Abstract The control signals of cellular networks have been used to infer the traffic conditions of the road network. In particular, consecutive handover events are being used to estimate the traffic speed. During traffic congestion, consecutive handover events may be rare because vehicles move slowly, and thus very few or no speed reports would be generated from the congested area.However, the traffic speed report rate during traffic congestion has not been investigated in the literature. In this paper, we present an analytic model to estimate the speed report rate from cellular network signaling in steady traffic conditions, that is, the traffic speed and flow are assumed constant. Real field trial data were used to validate our analytic model. In addition, computer simulations were conducted to study how speed reports are generated in dynamic traffic conditions when traffic speed and flow change rapidly. Our study indicates that in a typical cell of length 1.5 km with a typical expected call holding time of 1 min, no speed report was generated from a congested three‐lane highway. Our study demonstrates that the lack of speed reports from consecutive handover events during rush hours indicates severe traffic congestion, and new methods that can estimate traffic speed from cellular network data during severe traffic congestion need to be developed. Copyright © 2013 John Wiley & Sons, Ltd.

Vehicle speeds are often measured by intelligent transportation systems (ITSs) by utilizing sensors or software solutions. Our previous work proposed the Lin-Chang-Huangfu (LCH) scheme to compute the cell residence times by the standard counter values in mobile telecommunications switches. In this paper, we use mathematical and statistical developments to investigate the accuracy of the LCH scheme by deriving the bias of the cell residence times computed in this scheme. Then, we extend the LCH scheme with some filtering and compensation techniques for vehicle speed estimation and validate our approach with vehicle detector (VD) measurements at National Highway 3, Longtan Township, Taoyuan County, Taiwan. Our study indicates that the LCH scheme is an effective approach to vehicle speed estimation.

Conventional temporary telephone number (TTN) service provides a secondary telephone number to a service subscriber. The subscribers can protect privacy by sharing their TTNs without revealing their private numbers. However, TTN service is rarely provided because it requires a large amount of temporary telephone numbers. In this paper, we present a restricted form of TTN service - temporary call-back telephone number (TCN) service -- to reduce the amount of telephone numbers needed. A TCN is assigned only for the communications between a subscriber and the correspondent parties specified by the subscriber. Other users, except for the specified correspondent parties, cannot reach the subscriber through the assigned TCN. A TCN assignment can be specified by a telephone number mapping record that consists of a subscriber's number, a TCN, and a correspondent party's number. A TCN can be assigned to more than one subscriber, as long as the subscribers' specified correspondent parties are different. Analytic models using Markov chains have been developed to show that the TCN service significantly reduces the amount of temporary numbers required. The TCN service can be implemented using the Intelligent Network (IN) service architecture as a value-added service. TCN Subscribers can initiate calls to and receive calls from the specified correspondent parties without revealing their private telephone numbers. However, the TCN service is not a replacement of the conventional TTN service because only the specified correspondent parties can reach the subscriber by the assigned TCN.

In this paper, we develop a stream-based system, CoreView (CV) having launched at Chunghwa Telecom in Taiwan, that characterizes with T-connection or non-intrusion and is based on the mobile network signalling, to support mobile network diagnosis and comprehensive location services simultaneously in near real-time. With the CV-network diagnosis, can operators have expertized systems and save the expenses for the network maintenance. In addition, they have opportunity to enhance the profitability with the CV-location services.

Dynamic voltage and frequency scaling (DVFS) is an effective technique for reducing power consumption. A number of DVFS researches apply learning methods in an attempt to approach the DVFS prediction model instead of using complicated mathematical models. In this paper, we propose a lightweight learning-directed DVFS technique using Counter Propagation Networks (CPN) to identify the task behavior and predict the corresponding voltage/frequency setting precisely. An adjustable performance mechanism is also provided to users that have diverse performance requirement. The algorithm has been implemented on the Linux operating system and used a PXA270 development board. The results show that the learning-directed DVFS method could accurately predict the suitable frequency, given runtime statistics information of a running program. In this way, the user can easily control the energy consumption by specifying allowable performance loss factor.

In mobile telecommunications, the residence times of users at a cell or a location area are an important input parameter for network planning and performance evaluation of a mobile network. However, measurement of cell residence times in a commercially operated mobile network is not trivial, which typically requires tracing the movement of individual users. In this paper, we show how to use the standard counter values (number of handovers and call traffic) measured in a mobile telecommunications network to derive the cell residence times. These counter values can be obtained directly from telecommunications switches. Therefore, we can provide a quick and simple solution to compute cell residence times.

