共查询到20条相似文献,搜索用时 15 毫秒
1.
This paper presents an ATM-based transport architecture for next-generation multiservices personal communication networks (PCN). Such “multimedia capable” integrated services wireless networks are motivated by an anticipated demand for wireless extensions to future broadband networks. An ATM compatible wireless network concept capable of supporting a mix of broadband ISDN services including constant bit-rate (CBR), variable bit-rate (VBR), and packet data transport is explored from an architectural viewpoint. The proposed system uses a hierarchical ATM switching network for interconnection of PCN microcells, each of which is serviced by high-speed, shared-access radio links based on ATM-compatible cell, relay principles. Design issues related to the physical (modulation), media access control (MAC), and data-link layers of the ATM-based radio link are discussed, and preliminary technical approaches are identified in each case. An example multiservice dynamic reservation (MDR) TDMA media access protocol is then considered in further detail, and simulation results are presented for an example voice/data scenario with a proportion of time-critical (i.e., multimedia) packet data. Time-of-expiry (TOE) based queue service disciplines are also investigated as a mechanism for improving the quality-of-service (QoS) in this scenario 相似文献
2.
Satellite communications can play an important role in provisioning the next-generation telecommunications services and networks, provided that the protocols specifying these services and networks are satellite-compatible. After a brief discussion of narrowband circuit and packet mode integrated service digital network (ISDN) services, the paper focuses on emerging standards in frame relay, broadband ISDN (BISDN) and universal personal telecommunications (UPT). The specific parameters and procedures of frame relay and BISDN protocols which are affected by a satellite delay are identified, and congestion and resource management functions for frame relay and BISDN are discussed in detail. Specific ground functions and possible on-board functions are identified as potential candidates for implementation via neural network technology. Finally, the implication of UPT standards on satellite networks is discussed. 相似文献
3.
One of the promising applications of IEEE 802.16 (WiMAX)-based wireless mesh/relay networks is to provide infrastructure/backhaul support for IEEE 802.11-based mobile hotspots. In this article we present an architecture for integrating IEEE 802.11 WLANs with IEEE 802.16-based multihop wireless mesh infrastructure to relay WLAN traffic to the Internet. The major research issues in this integrated architecture are outlined and related work is reviewed. A game-theoretic model is developed for radio resource management in this integrated network architecture. In particular, a multiplayer bargaining game formulation is used for fair bandwidth allocation and optimal admission control of different types of connections (e.g., WLAN connections, relay connections, and connections from standalone subscriber stations) in an IEEE 802.16 base station/mesh router. Both connection-level and inconnection-level performances for this bandwidth management and admission control framework are presented 相似文献
4.
ISDN与LAN远程互连 总被引:1,自引:0,他引:1
本文主要介绍了ISDN与LAN远程互连的模式和互连设备,分析了ISDNMAC网桥和ISDNIP网关的体系结构,并提出一种简单易行的ISDNMAC网桥的方案。 相似文献
5.
To effectively provide the QoS of streaming services in mobile WiMAX systems, this paper proposes a cross-layer design between
the streaming server and mobile WiMAX base stations. We will show that for each user the implementation of multiple connections
with feedback information of the available transmission bandwidth is critical for supporting H.264/AVC-based scalable video
coding in which the transmission packets can be further separated into multiple levels of importance. To quantify the performance,
a mobile WiMAX simulation platform including both the video encoder/decoder and IEEE 802.16e MAC controls is developed. 相似文献
6.
Nguyen Duc 《Selected Areas in Communications, IEEE Journal on》1986,4(8):1188-1192
This paper proposes that the end user's perception of an "ISDN service" should reflect'three interrelated ISDN aspects, namely:bullet ISDN terminal capabilities,bullet ISDN access capabilities, andbullet ISDN network capabilities. Emphasis is placed on the ISDN terminal capabilities in supporting integrated services delivery of different levels to the end user (e.g., integrated bearer services and integrated teleservices delivery). Such a concept, integrated services delivery, is seen to suggest a useful framework for developing a wide range of possible ISDN commercial service/ product offerings. An ISDN service scenario is also described to illustrate some important communication capabilities made possible by an ISDN environment. 相似文献
7.
