Handover

About: Handover is a research topic. Over the lifetime, 24219 publications have been published within this topic receiving 296416 citations. The topic is also known as: handoff.

Call admission control for CDMA mobile communications systems supporting multimedia services

Abstract: The call admission control (CAC) belongs to the category of resource management. Since the radio spectrum is very scarce resource, CAC is one of the most important engineering issues for mobile communications. In this paper, we propose a CAC scheme for direct sequence code-division multiple-access cellular systems supporting mobile multimedia communications services. There are multiple call classes in multimedia services and the required signal-to-interference ratio (SIR) varies with call classes. Call admission decision in the proposed scheme is based on SIR measurement. We take account of the traffic asymmetry between uplink and downlink, which is the most important characteristic of multimedia traffic. In addition, the proposed scheme guarantees the priority of handoff call requests over new call requests. We evaluate the performance of the proposed scheme using Markov analysis. The performance measures which we focus on are the system throughput and the blocking probabilities of handoff calls and new calls. The outage probability of a call in progress is also calculated, which is the probability that the measured bit energy-to-noise density ratio of the call is smaller than the required value for maintaining adequate transmission quality. We present some numerical examples with practically meaningful parameter values and, as a result, show that the proposed CAC scheme can operate well in the mobile multimedia systems such as the International Mobile Telecommunications-2000 (IMT-2000) systems.

Method for compulsorily performing handover in broadband wireless communication system

Abstract: Disclosed is a method for enabling a mobile station existing in a serving cell area to perform a handover procedure in a broadband mobile communication system including the mobile station, a serving base station providing a service to the mobile station, and one or more target base stations containing at least one target cell area overlapping with the serving cell area occupied by the serving base station. The method includes transmitting a handover request message from the mobile station to the serving base station when it is detected that a performance of a handover is necessary; and transmitting a handover indication message containing handover cancel information to the serving base station when the mobile station determines a cancel of the handover while the mobile station is being handed over to one or more target base stations by the serving base station.

From LTE to 5G for Connected Mobility

Abstract: Long Term Evolution, the fourth generation of mobile communication technology, has been commercially deployed for about five years. Even though it is continuously updated through new releases, and with LTE Advanced Pro Release 13 being the latest one, the development of the fifth generation has been initiated. In this article, we measure how current LTE network implementations perform in comparison with the initial LTE requirements. The target is to identify certain key performance indicators that have suboptimal implementations and therefore lend themselves to careful consideration when designing and standardizing next generation wireless technology. Specifically, we analyze user and control plane latency, handover execution time, and coverage, which are critical parameters for connected mobility use cases such as road vehicle safety and efficiency. We study the latency, handover execution time, and coverage of four operational LTE networks based on 19,000 km of drive tests covering a mixture of rural, suburban, and urban environments. The measurements have been collected using commercial radio network scanners and measurement smartphones. Even though LTE has low air interface delays, the measurements reveal that core network delays compromise the overall round-trip time design requirement. LTE's breakbefore- make handover implementation causes a data interruption at each handover of 40 ms at the median level. While this is in compliance with the LTE requirements, and lower values are certainly possible, it is also clear that break-before-make will not be sufficient for connected mobility use cases such as road vehicle safety. Furthermore, the measurements reveal that LTE can provide coverage for 99 percent of the outdoor and road users, but the LTE-M or NarrowBand-IoT upgrades, as of LTE Release 13, are required in combination with other measures to allow for additional penetration losses, such as those experienced in underground parking lots. Based on the observed discrepancies between measured and standardized LTE performance, in terms of latency, handover execution time, and coverage, we conclude the article with a discussion of techniques that need careful consideration for connected mobility in fifth generation mobile communication technology.

Method and apparatus for handoff between a wireless local area network (WLAN) and a universal mobile telecommunication system (UMTS)

Abstract: Apparatus and method for providing an automatic handoff process of a dual-mode user equipment (UE) from either a wireless local area network (WLAN) to a universal mobile telecommunications system (UMTS) or from a UMTS to a WLAN. Handoffs may be initiated by the UE, based upon user preference, signal quality, comparison of location coordinates of the UE and the system to be switched to or signal quality. The available channels of one system may be sent to the UE by the other system or the UE may monitor channels of the system to be switched to and lock on to one. The handoff may also be initiated by the UMTS, the selection being power-based.

Method and apparatus for carrier assignment, configuration and switching for multicarrier wireless communications

Abstract: As part of carrier assignment and configuration for multicarrier wireless communications, a single uplink (UL) primary carrier may provide control information for multiple concurrent downlink (DL) carriers. Optionally, control information for each DL carrier may be transmitted over paired UL carriers. Carrier switching of UL and/or DL carriers, including primary and anchor carriers, may occur during normal operation or during handover, and may occur in only the UL or only the DL direction. A unidirectional handover is performed when only an UL carrier or only a DL carrier is switched as part of a handover. Switching of UL and/or DL carriers may be from one component carrier or a subset of carriers to another component carrier, another subset of carriers, or all carriers in the same direction.