Energy-Efficient Dynamic Directional Modulation With Electrically Small Antennas

Abstract

This letter proposes a compact and energy efficient Directional Modulation (DM) scheme for small and power constrained devices (e.g. Internet of Things wireless sensors). The scheme uses a uniform circular array of monopole antennas, with a single radiofrequency (RF) chain and antenna active at a time. The antennas can be located in close proximity, offering significant size reduction. Furthermore, the scheme was demonstrated to operate successfully with an array of 0.6  diameter. The system does not generate additional artificial noise, limiting interference to other systems. Finally, the antenna switching sequence can be randomly generated and without finetuned synchronization with the transmitter.

Energy-Efficient Physical Layer Security for Wearable IoT Devices

“…The scheme relies on switches in a multiport antenna structure, requiring only a single active port for transmission. It then uses phase compensations dependent on the desired secure direction of the legitimate user, and a random number n corresponding to the antenna port used for signal transmission (see [15] for a detailed discussion of the scheme). The method then offers several advantages compared to [11], [12], e.g.…”

“…Single port DM implementations using time-modulated arrays are proposed in [13], [14]; however, these methods are still demanding for wearable IoT implementation due to switch synchronization (which requires more computational power), and larger space for antenna packaging. In our previous work [15], we propose a single-port DM method relying on switches but without the need for any specific sequence, i.e. the switching can be controlled by a fully random mechanism, independent from the transceiver.…”

Directional Modulation for Enhanced Privacy in Smart Watch Devices

“…Other contributions in the field are presented e.g. in [15]- [31], phased arrays are used in [15]; switched antenna arrays are discussed in [16]- [18]; multi-user MIMO DM systems are studied in [19], [21], [23]; time-modulated arrays are investigated in [20] and [26]; hybrid MIMO phased arrays are studied for mm-Wave communication systems in [25]; and dynamic multi-beam DM using random changes of the artificial noise vector at the symbol rate is proposed in [22].…”

“…While the above methods present significant breakthroughs, their implementation for small IoT devices is not feasible due to the higher computational demands and the requirement of sophisticated switching sequences with careful synchronization. In our recent work [31], we propose a simple single active RF-chain DM scheme, where the switching sequence can be fully random and independent of the direction of the LU. Nevertheless, the implementation uses a 5-element array, which is still a large diameter and profile for smart watch device packaging.…”

Directional polarization modulation method based on time-modulated vector array

“…Conventional phased arrays use the suppression of the sidelobe level and formation of zero trap in the interference direction to achieve information transmission, but the effective information of signals in different directions is essentially the same. As an effective means of physical layer encryption, directional modulation [1][2][3][4][5] can achieve the desired direction transmits the correct communication signal and the signal in the non-desired direction is distorted irregularly. The transmitted signal is direction-dependent, which effectively prevents eavesdroppers in the non-desired direction from intercepting the communication signal.…”