Wu W.W. Livne A. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1991,79(2):103-111
A snapshot of the present status of ISDN (integrated services digital network) is presented in terms of standardization efforts, field trials and demonstrations, implementations and services, and equipment and devices. A review of opinions and controversies as well as future trends is also given. The authors emphasize the importance of the worldwide standardization effort and discuss the organizations that are responsible for establishing such standards. It is pointed out that, with the limitation and inflexibility of the narrowband ISDN and the broadband ISDN, issues for higher-rate services have become prominent. For broadband services, the problem is not merely increasing the speed of the operation. It affects the compatibility of switching technology, the workability of the local loop arrangement, the availability of rate adaption, and the efficiency of bandwidth utilization. Although some basic principles of narrowband ISDN can be carried to broadband ISDN, the technology is quite different. For example, the interconnection and transmission problems of video, HDTV, (high-definition television), and high-speed data are different from those of voice. Thus, the standard 64-kb/s B channel itself, the fundamental rate of ISDN transmission, appears inadequate for wideband services. At present, the solution is to establish the multiples of 64 kb/s for accommodation of broadband or higher rates 相似文献
8.
Si‐O Seo Se‐Jin Kim Seung‐Yeon Kim Young‐Il Kim Hyong‐Woo Lee Seungwan Ryu Choong‐Ho Cho 《ETRI Journal》2010,32(2):230-240
The IEEE802.16j standard uses non‐transparent relay stations to extend coverage. There are two types of non‐transparent relay modes, that is, the time‐division transmit and receive (TTR) relay mode which can operate with one of two types of frame structures, a single‐frame and multiframe structure, and the simultaneous transmit and receive (STR) relay mode. In this paper, we analyze the relay performance of TTR and STR relay modes in IEEE 802.16j MMR system. We also propose a fair resource allocation scheme for the downlink relay frame. Numerical results show that relay performance of the TTR with a single‐frame or a multiframe structure and that of the STR relay modes are almost the same in a two‐hop system. However, in a three‐hop system, the TTR mode with a single‐frame structure outperforms other relay modes. 相似文献
9.
Sangki Yun Hyogon Kim Heejo Lee Inhye Kang 《Selected Areas in Communications, IEEE Journal on》2007,25(4):689-698
The bandwidth efficiency of voice over IP (VoIP) traffic on the IEEE 802.11 WLAN is notoriously low. VoIP over 802.11 incurs high bandwidth cost for voice frame packetization and MAC/PHY framing, which is aggravated by channel access overhead. For instance, 10 calls with the G.729 codec can barely be supported on 802.11b with acceptable QoS - less than 2% efficiency. As WLANs and VoIP services become increasingly widespread, this inefficiency must be overcome. This paper proposes a solution that boosts the efficiency high enough to support a significantly larger number of calls than existing schemes, with fair call quality. The solution comes in two parts: adaptive frame aggregation and uplink/downlink bandwidth equalization. The former reduces the absolute number of MAC frames according to the link congestion level, and the latter balances the bandwidth usage between the access point (AP) and wireless stations. When used in combination, they yield superior performance, for instance, supporting more than 100 VoIP calls over an IEEE 802.11b link. The authors demonstrate the performance of the proposed approach through extensive simulation, and validate the simulation through analysis. 相似文献
10.
