A cluster-head selection and update algorithm for ad hoc networks

A novel cluster-head selection and update algorithm “Type-based Cluster-forming Algorithm (TCA)” is proposed, which outperforms both the lowest node ID (LID) and the Weighted Clustering Algorithm (WCA) in the ad hoc network scenario considered. The system’s performance is investigated in a scenario, when the 50 communicating nodes belong to three different groups, for example, a group of rescue workers, fire-fighters and paramedics. It is demonstrated that the carefully designed protocol is capable of outperforming the above-mentioned benchmarkers both in terms of a reduced number of cluster-head updates and cluster-change events. Hence its quality-of-service may be deemed higher

Noncoherent Multi-Way Relay Based on Fast Frequency-Hopping M-ary Frequency-Shift Keying

Information exchange among a group of users is implemented with the aid of fast frequency-hopping $M$-ary frequency-shift keying multi-way relay (FFH/MFSK MWR). The FFH/MFSK MWR scheme uses two time-slots per symbol for achieving the information exchange, regardless of the number of users involved. During the first time-slot, all the users communicate with a relay based on the FFH/MFSK principles. Then, without recovery of the symbols received, the relay forms a time-frequency (TF) matrix, which is forwarded to all the users during the second time-slot. During the second time-slot, each user receives signals from the relay and, based on which, detects the other users' information. In the FFH/MFSK MWR scheme, both the relay and the users use square-law assisted noncoherent techniques for detection. While the relay uses simple threshold detection, three types of detectors, namely the maximum likelihood multiuser detector (ML-MUD), sub-optimum ML-MUD (SML-MUD) and the majority vote based single-user detector (MV-SUD), are considered for detection at the users. Finally, in this paper, the error performance of the FFH/MFSK MWR systems is investigated by simulations, when assuming communications over Rayleigh fading channels

Performance Analysis of Multihop Wireless Links over Generalized-K Fading Channels

The performance of multihop links is studied in this contribution by both analysis and simulations, when communicating over Generalized-$K$ ($K_G$) fading channels. The performance metrics considered include symbol error rate (SER), outage probability, level crossing rate (LCR) and average outage duration (AOD). First, the expressions for both the SER and outage probability are derived by approximating the probability density function (PDF) of the end-to-end signal-to-noise ratio (SNR) using an equivalent end-to-end PDF. We show that this equivalent end-to-end PDF is accurate for analyzing the outage probability. Then, the second-order statistics of LCR and AOD of multihop links are analyzed. Finally, the performance of multihop links is investigated either by simulations or by evaluation of the expressions derived. Our performance results show that the analytical expressions obtained can be well justified by the simulation results. The studies show that the $K_G$ channel model as well as the expressions derived in this paper are highly efficient for predicting the performance metrics and statistics for design of multihop communication links

Design and analysis of a beacon-less routing protocol for large volume content dissemination in vehicular ad hoc networks

Largevolumecontentdisseminationispursuedbythegrowingnumberofhighquality applications for Vehicular Ad hoc NETworks(VANETs), e.g., the live road surveillance service and the video-based overtaking assistant service. For the highly dynamical vehicular network topology, beacon-less routing protocols have been proven to be efficient in achieving a balance between the system performance and the control overhead. However, to the authors’ best knowledge, the routing design for large volume content has not been well considered in the previous work, which will introduce new challenges, e.g., the enhanced connectivity requirement for a radio link. In this paper, a link Lifetime-aware Beacon-less Routing Protocol (LBRP) is designed for large volume content delivery in VANETs. Each vehicle makes the forwarding decision based on the message header information and its current state, including the speed and position information. A semi-Markov process analytical model is proposed to evaluate the expected delay in constructing one routing path for LBRP. Simulations show that the proposed LBRP scheme outperforms the traditional dissemination protocols in providing a low end-to-end delay. The analytical model is shown to exhibit a good match on the delay estimation with Monte Carlo simulations, as well