运用跨层设计思想和方法研究了超宽带(UWB)无线自组织(Ad hoc)网络媒体访问控制(MAC)层协议的设计,提出了一种可利用 UWB 技术定位性好的优势和实现跨层协作的 MAC 层协议。该协议通过物理层、MAC 层和网络层之间的跨层协作来解决自组...运用跨层设计思想和方法研究了超宽带(UWB)无线自组织(Ad hoc)网络媒体访问控制(MAC)层协议的设计,提出了一种可利用 UWB 技术定位性好的优势和实现跨层协作的 MAC 层协议。该协议通过物理层、MAC 层和网络层之间的跨层协作来解决自组织网络单信道无线传输过程中的隐藏终端和暴露终端问题以及网络能量节约问题,以提高网络的性能。仿真实验表明,该协议在平均吞吐量、平均端到端时延以及能量开销等性能指标上,均优于已有的 IEEE802.11和 MACA-BI MAC 协议。该协议的设计思想和方法为下一步的 UWB 无线 Ad hoc 网络研究奠定了理论和实验基础。展开更多
In Wireless Sensor Networks(WSNs),polling can obviously improve the throughput and decrease average access delay by allocating bandwidth efficiently and reasonably.In this paper,a Dynamic Polling Media Access Control ...In Wireless Sensor Networks(WSNs),polling can obviously improve the throughput and decrease average access delay by allocating bandwidth efficiently and reasonably.In this paper,a Dynamic Polling Media Access Control (DPMAC) scheme designed according to WSNs' features is proposed.DPMAC is a priority based access control protocol with the characteristics that its polling table is dynamically refreshed depending on whether the sensor node is active and that the bandwidth is dynamically allocated according to the traffic types.The access priorities are determined by the emergency levels of events and the scheduler proposed in our MAC is preemptive based on the deadline of the events.Simulation results show that DPMAC can efficiently utilize bandwidth and decrease average access delay and response time for emergency events with different access priorities in WSNs.展开更多
The IEEE 802.11e standard is proposed to provide QoS support in WLAN by providing prioritized differentiation of traffic. Since all the stations in the same priority access category (AC) have the same set of parameter...The IEEE 802.11e standard is proposed to provide QoS support in WLAN by providing prioritized differentiation of traffic. Since all the stations in the same priority access category (AC) have the same set of parameters, when the number of stations increases, the probability of different stations in the same AC choosing the same values will increase, which will result in collisions. Random adaptive MAC (medium access control) parameters scheme (RAMPS) is proposed, which uses random adaptive MAC differentiation parameters instead of the static ones used in the 802.11e standard. The performance of RAMPS is compared with that of enhanced distributed coordination access (EDCA) using NS2. The results show that RAMPS can reduce collision rate of the AC and improve the throughput by using adaptive random contention window size and inter-frame spacing values. RAMPS ensures that at any given time, several flows of the same priority have different MAC parameter values. By using the random offset for the inter-frame spacing value and the backoff time, RAMPS can provide intra-AC differentiation. The simulation results show that RAMPS outperforms EDCA in terms of both throughput and end-to-end delay irrespective of the traffic load.展开更多
Using directional antennas in Wireless Ad hoc Networks (WANETs) offers great potential of reducing the radio interference, and improving the communication throughput. Directional antennas, however, introduces new prob...Using directional antennas in Wireless Ad hoc Networks (WANETs) offers great potential of reducing the radio interference, and improving the communication throughput. Directional antennas, however, introduces new problems in the wireless Media Access Control (MAC), that is, the deafness and new hidden terminal problem, which may cause severe performance degradation. To solve the problems, we propose an effective Circular RTR Directional MAC (CRDMAC) protocol for WANETs by using a sub-transmission channel and Ready to Receive (RTR) packets, which modifies the IEEE 802.11 Distributed Coordinated Function (DCF). The sub-channel avoids collisions to other ongoing transmission, and the RTR packets notify the neighbor nodes that the mutual transmission has been finished. We evaluate the CRDMAC protocol through simulations and the results show that the proposed protocol outperforms existing DMAC (directional MAC) protocol and the CRCM (Circular RTS and CTS MAC) protocol in terms of throughput and packet drop rate.展开更多
文摘运用跨层设计思想和方法研究了超宽带(UWB)无线自组织(Ad hoc)网络媒体访问控制(MAC)层协议的设计,提出了一种可利用 UWB 技术定位性好的优势和实现跨层协作的 MAC 层协议。该协议通过物理层、MAC 层和网络层之间的跨层协作来解决自组织网络单信道无线传输过程中的隐藏终端和暴露终端问题以及网络能量节约问题,以提高网络的性能。仿真实验表明,该协议在平均吞吐量、平均端到端时延以及能量开销等性能指标上,均优于已有的 IEEE802.11和 MACA-BI MAC 协议。该协议的设计思想和方法为下一步的 UWB 无线 Ad hoc 网络研究奠定了理论和实验基础。
