1 IntroductionWith the rapid development of backbonenetworks,the subscriber accessnetwork,a major component of publictelecom network equipment and so-called the“last kilometer”,has turned out to bethe focus of atten...1 IntroductionWith the rapid development of backbonenetworks,the subscriber accessnetwork,a major component of publictelecom network equipment and so-called the“last kilometer”,has turned out to bethe focus of attention.Among various access technologies,thebroadband wireless access system featuresquick network construction,rapid investmentreturn and large bandwidth.It enables newnetwork operators to provide services quickly展开更多
Broadband Wireless Access (BWA) has become one of the major evolution trends in the fields of broadband access and mobile communications. However,some difficulties emerged during the application and industrialization ...Broadband Wireless Access (BWA) has become one of the major evolution trends in the fields of broadband access and mobile communications. However,some difficulties emerged during the application and industrialization of the BWA system,which calls for typical service models,key technology innovations and backbone support from broadband Internet. This article introduces a Broadband Wireless Multimedia (BWM) access system. It aims to build a new-type "triple play" BWA network by integrating terrestrial digital TV system and the BWA system,and by taking broadband Internet as its core network platform. A primary research shows that the new BWA system is an effective solution to the existing difficulties of BWA system. Moreover,it is quite competitive in service provision,service coverage,frequency planning,terminal power consumption and cost for network construction.展开更多
In this paper,we propose a novel polling algorithm to decrease the number of idle slots and collission slots during the polling cycle by evaluating the bandwidth request of the subscribe stations(SSs) in the next poll...In this paper,we propose a novel polling algorithm to decrease the number of idle slots and collission slots during the polling cycle by evaluating the bandwidth request of the subscribe stations(SSs) in the next polling cycle for broadband wireless access(BWA) systems.We firstly analyze the feature of silent time intervals and deduce the Hurst index which symbolizes the degree of self-similarity and long-relative nature.Then we represent the inactive OFF time intervals by the Pareto model and estimate the shape parameterαby the group measured data.Finally we can evaluate the transmission probability of a silent SS before the next polling cycle. By this algorithm,we can find the optimal transmission opportunities for the base station(BS) to achieve the least collision or void timeslots in order to achieve the largest bandwidth efficiency.The theoretical analysis and simulation results show that this polling algorithm can improve the performance for BWA system.展开更多
The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse ...The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse QoS requirements is proposed.As for this algorithm,each connection is assigned a priority,which is updated dynamically based on its service status concluding queue characteristic and channel state.A connection with the highest priority is scheduled each time.Analytical model is developed by assuming a Finite State Markov Chain(FSMC)channel model.Simulation results show that the proposed scheduling algorithm can improve the performance of mean waiting time and throughput in broadband wireless networks.展开更多
This paper utilizes the cross-layer architecture to implement adaptive resource allocation in Orthogonal Frequency Division Multiple Access （OFDMA） based on the broadband wireless access system. According to the cro...This paper utilizes the cross-layer architecture to implement adaptive resource allocation in Orthogonal Frequency Division Multiple Access （OFDMA） based on the broadband wireless access system. According to the cross-layer architecture, the information in link layer is used for adaptive resource allocation in OFMDA. A new cross-layer adaptive resource allocation algorithm is developed which can guarantee the users to be in minimum average waiting time in link-layer and get the better spectrum utilization. Numerical results show that our scheme is appealing and can get about half of average waiting time less and 0.5 bps/Hz spectrum utilization more than the scheme in 1EEE802.16a.展开更多