《Communications Magazine, IEEE》1994,32(6):39-43
Widespread use of personal computers (PCs) and PC networks is leading to a strongly increased demand for WAN data services in terms of number of accesses and required bandwidth. Narrowband ISDN (N-ISDN) and broadband ISDN (B-ISDN) have the potential to satisfy, respectively, the existing and developing requirements. However, a flexible evolution path needs to be identified for the provision of ISDN access facilities. Frame relaying and frame switching are prime candidates for such a common access facility, although not necessarily intrinsic B-ISDN data services. The article gives an overview of frame relaying and frame switching as possible candidates for harmonized access to N-ISDN and B-ISDN. Pre-ISDN, N-ISDN, and B-ISDN services with their characteristics in terms of cost and performance are first described. It is shown how frame relaying and switching are positioned with respect to the identified service requirements. Then some examples are given of selected scenarios, and the role played by specifically frame relaying to provide access to B-ISDN services, offering at the same time a seamless evolutionary path from N-ISDN to B-ISDN. The position of frame relaying and switching is discussed first in respect to application requirements, and then in architectural terms. Frame relay (and frame switching) services are then identified as services that provide the necessary low threshold and short lead time for rapid market penetration, in order to allow applications to indirectly take advantage of the benefits of ATM services 相似文献
11.
Rajeev Bhardwaj Bijan Jabbari 《International Journal of Satellite Communications and Networking》1991,9(5):363-380
Frame relay is a new ISDN (integrated services digital network) packet mode bearer service which is expected to provide an efficient means of information transport using high-speed transmission media. Several new applications requiring high bandwidth, such as file transfer, video and packetized voice, are suitable candidates to use this streamlined protocol. However, as there are no control frames present within the network for traffic flow management, congestion may arise during periods of peak offered loads. Efficient congestion control mechanisms are needed to make the frame relay effective. In this paper, after a brief discussion of the frame relay protocol, we consider the congestion problem in networks using this protocol and evaluate the performance. Specifically, we consider static and dynamic window flow control methods and develop models to determine the throughput under various load conditions. The throughput of the static window flow control model is determined by computing the frame loss probability and the virtual retransmission time, which is the time between arrivals of retransmitted frames at the destination. The frame loss probability is calculated by modelling the bottleneck resource as a finite state Markov chain. The results are validated by simulation. Furthermore, to analyse the dynamic interactions between the virtual circuits and their effect on the throughput and delay characteristics, we develop a simulation model which incorporates a dynamic window congestion control mechanism. It is shown that when the offered load is high, the performance of dynamic window flow control is superior to that of static window flow control. 相似文献
12.
Simple interconnection of high-speed local area networks (LAN's) can be accomplished without special technology through the use of table-free bridges. Self-guided frame routing allows frames to trace specific routes through bridged LAN's without requiring bridges to maintain address tables or perform table lookups. As a result, the technique applies to networks regardless of their operating speed or topological configuration and requires no interbridge protocols. The paper discusses a method known as source routing that provides tablefree bridging and self-guided frame routing for LAN's. Participation by the bridges that interconnect pairs of LAN's and by the stations whose frames they forward is described. Possible frame formats are shown as enhancements to the standard frame formats of the IEEE 802 and ISO 8802 local area networks. 相似文献
13.
针对IEEE802.11MAC(medium access control)协议中通信模式的缺陷,提出了一种新的协作MAC机制。该机制重点研究了分布式中继节点的选择算法,并定义了一种新的控制帧(retran)。目的节点通过发送retran帧启动协作机制,收到该帧的节点根据中继选择算法设置自身定时器,从而竞争产生“机会中继”,使其在源节点与目的节点之间搭建通信桥梁,该方法简单可行。仿真表明,随着网络中节点数的增加,新的机制对网络吞吐量和误比特性能的改善效果明显,从而提高了通信质量。 相似文献
14.
15.
《Communications Magazine, IEEE》1994,32(3):86-98
LAN emulation offers a best-effort, connectionless, packet transfer service at the MAC sublayer, implemented on top of a connection-oriented ATM network LAN emulation using switched virtual connections requires address resolution to locate the destination end station followed by connection establishment to the resulting ATM address. Address resolution may be implemented by a broadcast technique or by an address server. The broadcast method is the simplest for small networks but a combination of both is probably better. The use of the MAC address to identify an end station, with dynamic binding to its current physical location in the ATM network, allows the ATM LAN segment to be viewed as a virtual LAN. The virtual LAN model permits end stations to move and change physical location while maintaining connection to the same ATM LAN segment. This greatly simplifies the management of large data networks 相似文献
16.
