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1.
Spreading code protocols for a distributed spread-spectrum packet radio network are presented. A distributed single-hop system (i.e. each terminal can hear all other terminals) with the users approximately synchronized and a set of prespecified spreading codes are presented. The spreading code protocol is a policy for choosing a spreading code to be used, given that a terminal has a packet to send, and a policy for monitoring spreading codes, given that a terminal is idle. A slotted system where a packet occupies a number of slots is considered, and two protocols that involve changing the spreading code of a transmission after an initial header is transmitted are presented. In one protocol, the header is transmitted on a common code, and in the other it is transmitted on a receiver-based code, the rest of the packet being transmitted on a transmitter-based code. In the receiving mode, a terminal monitors either a common code, in the first case, or a receiver-based code in the latter. Upon recognizing its own address and the source address, the receiver dynamically switches to a despreading code corresponding to the source. Throughput results are obtained for the case of geometrically distributed packet lengths 相似文献
2.
Steven W. Boyd Jason D. Ellis Michael B. Pursley 《International Journal of Wireless Information Networks》2013,20(2):103-119
A low-complexity protocol is described and evaluated for adaptation of the modulation and coding for multicast transmission in half-duplex packet radio networks. The adaptive multicast transmission protocol is designed to compensate for changes in propagation conditions that occur from packet to packet during a session with one sender and multiple receivers. The protocol relies on simple receiver statistics to obtain the control information for adapting the modulation and coding, and it also provides scheduling to avoid collisions among acknowledgments from the receivers. The throughput provided by the protocol is compared with performance results for hypothetical ideal adaptive multicast transmission protocols that are given perfect channel state information. We illustrate the importance of adaptive modulation and channel coding in systems that employ fountain coding for packet erasure correction. 相似文献
3.
Lap Kong Law Srikanth V. Krishnamurthy Michalis Faloutsos 《Mobile Computing, IEEE Transactions on》2007,6(3):264-279
We find that current group communications protocols are far from "one size fits all", they are typically geared toward and optimized for particular scenarios. Multicasting, in general, works well if the density of group members is sparse and in low mobility; broadcasting, in contrast, works well with a high density of group members and in high mobility. Due to the dynamics of the network, one strategy may be preferable to the other at different times and in different localized regions. In this paper, we first quantify the trade-offs between broadcasting and multicasting and evaluate the suitability of a strategy in various scenarios of deployment. Based on the lessons learned, we design a protocol that adapts in response to the dynamics of the network. We named our protocol Fireworks. Fireworks is a hybrid two-tier multicast/broadcast protocol that provides efficient and lightweight multicast dissemination and self-adapts in response to variations in the density and distribution of group members to provide efficient performance. Fireworks creates pockets of broadcast distribution in areas with many members, while it creates and maintains a multicast backbone to interconnect these dense pockets. Fireworks offers packet delivery statistics comparable to that of a pure multicast scheme but with significantly lower overheads. We also show that Fireworks has a lower level of degrading influence on the performance of coexisting unicast sessions than either traditional multicast or broadcast methods 相似文献
4.
《Broadcasting, IEEE Transactions on》2002,48(3):237-245
Techniques using Reed-Solomon (RS) codes to recover lost packets in digital video/audio broadcasting and packet switched network communications are reviewed. Usually, different RS codes and their corresponding encoders/decoders are designed and utilized to meet different requirements for different systems and applications. We incorporate these techniques into a variable RS code and present encoding and decoding algorithms suitable for the variable RS code. A mother RS code can be used to produce a variety of RS codes and the same encoder/decoder can be used for all the derivative codes, with adding/detecting zeros, removing some parity symbols and adding erasures. A VLSI implementation for erasure decoding of the variable RS code is described and the achievable performance is quantitatively analyzed. A typical example shows that the signal processing speed is up to 2.5 Gbits/second and the processing delay is less than one millisecond, when integrating the decoder on a single chip. Therefore, the proposed algorithm and the encoder/decoder can universally be utilized for different applications with various requirements, such as transmission data rate, packet length, packet loss protection capacity, as well as layered protection and adaptive redundancy protection in DVB/DAB, Internet and mobile Internet communications. 相似文献
5.