随着无线接入系统的工作频段越来越高,传输带宽越来越宽,非视距(Non Light Of Sight,NLOS)传输的限制就越来越大。研究非视距传播环境下抗衰落技术,对解决非视距无线接入条件下系统的可靠性和有效性,提高工程应用能力具有重要意义。非...随着无线接入系统的工作频段越来越高,传输带宽越来越宽,非视距(Non Light Of Sight,NLOS)传输的限制就越来越大。研究非视距传播环境下抗衰落技术,对解决非视距无线接入条件下系统的可靠性和有效性,提高工程应用能力具有重要意义。非视距传输的关键实际上是抗多径衰落技术,包括OFDM、收发分集、子信道化、智能天线和自适应调制等技术。在分析非视距传播的条件和影响的基础上,对解决非视距传输问题的几个关键技术进行讨论,并对其在象WiMAX这样的宽带无线接入中的应用优势和影响进行了分析。展开更多
文摘1 IntroductionWith the rapid development of backbonenetworks,the subscriber accessnetwork,a major component of publictelecom network equipment and so-called the“last kilometer”,has turned out to bethe focus of attention.Among various access technologies,thebroadband wireless access system featuresquick network construction,rapid investmentreturn and large bandwidth.It enables newnetwork operators to provide services quickly
文摘Broadband Wireless Access (BWA) has become one of the major evolution trends in the fields of broadband access and mobile communications. However,some difficulties emerged during the application and industrialization of the BWA system,which calls for typical service models,key technology innovations and backbone support from broadband Internet. This article introduces a Broadband Wireless Multimedia (BWM) access system. It aims to build a new-type "triple play" BWA network by integrating terrestrial digital TV system and the BWA system,and by taking broadband Internet as its core network platform. A primary research shows that the new BWA system is an effective solution to the existing difficulties of BWA system. Moreover,it is quite competitive in service provision,service coverage,frequency planning,terminal power consumption and cost for network construction.
基金the National Natural Science Foundation of China(No.60675024)the Natural Science Foundation of Shandong(No.Y2008G37) the Soft Science Foundation of Shandong(No.2010RKGA1033)
文摘In this paper,we propose a novel polling algorithm to decrease the number of idle slots and collission slots during the polling cycle by evaluating the bandwidth request of the subscribe stations(SSs) in the next polling cycle for broadband wireless access(BWA) systems.We firstly analyze the feature of silent time intervals and deduce the Hurst index which symbolizes the degree of self-similarity and long-relative nature.Then we represent the inactive OFF time intervals by the Pareto model and estimate the shape parameterαby the group measured data.Finally we can evaluate the transmission probability of a silent SS before the next polling cycle. By this algorithm,we can find the optimal transmission opportunities for the base station(BS) to achieve the least collision or void timeslots in order to achieve the largest bandwidth efficiency.The theoretical analysis and simulation results show that this polling algorithm can improve the performance for BWA system.
文摘The MAC layer in IEEE802.16 is designed to differentiate service among traffic categories with different multimedia requirements.In this paper,a scheduling algorithm at MAC layer for multiple connections with diverse QoS requirements is proposed.As for this algorithm,each connection is assigned a priority,which is updated dynamically based on its service status concluding queue characteristic and channel state.A connection with the highest priority is scheduled each time.Analytical model is developed by assuming a Finite State Markov Chain(FSMC)channel model.Simulation results show that the proposed scheduling algorithm can improve the performance of mean waiting time and throughput in broadband wireless networks.
基金Supported by the National Natural Science Foundation of China (No.60072048) the Doctoral Program Fund of Ministry of Education of China (No.20010561007).
文摘This paper utilizes the cross-layer architecture to implement adaptive resource allocation in Orthogonal Frequency Division Multiple Access （OFDMA） based on the broadband wireless access system. According to the cross-layer architecture, the information in link layer is used for adaptive resource allocation in OFMDA. A new cross-layer adaptive resource allocation algorithm is developed which can guarantee the users to be in minimum average waiting time in link-layer and get the better spectrum utilization. Numerical results show that our scheme is appealing and can get about half of average waiting time less and 0.5 bps/Hz spectrum utilization more than the scheme in 1EEE802.16a.
文摘随着无线接入系统的工作频段越来越高,传输带宽越来越宽,非视距(Non Light Of Sight,NLOS)传输的限制就越来越大。研究非视距传播环境下抗衰落技术,对解决非视距无线接入条件下系统的可靠性和有效性,提高工程应用能力具有重要意义。非视距传输的关键实际上是抗多径衰落技术,包括OFDM、收发分集、子信道化、智能天线和自适应调制等技术。在分析非视距传播的条件和影响的基础上,对解决非视距传输问题的几个关键技术进行讨论,并对其在象WiMAX这样的宽带无线接入中的应用优势和影响进行了分析。
