Raptor码在卫星广播通信中的应用及其分析

重复编码技术是目前中国广播通信中应用较为广泛的信道编码码型,但其存在频谱效率过低的问题;文章提出采用新发明的Raptor码代替重复编码技术作为卫星广播通信的信道编码码型。研究表明：和重复编码技术相比,不同参数条件下的Raptor码都取得了2—4倍的频谱增益,并且其纠错性能和实现复杂度保持不变,因此采用Raptor码能够提高广播信道的信息分发速率。     

USB广播播放控制系统设计

USB广播播放控制系统采用“一线通”设计方案,整个外部设备与主控计算机只有一根USB线相联,简化了结构,提高了可靠性。详细介绍了系统的硬件电路的设计和软件模块的编程,包括接口与主控电路、数模模数转换电路、调频电路的设计以及USB固件程序、USB驱动程序、播放控制窗口程序的编制。该系统功能强大,性价比较高,在各类学校及企事业单位等小型广播站具有广阔的市场前景。     

Novel limited feedback scheme under the MIMO broadcast system

By deducing the distribution of the normalized channel covariance matrix, a novel limited feedback scheme is proposed under multiple users (MU) multiple-input multiple-output (MIMO) broadcast channel (BC) system. The proposed scheme has advantages in three aspects. First, it has no constraints on the number of users or antennas. Second, each user's feedback bits are independent of the number of receiving antennas. Third, the proposed scheme avoids the storage of large-size codebook on the transceivers. Simulation results show that the performance of the proposed scheme is close to the perfect channel state information (CSI) case and it just needs a small number of feedback bits.     

无线传感器网络中具有撤销功能的自愈组密钥管理方案

在有限域F_q上构造基于秘密共享的广播多项式,提出一种具有节点撤销功能的组密钥更新方案.同时,基于单向散列密钥链建立组密钥序列,采用组密钥预先更新机制,容忍密钥更新消息的丢失,实现自愈.分析表明,在节点俘获攻击高发的环境中,方案在计算开销和通信开销方面具有更好的性能.     

超立方体网络中基于局部安全信息的广播容错路由研究

针对具有错误节点和故障链路的超立方体网络,改进了一种算法实现可靠的容错广播路由。在没有安全结点的不安全的超立方体网络中,将网络分成一系列最大安全子立方体,根据提出的故障链路处理方法和选择广播路由的准则,改进了基于局部安全信息的广播路由算法。证明了根据文中算法,这些最大安全子立方体在满足文中要求的情况下,仍有可能实现可靠的广播路由,有效地提高了信息路由的可靠性。提供了实例介绍文中算法的原理和优点。     

广播电视同步支撑网系统的研究

同步支撑网伴随着现代电信和广播电视网的快速发展而诞生,在网络中发挥越来越重要的作用,专为广播电视数字化而开发的同步支撑网将时钟同步和节目同步紧密集成,大大提高了该系统的可靠性和可管理性。     

QoS‐Guaranteed Multiuser Scheduling in MIMO Broadcast Channels

This paper proposes a new multiuser scheduling algorithm that can simultaneously support a variety of different quality‐of‐service (QoS) user groups while satisfying fairness among users in the same QoS group in MIMO broadcast channels. Toward this goal, the proposed algorithm consists of two parts: a QoS‐aware fair (QF) scheduling within a QoS group and an antenna trade‐off scheme between different QoS groups. The proposed QF scheduling algorithm finds a user set from a certain QoS group which can satisfy the fairness among users in terms of throughput or delay. The antenna trade‐off scheme can minimize the QoS violations of a higher priority user group by trading off the number of transmit antennas allocated to different QoS groups. Numerical results demonstrate that the proposed QF scheduling method satisfies different types of fairness among users and can adjust the degree of fairness among them. The antenna trade‐off scheme combined with QF scheduling can improve the probability of QoS‐guaranteed transmission when supporting different QoS groups.     

Efficient identity-based security schemes for ad hoc network routing protocols

Wireless ad hoc networks consist of nodes with no central administration and rely on the participating nodes to share network responsibilities. Such networks are more vulnerable to security attacks than conventional wireless networks. We propose two efficient security schemes for these networks that use pairwise symmetric keys computed non-interactively by the nodes which reduces communication overhead. We allow nodes to generate their broadcast keys for different groups and propose a collision-free method for computing such keys. We use identity-based keys that do not require certificates which simplifies key management. Our key escrow free scheme also uses identity-based keys but eliminates inherent key escrow in identity-based keys. Our system requires a minimum number of keys to be generated by the third party as compared to conventional pairwise schemes. We also propose an authenticated broadcast scheme based on symmetric keys and a corresponding signature scheme.     

A Survivable Wavelength Division Multiplexing Passive Optical Network with Both Point-to-Point Service and Broadcast Service Delivery

Abstract

A survivable wavelength division multiplexing passive optical network enabling both point-to-point service and broadcast service is presented and demonstrated. This architecture provides an automatic traffic recovery against feeder and distribution fiber link failure, respectively. In addition, it also simplifies the protection design for multiple services transmission in wavelength division multiplexing passive optical networks.     

Simulation Models for Investigation of Multiuser Scheduling in MIMO Broadcast Channels

Spatial correlation is a result of insufficient antenna spacing among multiple antenna elements, while temporal correlation is caused by Doppler spread. This paper compares the effect of spatial and temporal correlation in order to investigate the performance of multiuser scheduling algorithms in multiple‐input multiple‐output (MIMO) broadcast channels. This comparison includes the effect on the ergodic capacity, on fairness among users, and on the sum‐rate capacity of a multiuser scheduling algorithm utilizing statistical channel state information in spatio‐temporally correlated MIMO broadcast channels. Numerical results demonstrate that temporal correlation is more meaningful than spatial correlation in view of the multiuser scheduling algorithm in MIMO broadcast channels. Indeed, the multiuser scheduling algorithm can reduce the effect of the Doppler spread if it exploits the information of temporal correlation appropriately. However, the effect of spatial correlation can be minimized if the antenna spacing is sufficient in rich scattering MIMO channels regardless of the multiuser scheduling algorithm used.