전력제어기법을 사용한 위치정보 기반의 이중채널 Ad hoc MAC 프로토콜

Abstract

Ad hoc network is a wireless network without fixed base stations or any wired backbone infrastructure. Ad hoc networks are very useful in military and other applications such as disaster and rescue area, home networking, WLAN, group communication, personal area network (PAN) and wireless communication between vehicles in telematics service. Ad hoc medium access control (MAC) protocols using a directional antenna have many benefits. The directional transmission increases a spatial reuse as there can be multiple transmissions in the transmission range without the collision of the transmitted packets. But, directional transmission causes deafness because node in the directional transmission does not hear and respond with RTS from other nodes in the coverage. The ToneDMAC (directional MAC with an out-of-band tone) protocol uses an out-of-band tone to inform the end of directional transmissions to nodes in the coverages of the transmitting and receiving nodes. An out-of-band tone mitigates deafness and improves throughput of ad hoc networks. The DUCHA (dual-channel MAC) protocol is proposed to prevent collisions between control frames and data frames using the separated channels. In the DUCHA protocol, RTS and CTS are transmitted over control channel and DATA is transmitted over data channel. The NCTS (negative CTS) and an out-of-band busy tone are used to prevent collisions of DATA and ACK in data channel. In this thesis, we propose the DUDMAC (dual-channel DMAC) protocol and the ToneDUDMAC (dual-channel DMAC protocol with an out-of-band tone) protocol for wireless communication between vehicles in telematics service. In the DUDMAC protocol, ORTS and OCTS in control channel overcome deafness and DDATA and DACK in data channel improve spatial reuse by using the efficient blocking algorithm for directional antennas. In the ToneDUDMAC protocol, DRTS and DCTS in control channel and DDATA and DACK in data channel improve spatial reuse. An omnidirectional busy tone mitigates deafness when nodes use DRTS and DCTS. Also, we propose the PCDUDMAC (Power Controlled DUDMAC) and PCToneDUDMAC (power controlled ToneDUDMAC) protocols. In the PCDUDMAC and PCToneDUDMAC protocols, the power control of DATA/ACK in data channel reduces interference and saves transmission power. The power controlled DUDMAC and ToneDUDMAC protocols improve spatial reuse by reducing the coverages of DATA/ACK. We confirm the throughput performance of the proposed MAC protocols in a single-hop random topology of 180 nodes and a 5-hop random topology of 60 nodes by using QualNet ver.3.8 simulator. The simulation results show that the DUDMAC protocol improves throughput by 436.5% and 65.2% relative to the DMAC protocol in the 5-hop and a single-hop topology, respectively. The ToneDUDMAC protocol improves throughput by 40.8% and 271.8% relative to the DUDMAC protocol and the ToneDMAC protocol in the 5-hop topology, respectively. In the single-hop topology, the ToneDUDMAC protocol improves throughput by 53.0% and 38.6% relative to the DUDMAC protocol and the ToneDMAC protocol in the 5-hop topology, respectively. The PCDUDMAC protocol and PCToneDUDMAC protocols improve throughput by 4.8% and 8.3% relative to the DUDMAC protocol and the ToneDUDMAC protocol in the single-hop topology, respectively. The PCDUDMAC protocol decreases average energy consumption by 22% relative to the DUDMAC protocol and the PCToneDUDMAC protocol decreases the average energy consumption by 16% relative to the ToneDUDMAC protocol in the single-hop topology.