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In future wireless ad hoc networks, transactions are expected to become one of the primary types of flows. Transactions require only a small number of packets to complete. Hence, providing optimal (shortest path) routes to such transactions consumes more energy than the actual data transfer. Conventional shortest path routing protocols are, thus, unsuitable for routing transactions. In this paper, we present a novel architecture, called TRANSFER, for transactions routing in large-scale wireless ad hoc networks. In our approach, we aim to reduce the total energy consumption by transactions as opposed to finding shortest path routes. Our architecture uses a hybrid approach, in which each mobile node obtains information about nodes in its proximity (zone), up to R hops away, using a proactive link-state protocol. Beyond the proximity, we introduce the novel notion of contacts that act as shortcuts to reduce the degrees of separation between the source of the transaction and the destination. We propose an efficient on-demand protocol for contact selection that does not assume knowledge of location information. Contacts are used during transactions and queries to discover valid routes in an energy-efficient manner. Extensive simulations are used to evaluate the performance of our protocol in terms of energy consumption and success rate. We compare our architecture to flooding, dynamic source routing (DSR), zone-routing protocol (ZRP), and two power-aware schemes. Our results show substantial power savings for our contact-based protocol, especially for large ad hoc networks. Index Terms--Adhoc networks, contact-based architecture, energy efficiency, network simulation, routing protocol.

A novel hybrid routing protocol - the Two-Zone Routing Protocol (TZRP) as a non-trivial extension of Zone Routing Protocol is proposed. TZRP uses two different zones to decouple the protocols ability to adapt to traffic characteristics from the ability to adapt to mobility.

The ATM VP-based leased line network communication demands varied combination of configurations that link the routes to the actual facilities. An integer programming formulation of the problem and an algorithm to solve it are proposed. It is proved that an algorithm can be used to solve problems with small computing lines.

The Session Initiation Protocol (SIP) and ISDN User Part (ISUP) congestion control functions are compared and the mechanisms that could be deployed in SIP networks, in order to achieve parity with ISUP networks are analyzed. The studies show that the methods for handling congestion and network overload are similar in ISUP and SIP applications.

The main processing requirements of Session Initiation Protocol (SIP) elements and the number of performance metrics required for supporting large customer bases and providing adequate performance on economical components are described. Results indicate that the SIP elements are influenced by parsing, string handling, memory allocation and thread architecture.

An architecture that assists in mobility management in Session Initiation Protocol (SIP) sessions in a heterogeneous network environment is described. The studies indicate that the new architecture is capable of combining mobility management and session control for SIP-based applications.

The problem of digital finite communication bandwidth (DFCB) control has come to the attention of the research community in connection with a growing interest in the development of distributed and/or networked control systems. In these systems, actuators, sensors, and other components are connected via data-rate constrained links such as wireless radio, etc. In this paper, we consider a scalar model of DFCB control that accommodates time-varying data-rate constraints, such as might occur with intermittent network congestion, and asynchronism of sampling and control actuation. Because of the possibly unpredictable fluctuation of the data-rate, we are interested in feedback control designs that will tolerate significantly constrained data-rates on feedback loops, while providing acceptable performance when such data-rate constraints are not in force. In light of a very basic notion of acceptable performance, we show that control designs with different number of quantization levels tolerate constrained data-rates differently. This leads to the conclusion that binary control represents the most robust control quantization under data-rate constraints imposed by time-varying congestion on the feedback communication channel. The advantage margin of binary control is further investigated numerically with and without the sampling-control asynchronism being considered. We show that the advantage margin is more substantial when the sampling-control asynchronism is significant. A design of quantized (binary) feedback with side channel information is proposed, and stability properties are discussed. We conclude the paper by examining performance limitations of our binary coding in the presence of noise. Index Terms--Coding, communication protocols, quantized control, sampling-control asynchronism.

Two of the fundamental issues in designing protocols for message passing between mobile agents (MAs) are tracking the migration of the target agent and forwarding messages to it. Even with an ideal fault-free network-transport mechanism, messages can be dropped during MA migration. Therefore, in order to provide reliable message delivery, protocols need to overcome message loss caused by asynchronous operations of agent migration and message forwarding. In this paper, two known message forwarding approaches, namely push and pull, are explored to design adaptive and reliable message delivery protocols. Based on a commonly used MA tracking model, the pros and cons of these two approaches are evaluated, both qualitatively and quantitatively. The comparative performance evaluation is presented in terms of network traffic and delay in message processing. We also propose improvements to the pull approach to reduce network traffic and the message delay. We conclude that with different message passing and migration patterns and varying requirements of real-time message processing, specific applications can select different message delivery approaches to achieve the desired level of performance and flexibility. Index Terms--Mobile agents (MAs), pull, push, reliable message delivery.

A novel, efficient and low cost start-up and restart synchronization approach for TDMA environments is presented by focusing on bus-based communication protocols. The approach utilizes information about a node's message length that forms a unique sequence to achieve synchronization such that communication overhead can be avoided.

Different static and dynamic schemes are explored to select the virtual lanes for outgoing messages and mix the load among them without restricting any particular type of message to be carried only by a particular virtual network. In addition, the network latency, the number of message buffers per virtual lane, and the depth of network interface output queues affect the relative performance of various virtual lane selection algorithms are examined.

A self-stabilizing asynchronous phase synchronization protocol for uniform unidirectional rings is presented. Provided that K and b satisfy the limitation K x b > n(b-1), the proposed protocol is correct under the parallel model and takes at most 2(K x b) rounds to stabilize.