Transmission Radius Control in Wireless Ad Hoc Networks with Smart Antennas

Abstract

In this paper, we present a model to analyze the performance of three transmission strategies with smart antennas, i.e. directional antennas with adjustable transmission power. Generally, a larger transmission radius contributes a greater progress if a transmission is successful. However, it has a higher probability of collision with other concurrent transmissions. Smart antennas mitigate collisions with sectorized transmission ranges. They also extend the transmission radii. By modelling three transmission strategies, namely, Nearest with Forward Progress (NFP), Most Forward with Fixed Radius (MFR), and Most Forward with Variable Radius (MVR), our analysis illustrates that the use of smart antennas can greatly reduce the possibility of conflicts. The model considers the interference range and computes the interference probability for each transmission strategy. We have analyzed two Medium Access Control (MAC) protocols using our interference model, namely, the slotted ALOHA protocol and the slotted CSMA/CAlike protocol. The result shows that, for slotted ALOHA, NFP yields the best one-hop throughput, whereas MVR provides the best average forward progress. The overall performance is substantially improved with the slotted CSMA/CA-like protocol, and the network becomes more resilient.

Virtual Sensing Directional Hub MAC (VSDH-MAC) Protocol with Power Control

“…Most previous works on the use of directional antennas have assumed the use of idealized antenna patterns where each antenna beam is distinct, with no overlap with adjacent beams and having a constant antenna gain across the beam [7][8][9][10][11][12][13][14][15]. Some work has assumed that the nodes are capable of knowing each other's position [7,[9][10][11] or that nodes have complex, steerable antennas [7,12].…”

“…Some of the protocols proposed also require multiple channels to successfully operate [8,13,16]. Only a few papers within the literature [14,[17][18][19] have considered the energy consumption of the protocol, which is an important factor for low power nodes [20].…”

Adaptive Radar Beamforming for Interference Mitigation in Radar-Wireless Spectrum Sharing

“…and are the time delay and the Doppler shift of the transmitted waveform caused by target scattering, respectively. The transmit steering vector and receive steering vector in the broadside direction are: (5) where is the radar wavelength. Taking into consideration of the initial transmit waveform coding, the modified transmit steering vector is defined as as (6) Since the transmitted waveforms are from all elements, the target signal vector out of the matched filters in Fig.…”

“…In order for collocated radar and wireless systems to be properly operational at the same frequency, both radar and wireless systems need to eliminate interferences from each other through mitigation processing [3]. Among all possible interference mitigation approaches, beamforming via array processing is the only viable option for interference mitigation between two non-cooperative spectrum-sharing systems [4], [5]. Traditionally, receiving beamforming has been used in radar to cancel sidelobe interferences, but is incapable to remove the mainlobe interference due to the fact that target signals are always expected to appear in the mainlobe direction [6], [7].…”

On the Selection of Transmission Range in Underwater Acoustic Sensor Networks

“…This is due to the fact that (i) as pointed out in [8], a transmission power from a sensor node just enough to reach its nearest neighbor in the direction towards the final destination gives the optimal use of energy, and (ii) as shown in [16], NFP yields the highest one-hop throughput. Appropriate adjustments to the derivation based on [17] are made for our study.…”