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Showing papers on "Handover published in 1996"


Journal ArticleDOI
TL;DR: The author presents an overview of published work on handover performance and control and discusses current trends in handover research, and focuses on macrocells, but includes a brief discussion on how things change as cell sizes shrink.
Abstract: Handover is the mechanism that transfers an ongoing call from one cell to another as a user moves through the coverage area of a cellular system. As smaller cells are deployed to meet the demands for increased capacity, the number of cell boundary crossings increases. The author presents an overview of published work on handover performance and control and discusses current trends in handover research. He discusses investigations that are applicable to a single tier of cells. He focuses on macrocells, but includes a brief discussion on how things change as cell sizes shrink. By assuming an overlay of macrocells and microcells he summarizes issues and approaches unique to such systems.

594 citations


Journal ArticleDOI
TL;DR: It is shown that the distributed call admission control scheme limits the handoff dropping or the cell overload probability to a predefined level almost independent of load conditions, an important requirement of future wireless/mobile networks with quality-of-service (QoS) provisioning.
Abstract: The major focus of this paper is distributed call admission control in mobile/wireless networks, the purpose of which is to limit the call handoff dropping probability in loss systems or the cell overload probability in lossless systems. Handoff dropping or cell overload are consequences of congestion in wireless networks. Our call admission control algorithm takes into consideration the number of calls in adjacent cells, in addition to the number of calls in the cell where a new call request is made, in order to make a call admission decision. This is done by every base station in a distributed manner without the involvement of the network call processor. The admission condition is simple enough that the admission decision can be made in real time. Furthermore, we show that our distributed call admission control scheme limits the handoff dropping or the cell overload probability to a predefined level almost independent of load conditions. This is an important requirement of future wireless/mobile networks with quality-of-service (QoS) provisioning.

488 citations


Proceedings ArticleDOI
24 Mar 1996
TL;DR: It is shown that the well-known guard channel policy is optimal for the MLNOBJ problem, while a new fractional guard channels policy is ideal for the MINBLOCK and MINC problems.
Abstract: Two important quality-of-service (QoS) measures for current cellular networks are the fractions of new and handoff "calls" that are blocked due to unavailability of "channels" (radio and/or computing resources). Based on these QoS measures, we derive optimal admission control policies for three problems: minimizing a linear objective function of the new and handoff call blocking probabilities (MINOBJ), minimizing the new call blocking probability with a hard constraint on the handoff call blocking probability (MINBLOCK) and minimizing the number of channels with hard constraints on both of the blocking probabilities (MINC). We show that the well-known guard channel policy is optimal for the MLNOBJ problem, while a new fractional guard channel policy is optimal for the MINBLOCK and MINC problems. The guard channel policy reserves a set of channels for handoff calls while the fractional guard channel policy effectively reserves a non-integral number of guard channels for handoff calls by rejecting new calls with a probability that depends on the current channel occupancy. It is also shown that the fractional policy results in significant savings (20-50%) in the new call blocking probability for the MINBLOCK problem and provides some, though small, gains over the integral guard channel policy for the MINC problem. Further, we also develop computationally inexpensive algorithms for the determination of the parameters for the optimal policies.

388 citations


Journal ArticleDOI
TL;DR: The probability of erroneous assignment of a mobile to a microcell or macrocell is shown to be significantly lower than previous approaches, and a systematic way for finding an optimal partition of frequency spectrum between microcells and macrocells is proposed.
Abstract: In this paper, we study spectrum management in a two-tier microcell/macrocell cellular system. Two issues are studied: micro-macro cell selection and frequency spectrum partitioning between microcells and macrocells. To keep the handoff rate in a two-tier cellular system at an acceptable level, low mobility users (with speed /spl upsi/ V/sub 0/) should undergo handoffs at macrocell boundaries. The mobile determines user mobility from microcell sojourn times and uses it for channel assignment at call origination and handoff. The probability of erroneous assignment of a mobile to a microcell or macrocell is shown to be significantly lower than previous approaches. We investigate the optimal velocity threshold, V/sub 0/, and propose that it may be dynamically adjusted according to traffic load. Finally, we propose a systematic way for finding an optimal partition of frequency spectrum between microcells and macrocells. This partitioning is based on the traffic load and velocity distribution of mobiles in the system.

