The paper presents an analysis of the tracking component of SIP paging that has recently been introduced. Tracking protocol enables the tracking agent to keep track of the mobiles’ handoffs between access points. The tracking protocol can be modeled using soft-state and hard-state approaches. We analytically compare each of these approaches for state inconsistency ratio, message rate and the overall cost and determine the ranges of system parameters for which the soft-state approach is superior. Simulation model we developed enables us to evaluate the traffic introduced by the tracking protocol and the cache (state) size.

The paper addresses location tracking and paging IEEE 802.11 wireless LAN hosts that are in power save mode. We design a protocol for paging (tracking agent based paging or TAP) IEEE 802.11 wireless LAN hosts. Mobile nodes in each IEEE 802.11 basic service set constitute a layer-2 paging area, which coexists within layer-3 paging areas. The tracking agent is in charge of the L2 paging state, and it continuously updates the paging state after each L2 handoff. Paging on the wireless link is done by extended beacons, and does not involve periodic L3 messages. Signaling in TAP is based on IEEE's inter-access point protocol with minor extensions. We show that TAP can be integrated with various IP paging algorithms such as mobile IPv6 hierarchical paging, home agent and foreign agent paging. We evaluate the performance of the combined L3-L2 paging protocols analytically and by simulation and show that TAP combined with mobile IPv6 hierarchical paging achieves superior power savings compared individually to mobile IPv6 hierarchical paging without TAP or home agent paging algorithms.

We design a methodology for fast IPv4 and IPv6 address acquisition by mobile layer-2 entities in a wireless LAN. The main idea is to do the IP address assignment whenever it is necessary, not after the mobile establishes a layer-2 connection with a new access point. In order to achieve this, we propose to encapsulate the current IP address of the mobile to the association or re-association message in 802.11 WLANs. We present procedures of address acquisition for IPv4, IPv6 and Mobile IPv4, Mobile IPv6. Due to the hidden station problem, the mobile cannot successfully achieve the duplicate address detection (DAD) procedure in IPv6. Our proposal does not require the DAD, so the impact of the hidden station problem in IPv6 address assignment is eliminated. The proposed address assignment procedure, which is executed with layer-2 association, is faster than the existing DHCP-based stateful IP assignment.

We design a protocol for paging (tracking agent based paging or TAP) IEEE 802.11 wireless LAN hosts. Mobile nodes in IEEE 802.11 BSS constitute a layer-2 paging area. The tracking agent (TA) is in charge of the paging state, and TA continuously updates the paging state after each layer-2 handoff. Paging on the wireless link is done by extended beacons, and does not involve periodic layer-3 messages. Signaling in TAP is based on IEEE's IAPP (inter-access point protocol) with minor extensions. We evaluate the performance of TAP and show that TAP achieves superior power savings.

Handling of QoS priorities to differentiate flows is critical in the next generation Internet with ever increasing traffic. We present a scheme called p-persistent binary tree arbiter (PBTA) that approximates the general processor sharing (GPS) model. PBTA arbitrates between contending flows based on various quality of service parameters which are mapped to their weights or priorities; and, by being stateful, it provides a fair arbitration among the contending flows across the individual timeslots. Our simulations show that PBTA provides a fair technique among the flows by providing the proper service ratios and transit times conforming to the appropriate traffic classes. The advantage of the scheme is that it requires no modifications to the other scheduling algorithms. The preliminary FPGA implementation shows that the mechanism is implementable, fast, and conservative in chip area.

Arbitration between various contenders using given priority parameters is difficult to implement in hardware. We present a solution that solves this problem with minimal hardware. The solution presented is simple, fair, starvation-free, and fast. A contention resolving technique, called binary tree arbitration, is taken as a basis for implementing a "weighted fair" contention resolution technique that picks among "n" contenders, which could translate to flows, packets/cells, or connections. The extensions are priority and embedded binary tree arbitrations. Theoretical formulations of these techniques are presented. The results of their comparisons to software and hardware simulations, to show their relative conformance, are also presented.

