes. However, with the recently emerged software defined vehicular network (SDVN) technologies, link stability can be better improved through the availability of global network information. Thus, in this paper, we present a novel software-defined network (SDN) based routing scheme for P2P connection under urban inter-vehicle networks that can find a global optimal route between source and destination. This is a cross-layer routing protocol in VANETs, which utilizes metrics not only considering the position and velocity of vehicles, but also channel allocation and link duration when selecting the relay vehicles. Consequently, it starts a route discovery process which can improve the network performance in terms of end-to-end delay and low overhead. Furthermore, packet loss is largely minimized by the relatively stable paths. With the help of realistic simulation, we show that the proposed routing framework performs better than other three latest SDVN and conventional VANET protocols in routing overhead, average end-to-end delay, packet drop ratio, and average throughput. Therefore, our routing scheme is more suitable for 5G-enabled vehicular ad-hoc networks in future.

A lightweight secure communication scheme, i.e., orthogonal frequency division multiplexing with index modulation using artificial noise (OFDM-IM AN), is proposed in this letter, which integrates the artificial noise into OFDMIM to interfere the eavesdropper (Eve) from physical layer. In the proposed scheme, ANs are generated using channel state information (CSI) of legitimate link through a differential way, so the ANs will be eliminated at the legal receiver by the differential demodulation. Since the wiretap channel is independent of the legitimate channel, Eve will be confused by AN and make wrong detection. We derive both the tight upper bound on the bit error rate (BER) and the security rate of the proposed scheme. Simulation results show that though the BER performance of OFDM-IM AN is worse than that of OFDM-IM with the same configuration, the proposed scheme can enhance the security of OFDM-IM with a low complexity.