243 citations


Patent
01 May 1996
TL;DR: In this paper, the location of a mobile unit M of a cellular radio system is determined by determining the differences in timing of a characteristic feature of the transmission of the control channel of each base station A, B, C, D, E as measured at the mobile unit.
Abstract: The location of a mobile unit M of a cellular radio system is determined by determining the differences in timing of a characteristic feature of the transmission of the control channel of each base station A, B, C, D, E as measured at the mobile unit. Preferably the characteristic feature is the training sample already used by the mobile unit in cellular systems to measure signal strength in order to inform handover decisions. By determining the differences between time of arrival of transmissions from four base stations A, B, C, D, position in two dimensions can be derived without prior knowledge of the actual distance to any of the base stations. A fifth base station E allows position in three dimensions to be determined.

153 citations


Journal ArticleDOI
TL;DR: The authors propose a novel procedure called "nearest common node rerouting (NCNR)", designed to perform the rerouted of user connections due to a handoff event in a fast and efficient manner.
Abstract: Handoff is the procedure by which a user's radio link is transferred between radio ports in the network without an interruption of the user connection. We discuss how a wireless asynchronous transfer mode (ATM) network may reroute a user connection during a handoff. The authors propose a novel procedure called "nearest common node rerouting (NCNR)". NCNR is designed to perform the rerouting of user connections due to a handoff event in a fast and efficient manner. The authors conclude by comparing NCNR to other rerouting schemes discussed in the literature.

139 citations


Patent
02 Dec 1996
TL;DR: In this article, the approximate distance and direction of a mobile unit from a plurality of cells in order to determine whether and how to handoff the mobile unit and which cell may be the best serving cell.
Abstract: A system and method for measuring the approximate distance and direction of a mobile unit from a plurality of cells in order to determine whether and how to handoff the mobile unit and which cell may be the best serving cell. The CDMA timing system is used to provide an estimate of the subscriber's location to be determined by a CDMA base station. A distance calculation is made by the serving cell site sending a request for signal strength message to a mobile unit. The mobile unit measures pilot signal strength and a time offset from the expected time of such pilot signals. The signal strength and time offsets are returned to the cell site. a processor in the system can then determine if a handoff is really desirable, and with which of the cell sites is the best serving all for the mobile unit the mobile unit with a high degree of confidence that the call will be maintained. Also, an adaptive database may be implemented wherein a mobile unit is tracked to the edge of the coverage area and, a database is kept of successful handoffs to another carrier.

135 citations


Patent
01 Nov 1996
TL;DR: In this article, a radio data transmission system which transmits data in cell form can be reduced by synchronizing the cell transmission between the new (50) and the old (40) base stations, whereby the new base station continues the transmission by starting from the first failed cell.
Abstract: In a radio data transmission system which transmits data in cell form, the risk of cell loss or the risk of out-of-ordering during handover can be diminished by synchronizing the cell transmission between the new (50) and the old (40) base stations. The old base station (40) delivers to the new base station (50) and/or the switch (51), information on the last cell that was transmitted successfully and in the right order through the old base station, whereby the new base station continues the transmission by starting from the first failed cell. Cells need not be identified one by one if group numbering is applied in which the first or the last cell of a given group (31, 32, 33, 34) or a given counter cell is numbered, and the rest can be indicated, where necessary, by counting the distance from the numbered cell.

132 citations


Journal ArticleDOI
TL;DR: It is concluded that the larger the area the soft handoff region is, the better users in the cellular network will feel.
Abstract: The code-division multiple-access (CDMA) scheme has been considered as one possible choice of the future standards for cellular networks because of its various advantages. Since there can be only one carrier frequency being used in CDMA systems, a handoff scheme with diversity, a so-called "soft handoff", was proposed for higher communication quality and capacity. A mathematical model is developed to analyze the soft handoff process. Markov's concept is applied to describe the system's steady state statistical behavior. System performance such as blocking probability, handoff refused probability, and channel efficiency are also determined. It is concluded that the larger the area the soft handoff region is, the better users in the cellular network will feel.

