The reliability, scalability, and stability of routing schemes are open challenges in highly evolving vehicular ad hoc networks (VANETs). Cluster-based routing is an efficient solution to cope with the dynamic and inconsistent structure of VANETs. In this paper, we propose a cluster-based routing scheme (hereinafter referred to as connectivity-based clustering), where link connectivity is used as a metric for cluster formation and cluster head (CH) selection. Link connectivity is a function of vehicle density and transmission range in the proposed connectivity-based clustering scheme. Moreover, we used a heuristic approach of spectral clustering for the optimal number of cluster formation. Lastly, an appropriate vehicle is selected as a CH based on the maximum Eigen-centrality score. The simulation results show that the suggested connectivity-based clustering scheme performs well in the optimal number of cluster selections, strongly connected (STC) route selection, and route request messages (RRMs) in the discovery of a particular path to the destination. Thus, we conclude that link connectivity and the heuristic approach of spectral clustering are valuable additions to existing routing schemes for high evolving networks.

In this paper, we investigate the user fairness power allocation (PA) for video transmission in a non-orthogonal multiple access (NOMA)-assisted wireless system with a pair of users. Considering that video transmission is usually delay-sensitive, the video quality can be adaptively adjusted based on the network conditions. First, a new performance metric, called the average video quality degradation probability, is proposed to describe the adaptive video quality. Then, based on the principles of NOMA and user queue model, the average video quality degradation probability of both users is derived. Next, a bisection search based power allocation (PA) algorithm is proposed to balance the video quality between the NOMA pair. Simulation results demonstrate that the proposed NOMA scheme is more effective to achieve the user fairness compared with the fixed NOMA scheme, the fractional transmit power allocation (FTPA) based NOMA scheme, the achievable rate fairness (ARF) NOMA scheme, and the optimized time division multiple access (TDMA) scheme.

In the interference-limited communication scenarios, the interference impairs the data transmission and further degrades the delay performance. In this letter, the stochastic delay guarantee for a wireless dual-hop network with an interference-limited relay is investigated. Considering the randomness of wireless fading in both data links and interference links, the stochastic service process provided by the network is characterized in terms of the moment generation function (MGF). Due to the stochastic service process, the delay should be a random variable (RV). The delay-outage probability is defined as the probability that the actual transmission delay exceeds a threshold value. To evaluate the stochastic delay guarantee, we derive an upper bound on the minimum acceptable delay threshold and a lower bound on the maximum supportable transmitted data size with the constraint of the delay-outage probability, respectively. Simulation results show that the bounds obtained by the theoretical analysis are reasonably tight and well reflect the effect of the interference on the stochastic delay guarantee.