Xizhi An

Towards Power Efficient MAC Protocol for In-Body and On-Body Sensor Networks

This paper presents an empirical discussion on the design and implementation of a power-efficient Medium Access Control (MAC) protocol for in-body and on-body sensor networks. We analyze the performance of a beacon-enabled IEEE 802.15.4, PB-TDMA, and S-MAC protocols for on-body sensor networks. We further present a Traffic Based Wakeup Mechanism that utilizes the traffic patterns of the BAN Nodes (BNs) to accommodate the entire BSN traffic. To enable a logical connection between different BNs working on different frequency bands, a method called Bridging function is proposed. The Bridging function integrates all BNs working on different bands into a complete BSN.

Outage Probability Analysis for Cognitive Radios with Reception Diversity

Outage probability for cognitive radios is investigated in this paper. The scenario under consideration requires the cognitive radio to sense whether the primary user (PU) link is free (or exists a spectrum hole) before making an active transmission using that link. The use of multiple antennas at the cognitive receiver provides array gains at the sensing stage. We derive a closed-form outage probability for cognitive transmissions by classifying them into several cases.

Performance Analysis of Uncompressed Video Streaming over IEEE 802.15.3c MAC Protocol

In this paper, we analyze and evaluate the performance of IEEE 802.15.3c MAC standard, especially for high-definition uncompressed video transmission. At first, the improvements of IEEE 802.15.3c MAC, such as aggregation method and block ACK, are discussed. Then the transmission efficiency concerned with superframe size, channel time allocation, ACK policies, and payload size etc. is analyzed. Simulation results show performance of video streaming over MAC under different conditions. Based on these results, we propose some useful suggestions in order to fully exploit the network capacity and perfectly represent such video application.

Impact of Sleep on PHY-MAC in UWB Networks

Energy conservation is an important issue in wireless networks, especially for self-organized, low power, low data-rate impulse-radio ultra-wideband (IR-UWB) networks, where every node is a battery-driven device. To conserve energy, it is necessary to turn node into sleep state when no data exist. This paper addresses the impact of two kinds of sleeping protocols (slotted and unslotted) on PHY-MAC in UWB networks. We introduce an analytical model for energy consumption of a node and evaluate the performance of the proposed sleeping protocols. Simulation results show that the energy consumption per packet of slotted sleeping is less than that of unslotted one for bursty load case, but with respect to the load access delay unslotted one consumes less energy, that maximize node lifetime

An Energy-efficient Routing Scheme for UWB Sensor Networks

In this paper, an energy-efficient routing scheme for sensor networks based on ultra-wideband (UWB) technique is proposed and evaluated. This scheme makes use of the positioning capability of UWB and takes into account the energy efficiency in the network. By modeling the property of energy consumption, it is found that energy and quality-of-service (QoS) issues are tightly related with route selection. Accordingly, a new routing algorithm is derived to search for energy-efficient routes that can support adequate QoS requirements. The simulation results have proved the advantages of this routing scheme

A new multiple access protocol for time-hopping UWB ad-hoc wireless networks

Ultra-wide bandwidth (UWB) is a prospective radio technology for wireless networks. As being approval by FCC, UWB radio has received much attention. In this paper, we propose a new multiple access protocol for time-hopping UWB ad-hoc network. As UWB system is a carrier-less impulse radio system, it is cumbersome to implement the carrier sensing capability needed in popular approaches such as carrier-sense, multiple access with collision avoidance (CSMA/CA) MAC protocols. The novel multiple access scheme to detect the busy medium and reduce the probability of collisions in TH UWB ad-hoc network is given out and evaluated. In UWB TH modulation, the spreading codes for target node are used. In our scheme, another binary PN sequence according to the destination node is also added to the modulation scheme to sense the busy medium before transmission. Communications outside the definition of directly transmission region (DTR) have to relay over intermediate nodes.

Performance Evaluation of TH-BPPM and TH-BPAM with Private MAC in UWB Ad-hoc Networks

Ultra-wideband (UWB) is a killer technology for short-range wireless communications. In the past, most of the UWB research focused on physical layer but the unique characteristics of UWB make it different to design the upper layer protocols than conventional narrow band systems. Cross-layer protocols have received high attention for UWB networks. In this paper, we investigate the performance of two physical layer schemes: time hopping binary pulse position modulation (TH-BPPM) and time hopping binary pulse amplitude modulation (TH-BPAM) with proposed private MAC protocol for UWB ad-hoc networks. From pulse level to packet level simulation is done in network simulator ns-2 with realistic network environments for varying traffic load, mobility and network density. Our simulation result shows TH-BPAM outperforms TH-BPPM in high traffic load, mobility and dense network cases but in a low traffic load case identical performance is achieved.

Analysis of Energy Consumption and Sleeping Protocols in PHY-MAC for UWB Networks

Energy conservation is an important issue in wireless networks, especially for self-organized, low power, low data-rate impulse-radio ultra-wideband (IR-UWB) networks, where every node is a battery-driven device. To conserve energy, it is necessary to turn node into sleep state when no data exist. This paper addresses the energy consumption analysis of direct-sequence (DS) versus time-hopping (TH) multiple accesses and two kinds of sleeping protocols (slotted and unslotted) in PHY-MAC for UWB networks. We introduce an analytical model for energy consumption of a node in both TH and DS multiple accesses and evaluate the energy consumption comparison between them and also evaluate the performance of the proposed sleeping protocols. Simulation results show that the energy consumption per packet of DS case is less than TH case and for slotted sleeping is less than that of unslotted one for bursty load case, but with respect to the load access delay unslotted one consumes less energy, that maximize node lifetime.

Novel location-aided routing scheme for ultra-wideband ad-hoc networks

In this paper, a novel location-aided routing (LAR) scheme for ultra-wideband (UWB) ad-hoc networks is proposed and evaluated. Our LAR scheme utilizes the positioning capability of UWB systems and takes into account the TCP performance on a route. Based on the estimation of TCP throughput, LAR selects the route that can bear highest throughput. The simulation results show that, as compared with the other routing scheme, LAR can greatly improve the TCP throughput not only on one single connection but also on the whole network.

A Practical Location-aided Energy-aware Routing Method for UWB-based Sensor Networks

In this paper, a practical location-aided routing method for sensor networks based on ultra-wideband (UWB) technique is proposed and evaluated. This method makes use of the positioning function of UWB and takes info account the energy consumption in the network. By modeling the property of energy consumption, we find that energy and quality-of-service (QOS) issues are greatly influenced by the route selected. Accordingly, a new routing algorithm is derived to search for energy-efficient routes that can support adequate QOS requirements. The simulation results have proved the advantages of this routing scheme