In this work, we propose a new distributed signaling scheme, within the GMPLS framework for establishing lightpaths in wavelength-routed networks with sparse wavelength conversion. Analytical models are developed to evaluate the performance of the proposed scheme. Theoretical and simulation results show that compared to the classic schemed designed primarily for networks with no wavelength conversion, the proposed signaling scheme can achieve much lower blocking probability.

This paper details the wireless location-aware and content aware push application delivery over the packet-switched wireless core network. The directory server, which is deployed besides the WAP server in order to support the push applications by storing the user profile, IMSI and user IP address, requires static IP addressing to support such 3G applications. In current system, the incoming IP packets destined for dynamic IP users are discarded at the GGSN level. This paper introduces a methodology to provide push services to dynamic IP addressed-mobile users in 2.5G/3G networks, and minimize the unsuccessful-network-requested PDP context activation for static IP users. The proposed method is based on the protection and mobile user activity procedures, SMS service, and a new signaling mechanism to forward the HLR-based flags to the WAP/directory server.

When establishing lightpaths in an all-optical DWDM network, it is possible that concurrent lightpaths requests will block one another if the lightpaths attempt to reserve the same wavelength of the same link. In this paper, we propose a novel signaling mechanism, referred to as label prioritization, which attempts to reduce the backward-link blocking in GMPLS-centric all-optical networks by assigning different priorities to the suggested wavelengths of each connection request. The prioritization of the wavelength encourages concurrent lightpath requests to choose different wavelengths, thereby reducing the possibility that the requests will be blocked. The label prioritization mechanism consists of a signaling extension to GMPLS to support the label prioritization and a modification in the optical switch controller to support the signaling extension. Simulation results show that the label prioritization method can effectively reduce wavelength conflicts.

The paper addresses dormant mode operation support for wireless local area network (WLAN)-UMTS roaming for dual-mode users. Dormant mode operation means that the dormant MS stays in its dormant mode when it roams from WLAN to UMTS or UMTS to WLAN and keep its sessions open using mobile IP. Current technology doesn't support dormant mode operation when users roam between inter-technologies. User may roam in one of the technologies only. We propose a methodology to support the dormant mode roaming between inter-technologies, namely wireless local area networks and UMTS (or GPRS). The methodology is based on letting the access point of WLAN or GGSN of UMTS perform necessary registration functions in lieu of the mobile.

A problem of many distributed lightpath provisioning schemes is wavelength contention, which occurs when a connection request attempts to reserve a wavelength channel that is no longer available. This situation results from the lack of updated global link-state information at every node. In networks with highly dynamic traffic loads, wavelength contention may seriously degrade the network performance. To overcome this problem, we propose a new framework for distributed signaling and introduce a class of schemes referred to as intermediate-node initiated reservation. In the new scheme, reservations may be initiated at any set of nodes along the route; in contrast, reservations can only be initiated by the destination node in the classic destination initiated reservation (DIR) scheme. As a result, the possibility of having outdated information due to propagation delay is significantly lowered. Specifically, we consider two schemes within this framework, for networks with no wavelength conversion and for networks with sparse wavelength conversion, respectively. Theoretical and simulation results show that, compared with the classic DIR scheme, the new schemes can significantly improve the network blocking performance. The accuracy of the analytical models is also confirmed by extensive numerical simulations.

We propose four-layer optimization for UMTS coverage area: (i) cell-oriented intra-SGSN layer, which is optimized RA areas covering the intra-SGSN signaling cost, paging cost and RA load balancing, (ii) RA-oriented intra-MSC layer, which is optimized location areas covering the intra-MSC signaling cost and LA load balancing,(iii) RA-oriented inter-SGSN layer, which is optimized SGSN coverage areas covering the inter-SGSN signaling cost, RNC and SGSN load balancing, (iv) LA-oriented inter-MSC layer, which is optimized MSC coverage areas covering the inter-MSC signaling cost and MSC load balancing. We first calculate the multi-objective cost functions for each layers in UMTS, namely intra-SGSN and inter-SGSN layers. We then simulate an UMTS network using the niched Pareto genetic algorithm, which deals with multiple objectives by incorporating the concept of Pareto domination in its selection operator, and applying a niching pressure to spread its population out along the Pareto optimal tradeoff surface. We also define geographical footprints, and its impact on the network cost.