131 citations


Proceedings ArticleDOI
23 Jun 1996
TL;DR: A signaling and control architecture for mobility support in a "wireless ATM" network that provides integrated broadband services to mobile terminals is presented, and preliminary solutions are given for selected major functions.
Abstract: This paper presents a signaling and control architecture for mobility support in a "wireless ATM" network that provides integrated broadband services to mobile terminals. ATM signaling and wireless control capabilities required for mobility services are discussed, and preliminary solutions are given for selected major functions. Potential extensions to ITU standard Q.2931 ATM signaling are proposed to support mobility related functions such as handoff and service parameter/QOS renegotiation. A custom wireless control protocol for supporting terminal migration, resource allocation, handoff, etc. is outlined for a wireless ATM network. Preliminary experimental results validating the proposed handoff control protocol on an ATM network testbed are briefly outlined.

110 citations


Proceedings ArticleDOI
23 Jun 1996
TL;DR: selected network-based multimedia/video applications operating at moderate bit-rates (-0.5-1 Mbps) in ABR/AALS/TCP mode have been successfully demonstrated on the laptop PC.
Abstract: A prototype microcellular wireless ATM network (WATMnet) capable of providing integrated multimedia communication services to mobile terminals is described in this paper. The experimental system's hardware consists of laptop computers (NEC Versa-M) with WATMnet interface cards, multiple VME/i960 processor-based WATMnet base stations, and a mobility-enhanced local-area ATM switch. The prototype wireless network interface cards operate at peak bit-rates up to 8 Mbps, using low-power 2.4 GHz ISM-band modems. Wireless network protocols at the portable terminal and base station interfaces support ABR, VBR and CBR transport services compatible with ATM using a dynamic TDMA/TDD MAC protocol for channel sharing and data link control (DLC) protocol for error recovery. A custom wireless control protocol is also implemented between the portable and base units for support of radio link related functions such as user registration and handoff. All network entities including the portable, base and switch use a mobility-enhanced version of ATM ("Q.2931+") signaling for switched virtual circuit (SVC) connection control functions, including handoff. Early experiments with the WATMnet prototype have been conducted to validate major protocol and software aspects, including DLC, wireless control and mobility signaling for handoff. Selected network-based multimedia/video applications operating at moderate bit-rates (-0.5-1 Mbps) in ABR/AALS/TCP mode have been successfully demonstrated on the laptop PC.

Patent
31 Dec 1996
TL;DR: In this article, a simple and flexible over-air protocol for use with a mobile telephone system, having hand-held telephones in a microcell or other type of cellular communication system is presented.
Abstract: A simple and flexible over-air protocol for use with a mobile telephone system, having hand-held telephones in a microcell or other type of cellular communication system. A method in which user stations communicate with one or more base stations to place and receive telephone calls, in which the user stations are provided a secure voice or data link and have the ability to handoff calls between base stations while such calls are in progress. Each base station has a set of "air channels" to which it transmits in sequence. The air channels supported by each base station are called that base station's "polling loop". A user station receives general polling information on an unoccupied air channel, transmits responsive information to the base station, and awaits acknowledgment from the base station. Each base station may therefore simultaneously maintain communication with as many user stations as there are air channels in its polling loop. The ability of a user station to communicate on any unoccupied air channel makes the protocol air-channel agile, while the stability of user station and base station clocks may define air channels, gaps, and minor frames.

Proceedings ArticleDOI
24 Mar 1996
TL;DR: This work provides explicit analytic expressions for the two kinds of blocking probabilities in two asymptotic regimes, i.e., for very slow mobile users and for very fast mobile users, and shows the fundamental differences between these blocking probabilities.
Abstract: In cellular networks, blocking occurs when a base station has no free channel to allocate to a mobile user. One distinguishes between two kinds of blocking, the first is called new call blocking and refers to blocking of new calls, the second is called handoff blocking and refers to blocking of ongoing calls due to the mobility of the users. We first provide explicit analytic expressions for the two kinds of blocking probabilities in two asymptotic regimes, i.e., for very slow mobile users and for very fast mobile users, and show the fundamental differences between these blocking probabilities. Next, an approximation is introduced in order to capture the system behavior for moderate mobility. The approximation is based on the idea of isolating a set of cells and having a simplifying assumption regarding the handoff traffic into this set of cells, while keeping the exact behavior of the traffic between cells in the set. It is shown that a group of 3 cells is enough to capture the difference between the blocking probabilities of handoff call attempts and new call attempts.