To attract more users to use mobile packet services, mobile operators have begun to provide flat-rate packet services in the WCDMA system with High Speed Downlink Packet Access (HSDPA). Since usage does not incur extra cost, flat-rate users may always stay on line and occupy most of the radio channel resources. In this paper, we consider a HSDPA network serving two types of user packets: charged packets (CPs) and flat-rate packets (FRPs). We consider the balance between serving the FRPs and CPs. Four downlink packet scheduling methods were studied in this paper. Our study using Markov process shows that Dynamic Discard Timer for FRPs and Dynamic Guard Slots for CPs methods are more effective in transmitting downlink CPs especially when the downlink FRP traffic is high. Therefore, they are better in guaranteeing the system throughput for CPs, and thus the operator revenue can be better protected.

Universal Mobile Telecommunications System (UMTS) supports Internet protocol (IP) multimedia services through IP multimedia core network subsystem (IMS). Since the IMS information is delivered through the general packet radio service (GPRS) transport network, a UMTS mobile station (MS) must activate GPRS packet data protocol (PDP) context before it can register to the IMS network. In the Third-Generation Partnership Project (3GPP) specifications, authentication is performed at both the GPRS and the IMS networks before an MS can access the IMS services. We observe that many steps in this 3GPP "two-pass" authentication procedure are identical. Based on our observation, this paper proposes an one-pass authentication procedure that only needs to perform GPRS authentication. At the IMS level, authentication is implicitly performed in IMS registration. Our approach may save up to 50% of the IMS registration/authentication traffic, as compared with the 3GPP two-pass procedure. We formally prove that the one-pass procedure correctly authenticate the IMS users.

Abstract Owing to the increasing population of mobile subscribers, the rapidly expanding signaling traffic has become a challenge to the mobility management in PCS networks. Multiple database schemes to reduce signal traffic and to solve the bottleneck problem of the singlehome location register(HLR) architecture have been proposed by many researchers. However, in most of the multiple location databases or HLR systems, extra signaling is required for the multiple database updates. We propose a batch‐update strategy, instead of the immediate update method, for the location‐tracking schemes with replication to reduce the signaling overhead. In this paper, we first introduce a distributed HLRs architecture in which each HLR is associated with a localized set of VLRs and the location registrations and queries are processed locally. Then we propose our batch‐update strategy and present two pointing schemes for inter‐HLR call deliveries. The numerical result shows that our approach can effectively decrease the signaling cost of location registration and call delivery compared with the IS‐41 standard. Copyright © 2002 John Wiley & Sons, Ltd.

We first compare the performance of the direction-based location update (DBLU) schemes with that of the distance-based location update scheme under various mobility behaviors of the mobile hosts (MTs). The comparison results show that under the random walk model, the base DBLU scheme outperforms the distance-based location update scheme when the mobility to call ratios (MCRs) of the MTs are low. However, it has been shown that the MTs are likely to possess forward-prone movement characteristics in microcellular architectures. If the MTs are indeed prone to make forward movements, the base DBLU scheme will be better than the distance-based location update scheme in all the MCRs according to our analysis. Therefore we further propose two enhanced DBLU schemes, namely the forward direction-based location update (FDBLU) and the restricted forward direction-based location update (RFDBLU) schemes, for the location tracking of the MTs in micro-cellular architectures. Analytical results also show that both FDBLU and RFDBLU schemes outperform the base DBLU scheme, and RFDBLU scheme is the best among the direction-based location update schemes.

Abstract This paper investigates the channel assignment problem of dual‐band PCS systems where single‐band and dual‐band handsets co‐exist. Load‐balancing channel assignment schemes are proposed to improve the system performance. To balance the loads of both bands, the BSC selects a band to serve a call request of a dual‐band handset based on the loads of both bands. In addition, a channel re‐assignment scheme is used to further improve the system capacity. Analytic models and computer simulations have been developed to evaluate the performance of the load‐balancing schemes. The results indicate that both load‐balancing and channel re‐assignment techniques significantly increase the system capacity as the percentage of dual‐band handsets increases. Furthermore, the load‐balancing with channel re‐assignment scheme that combines both techniques achieves the best system performance even when the percentage of dual‐band handset is as low as 25%. In addition, we describe an approach to reduce the signal overhead of the load‐balancing schemes. Copyright © 2002 John Wiley & Sons, Ltd.