The problem of minimizing the number of transmissions for a multicast transmission under the condition that the packet delay is minimum in single-hop wavelength division multiplexing (WDM) networks is studied in this paper. This problem is proved to be NP-complete. A heuristic multicast scheduling algorithm is proposed for this problem. Extensive simulations are performed to compare the performance of the proposed heuristic algorithm with two other multicast scheduling algorithms, namely, the greedy and no-partition scheduling algorithms. The greedy algorithm schedules as many destination nodes as possible in the earliest data slot. The no-partition algorithm schedules the destination nodes of a multicast packet to receive the packet in the same data slot without partitioning the multicast transmission into multiple unicast or multicast transmissions. Our simulation results show that (i) an algorithm which partitions a multicast transmission into multiple unicast or multicast transmissions may not always produce lower mean packet delay than the no-partition algorithm when the number of data channels in the system is limited and (ii) the proposed heuristic algorithm always produces lower mean packet delay than the greedy and the no-partition algorithms because this algorithm not only partitions a multicast transmission into multiple unicast or multicast transmissions to keep the packet delay low but also reduces the number of transmissions to conserve resources. 相似文献
6.
Fucai Yu Soochang Park Euisin Lee Sang‐Ha Kim 《Wireless Communications and Mobile Computing》2012,12(11):969-984
Nodes mobility brings flinty challenges to multicast in Mobile ad hoc Networks (MANETs). To track nodes mobility, flooding messages are widely used for data delivery structure construction and maintenance in many multicast protocols. These periodic flooding messages significantly consume network resources, such as energy and bandwidth, and result in network collisions. To release data delivery structure maintenance onus, profited from GPS location service, a number of stateless location based multicast protocol were proposed, where a destination list is encapsulated into each data packet for data packet orientation. However, due to data packet capability limitation, the way of encapsulating a destination list in each data packet header restricts the protocol scalability. To solve the scalability issue of multicast protocols, we propose a Scalable Location Guide Overlay Multicast (SLGOM) for MANETs. Analysis and simulation results show that SLGOM achieves high performance in large multicast group and significantly improves the scalability of stateless multicast with respect to group size. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
7.
Jinsuk Baek Paul S. Fisher Minho Jo Hsiao‐Hwa Chen 《International Journal of Communication Systems》2012,25(5):553-570
A new video transport protocol for multicast agents in wireless mesh networks (WMNs) is proposed in this paper. The proposed protocol enables a significant reduction in the transmission overhead, while providing reliable communication for its use in multicast applications. This proposed reliable protocol provides a practical approach for an overlay peer‐to‐peer multicast facility supported within the application layer. This obviates the need to give upgraded routers capable of handling multicast broadcasting or modify the existing protocol stack. The protocol tolerates partial losses in multimedia transmissions, while supporting control of the delay sensitivity of such transmissions in WMNs. The key issue in this protocol is the ability to detect packet loss, anticipate retransmission requests, and use the anticipated retransmission requests to transmit the lost packets prior to requests from other receiving agents. The proposed protocol allows for the receiver to determine if retransmission of lost packets is required, ensuring the greatest flexibility needed for a reliable multicast protocol. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
8.
Challal Yacine Bettahar Hatem Bouabdallah Abdelmadjid 《Communications Surveys & Tutorials, IEEE》2004,6(3):34-57
Multicasting is an efficient communication mechanism for group-oriented applications such as videoconferencing, broadcasting stock quotes, interactive group games, and video on demand. The lack of security obstructs a large deployment of this efficient communication model. This limitation motivated a host of research works that have addressed the many issues relating to securing the multicast, such as confidentiality, authentication, non-repudiation, integrity, and access control. Many applications, such as broadcasting stock quotes and video-conferencing, require data origin authentication of the received traffic. Hence, data origin authentication is an important component in the multicast security architecture. Multicast data origin authentication must take into consideration the scalability and the efficiency of the underlying cryptographic schemes and mechanisms, because multicast groups can be very large and the exchanged data is likely to be heavy in volume (streaming). Besides, multicast data origin authentication must be robust enough against packet loss because most multicast multimedia applications do not use reliable packet delivery. Therefore, multicast data origin authentication is subject to many concurrent and competitive challenges, when considering these miscellaneous application-level requirements and features. In this article we review and classify recent works dealing with the data origin authentication problem in group communication, and we discuss and compare them with respect to some relevant performance criteria. 相似文献
9.
The code sensingR
3 code protocol designed for wireless data networks is proposed and its performance is analysed in this paper. The communication between two terminals is initiated by hand-shaking packets (the REQ and ACK packets), followed by data packet transmission. The destructive collisions among terminals are avoided by utilising busy code sensing and chip-rate division multiple access (CRDMA) techniques in transmissions of the REQ packet and the data packet (or ACK packet). A two-dimensional continuous-time Markov model is used to analyse the behaviour of the network. Analytical results are given which show that a remarkable improvement in throughput-delay performance can be achieved by the proposed protocol when compared to those for other reported protocols. 相似文献
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11.
