The IEEE 802.11n standard has provided prominent features that greatly contribute to ubiquitous wireless networks.Over the last ten years,voice over IP(VoIP)has become widespread around the globe owing to its low-cost...The IEEE 802.11n standard has provided prominent features that greatly contribute to ubiquitous wireless networks.Over the last ten years,voice over IP(VoIP)has become widespread around the globe owing to its low-cost or even free call rate.The combination of these technologies(VoIP and wireless)has become desirable and inevitable for organizations.However,VoIP faces a bandwidth utilization issue when working with 802.11 wireless networks.The bandwidth utilization is inefficient on the grounds that(i)80 bytes of 802.11/RTP/UDP/IP header is appended to 10–730 bytes of VoIP payload and(ii)765μs waiting intervals follow each 802.11 VoIP frame.Without considering the quality requirements of a VoIP call,be including frame aggregation in the IEEE 802.11n standard has been suggested as a solution for the bandwidth utilization issue.Consequently,several aggregation methods have been proposed to handle the quality requirements of VoIP calls when carried over an IEEE 802.11n wireless network.In this survey,we analyze the existing aggregation methods of VoIP over the A-MSDU IEEE 802.11n wireless standard.The survey provides researchers with a detailed analysis of the bandwidth utilization issue concerning the A-MSDU 802.11n standard,discussion of the main approaches of frame aggregation methods and existing aggregation methods,elaboration of the impact of frame aggregation methods on network performance and VoIP call quality,and suggestion of new areas to be investigated in conjunction with frame aggregation.The survey contributes by offering guidelines to design an appropriate,reliable,and robust aggregation method of VoIP over 802.11n standard.展开更多
The rapid development of Wireless Local Area Network (WLAN) has not yet broken the bottleneck that the low transmission speed hinders the further development of WLAN. Now, some key technologies for next generation mob...The rapid development of Wireless Local Area Network (WLAN) has not yet broken the bottleneck that the low transmission speed hinders the further development of WLAN. Now, some key technologies for next generation mobile communications can solve the problem by supporting high-speed transmission and ensuring reliable performance. IEEE 802.11n has made general amendment to 802.11. Based on IEEE 802.11n, the transmission speed can be doubled by the application of Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output (MIMO) technologies on the physical layer. In addition, the enhanced Medium Access Control (MAC) system performance, optimized data frame and improved network throughput can all be achieved by the adoption of frame convergence, Transmission Opportunity (TXOP) and block-acknowledge technologies on the MAC layer. A new error correction method, called Low Density Parity Check Code (LDPC), can also be adopted for the receiver to enjoy low Bit Error Ratio (BER) with low S/N, thus improving signal coverage.展开更多
文摘The IEEE 802.11n standard has provided prominent features that greatly contribute to ubiquitous wireless networks.Over the last ten years,voice over IP(VoIP)has become widespread around the globe owing to its low-cost or even free call rate.The combination of these technologies(VoIP and wireless)has become desirable and inevitable for organizations.However,VoIP faces a bandwidth utilization issue when working with 802.11 wireless networks.The bandwidth utilization is inefficient on the grounds that(i)80 bytes of 802.11/RTP/UDP/IP header is appended to 10–730 bytes of VoIP payload and(ii)765μs waiting intervals follow each 802.11 VoIP frame.Without considering the quality requirements of a VoIP call,be including frame aggregation in the IEEE 802.11n standard has been suggested as a solution for the bandwidth utilization issue.Consequently,several aggregation methods have been proposed to handle the quality requirements of VoIP calls when carried over an IEEE 802.11n wireless network.In this survey,we analyze the existing aggregation methods of VoIP over the A-MSDU IEEE 802.11n wireless standard.The survey provides researchers with a detailed analysis of the bandwidth utilization issue concerning the A-MSDU 802.11n standard,discussion of the main approaches of frame aggregation methods and existing aggregation methods,elaboration of the impact of frame aggregation methods on network performance and VoIP call quality,and suggestion of new areas to be investigated in conjunction with frame aggregation.The survey contributes by offering guidelines to design an appropriate,reliable,and robust aggregation method of VoIP over 802.11n standard.
基金Programs ofNational Natural Science Foundation of China(No. 60372048, No. 60496316)
文摘The rapid development of Wireless Local Area Network (WLAN) has not yet broken the bottleneck that the low transmission speed hinders the further development of WLAN. Now, some key technologies for next generation mobile communications can solve the problem by supporting high-speed transmission and ensuring reliable performance. IEEE 802.11n has made general amendment to 802.11. Based on IEEE 802.11n, the transmission speed can be doubled by the application of Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output (MIMO) technologies on the physical layer. In addition, the enhanced Medium Access Control (MAC) system performance, optimized data frame and improved network throughput can all be achieved by the adoption of frame convergence, Transmission Opportunity (TXOP) and block-acknowledge technologies on the MAC layer. A new error correction method, called Low Density Parity Check Code (LDPC), can also be adopted for the receiver to enjoy low Bit Error Ratio (BER) with low S/N, thus improving signal coverage.