Patent
26 Mar 1996
TL;DR: In this paper, a system and method of providing users of a mobile cellular telecommunication network, who subscribe to priority service, with priority access to voice or traffic channels during periods of congestion was proposed.
Abstract: A system and method of providing users of a mobile cellular telecommunication network, who subscribe to priority service, with priority access to voice or traffic channels during periods of congestion (62) on these channels. The system provides priority to designated priority users for call origination, call termination, and handoff to congested cells. When the network is not congested (63-64), any channel is available for use by any user, whether a designated priority user or not. During periods of congestion, the system enables a service provider to designate (65) whether a reserved bank of channels, a queue technique, or a combination of both is to be utilized to provide priority access and channel assignment (PACA). Call requests are positioned (71) in a queue according to the priority level of the associated subscriber, and by time of arrival within each priority level.

Patent
23 May 1996
TL;DR: In this article, the authors proposed a method for improving the reliability of a handover in a cellular radio system, which comprises in each cell at least one base station (100) communicating with terminal equipments (102) located within its coverage area, which base stations calculate the location of each terminal equipment in the coverage area of the base station on the basis of the direction angle and distance of the terminal equipment.
Abstract: The invention relates to a cellular radio system and a method for improving the reliability of a handover in a cellular radio system, which comprises in each cell at least one base station (100) communicating with terminal equipments (102) located within its coverage area, which base stations calculate the location of each terminal equipment in the coverage area of the base station on the basis of the direction angle and distance of the terminal equipment, and which terminal equipments measure the signal strength from the base stations that are in the list of nearby base stations maintained by the terminal equipment, in order to determine the need for a handover. In order to enable fast measurements and reliable handover, the list of nearby base stations maintained by each terminal equipment (102) is updated on the basis of the location calculated for each terminal equipment.

Patent
Ghisler Walter1
26 Apr 1996
TL;DR: In this article, a mobile switching center switches from the base station to a connection with the sub-section, while the mobile station continues to listen to the identification frequencies and reports the signal strength on its connection.
Abstract: A mobile telephone system has in a cell a base station and sub-stations which are connected to a mobile switching center. The mobile telephone system has control channels and frequencies which are time divided to traffic channels. Some of the frequencies are selected as identification frequencies. Each of the sub-stations is assigned a unique set of frequencies from among the identification frequencies and constantly transmit their respective frequency set. A mobile station connected to the base station listens to the identification frequencies and reports the strongest of these frequencies to the mobile switching center. The mobile switching center compares the reported frequencies with the unique set of frequencies, compares the reported signal strength with a threshold value and selects the nearest sub-station for handoff. The mobile switching center switches from the base station to a connection with the sub-section. The mobile station continues to listen to the identification frequencies and reports the signal strength on its connection. When the strength of the signals from the selected sub-station is low, the connection is switched back to the base station.

Patent
25 Jan 1996
TL;DR: In this paper, a handoff method is presented for transferring communications between two time domain systems including the steps of initiating time adjusted operation by a mobile station on a flexible time domain system and informing the flexible time-domain system of at least one particular activity requirement of the mobile station.
Abstract: A handoff method is shown in the figure providing for the mobile station to transfer its communications between two time domain systems including the steps of initiating time adjusted operation by a mobile station on a flexible time domain system and informing the flexible time domain system of at least one particular activity requirement of the mobile station.