Eric Astier Abdelhakim Hafid Sultan Aljahdali 《Wireless Communications and Mobile Computing》2012,12(9):822-836
Mesh‐based multicast routing protocols for mobile ad hoc networks (MANETs) build multiple paths from senders to receivers to deliver packets even in the presence of links breaking. This redundancy results in high reliability/robustness but may significantly increase packet overhead. This paper proposes a mesh‐based multicast protocol, called centered protocol for unified multicasting through announcements (CPUMA), that achieves comparable reliability as existing mesh‐based multicast protocols, however, with significantly much less data overhead. In CPUMA, a distributed core‐selection and maintenance algorithm is used to find the source‐centric center of a shared mesh. We leverage data packets to center the core of each multicast group shared mesh instead of using GPS or any pre‐assignment of cores to groups (the case of existing protocols). The proposed centering scheme allows reducing data packet overhead and creating forwarding paths toward the nearest mesh member instead of the core to reduce latency. We show, via simulations, that CPUMA outperforms existing multicast protocols in terms of data packet overhead, and latency while maintaining a constant or better packet delivery ratio, at the cost of a small increase in control overhead in a few scenarios. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
12.
Lijun Tan Qi Tu Zhang 《Selected Areas in Communications, IEEE Journal on》1996,14(9):1717-1727
Most code-division multiple-access (CDMA) systems described in the literature provide only one single service (voice or data) and employ the strategy of “one-code-for-one-terminal” for code-assignment. This assignment, though simple, fails to efficiently exploit the limited code resource encountered in practical situations. We present a new protocol called reservation-code multiple-access (RCMA), which allows all terminals to share a group of spreading codes on a contention basis and facilitates introducing voice/data integrated services into spread-spectrum systems. The RCMA protocol can be applied to short-range radio networks, and microcell mobile communications, and can be easily extended to wide area networks if the code-reuse technique is employed. In RCMA, a voice terminal can reserve a spreading code to transmit a multipacket talkspurt while a data terminal has to contend for a code for each packet transmission. The voice terminal will drop a long delayed packet while the data terminal just keeps it in the buffer. Therefore, two performance measures used to assess the proposed protocol are the voice packet dropping probability and the data packet average delay. Theoretical performance is derived by means of equilibrium point analysis (EPA) and is examined by extensive computer simulation 相似文献
13.
Recent advances in pervasive computing and wireless technologies have enabled novel multicast services anywhere, anytime, such as mobile auctions, advertisement, and e-coupons. Routing/multicast protocols in large-scale ad-hoc networks adopt two-tier infrastructures to accommodate the effectiveness of the flooding scheme and the efficiency of the tree-based scheme. In these protocols, hosts with a maximal number of neighbors are chosen as backbone hosts (BHs) to forward packets. Most likely, these BHs will be traffic concentrations or bottlenecks of the network and spend significant amount of time forwarding packets. In this paper, a distinct strategy is proposed for constructing a two-tier infrastructure in a large-scale ad-hoc network. Hosts with a minimal number of hops to the other hosts rather than those with a maximal number of neighbors will be adopted as BHs in order to obtain shorter multicast routes. The problem of determining BHs can be formulated with linear programming. BHs thus found have the advantages of shorter relay and less concentration. Besides, BHs are selected on-demand and can be globally reused for different multicast groups without flooding again. Simulation results show that the proposed protocol has shorter transmission latency, fewer control/data packets and higher receiving data packet ratios than other existing multicast protocols. Besides, the two-tier infrastructure constructed by the proposed protocol is more stable. 相似文献
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15.
一种基于状态机的串口通信协议的设计与实现 总被引:2,自引:0,他引:2
为解决串口通信中的数据传输容易出错、可靠性差、安全性不高且容错能力低等问题,设计并实现了一种基于状态机的串口通信协议,并将此协议应用到称重仪表的上位机通信中。本文介绍了串口通信协议的数据包格式以及其通信状态机,并给出了协议实现的部分示例代码及算法流程图。在数据包格式定义中通过设置起始标志、数据长度、校验、结束标志等字段,保证数据传输的正确性;并在数据包接收过程中引入状态机方法,简化编程模型的同时,提高了通信过程的可靠性、安全性以及数据传输的容错能力。 相似文献
16.
