ALOHA With Collision Resolution(ALOHA-CR): Theory and Software Defined Radio Implementation

A cross-layer scheme, namely ALOHA With Collision Resolution (ALOHA-CR), is proposed for high throughput wireless communications in a cellular scenario. Transmissions occur in a time-slotted ALOHA-type fashion but with an important difference: simultaneous transmissions of two users can be successful. If more than two users transmit in the same slot the collision cannot be resolved and retransmission is required. If only one user transmits, the transmitted packet is recovered with some probability, depending on the state of the channel. If two users transmit the collision is resolved and the packets are recovered by first over-sampling the collision signal and then exploiting independent information about the two users that is contained in the signal polyphase components. The ALOHA-CR throughput is derived under the infinite backlog assumption and also under the assumption of finite backlog. The contention probability is determined under these two assumptions in order to maximize the network throughput and maintain stability. Queuing delay analysis for network users is also conducted. The performance of ALOHA-CR is demonstrated on the Wireless Open Access Research Platform (WARP) test-bed containing five software defined radio nodes. Analysis and test-bed results indicate that ALOHA-CR leads to significant increase in throughput and reduction of service delays

In-package wireless communication with TSV-based antenna

Network-on-Chip (NoC) has been shown to be the most viable alternative to an interconnect bus for the scalability of the system [1]. On-chip antennas, implementing wireless interconnects, are introduced for improved scalability of NoCs in [2]. On-chip wireless links offer improved network performance due to long distance communication, additional bandwidth, and broadcasting capabilities of antennas. The most prominent on-chip antenna designs are the planar logperiodic and meander which have a surface-propagation of the EM waves of the antenna. The main detriment of these antennas, and surface-propagation in general, is the poor signal attenuation (i.e. path loss) even at small distances of 5mm. This work challenges the on-chip antenna design conventions, and pushes toward a Through-Silicon Via (TSV)- based antenna design called TSV_A that establishes wireless communication through the silicon substrate medium with only a 3 dB loss over a 30mm on-chip distance

Experimental characterization of resource allocation algorithms in MIMO-OFDM ad hoc networks

Presented at the 2007 IEEE Radio and Wireless Symposium, Long Beach, CA.There is a great potential for wireless communication systems that use Multiple Input Multiple Output (MIMO) technology. Ad hoc and wireless local area networks (WLANs) have both been the focus of recent research [1], [2]. Of particular interest, are resource allocation algorithms that maximize the capacity of MIMO network links in the face of co-channel interference. MIMO communication platforms allow an additional degree of freedom that can be exploited to reduce the interference experienced by network links [3]. Recent work [3], [4], provides interesting insight into methods that can be used to allocate power appropriately in a network such that the system capacity is improved. The purpose of this paper is to quantitatively evaluate the performance of practical these techniques on a MIMO WLAN testbed and extend them to use OFDM signaling

A 4 by 10 series 60 GHz microstrip array antenna fed by Butler matrix for 5G applications

This paper presents a low-cost, beam-steerable 4 x 10 antenna array system operating at 60 GHz. The proposed antenna system is fed by a 4 x 10 Butler Matrix network designed using microstrip line (ML) structure. Chebyshev tapered microstrip antenna arrays with 10 series-fed elements are connected to four output ports of the feed network. Four steerable beams with maximum 16.5 dBi system gain and 1GHz bandwidth(BW) satisfy the requirements of millimeter wave propagation study and handset application for 5G communication

Design and fabrication of two-port three-beam switched beam antenna array for 60 GHz communication

This article presents a novel, low-cost, beam-switchable $2 \times 10$2x10 antenna array system operating at 60 GHz. This antenna system is constructed of two rows of Chebyshev-tapered microstrip antenna arrays. Each row is a 10 element series-fed array which are fed by a $90 \circ$90 circle coupler. The designed antenna array has only two input ports, but it is capable of generating three switchable beams. This antenna system can spatially scan $90 \circ$90 circle with at least -5 dB normalised gain using only one SPDT switch and a single transceiver. The maximum gain realised by the system was measured as 16.4 dBi and the bandwidth (BW) was >1 GHz. The features of the proposed antenna system make it applicable to do mmWave research such as beamforming algorithms and channel sounding, and to use in handsets for 5G communication

Power Management in MIMO Ad Hoc Networks: A Game-Theoretic Approach

Abstract-This paper considers interference characterization and management in wireless ad hoc networks using MIMO techniques. The power allocation in each link is built into a non-cooperative game where a utility function is identified and maximized. Due to poor channel conditions, some links have very low data transmission rates even though their transmit powers are high. Therefore, a mechanism for shutting down links is proposed in order to reduce cochannel interference and improve energy efficiency. The multiuser water-filling and the gradient projection methods are compared with the proposed game theoretic approach in terms of system capacity and energy efficiency. It is shown that using the proposed method with the link shut-down mechanism allows the MIMO ad hoc network to achieve the highest energy efficiency and the highest system capacity

A computational fluid dynamics approach for optimization of a sensor network

Presented at the 2006 IEEE International Workshop on Measurement Systems for Homeland Security, Contraband Detection and Personal Safety. Alexandria, VA.We optimize the placement of sensors for detecting a nuclear, biological, or chemical (NBC) attack in a dense urban environment. This approach draws from two main areas: (1) computational fluid dynamic (CFD) simulations and (2) sensor placement algorithms. The main objective was to minimize detection time of a NBC sensor network for attacks on a generic urban environment. To this end we conducted simulations in the generic urban environment using thirty-three (33) unique attack locations, thirty-three (33) candidate sensor locations, prevailing wind conditions, and the properties of the chemical agent, chlorine gas. A total of ninety-nine (99) simulated attack scenarios were created (three sets of thirty-three unique attack simulations) and used for optimization. Simulated surrogate agent concentration data were collected at each candidate sensor location as a function of time. The integration of this concentration data with respect to time was used to calculate the ”consumption” of the network and the sensor placement algorithm minimized consumption to the network while minimizing the number of sensors placed. Our results show how a small number of properly placed sensors (eight(8), in our case) provides the best achievable coverage (additional sensors do not help)