软件通信体系结构(Software Communication Architecture,SCA)标准是针对软件无线电设备缺乏互操作性而制定的标准,通过定义设备组件对底层的硬件进行屏蔽,实现上层应用与底层硬件相互分离,SCA符合性测试通过验证实际的应用是否符合SCA...软件通信体系结构(Software Communication Architecture,SCA)标准是针对软件无线电设备缺乏互操作性而制定的标准,通过定义设备组件对底层的硬件进行屏蔽,实现上层应用与底层硬件相互分离,SCA符合性测试通过验证实际的应用是否符合SCA标准中的定义,从而保证应用的跨平台性与通用性。当前国内外对SCA符合性测试的研究较少,测试过程中存在诸多问题,如各需求的测试之间存在依赖关系,某些需求测试的进行可能造成后续需求测试无法执行等,导致目前缺乏自动化的测试方法。针对这些问题,提出了一种测试序列自动生成方法,并基于扩展有限状态机的基本原理构造了SCA符合性测试模型。该模型能够直观地反映测试过程,分析测试中软件无线电系统存在的各种状态,判断测试用例执行序列的可行性,指导测试序列的构建,再结合基于集合的贪心算法对测试序列集进行优化。实验结果表明该方法能有效地保证测试覆盖度,并且提升测试效率。展开更多
为研究城市战场环境下战术自组织网络(tactical mobile ad hoc network,TacMAN)通信节点间的信道特性,针对城区场景超短波频段展开信道测量与建模。测量结果表明,TacMAN通信场景下,多径信号存在明显的非平稳性和生灭现象。针对信道非平...为研究城市战场环境下战术自组织网络(tactical mobile ad hoc network,TacMAN)通信节点间的信道特性,针对城区场景超短波频段展开信道测量与建模。测量结果表明,TacMAN通信场景下,多径信号存在明显的非平稳性和生灭现象。针对信道非平稳性,首先设计了一种多径识别与跟踪算法,有效地估计出多径信号的存在概率。其次,使用基于马尔科夫链的改进型抽头延迟线(tapped delay line,TDL)模型对实测数据的非平稳过程进行建模。最后基于赤池信息准则(akaike information criterion,AIC)给出了小尺度衰落的统计模型,分析表明双高斯混合分布(bimodal Gaussian mixture distribution,BGMD)和Ricean分布分别是描述模型首径与最强径幅度分布的最佳模型。论文建立的非平稳信道模型可以较好地描述TacMAN场景下信道特性,为提高相关军事通信场景下通信系统的性能提供参考。展开更多
Abstract： This work proposes a Field Programmable Gate Array （FPGA）-oriented architecture for the IEEE 802.11 Distributed Coordination Function （DCF） transceiver. We describe the functional blocks carrying out th...Abstract： This work proposes a Field Programmable Gate Array （FPGA）-oriented architecture for the IEEE 802.11 Distributed Coordination Function （DCF） transceiver. We describe the functional blocks carrying out the Carrier Sense Multiple Accesses with Collision Avoidance （CSMA/CA）, develop the interfaces to the application layer and the physical layer, and implement it on FPGA devices by utilizing Very-high-speed-integrated-circuit Hardware Description Language （VHDL）.展开更多
In relay-assisted multi-user system, relay coding is important to enhance the robustness and reliability of cooperative transmission. For better adaptability and efficiency, two joint network and fountain coding(JNFC)...In relay-assisted multi-user system, relay coding is important to enhance the robustness and reliability of cooperative transmission. For better adaptability and efficiency, two joint network and fountain coding(JNFC) schemes are proposed. When the condition of all direct channels is worse, JNFC scheme based on distributed LT(DLT) codes is used. Otherwise, JNFC scheme based on multi-dimensional LT(MD-LT) codes is suited. For both two above-mentioned schemes, the united degree distribution design method for short-length fountain codes is proposed. For the latter scheme, MD-LT codes are proposed for equal error protection(EEP) of each user. Simulation results and analysis show that the united degree distribution need less decoding overhead compared with other degree distribution for short-length fountain codes. And then, all users are protected equally in despite of asymmetric uplinks.展开更多
In this paper, a rate adaptive protocol AMARF (Adaptive Multirate Auto Rate Fallback) for multirate IEEE 802.11 networks is proposed. In AMARF, each data rate is assigned a unique success threshold, which is a criteri...In this paper, a rate adaptive protocol AMARF (Adaptive Multirate Auto Rate Fallback) for multirate IEEE 802.11 networks is proposed. In AMARF, each data rate is assigned a unique success threshold, which is a criterion to judge when to switch a rate to the next higher one, and the success thresholds can be adjusted dynamically in an adaptive manner according to the running conditions, such as packet length and channel parameters. Moreover, the proposed protocol can be implemented by software without any change to the current IEEE 802.11 standards. Simulation result shows that AMARF yields significantly higher throughput than other existing schemes including ARF and its variants, in various running conditions.展开更多