针对CATV网的带宽优势,提出了一种面向CATV网的IP多播流分发服务机制,客户端通过DVB卡分层接收流式文件,并利用IP网作为回传链路。该方案解决了单向广播网无法回传丢包及网络服务情况的问题,对于网络的突发性长时间丢包具有一定的稳健性。仿真结果显示该方案可靠性强,扩展性好,特别适合具有较多接收者的视频流分发。 相似文献
17.
Reliable Multicast in Multi-Access Wireless LANs 总被引:8,自引:0,他引:8
Multicast is an efficient paradigm for transmitting data from a sender to a group of receivers. In this paper, we focus on multicast in single channel multi-access wireless local area networks (LANs) comprising several small cells. In such a system, a receiver cannot correctly receive a packet if two or more packets are sent to it at the same time, because the packets collide. Therefore, one has to ensure that only one node sends at a time. We look at two important issues. First, we consider the problem of the sender acquiring the multi-access channel for multicast transmission. Second, for reliable multicast in each cell of the wireless LAN, we examine ARQ-based approaches. The second issue is important because the wireless link error rates can be very high.We present a new approach to overcome the problem of feedback collision in single channel multi-access wireless LANs, both for the purpose of acquiring the channel and for reliability. Our approach involves the election of one of the multicast group members (receivers) as a leader or representative for the purpose of sending feedback to the sender. For reliable multicast, on erroneous reception of a packet, the leader does not send an acknowledgment, prompting a retransmission. On erroneous reception of the packet at receivers other than the leader, our protocol allows negative acknowledgments from these receivers to collide with the acknowledgment from the leader, thus destroying the acknowledgment and prompting the sender to retransmit the packet.Using analytical models, we demonstrate that the leader-based protocol exhibits higher throughput in comparison to two other protocols which use traditional delayed feedback-based probabilistic methods. Last, we present a simple scheme for leader election. 相似文献
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19.
Many important applications in wireless mesh networks require reliable multicast communication, i.e., with 100% packet delivery ratio (PDR). Previously, numerous multicast protocols based on automatic repeat request (ARQ) have been proposed to improve the packet delivery ratio. However, these ARQ-based protocols can lead to excessive control overhead and drastically reduced throughput. In this paper, we present a comprehensive exploration of the design space for developing high-throughput, reliable multicast protocols that achieve 100% PDR.Motivated by the fact that 802.11 MAC layer broadcast, which is used by most wireless multicast protocols, offers no reliability, we first examine if better hop-by-hop reliability provided by unicasting the packets at the MAC layer can help to achieve end-to-end multicast reliability. We then turn to end-to-end solutions at the transport layer. Previously, forward error correction (FEC) techniques have been proved effective for providing reliable multicast in the Internet, by avoiding the control packet implosion and scalability problems of ARQ-based protocols. In this paper, we examine if FEC techniques can be equally effective to support reliable multicast in wireless mesh networks. We integrate four representative reliable schemes (one ARQ, one FEC, and two hybrid) originally developed for the Internet with a representative multicast protocol ODMRP and evaluate their performance.Our experimental results via extensive simulations offer an in-depth understanding of the various choices in the design space. First, compared to broadcast-based unreliable ODMRP, using unicast for per-hop transmission only offers a very small improvement in reliability under low load, but fails to improve the reliability under high load due to the significantly increased capacity requirement which leads to congestion and packet drop. Second, at the transport layer, the use of pure FEC can significantly improve the reliability, increasing PDR up to 100% in many cases, but can be inefficient in terms of the number of redundant packets transmitted. In contrast, a carefully designed ARQ–FEC hybrid protocol, such as RMDP, can also offer 100% reliability while improving the efficiency by up to 38% compared to a pure FEC scheme. To our best knowledge, this is the first in-depth study of high-throughput, reliable multicast protocols that provide 100% PDR for wireless mesh networks. 相似文献
20.
针对光城域网对综合业务的电信级需求,以城域网三网业务融合传送为主要领域,以基于弹性分组环RPR实现多业务传送为主要手段,研究了多业务传送与交换的简化方法,介绍了自主国际标准ITU-T X.87/Y.1324的协议要点、组网拓扑结构、传输架构、系统节点的组成和MSR通用帧格式。通过与RPR的比较,得出如下结论:MSR解决了语音、数据和视频等多业务(支路)分别在RPR各节点上,下的传送、支路组播、支路保护和性能监测问题。MSR成本较低,而且在同一网络平台上提供语音、数据和视频等支路业务需要这样的功能,它是目前基于分组的城域网多业务传送和出租的有效方法。 相似文献