Patent
Burkhard Pauli1, Ralf Neuhaus1, Hans-Dieter Ide1, Horst Flake1, Otger Wewers1 
29 May 1996
TL;DR: In this paper, the authors propose a cellular cordless telecommunications system which makes it possible to implement a large number of performance features, such as synchronization, roaming, handover, internal links, hold, check-back, transfer etc.
Abstract: In order to design a cellular cordless telecommunications system which makes it possible to implement a large number of performance features, for example synchronization, roaming, handover, internal links, hold, check-back, transfer etc. in the cellular cordless telecommunications system without any additional wire link between the cordless base stations in the cellular cordless telecommunications system, the cordless base stations are connected to an S0 bus (i.e., a basic access line for a multi-device configured system).

Proceedings ArticleDOI
29 Sep 1996
TL;DR: This paper discusses how a wireless asynchronous transfer mode (ATM) network may reroute a user connection during a handoff and proposes a novel procedure called "nearest common node rerouting (NCNR), designed to perform the rerouted of user connections due to a handoffs event in a fast and efficient manner.
Abstract: Handoff is the procedure by which a user's radio link is transferred between radio ports in the network without an interruption of the user connection. In this paper, we discuss how a wireless asynchronous transfer mode (ATM) network may reroute a user connection during a handoff. We propose a novel procedure called "nearest common node rerouting (NCNR)". NCNR is designed to perform the rerouting of user connections due to a handoff event in a fast and efficient manner. We conclude by comparing NCNR to other rerouting schemes discussed in the literature.

Proceedings ArticleDOI
01 Nov 1996
TL;DR: The handover procedure is simple enough to be implementable as a limited enhancement to ATM switch platforms for fixed network, yet provides lowdelay and lossless handover when used together with a suitable radio interface.
Abstract: Handover is one of the key research topics for the emerging wireless ATMnetworks This paper describes a handover mechanism for intra-switch handovers for wireless ATM The handover procedure is simple enough to be implementable as a limited enhancement to ATM switch platforms for fixed network, yet provides lowdelay and lossless handover when used together with a suitable radio interface The paper also reports on initial simulation result

Proceedings ArticleDOI
24 Mar 1996
TL;DR: Simulation results obtained from a trace-driven mobile network simulator reveal that both prior path and distributed hunt discoveries outperform the others by providing the fastest convergence with shorter resulting paths and higher circuit reuse efficiency.
Abstract: In a connection-oriented wireless LAN, the mobility of mobile hosts results in the establishment and disconnection of new and old virtual circuits. The resulting increase in signalling traffic along with the need to support multimedia stream handovers demand a fast, continuous and bandwidth-efficient handover protocol. We adopt a handover scheme based on partial re-establishments, where a new partial path converges to an existing path. Connection rerouting (CR) operations are then performed at the convergence/crossover switch (CX). To achieve localised handovers, a wireless cell clustering scheme is proposed. The clustering of base stations to cluster switches (CLSs) provides fast intra-cluster handovers since the CR operations are performed at the CLS. To support fast inter-cluster handovers, four CX discovery schemes (loose select, prior path, distributed hunt and backward tracking) are introduced. Simulation results obtained from a trace-driven mobile network simulator on four different network topologies (random, star, tree and hierarchical redundancy) reveal that both prior path and distributed hunt discoveries outperform the others by providing the fastest convergence with shorter resulting paths and higher circuit reuse efficiency.

Patent
13 Jun 1996
TL;DR: In this article, when a mobile station satisfies a criterion for automatic intercellular handover from a source cell to a target cell, the speed of movement of the mobile station with respect to the base station of the target cell is estimated on the basis of the measured levels of the signal which the mobile stations has received from this base station before the handover criterion is satisfied.
Abstract: In a multicellular radio communications network, when a mobile station satisfies a criterion for automatic intercellular handover from a source cell to a target cell, the speed of movement of the mobile station with respect to the base station of the target cell is estimated on the basis of the measured levels of the signal which the mobile station has received from this base station before the handover criterion is satisfied. Depending on the layers of the cells concerned, it is then possible to take account of this speed estimate in order to decide whether or not to trigger intercellular handovers.