High throughput and fair resource sharing are two of the most important objectives in designing a medium access control (MAC) protocol. Currently, most MAC protocols including IEEE 802.11 DCF adopt a random access based approach in a distributed manner in order to coordinate the wireless channel accesses among competing stations. In this paper, we first identify that a random access?Cbased MAC protocol may suffer from MAC protocol overhead such as a random backoff for data transmission and a collision among simultaneously transmitting stations. Then, we propose a new MAC protocol, called sequential coordination function (SCF), which coordinates every station to send a data frame sequentially one after another in a distributed manner. By defining a service period and a joining period, the SCF eliminates unnecessary contentions during the service period, and by explicitly determining the sequence of frame transmission for each stations, it reduces collision occurrences and ensures fairness among stations in the service period. The performance of SCF is investigated through intensive simulations, which show that the SCF achieves higher throughput and fairness performances than other existing MAC protocols in a wide range of the traffic load and the number of stations. 相似文献
17.
18.
Frame relay is a significant networking technology in the current data networking environment. Given its inherent advantages, it is particularly well-suited to LAN interconnection. In a public network, frame relay has key advantages for end users in terms of performance and cost efficiency. The effectiveness of frame relay in public networks, the management of public frame relay networks, the evolution from frame to cell services, and product implementations are discussed. The advantages frame relay has over existing technologies are described 相似文献
19.
Lopez-Aguilera Elena Heusse Martin Grunenberger Yan Rousseau Franck Duda Andrzej Casademont Jordi 《Mobile Computing, IEEE Transactions on》2008,7(10):1213-1227
In a typical deployment of IEEE 802.11 wireless LANs in the infrastructure mode, an access point acts as a bridge between the wireless and the wired part of the network. Under the current IEEE 802.11 DCF access method, which provides equal channel access probability to all devices in a cell, the access point cannot relay all the frames it receives on the downlink. This causes significant unfairness between uplink and downlink flows, long delays, and frame losses. The main problem is that the access point requires more transmission attempt probability than wireless stations for correct operation at the transport layer. In this paper, we propose to solve the unfairness problem in a simple and elegant way at the MAC layer. We define the operation of an Asymmetric Access Point that benefits from a sufficient transmission capacity with respect to wireless stations so that the overall performance improves. The proposed method of operation is intrinsically adaptive so that when the access point does not need the increased capacity, it is used by wireless stations. We validate the proposed access method by simulation to compare it with other solutions based on IEEE 802.11e. Moreover, we provide measurement data gathered on an experimental prototype that uses wireless cards implementing the proposed method. 相似文献
20.
Advanced Infrared (AIr) is a proposed standard of the Infrared Data Association (IrDA) for indoor infrared LANs. AIr Medium Access Control (MAC) employs Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) techniques with Request To Send/Clear To Send (RTS/CTS) frame exchange to address the hidden station problem. A long Collision Avoidance Slot (CAS) duration, that includes the beginning of the CTS frame, is defined to cope with collisions caused from hidden stations. AIr MAC employs linear adjustment of the Contention Window (CW) size to minimize delays emerging from the long CAS duration. This paper provides a simple and accurate analytical model for the linear CW adjustment that calculates AIr throughput assuming a finite number of stations and error free channel transmissions. Validity of the model is verified by comparing analysis with simulation results. By examining the first derivative of the throughput equation, we derive the optimum CW size that maximizes throughput as a function of the network size. In the case of the AIr protocol, where a collision lasts exactly one CAS, different conclusions result for maximum throughput as compared with the corresponding conclusions for the similar IEEE 802.11 protocol. Using the proposed model, we present an extensive AIr throughput performance evaluation. The effectiveness of physical and link layer parameters on throughput performance is explored. The proposed long CAS duration combined with CW linear adjustment are proven quite effective. Linear CW adjustment combined with the long CAS duration offer an efficient collision avoidance scheme that does not suffer from collisions caused from hidden stations. 相似文献