Abstract Based on media gateway control protocol (MGCP), this paper describes GSM‐IP, a voice over IP service for GSM mobile network. With the signaling protocol translation mechanism provided by the MGCP signaling gateway, we demonstrate how to interwork the MGCP elements with the home location register, visitor location register and mobile switching center in the GSM network. Then we present the message flows for GSM‐IP registration, call origination, call delivery, call release and inter‐system handoff procedures. We show the feasibility of integrating GSM with the MGCP‐based VoIP network without modifying the GSM network. Furthermore, our approach does not introduce new protocol primitives to MGCP. Copyright © 2001 John Wiley & Sons, Ltd.

A personal communications services (PCS) network system constantly tracks the locations of the mobile stations (MS) so that incoming calls can be delivered to the target mobile stations. The overall architecture of the PCS mobility management in GSM is presented. In general, a two-level database is used to store the mobile station location information. The mobile station location update procedure and the call delivery procedure are described in detail. In case of location database failure, incoming calls may be lost. The database failure restoration procedure to reduce the number of lost calls in GSM are also described. Moreover, an efficient home location register (HLR) failure recovery procedure which utilizes the MS movement information to speedup the recovery procedure is also presented.

For a reconfigurable architecture, the harvest rate is the expected percentage of defect-free processors that can be connected into the desired topology. The authors give an analytical estimation for the harvest rate of reconfigurable multipipelines based on the following model: there are n pipelines each with m stages, where each stage of a pipeline is defective with identical independent probability 0.5 and spare wires are provided for reconfiguration. By formulating the "shifting" reconfiguration as weighted chains in a partial ordered set, they prove when n=/spl theta/(m), the harvest rate is between 34% and 72%.

Diagnosis strategies are investigated for repairable VLSI and WSI structures based on integrated diagnosis and repair. Knowledge of the repair strategy, the probability of each unit being good, and the expected test time of each unit is used by the diagnosis algorithm to select units for testing. The general problem is described, followed by an examination of a specific case. For k-out-of-n structures, a complete proof is given for the optimal diagnosis procedure of Y. Ben-Dov (1981). A compact representation of the optimal diagnosis procedure is described, which requires O(n/sup 2/) space and can be generated in O(n/sup 2/) time. Simulation results are provided to show the improvement in diagnosis time over online repair and offline repair.>

The authors investigate wafer probing strategies for the diagnosis of repairable VLSI and WSI (wafer scale integration) structures based on integrated diagnosis and repair. Knowledge of the repair strategy, the probability of each unit being good, and the expected test time each unit are used by the diagnosis algorithm to select units for wafer probe testing. The general problem is described followed by an examination of a specific case. Wafer probe diagnosis of k-out-of-n systems is analyzed and optimal diagnosis algorithms are derived. A compact representation of the optimal diagnosis scheme which needs O(n/sup 2/) space and can be generated in O(n/sup 2/) time is described.>

The problem of diagnosis and spare allocation for random-access memory (RAM) with coupling faults is addressed. A number of spare allocation algorithms for RAM with row and column redundancy have recently been proposed. These procedures, however, have been restricted to repair stuck-at faults. The authors examine both diagnosis and repair of coupling faults in RAMs utilizing spare rows and columns. It is shown that a coupling fault is repaired if its coupling cell is replaced by utilizing a spare row or its coupled cell is replaced by utilizing a spare row or column. By specifying both the coupled cell and coupling cell, the amount of redundancy required to repair a given set of faults may be reduced. A diagnosis procedure for RAM is provided to locate stuck-at faults as well as coupling faults. A graph model is used to describe the repair of coupling faults. A repair procedure has been implemented to allocate rows and columns for repair.>

The problem of diagnosis and spare allocation for a random access memory (RAM) with coupling faults, utilizing spare rows and columns, is examined. It is shown that a coupling fault is repaired if its coupling cell is replaced by a spare row or its coupled cell is replaced by a spare row or column. By specifying both the coupled cell and coupling cell the amount of redundancy required to repair a given set of faults can be reduced. A diagnosis procedure is provided to locate stuck-at faults as well as coupling faults. A graph model is used to describe the repair of coupling faults, and a repair procedure is implemented to allocate rows and columns for repair.>