Patent
19 Jan 1996
TL;DR: In this paper, a mobile communication system is disclosed which precludes the necessity for mobile station to perform processing for microcell zone switching even when it moves from one microcell to another and which permits high-speed macrocell zone handover.
Abstract: A mobile communication system is disclosed which precludes the necessity for mobile station to perform processing for microcell zone switching even when it moves from one microcell zone to another and which permits high-speed microcell zone handover The service area of mobile communication is split into a plurality of macrocells; the macrocells are each subdivided into a plurality of microcells; a microcell base station equipped with a transmitting and receiving antenna and a power amplifier is installed in each microcell; a different communication channel is assigned to individual mobile station in the macrocell; even when the mobile station moves from one microcell to another, no channel handover takes place; and only when the mobile station moves from one macrocell to another, a mobile network control center which supervises the macrocell base stations effects channel handover

Patent
10 Sep 1996
TL;DR: In this article, a soft handoff operation using the ratio of the received forward link pilot signal power to the sum of all interference signals power to transfer a portion of traffic load in the present serving cell with high traffic density to an adjacent cell with a low traffic density is proposed.
Abstract: A method for shedding traffic load in a code division multiple access mobile communication system, the method performing a soft handoff operation using the ratio of the received forward link pilot signal power to the sum of all interference signals power to transfer a portion of traffic load in the present serving cell with a high traffic density to an adjacent cell with a low traffic density. When the amount of traffic load in the present serving cell is increased and thus exceeds a link capacity of the present serving cell, handoff parameters of all mobile stations in the present serving cell can be updated on the basis of a power allocation state managed by a base station without reducing the coverage of a forward link. On the basis of the updated handoff parameters, the soft handoff operation is performed from a part of the mobile stations in the present serving cell with the high traffic density (for example, mobile stations at the edge of the present serving cell) to the adjacent cell with the low traffic density. Therefore, the excessive traffic load amount in the present serving cell can effectively be shed.

Patent
Shoji Tanaka1
04 Oct 1996
TL;DR: In this paper, the mobile station judge whether or not it is necessary for the base station to carry out a base transmission power control in accordance with the information and a base maximum transmission power.
Abstract: A mobile communication system of a cellular type has in each cell a base station (12a-12c) for carrying out bidirectional communication between the base station and a mobile station (11). The base station announces a transmission power of the base station and up link reception power and up link signal quality as information to the mobile station. The mobile station judges whether nor not it is necessary to carry out a hand-over control in accordance with the information and a predetermined hand-over control information. The mobile station judges whether or not it is necessary to carry out said hand-over control in accordance with a down link received signal strength indicator, a down link received signal quality, and the predetermined hand-over control information. The mobile station may judge whether or not it is necessary for the base station to carry out a base transmission power control in accordance with the information and a base maximum transmission power. Furthermore the mobile station may judge whether or not it is necessary for the mobile station to carry out a mobile transmission power control in accordance with the information and a mobile maximum transmission power.

Patent
17 Dec 1996
TL;DR: In this paper, the authors propose a method for hard handoff of a call from a first cell site of a CDMA cellular network to a target cell sites of a second cellular network, such as an AMPS network or a second CDMA network.
Abstract: A method for performing a hard handoff of a call from a first cell site of a CDMA cellular network to a target cell site of a second cellular network, such as an AMPS network or a second CDMA network. As a mobile unit operating in the first CDMA network moves toward the second cellular network, the first cell site uses two separate RTD thresholds for comparison with a measured RTD distance between the mobile unit and the first cell site. Handoff is initiated when the RTD distance exceeds the first RTD threshold and is completed when the RTD distance exceeds the second RTD threshold. If the first cell site is not co-located with a cell site of the second network, the first cell site utilizes receivers placed in the target cell site for handoff. If the first cell site is co-located with a second cell site of the second network, the second cell site of the second network is always the target cell site.

