Yen-Da Chen

CAPC: a collision avoidance power control MAC protocol for wireless ad hoc networks

The letter identifies a power control induced hidden terminal problem, named POINT problem, and proposes a collision avoidance power control (CAPC) MAC protocol to solve the POINT problem for wireless ad hoc networks. CAPC takes the interference range into consideration and uses the appropriate power to exchange Data/ACK, instead of the exact power in order to resist the interference of other stations. Simulation results verify that CAPC can effectively prevent the POINT problem.

A Distributed Active Sensor Selection Scheme for Wireless Sensor Networks

The paper proposes a distributed active sensor selection scheme, named DASS, for WSNs, under the requirement of complete coverage of a sensing field. By means of Voronoi diagram, the sensor can find appropriate sensors to work together for the sensing tasks. DASS can find as few number of sensors as possible to be in charge of the sensing task. Simulation results show that DASS can efficiently select few sensors to cover the whole sensing field. Furthermore, the network lifetime can be protracted significantly in comparison with the state-of-the-art schemes.

Dynamic bandwidth allocation for QoS routing on TDMA-based mobile ad hoc networks

The paper proposes several dynamic bandwidth allocation strategies for QoS routing on TDMA-based mobile ad hoc networks. Comprehensively, these strategies are called a distributed slots reservation protocol (DSRP). In DSRP, QoS routing only depends on one-hop neighboring information of each mobile host (MH). In addition, slot inhibited policies (SIPs) and slot decision policies (SDPs) are proposed to determine which slots are valid to use and which slots in the valid slots can be used actually, respectively. In SDPs, three heuristic policies, 3BDP, LCFP, and MRFP, are proposed to increase the success rate of a QoS route and alleviate the slot shortage problems. Moreover, a slot adjustment protocol (SAP) is proposed for a conflicting MH to coordinate the slot usage of its neighbors during the route reservation phase in order to accommodate more routes in the network. The slot adjustment algorithm (SAA) invoked in SAP is a branch-and-bound algorithm, which is an optimum algorithm in terms of the number of slots to be adjusted, on the premise that not to break down any existing route. QoS route maintenance and improvement are also provided. By the simulation results, the proposed protocol cannot only increase the success rate in search of a route with bandwidth requirement guaranteed but also raise the throughput and efficiency of the network.

A Physical/Virtual Carrier-Sense-Based Power Control MAC Protocol for Collision Avoidance in Wireless Ad Hoc Networks

A kind of hidden terminal problem, called the POINT problem, which is caused by the expansion of the interference range of the receiver due to the controlled transmission power of the sender, is deemed a notorious problem in wireless ad hoc networks. This paper utilizes physical and virtual carrier-sensing schemes to avoid the POINT problem. We analyze the relationships among the transmission range, the carrier-sensing range, and the interference range in case power control is adopted, and based on the analyzed results, we propose four mechanisms to prevent the POINT problem from occurring in wireless ad hoc networks. This paper further analyzes the superiority of each mechanism under certain situations and proposes an adaptive range-based power control (ARPC) MAC protocol to make use of the advantages of the four mechanisms to avoid the POINT problem from happening. The proposed protocol cannot only prevent collisions caused by the POINT problem, but it can also reduce the energy consumption of STAs. Simulation results also verify the advantages of the proposed protocol.

A distributed slots reservation protocol for QoS routing on TDMA-based mobile ad hoc networks

The paper presents a distributed slots reservation protocol (DSRP) for QoS routing on TDMA-based mobile ad hoc networks. According to one-hop neighboring information, slot decision policy (SDP) is proposed to select the time slots in order to construct a route satisfying the QoS requirement. The hidden-terminal and exposed-terminal problems are solved as well. In addition, a slot adjustment mechanism is proposed to adjust the slots in a mobile host if a slot conflict occurs in the reservation period. Route maintenance is also provided to maintain a route when the network topology is changed. By the simulation results, the proposed protocol can not only increase the search of a route with bandwidth requirement guaranteed but also raise the throughput and efficiency of the network.