In order to guarantee the overall return on investment (ROI), improve user experience and quality of service (QoS), save energy, reduce electra magnetic interference (EMI) and radiation pollution, and enable the susta...In order to guarantee the overall return on investment (ROI), improve user experience and quality of service (QoS), save energy, reduce electra magnetic interference (EMI) and radiation pollution, and enable the sustainable deployment of new profitable applications and services in heterogeneous wireless networks coexistence reality, this paper proposes a cross-network cooperation mechanism to effectively share network resources and infrastructures, and then adaptively control and match multi-network energy distribution characteristics according to actual user/service requirements in different geographic areas. Some idle or lightly-loaded base stations (BS or BSs) will be temporally turned off for saving energy and reducing EMI. Initial simulation results show that the proposed approach can significantly improve the overall energy efficiency and QoS performance across multiple cooperative wireless networks.展开更多
Recently, a multiple symbol differential （MSD） sphere decoding （SD） algorithm for unitary spacetime modulation over quasi-static channel has been proved to achieve the performance of maximumlikelihood （ML） detec...Recently, a multiple symbol differential （MSD） sphere decoding （SD） algorithm for unitary spacetime modulation over quasi-static channel has been proved to achieve the performance of maximumlikelihood （ML） detection with relatively low complexity. However, an error floor occurs if the algorithm is applied over rapid-fading channels. Based on the assumption of continuous fading, a multiple symbol differential automatic sphere decoding （MSDASD） algorithm is developed by incorporating a recursive form of an ML metric into automatic SD （ASD） algorithm. Furthermore, two algorithms, termed as MSD approximate ASD （MSDAASD） and MSD pruning ASD （MSDPASD）, are proposed to reduce computational complexity and the number of comparisons, respectively. Compared with the existing typical algorithms, i.e., multiple symbol differential feedback detection （MS-DFD） and noncoherent sequence detection （NSD）, the performance of the proposed algorithms is much superior to that of MS-DFD and a little inferior to that of NSD, while the complexity is lower than that of MS-DFD in most cases and significantly lower than that of NSD.展开更多
文摘软件通信体系结构(Software Communication Architecture,SCA)标准是针对软件无线电设备缺乏互操作性而制定的标准,通过定义设备组件对底层的硬件进行屏蔽,实现上层应用与底层硬件相互分离,SCA符合性测试通过验证实际的应用是否符合SCA标准中的定义,从而保证应用的跨平台性与通用性。当前国内外对SCA符合性测试的研究较少,测试过程中存在诸多问题,如各需求的测试之间存在依赖关系,某些需求测试的进行可能造成后续需求测试无法执行等,导致目前缺乏自动化的测试方法。针对这些问题,提出了一种测试序列自动生成方法,并基于扩展有限状态机的基本原理构造了SCA符合性测试模型。该模型能够直观地反映测试过程,分析测试中软件无线电系统存在的各种状态,判断测试用例执行序列的可行性,指导测试序列的构建,再结合基于集合的贪心算法对测试序列集进行优化。实验结果表明该方法能有效地保证测试覆盖度,并且提升测试效率。
文摘为研究城市战场环境下战术自组织网络(tactical mobile ad hoc network,TacMAN)通信节点间的信道特性,针对城区场景超短波频段展开信道测量与建模。测量结果表明,TacMAN通信场景下,多径信号存在明显的非平稳性和生灭现象。针对信道非平稳性,首先设计了一种多径识别与跟踪算法,有效地估计出多径信号的存在概率。其次,使用基于马尔科夫链的改进型抽头延迟线(tapped delay line,TDL)模型对实测数据的非平稳过程进行建模。最后基于赤池信息准则(akaike information criterion,AIC)给出了小尺度衰落的统计模型,分析表明双高斯混合分布(bimodal Gaussian mixture distribution,BGMD)和Ricean分布分别是描述模型首径与最强径幅度分布的最佳模型。论文建立的非平稳信道模型可以较好地描述TacMAN场景下信道特性,为提高相关军事通信场景下通信系统的性能提供参考。
基金the National Natural Science Foundation of China
文摘Abstract： This work proposes a Field Programmable Gate Array （FPGA）-oriented architecture for the IEEE 802.11 Distributed Coordination Function （DCF） transceiver. We describe the functional blocks carrying out the Carrier Sense Multiple Accesses with Collision Avoidance （CSMA/CA）, develop the interfaces to the application layer and the physical layer, and implement it on FPGA devices by utilizing Very-high-speed-integrated-circuit Hardware Description Language （VHDL）.
