Computer communication networks have come of age. Today, there is hardly any professional, particularly in engineering, that has not been the user of such a network. This proliferation requires the thorough understanding of the behavior of networks by those who are responsible for their operation as well as by those whose task it is to design such networks. This is probably the reason for the large number of books, monographs, and articles treating relevant issues, problems, and solutions in this field. Among all computer network architectures, those based on broadcast mul tiple access channels stand out in their uniqueness. These networks appear naturally in environments requiring user mobility where the use of any fixed wiring is impossible and a wireless channel is the only available option. Because of their desirable characteristics multiple access networks are now used even in environments where a wired point-to-point network could have been installed. The understanding of the operation of multiple access network through their performance analysis is the focus of this book.

Broadcast media, such as satellite, ground radio, and multipoint cable channels, can easily provide full connectivity for communication among geographically distributed users. One of the most important problems in the design of networks (referred to as packet broadcast networks) that can take practical advantage of broadcast channels is how to achieve efficient sharing of a single common channel. Many multiple access protocols, or algorithms, for packet broadcast networks have been proposed, and much work has been done on the performance evaluation of the protocols. A variety of techniques have been used to analyze the performance; however, this is the first book to provide a unified approach to the performance evaluation problem by means of an approximate analytical technique called equilibrium point analysis. Two types of packet broadcast networks - satellite networks and local area networks are considered, and eight multiple access protocols are studied and their performance analyzed in terms of throughput and average message delay. Contents Part I: Fundamentals - Multiple Access Protocols and Performance - Equilibrium Point Analysis - Part II: Satellite Networks - S-ALOHA - R-ALOHA - ALOHA-Reservation - TDMAReservation - SRUC - TDMA - Performance Comparisons of the Protocols for Satellite Networks - Part III: Local Area Networks - Buffered CSMACD - BRAM Performance Analysis of Multiple Access Protocols is included in the Computer Systems Series, Research Reports and Notes, edited by Herb Schwetman.

Using Carrier Sense Multiple Access with Collision Detection (CSMA/CD), Ethernet Local Area Networks (LANs) suffers from capture effect in packet loss. As a result of capture effect, some nodes may be locked-out using the medium for a period of time. Hence, CSMA/CD based Enthernet is unsuitable for real-time multimedia traffic. It does not guarantee delay bound, behaves poorly under heavy load conditions. To overcome these shortcomings and enhance performace of CSMA/CD base LAN, three new concepts are added to the conventional CSMA/CD. Firstly, each node in the LAN has a finite buffer. A nodes competes for access to the medium after its buffer is full. It will transmit all packets in the buffer if access is permitted. To minimize the waiting delay of packets in the buffer prior to transmission, a time-out period is set, beyond which a node is tries to transmit considering its buffer is full. Due to buffer, the number of nodes trying to transmit at a time is reduced, thereby collision rates is reduced. Capture effect, locked-out probability, bandwidth loss, and backoff delays are also reduced. To support all types of traffic ( mainly real-time traffic), the optimum buffer size obtained is 10 packets/buffer. Using this buffer, multimedia traffic can be sent in a streamed fashion within a delay bound. Secondly, the maximum retransmission attempt limit and backoff limit are reduced to 10 and 8 times respectively to guarantee a tolerable delay for multimedia applications. A new special-jamming signal is introduced. It gives transmission priority to the node that already has finished its maximum retransmission attempt. This prevents packet loss and quality degradation of received normal data traffic and multimedia traffic. The final one is the priority scheduler, which is activated when multiple modes send the special-jamming signal at a time. It gives permission to the node having either the lowest time-stamp of the smallest source of address (SA) to transmit while other nodes wait until their access is permitted accordingly. The proposed protocol is based on bus topology for a single channel LAN. Throughput, transmission efficiency, average delay and percentage of collision of the proposed network is evaluated against number of nodes, bus length and offered load within two enviroments, i.e. Fast Ethernet and Gigabit Enthernet. The results show significant performance improvement. Throughput, transmission efficiency are increased more than 10% average. On the other hand, average delay and percentage of collision are reduced to less than 2 ms and 3.5% respectively compared to the conventional CSMA/CD based LAN.

The fast growing traffic demand in telecommunication networks, by use of the Internet and an increasing number of broadband services for multimedia com munications, requires new high performance networking technologies. As such, optical WDM networks are playing a pivotal role. Wavelength Division Mul tiplexing (WDM) with many hundreds of wavelength channels per fiber is ex tensively being exploited in wide area networks. With respect to the ongoing trend towards a completely packet-switched mode of operation for all services, WDM networks must be prepared accordingly. This work concentrates on optical packet-switched networking in local and metro area networks for realizing high-performance applications like virtual re ality, medical imaging, and supercomputing. It is well known that in those networks using a star, bus, or ring shared medium, an access protocol is nec essary to guarantee controlled and fair access for all attached nodes. Similar access protocols are to be developed and analyzed for WDM local and metro area networks. Already, many media access protocols for these networks have been described in the literature. However, some aspects of Quality-of-Service (QoS) for different service classes are still an open issue and subject to inten sive research activities. In the introduction, the author, Dr. Kemal Bengi, gives a short classification of media access protocols and network architectures for WDM local and metro area networks. The need for service classes is also em phasized.

The single mode optical fiber possesses an enormous bandwidth of more than 30 THz in the low-loss optical region of 1.3 $\mu$m and 1.5 $\mu$m. Through Wavelength Division Multiplexing (WDM), the optical fiber bandwidth can be divided into a set of high-speed channels, where each channnel is assigned its own unique wavelength. An M x M passive optical star coupler is a simple broadcast medium, in which light energy incident at any input is uniformly coupled (or distributed) to all the outputs. Thus, a passive star along with the WDM channels can be used to configure a Local Area Network (LAN). In this LAN, users require tunable devices to access a complete or a partial set of the WDM channels. Due to these multiple channels, many concurrent packet transmissions corresponding to different user pairs are possible and thus the total system throughput can be much higher than the data rates of each individual channel. To fairly arbitrate the data channels among the users, media access protocols are needed. Depending upon the number of data channels and the number of users, two possible situations arise. In the first case, the number of users is much larger than the number of data channels and in the second, the number of users equals to the the number of channels. In both cases, data channel contention may arise if multiple users access the same given channel and must be resolved. This thesis proposes media access protocols for passive optical star networks. All the proposed protocols are slotted in nature, i.e., the time axis on each channel is divided into slots. The well known Slotted-ALOHA and Reservation ALOHA protocols are extended to the multi channel network environment. The thesis also proposes switching protocols (equal number of channels and users), contention-based reservation protocols for this network architecture. To interconnect these star networks, a multi-control channel protocol is also proposed along with two interconnecting techniques. Since there are multiple data channels, the data packets on different channels may be destined to the same user. However, if the user is equipped with only one receiver, the user can receive only one packet and ignores others. This is called a 'receiver collision' and the thesis also studies the effect of these receiver collisions on the data channels. Two network architectures, one for a packet circulating ring network and the other for a circuit switched application are described. Finally, the thesis studies some implementation considerations for these protocols.