BENoC: A Bus-Enhanced Network on-Chip for a Power Efficient CMP

Network-on-Chips (NoCs) outperform buses in terms of scalability, parallelism and system modularity and therefore are considered as the main interconnect infrastructure in future chip multi-processor (CMP). However, while NoCs are very efficient for delivering high throughput point-to-point data from sources to destinations, their multi-hop operation is too slow for latency sensitive signals. In addition, current NoCS are inefficient for broadcast operations and centralized control of CMP resources. Consequently, state-of-the-art NoCs may not facilitate the needs of future CMP systems. In this paper, the benefit of adding a low latency, customized shared bus as an internal part of the NoC architecture is explored. BENoC (Bus-Enhanced Network on-Chip) possesses two main advantages: First, the bus is inherently capable of performing broadcast transmission in an efficient manner. Second, the bus has lower and more predictable propagation latency. In order to demonstrate the potential benefit of the proposed architecture, an analytical comparison of the power saving in BENoC versus a standard NoC providing similar services is presented. Then, simulation is used to evaluate BENoC in a dynamic non-uniform cache access (DNUCA) multiprocessor system.     

Connection establishment in high-speed networks

Protocols for establishing, maintaining, and terminating connections in packet-switched networks have been studied, and numerous standards have been developed to address this problem. The authors reexamine connection establishment in the context of a high-speed packet network, introduce a protocol for connection establishment/takedown that is appropriate for such a network, and explain its advantages over previously proposed protocols. The main features of the proposed protocol are: fast bandwidth reservation in order to avoid as much as possible reservation conflicts, guaranteed release of the reserved bandwidth even under modal and link failures, and soft recovery from processor failures, which allows the maintenance of existing connections under processor failure provided the switch and links do not fail. The underlying model that is used is the PARIS/plaNET network, but the protocol can be adapted to other fast packet networking architectures as well     

Analysis of a correlated queue in a communication system

A family of queues is studied for which the service time B_n of customer n and the interarrival time I_n between customers n-1 and n exhibit some sort of proportionality. The focus is on dependencies that arise naturally in the context of communication systems, where the finite speed of the communication links constrains the amount of data that can be received in a given time interval. The simple case of a deterministic proportionality relation between the service time of a customer and its preceding interarrival time is considered. This is extended to allow the addition of an independent, generally distributed overhead to the service time of each customer. Several models that capture the ON-OFF behavior of communication links in packet networks are considered. In all cases, expressions for the delay experienced by a packet in the system are provided. Numerical examples illustrate the impact of dependencies through comparison with less accurate models. The results should be of relevance to environments other than communication as well     

Real-time packet switching: a performance analysis

The authors model the internal structure of a packet-switching node in a real-time system and characterize the tradeoff between throughput, delay, and packet loss as a function of the buffer size, switching speed, etc. They assume a simple shared-single-path switch fabric, though the analysis can be generalized to a wider class of switch fabrics. They show that with a small number of buffers the node will provide a guaranteed delay bound for high-priority traffic, a low average delay for low-priority traffic, no loss of packets at the input and low probability of packet loss at output     

Erasure, capture, and random power level selection inmultiple-access systems

Multiple-access algorithms that handle erasures as well as captures are introduced. The algorithms are evaluated according to the maximal throughput that they can support for a Poisson arrival process. An example is given which shows that, in practice, the positive effect of captures compensates the negative effect of erasures. An approach that effectively utilizes the capture phenomena is introduced. This approach incorporates a random power-level-selection scheme that allows each node to choose randomly to transmit in one of several allowable levels of power. Design issues such as number of levels, selection schemes, etc. are discussed     

Throughput properties of fair policies in ring networks

Considers a slotted ring in which simultaneous transmission of messages by different stations is allowed, a property referred to as spatial reuse. Ring networks with spatial reuse can achieve significantly higher throughput than standard token rings but they also introduce the possibility of starvation for some nodes on the ring. To alleviate this problem, various policies have been suggested in the literature. The present objective is to characterize the node throughputs achievable by general transmission policies in ring networks with spatial reuse and then to evaluate the throughput trade-off for a class of policies that has been proposed in the literature in order to avoid starvation. Specifically, the authors study a policy that is based on the idea of allocating transmission quotas to the nodes. Each node is guaranteed transmission of his quota within a specified interval. The authors show that by appropriately allocating the quotas, policies that satisfy general optimality criteria-in particular criteria related to fairness-can be designed. They also study the asymptotic behavior of the quota policy when either the quotas or the number of nodes increase     

Distributed Protocols for Networks with Mobile Users — The Mobilizer Approach

This paper introduces a novel approach, called Mobilizer, of operating synchronous communication protocols in cellular mobile environment. First, we present a distributed protocol, called Mobile Propagation of Information (MPI), for broadcasting information in mobile environment. Then, we present the Mobile Propagation of Information with Feedback (MPIF) protocol, which can be used to implement the Mobilizer approach, i.e., enable broadcast-based synchronous protocols run over distributed networks with mobile users. We prove the correctness of the protocols and show that the additional message complexity overhead, induced due to the Mobilizer, is linear with the number of users' movements.