Journal ArticleDOI
TL;DR: A new architecture for the third-generation mobile systems, capture-division packetized access (CDPA), that overcomes most of the limitations of present cellular systems and is very effective in local area systems where the required high bandwidth is obtained by using a pico-cell structure.
Abstract: This paper presents a new architecture for the third-generation mobile systems, capture-division packetized access (CDPA), that overcomes most of the limitations of present cellular systems. It addresses the three main issues of radio access, namely the channel reuse, the multiple access, and the handover problems, in complete adherence to packet-switching principles. The CDPA channel reuse mechanism is a completely new alternative with respect to time-division, frequency-division, or code-division multiple-access (TDMA, FDMA, and CDMA, respectively), which achieve communication parallelism by subdividing the bandwidth a priori among cells. In CDPA, a single frequency channel is used and parallel transmissions are achieved through the "capture" capability of receivers. The hybrid reservation-polling multiple access mechanism used in CDPA is able to integrate any kind of traffic and guarantees almost immediate retransmission of packets that are not captured, thus assuring their correct reception. Finally, the packet-switching approach allows connectionless communications with any base station (BS), and eliminates the need for extra radio traffic in managing handovers. This turns out to be very effective in local area systems where the required high bandwidth is obtained by using a pico-cell structure. We present the CDPA architecture, discuss some implementation issues, and evaluate its performance under a variety of system parameters and operating conditions, using analytical and simulation methods.

Journal ArticleDOI
Ruixi Yuan1, Subir Biswas1, L.J. French1, Jun Li1, Dipankar Raychaudhuri1 
TL;DR: This paper presents a signaling and control architecture for mobility support in a “wireless ATM” network that provides integrated broadband services to mobile terminals and preliminary results are given which validate the proposed handoff control protocol on an ATM network testbed.
Abstract: This paper presents a signaling and control architecture for mobility support in a “wireless ATM” network that provides integrated broadband services to mobile terminals. A system level protocol architecture for a wireless ATM network is outlined. The proposed protocol stack incorporates new wireless link MAC, DLC and wireless control sublayers, together with appropriate mobility extensions to the existing ATM network control layer. Wireless control and ATM signaling capabilities required for mobility support are discussed, and preliminary solutions are given for selected major functions. Potential extensions to standard Q.2931 ATM signaling are proposed to support handoff and service parameter/QoS renegotiation required for mobility. An associated wireless control protocol for supporting terminal migration, resource allocation, and handoff is discussed. Preliminary experimental results are given which validate the proposed handoff control protocol on an ATM network testbed.

Patent
01 Feb 1996
TL;DR: In this article, the authors proposed a handoff protocol for wireless LAN handoff, where there are at least two MTs, two base stations and two switches in wireless LAN.
Abstract: There are at least two MTs(Mobile terminal), two base stations and two switches in wireless LAN handoff. Each MT will be located in area managed by one base station, and each base station is connected to one switch, and in the mean time switches are interconnected by wired LAN. The handoff composes the steps of: building one VCC(virtual channel connection) between the first MT and the second MT; when the second MT moves from the first base station to the second base station, the changing procedures of the first MT and the second MT VCC are: 1. when the first and the second base station connect to same switch, changing the VCC value in the first switch, deleting VCC in the first base station and adding changed VCC value to the second base station; and 2. the first base station connects to the first switch, and the second base station connects to the second switch, by changing at least two switches and VCC values of the first and the second base station to adapting path-adding method.

Proceedings ArticleDOI
28 Apr 1996
TL;DR: In this article, the blocking probability in a hierarchical network with two mobility behaviors is analyzed and an analytical model for the teletraffic performance is developed and used to calculate the forced termination probability in different configurations.
Abstract: This contribution deals with the blocking probability in a hierarchical network with two mobility behaviors. A continuous coverage is achieved with micro-cells that accommodate both fresh calls and handover requests. Over this micro-cell coverage umbrella-cells, which only accept handover, are implemented. At every handover, the sojourn time of the terminal in the cell is measured. If it is lower than a threshold, the terminal is considered as rapid and directed towards an umbrella cell. Otherwise the communication stays at the microcell level. Furthermore, if there is no available channel in a micro-cell, the call is handed over the corresponding umbrella-cell. The strategy tends to favor handover to umbrella-cells for high-speed terminals. An analytical model for the teletraffic performance is developed and used to calculate the forced termination probability in different configurations. The performance of the strategy is then studied.