Esmael Dinan

Spreading codes for direct sequence CDMA and wideband CDMA cellular networks

This article presents an overview of the spreading techniques for use in direct sequence CDMA cellular networks. We review the theoretical background for sequences used in CDMA and wideband CDMA, and discuss the main characteristics of the maximal length, Gold (1967, 1968), and Kasami sequences, as well as variable- and fixed-length orthogonal codes. We also describe different methods of multiple spreading for channelization and scrambling in CDMA and W-CDMA realizations.

Analytical framework for dynamic traffic partitioning in MPLS networks

Internet traffic engineering is concerned with the performance optimization of IP networks. Multiprotocol Label Switching (MPLS) is an important technology that supports the Internet traffic engineering function. This paper considers a network performance optimization problem related to traffic engineering over MPLS. We investigate the use of a dynamic traffic partitioning and assignment methodology to adaptively map ingress traffic into several parallel Label Switched Paths (LSPs) in MPLS based IP networks. We present a stochastic framework for the traffic partitioning problem. Within this framework, a set of parallel edge disjoint LSPs is modeled by parallel queues and a partitioning algorithm is devised for different service classes that is adaptive to the prevailing state of the network. The performance of this approach is illustrated with numerical examples.

Label switched packet transfer for wireless cellular networks

Packet transfer using a connectionless mode provides considerable simplification in mobility and handoff functionalities in wireless networks. We develop an architecture using label switched packet forwarding to enhance traffic control and accommodate service differentiation in the network. We present the protocol structure, mobility support, and routing, which are essential in this architecture. The use of the label merging technique is discussed to support multiple radio links between a mobile and a multiplicity of base stations. Preliminary performance results are presented for the effect of diversity areas on the admission control policy.

Performance analysis of a multilink packet access for next generation wireless cellular systems

Third generation wireless networks are expected to carry traffic from heterogeneous sources of voice, data, video or multimedia with a specified quality of service. We investigate how packet transfer mode over the radio interface can increase the efficiency of radio resources when there is multiple coverage of overlapping cells. Our discussion is focused primarily on multiple link packet protocol operation and its performance. We present an analysis of the system performance using a Markov modulated Poisson process (MMPP) for the aggregate of ON-OFF state traffic and for the overflow processes and quantify the performance improvement through a numerical example.

Optimal Traffic Partitioning in MPLS Networks

Multiprotocol Label Switching (MPLS) is an emerging Internet technology that facilitates traffic engineering in service provider networks. This paper considers a network performance optimization problem related to traffic engineering over MPLS. We investigate the issue of dynamic partitioning of MPLS ingress traffic into several parallel Label Switched Paths (LSP). Specifically, we present a stochastic framework for the traffic partitioning problem. Within this framework, a set of parallel edge disjoint LSPs is modeled by parallel queues and a partitioning algorithm is devised for different service classes that is adaptive to the prevailing state of the network. The performance of this approach is illustrated by numerical examples.

Modeling and performance of a multilink packet access for wireless cellular systems

This paper considers the problem of packet transfer over the radio interface of a cellular network, in which the diversity area may provide alternate resources for mobiles communicating with base stations. A multilink architecture is proposed for the forward link of packet cellular networks. We develop a model for the access mechanism using a two-state MMPP (Markov modulated Poisson process) for the aggregate arrival and a seven-state MMPP for the overflow traffic approximation. An analytical approach is used to calculate the system performance including the probability distribution of packet transmission delay and packet loss rate. We show how a simplified approximate model based on a much smaller number of states for the resulting MMPP can capture the system performance in a reasonably accurate way. We quantify the performance improvement through a numerical example and also compare the results to those obtained from the simulation model.

The Effects of Antenna Orientation Errors on UMTS Network Performance

Inconsistencies in setting up antenna azimuth and tilt during installation may reduce overall network performance. However, the degree of quality degradation depends on the amount of the discrepancy between the designed and installed parameters. The paper investigates the effect of these errors on UMTS RAN key performance indicators, including coverage, signal quality (EC/I0), and soft-handoff areas. Two examples are studied that include real field tests and measurement data. The studies show the effect of azimuth and tilt installation inaccuracies on UMTS network quality

Scheduling algorithms for soft handoff in cellular packet CDMA

We investigate and evaluate the performance of two scheduling algorithms for forward link packet access: in CDMA based cellular networks. Both algorithms use round-robin scheduling, ensuring fair access to users in overlapping and non-overlapping areas. One method provides time diversity whereas the other provides time as well as space diversity to users located in the handoff regions. The performance is also compared with that of a conventional hard handoff.

An efficient media access protocol for packet-switched wavelength-division multiplexed photonic networks

A reservation-based protocol based on a Pipelining Cyclic Scheduling Algorithm (PCSA) is proposed for packet-switched single-hop photonic networks. This protocol contains a mechanism to avoid contention at the receivers. Packets arrive in order and the transmission delay and its variations are optimized. The effects of propagation delay and processing time are almost compensated for by a pipelining technique. Analytical models and analysis are developed. The transmission delay is calculated as a function of the offered load, the number of nodes, propagation delay and processing time. Finally, the results of the analysis and simulations are compared.

Resource allocation for soft handoff in wireless packet CDMA system

Packet-oriented wireless networks provide additional flexibility in the allocation of resources to mobiles during soft handoff periods. In this paper, two different scheduling disciplines are developed for transmission of packets in the forward link of a cellular CDMA. Both algorithms are based on a double round robin approach. One is based on site selection diversity while the other uses the combining diversity technique. The algorithms provide a fair access to the radio resources among users located in the handoff and non-handoff areas. We present performance results, compare the two techniques and quantify the benefits of using site selection diversity.