Adaptive Range-Based Power Control for Collision Avoidance in Wireless Ad Hoc Networks

The paper analyzes the relationships among the transmission range, carrier sensing range, and interference range in case that power control is adopted and proposes an adaptive range-based power control (ARPC) MAC protocol for wireless ad hoc networks to avoid collisions. Based on the analysis results, four mechanisms, STRC, RTRC, SCRC, and RCRC are proposed to prevent from collisions. The paper further analyzes the superiority of each mechanism under certain situations and proposes the ARPC MAC protocol to make use of the advantages of the four mechanisms to avoid collisions. The proposed protocol can not only reduce energy consumption of STAs, but also prevent from collisions. Simulation results also verify the advantages of the proposed protocol.

A Collision Avoidance Multi-channel MAC Protocol with Physical Carrier Sensing for Mobile Ad Hoc Networks

Carrier sensing mechanism has been adopted in IEEE 802.11 MAC for collision avoidance under single channel based wireless ad hoc networks. However, due to the hardware limitation, the carrier sensing mechanism can not help much in single transceiver and multi-channel scenarios. In this paper, we propose a pipelining multi-channel (pi-Mc) MAC protocol for multi-channel ad hoc networks. The core idea of pi-Mc is similar to the pipeline technique. Without collecting each channel usage information, pi-Mc not only uses overall channel resources for transmission, but also can prevent DATA collisions. The performance of pi-Mc is compared with two well-known multi-channel MAC protocols and IEEE 802.11 DCF. Simulation results show that pi-Mc is able to achieve 2.50 times the throughput of IEEE 802.11 DCF, as well as respectively outperform DCA and MMAC with a factor of up to 1.43 and 1.32 under three available channels.

Preserving Target Area Coverage in Wireless Sensor Networks by Using Computational Geometry

The activity scheduling of sensors to alternately wake up for sensing obligation such that the network lifetime can be efficiently prolonged is a very important issue in wireless sensor networks (WSNs). Target area coverage is a new coverage problem in wireless sensor networks. The paper addresses the target area coverage problem and schedules sensors to alternatively wake up to collaboratively cover and sense the target area. A geometric-based activity scheduling scheme, named GAS scheme, for WSNs to fully cover a target area is proposed. By means of computational geometry, the sensors can self-determine when to sleep or wake up while preserving the sensing coverage. GAS is able to find as few sensors as possible to cover the target area, which is termed a cover set. In addition, GAS can find as many number of cover sets as possible to be alternately in charge of the sensing task. Simulation results show that GAS can efficiently schedule the sensor when to switch between active and sleep modes. Furthermore, the network lifetime can be prolonged significantly in comparison with the state-of-the-art schemes.

CS-MAC: A Channel Stealing MAC protocol for improving bandwidth utilization in underwater wireless acoustic networks

Due to the nature of water, instead of radio wave, sound wave is used for transmission in underwater wireless acoustic networks (UWANs). Based on the analysis of this paper, comparison to the performance in wireless ad hoc networks, hidden terminal problem and exposed terminal problem have a higher impact on that in UWANs. In this paper, a Channel Stealing MAC (CS-MAC) protocol is proposed not only to prevent hidden terminal problem but also to mitigate exposed terminal problem in UWANs. Some geometry theorems are provided for node to increase channel utilization in CS-MAC. Performance is evaluated by ns-2, and simulation results also verify that CS-MAC outperforms in channel utilization and transmission delay.

A channel-aware depth-adaptive routing protocol for underwater acoustic sensor networks

In underwater acoustic networks, a transmission is done by means of acoustic wave. However, acoustic transmissions suffer long propagation delay and high bit error rate, especially for real time applications. Since speed of sound and underwater noises are varied with water depth, therefore, this paper takes sound speed and underwater noises into account and proposes a channel-aware depth-adaptive routing protocol, named CDRP, for underwater acoustic sensor networks to relief propagation delay and transmission error rate. In CDRP, the source constructs a virtual ideal path to the sink while it has data to send. According to its one-hop neighbor information, the source then chooses one or several proper forwarders to relay the data. Likewise, the forwarders select next forwarders in the same way until the data is sent to the sink. To our best knowledge, CDRP is the first routing protocol considering the effects of underwater noise and sound speed with depth variation. The simulation results show that CDRP has better performance in end-to-end delay and packet delivery ratio.