DVB-RCS return link radio resource management for broadband satellite systems using fade mitigation techniques at ka band

Current Broadband Satellite systems supporting DVB-RCS at Ku band have static physical layer in order not to complicate their implementation. However at Ka band frequencies and above an adaptive physical layer wherein the physical layer parameters are dynamically modified on a per user basis is necessary to counteract atmospheric attenuation. Satellite Radio Resource Management (RRM) at the Medium Access Control (MAC) layer has become an important issue given the emphasis placed on Quality of Service (QoS) provided to the Users. The work presented here tackles the problem of Satellite RRM for Broadband Satellite systems using DVB-RCS where a fully adaptive physical layer is envisaged at Ka band frequencies. The impact of adaptive physical layer and user traffic conditions on the MAC layer functions is analyzed and an algorithm is proposed for the RRM process. Various physical layer issues associated with the resource management problem are also analyzed

Adaptive Multicast of Multi-Layered Video: Rate-Based and Credit-Based Approaches

Network architectures that can efficiently transport high quality, multicast video are rapidly becoming a basic requirement of emerging multimedia applications. The main problem complicating multicast video transport is variation in network bandwidth constraints. An attractive solution to this problem is to use an adaptive, multi-layered video encoding mechanism. In this paper, we consider two such mechanisms for the support of video multicast; one is a rate-based mechanism that relies on explicit rate congestion feedback from the network, and the other is a credit-based mechanism that relies on hop-by-hop congestion feedback. The responsiveness, bandwidth utilization, scalability and fairness of the two mechanisms are evaluated through simulations. Results suggest that while the two mechanisms exhibit performance trade-offs, both are capable of providing a high quality video service in the presence of varying bandwidth constraints.Comment: 11 page

Equilibrium bandwidth and buffer allocations for elastic traffics

Consider a set of users sharing a network node under an allocation scheme that provides each user with a fixed minimum and a random extra amount of bandwidth and buffer. Allocations and prices are adjusted to adapt to resource availability and user demands. Equilibrium is achieved when all users optimize their utility and demand equals supply for nonfree resources. We analyze two models of user behavior. We show that at equilibrium expected return on purchasing variable resources can be higher than that on fixed resources. Thus users must balance the marginal increase in utility due to higher return on variable resources and the marginal decrease in utility due to their variability. For the first user model we further show that at equilibrium where such tradeoff is optimized all users hold strictly positive amounts of variable bandwidth and buffer. For the second model we show that if both variable bandwidth and buffer are scarce then at equilibrium every user either holds both variable resources or none

The Renegotiable Variable Bit Rate Service: Characterisation and prototyping

he traffic generated by multimedia applications presents a high degree of burstiness that can hardly be described by a static set of traffic parameters. We present a dynamic QoS negotiation scheme applied to a prototype application that provides temporized data transfer. The dynamic and efficient usage of the resources can be reached with the introduction of the renegotiable variable bit rate (RVBR) service, which is based on the renegotiation of the traffic specification. We describe and discuss the RVBR service and how it applies to resource reservation for Internet traffic with RSVP. We propose an architecture design that we evaluate by accomplishing a prototype implementation, whose performance is measured with temporized file transfer using real MPEG2 video traces. The results we obtained indicate that renegotiation is an efficient mechanism for accommodating traffic fluctuations over the burst time-scale and that the RVBR service can be easily implemented in real applications, using available technology

A Definition of General Weighted Fairness and its Support in Explicit Rate Switch Algorithms

In this paper we give a general definition of weighted fairness and show how this can achieve various fairness definitions, such as those mentioned in the ATM Forum TM 4.0 Specifications. We discuss how a pricing policy can be mapped to general weighted (GW) fairness. The GW fairness can be achieved by calculating the $ExcessFairshare$ (weighted fairshare of the left over bandwidth) for each VC. We show how a switch algorithm can be modified to support the GW fairness by using the $ExcessFairshare$. We use ERICA+ as an example switch algorithm and show how it can be modified to achieve the general fairness. Simulations results are presented to demonstrate that the modified switch algorithm achieves GW fairness. An analytical proof for convergence of the modified ERICA+ algorithm is given in the appendix.Comment: Proceedings of ICNP'98, October199

Dynamic bandwidth allocation in multi-class IP networks using utility functions.

PhDAbstact not availableFujitsu Telecommunications Europe Lt

Data distribution satellite

A description is given of a data distribution satellite (DDS) system. The DDS would operate in conjunction with the tracking and data relay satellite system to give ground-based users real time, two-way access to instruments in space and space-gathered data. The scope of work includes the following: (1) user requirements are derived; (2) communication scenarios are synthesized; (3) system design constraints and projected technology availability are identified; (4) DDS communications payload configuration is derived, and the satellite is designed; (5) requirements for earth terminals and network control are given; (6) system costs are estimated, both life cycle costs and user fees; and (7) technology developments are recommended, and a technology development plan is given. The most important results obtained are as follows: (1) a satellite designed for launch in 2007 is feasible and has 10 Gb/s capacity, 5.5 kW power, and 2000 kg mass; (2) DDS features include on-board baseband switching, use of Ku- and Ka-bands, multiple optical intersatellite links; and (3) system user costs are competitive with projected terrestrial communication costs