This paper covers the MAC sublayer fairness in the 802.11 networks. We first summarize the basic sublayer functionality specified by the 802.11 DCF-MAC standard. Then, the modified time-based media access method is proposed to provide an optimal fair access in any given wireless topology. The modified time-based method is based on our previously proposed time-based media access method. Although the time-based method significantly eliminates the fairness problem, they cannot provide the optimal fair access. By the introduction of the modified time-based method, not only it provides the optimal fairness, but also the need of estimating the weight factor is eliminated. The modified and time-based methods require periodic link information from the local neighboring stations. We also propose an information update procedure to exchange link information using a polling mechanism to employ the proposed method.

This paper covers new backoff algorithms, which decrease collisions on the non-reserved broadcast packets in wireless ad-hoc networks. Control information broadcasts provide the understanding of the local neighborhood topology to achieve some necessary network mechanisms in the ad-hoc networking. However, the exponential backoff algorithm introduces collisions due to non-reservation characteristics of the broadcast messaging. We propose a hierarchical and weighted-hierarchical backoff algorithm to decrease the percentage of collisions. These new algorithms classify the stations in a distributed manner within their local neighborhood. Each classified station uses the some portion of the backoff window size, which is assigned to this hierarchical group of stations. A local neighborhood discovery procedure is also proposed for stations to advertise their number of logical connections within their local neighborhoods. The proposed backoff algorithms use this procedure to advertise the connection values.

The wireless medium is a s=ce shared resource in mobde computing.Consequently, the media access control (MAC) layer influences the fairness and robustness of the wireless network.According to the current MAC protocok, stations are not able to gain access equdy to the shared wireless medium.This problem is conunody known as the fairness problem.The fairness problem occurs mostly bemuse of the existence of hidden stations and the presumption of a non-Wy connected wird=s network topology.This paper addresses solutions to the fairness problem in wireless networks.persistent carrier sense mdtiple access based dg~ rithms are proposed in which a fair wirel=s access for each user is accomplished using a precsdtiated N acce~Probabfity, Pij, . .that represents the Eti access probabtity horn station i to j. Lii access probabfities are dcdated at the source station in two ways using connection-based and time-based media access methods.According to the used methods, each active user broadcasts information on either the number of Iogicd connections or the average cent ent ion time to the stations within the communication reach.This information exchange provides partird understanding of the topology of the network to the stations.Each station reserves a specific priority for itse~to gain access to the shared medium.It is suggested that the information is exchanged during the W access discovery procedure for the connection-based method, and periodidy for the time-based method.Link access probabtit ies are modified every time the exchanged information is received.The proposed algorithms are dynamic and sensitive to the changes in the network topology.The sdgoritb have been implemented in a specific media access control protocol [1], but they are app~mble to d media access control protocok.Simdation restits show that the algorithms restit in an order of magnitude performance improvement in terms of throughput in a wirel= network.

In this paper, we present the performance of go-back-N and selective-reject automatic repeat request modes of high level data link control (HDLC) and the effect of the window size, packet error rate and processor speed in the maximum utilization in infrared wireless transmission systems. The maximum utilization (efficiency) performance of these protocols in half-duplex and full-duplex environments are being driven under different channel conditions. We demonstrate which link parameter is dominant in the performance under different link conditions, and also optimal packet sizes for ARQ schemes. It is also concluded that processing time affects the performance more than channel capacity after accomplishing a certain bit error rate.

In this paper, we evaluate the performance of infrared communication methods using repetition-rate coding over L-PPM wireless links to provide reliable infrared transmission throughout indoor environments. All receivers adapt the communication data rate by monitoring the channel, and they instruct transmitters to use highest rate if it is possible. Reducing the user data rate by a factor of RR (rate reduction) results in an RR-fold SNR improvement. We analyze how repetition-rate coding improves the capture probability of the infrared modem over L-PPM links. We also discuss the effect of RR-fold transmission in utilization using go-back-N and selective reject ARQ schemes.