With the commencement of the 5 ^th generation (5G) of wireless networks, researchers around the globe have started paying their attention to the imminent challenges that may emerge in the beyond 5G (B5G) era. Various revolutionary technologies and innovative services are offered in 5G networks, which, along with many principal advantages, are anticipated to bring a boom in the number of connected wireless devices and the types of use-cases that may cause the scarcity of network resources. These challenges partly emerged with the advent of massive machine-type communications (mMTC) services, require extensive research innovations to sustain the evolution towards enhanced-mMTC (e-mMTC) with the scalable network cost in 6 ^th generation (6G) wireless networks. Towards delivering the anticipated massive connectivity requirements with optimal energy and spectral efficiency besides low hardware cost, this paper presents an enabling framework for 6G networks, which utilizes two emerging technologies, namely, non-coherent communications and backscatter communications (BsC). Recognizing the coherence between these technologies for their joint potential of delivering e-mMTC services in the B5G era, a comprehensive review of their state-of-the-art is conducted. The joint scope of non-coherent and BsC with other emerging 6G technologies is also identified, where the reviewed technologies include unmanned aerial vehicles (UAVs)-assisted communications, visible light communications (VLC), quantum-assisted communications, reconfigurable large intelligent surfaces (RLIS), non-orthogonal multiple access (NOMA), and machine learning (ML)-aided intelligent networks. Subsequently, the scope of these enabling technologies for different device types (e.g., UAVs, body implants, etc), service types (e.g., e-mMTC), and optimization parameters (e.g., spectrum, energy, cost) is analyzed. Finally, in the context of the proposed non-coherent and BsCs based framework for e-mMTCs, some promising future research directions and open research challenges are highlighted.

This paper proposes Single Carrier-FDMA radar, which is not only a solution to the shortcomings of OFDM radars but also offers improved Ambiguity Function and autocorrelation properties. Unlike OFDM, the proposed SC-FDMA radar (with interleaved subcarrier mapping) does not suffer from high peak to average power ratio (PAPR) issue and hence does not affect the efficiency of the transmitter’s power amplifier. SC-FDMA utilizes all the benefits of single-carrier modulation, orthogonal frequency division multiplexing and frequency domain equalization. The wideband characteristics of SC-FDMA are beneficial in achieving high range resolution for radar applications. The paper presents a complete architecture of SC-FDMA radar with interleaved subcarrier mapping. The proposed radar system is analyzed for its ambiguity function, auto-correlation properties, and PAPR. The performance of the proposed radar waveform is compared with those of the notable existing radar waveforms including a standard OFDM radar, CAN, Hadamard, and PWCIA. It is observed from the comparative analysis, that the proposed scheme outperforms OFDM and the other notable waveforms. The proposed work can be extended to develop multiple tasking radars as the different source signals can correspond to independent tasks to be performed simultaneously.

In Wireless Sensor Network (WSN), the nodes have limitations in terms of energy-constraint, unreliable links, and frequent topology change. In this paper we propose an energy-aware routing protocol, that outperforms the existing ones with an enhanced network lifetime and more reliable data delivery. Major issues in the design of a routing strategy in wireless sensor networks are to make efficient use of energy and to increase reliability in data delivery. The proposed approach reduces both energy consumption and communication-bandwidth requirements and prolongs the lifetime of the wireless sensor network. Using both analysis and extensive simulations, we show that the proposed dynamic routing helps achieve the desired system performance under dynamically changing network conditions. The proposed algorithm is compared with one of the best existing routing algorithms, GRAB. Moreover, a modification in GRAB is proposed which not only improves its performance but also prolongs its lifetime.

Security is always a major concern in wireless sensor networks (WSNs). Identity based attacks such as spoofing and sybil not only compromise the network but also slow down its performance. This paper proposes a low complexity sybil attack detection scheme, that is, based on signed response (SRES) authentication mechanism developed for Global System for Mobile (GSM) communications. A probabilistic model is presented which analyzes the proposed authentication mechanism for its probability of sybil attack. The paper also presents a simulation based comparative analysis of the existing sybil attack schemes with respect to the proposed scheme. It is observed that the proposed sybil detection scheme exhibits lesser computational cost and power consumption as compared to the existing schemes for the same sybil detection performance.