基金supported in part by a grant from the Ph.D. Programs Foundation of Ministry of Education of China under Grants No. 20094307110004National Natural Science Foundation of China under Grants No.61372098, No.61101074Natural Science Foundation of Hunan Province, China under Grants No.12jj2037
文摘In relay-assisted multi-user system, relay coding is important to enhance the robustness and reliability of cooperative transmission. For better adaptability and efficiency, two joint network and fountain coding(JNFC) schemes are proposed. When the condition of all direct channels is worse, JNFC scheme based on distributed LT(DLT) codes is used. Otherwise, JNFC scheme based on multi-dimensional LT(MD-LT) codes is suited. For both two above-mentioned schemes, the united degree distribution design method for short-length fountain codes is proposed. For the latter scheme, MD-LT codes are proposed for equal error protection(EEP) of each user. Simulation results and analysis show that the united degree distribution need less decoding overhead compared with other degree distribution for short-length fountain codes. And then, all users are protected equally in despite of asymmetric uplinks.
文摘In this paper, a rate adaptive protocol AMARF (Adaptive Multirate Auto Rate Fallback) for multirate IEEE 802.11 networks is proposed. In AMARF, each data rate is assigned a unique success threshold, which is a criterion to judge when to switch a rate to the next higher one, and the success thresholds can be adjusted dynamically in an adaptive manner according to the running conditions, such as packet length and channel parameters. Moreover, the proposed protocol can be implemented by software without any change to the current IEEE 802.11 standards. Simulation result shows that AMARF yields significantly higher throughput than other existing schemes including ARF and its variants, in various running conditions.
基金supported by the National Natural Science Foundation of China ( NSFC)( No. 60902041)Chinese Academy of Sciences ( No. 2010045)the Ministry of Science and Technology( MOST) of China ( No. 2010DFB10410,No. 2009DFB13080 and No. 2009ZX03003-009)
文摘In order to guarantee the overall return on investment (ROI), improve user experience and quality of service (QoS), save energy, reduce electra magnetic interference (EMI) and radiation pollution, and enable the sustainable deployment of new profitable applications and services in heterogeneous wireless networks coexistence reality, this paper proposes a cross-network cooperation mechanism to effectively share network resources and infrastructures, and then adaptively control and match multi-network energy distribution characteristics according to actual user/service requirements in different geographic areas. Some idle or lightly-loaded base stations (BS or BSs) will be temporally turned off for saving energy and reducing EMI. Initial simulation results show that the proposed approach can significantly improve the overall energy efficiency and QoS performance across multiple cooperative wireless networks.
基金Supported by the National Basic Research Program of China (973 Program) (Grant No. 2009CB320403)the National Defense Pre-researchProject of the 11th Five-Year-Plan of China (Grant No. 1060741001020102)
文摘Recently, a multiple symbol differential （MSD） sphere decoding （SD） algorithm for unitary spacetime modulation over quasi-static channel has been proved to achieve the performance of maximumlikelihood （ML） detection with relatively low complexity. However, an error floor occurs if the algorithm is applied over rapid-fading channels. Based on the assumption of continuous fading, a multiple symbol differential automatic sphere decoding （MSDASD） algorithm is developed by incorporating a recursive form of an ML metric into automatic SD （ASD） algorithm. Furthermore, two algorithms, termed as MSD approximate ASD （MSDAASD） and MSD pruning ASD （MSDPASD）, are proposed to reduce computational complexity and the number of comparisons, respectively. Compared with the existing typical algorithms, i.e., multiple symbol differential feedback detection （MS-DFD） and noncoherent sequence detection （NSD）, the performance of the proposed algorithms is much superior to that of MS-DFD and a little inferior to that of NSD, while the complexity is lower than that of MS-DFD in most cases and significantly lower than that of NSD.