基金supported by the National Natural Science Foundation of China under Grants No.61172068,61003300the Key Program of NSFC Guangdong Union Foundation under Grant No.U0835004+2 种基金the National Grand Fundamental Research 973 Program of China under Grant No.A001200907the Fundamental Research Funds for the Central Universities under Grant No.K50511010003Program for New Century Excellent Talents in University under Grant No.NCET-11-0691
文摘In Wireless Sensor Networks(WSNs),polling can obviously improve the throughput and decrease average access delay by allocating bandwidth efficiently and reasonably.In this paper,a Dynamic Polling Media Access Control (DPMAC) scheme designed according to WSNs' features is proposed.DPMAC is a priority based access control protocol with the characteristics that its polling table is dynamically refreshed depending on whether the sensor node is active and that the bandwidth is dynamically allocated according to the traffic types.The access priorities are determined by the emergency levels of events and the scheduler proposed in our MAC is preemptive based on the deadline of the events.Simulation results show that DPMAC can efficiently utilize bandwidth and decrease average access delay and response time for emergency events with different access priorities in WSNs.
基金Project(60673164) supported by the National Natural Science Foundation of ChinaProject(06JJ10009) supported by the Natural Science Foundation of Hunan Province, China+2 种基金Project(20060533057) supported by the Specialized Research Fund for the Doctoral Program of Higher Education of ChinaProject(2008CB317107) supported by the Major State Basic Research and Development Program of ChinaProject(NCET-05-0683) supported by the Program for New Century Excellent Talents in University
文摘The IEEE 802.11e standard is proposed to provide QoS support in WLAN by providing prioritized differentiation of traffic. Since all the stations in the same priority access category (AC) have the same set of parameters, when the number of stations increases, the probability of different stations in the same AC choosing the same values will increase, which will result in collisions. Random adaptive MAC (medium access control) parameters scheme (RAMPS) is proposed, which uses random adaptive MAC differentiation parameters instead of the static ones used in the 802.11e standard. The performance of RAMPS is compared with that of enhanced distributed coordination access (EDCA) using NS2. The results show that RAMPS can reduce collision rate of the AC and improve the throughput by using adaptive random contention window size and inter-frame spacing values. RAMPS ensures that at any given time, several flows of the same priority have different MAC parameter values. By using the random offset for the inter-frame spacing value and the backoff time, RAMPS can provide intra-AC differentiation. The simulation results show that RAMPS outperforms EDCA in terms of both throughput and end-to-end delay irrespective of the traffic load.
基金supported by the Grant-in-Aid for Scientific Research of Japan Society for Promotion of Science(JSPS)Collaboration Research Grant of National Institute of Informatics (NII) ,Japan
文摘Using directional antennas in Wireless Ad hoc Networks (WANETs) offers great potential of reducing the radio interference, and improving the communication throughput. Directional antennas, however, introduces new problems in the wireless Media Access Control (MAC), that is, the deafness and new hidden terminal problem, which may cause severe performance degradation. To solve the problems, we propose an effective Circular RTR Directional MAC (CRDMAC) protocol for WANETs by using a sub-transmission channel and Ready to Receive (RTR) packets, which modifies the IEEE 802.11 Distributed Coordinated Function (DCF). The sub-channel avoids collisions to other ongoing transmission, and the RTR packets notify the neighbor nodes that the mutual transmission has been finished. We evaluate the CRDMAC protocol through simulations and the results show that the proposed protocol outperforms existing DMAC (directional MAC) protocol and the CRCM (Circular RTS and CTS MAC) protocol in terms of throughput and packet drop rate.
