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Method and System for Throughput Improvement and Handover Decision Expedition in a Gap Measurement Based Inter-Frequency Handover

IP.com Disclosure Number: IPCOM000243670D
Original Publication Date: 2015-Oct-09
Included in the Prior Art Database: 2015-Oct-09
Document File: 4 page(s) / 82K

Publishing Venue

Motorola

Related People

Chen, Ethan: INVENTOR [+3]

Abstract

The 3GPP standard inter-frequency handover method employs a gap measurement mechanism in order for devices to take measurements by switching between the serving frequency and the handover candidate frequencies. The method suffers from throughput degradation during gaps and slow handover decision. The inter-PLMN (Public Land Mobile Network) handover solution that enables a public safety LTE (Long Term Evolution) network to use commercial carrier networks as seamless supplemental coverage is based on the standard inter-frequency handover and suffers from the same drawbacks. In this paper, we present a new method that takes advantage of a spare transceiver in an LTE-advanced chipset based public safety device to achieve inter-frequency measurements following the configured measurement gaps but without the throughput degradation during gaps. The method includes the notification of such public safety device capability to the base station and the customization of the scheduler to bypass measurement gaps for continuous data scheduling. The method is completely compliant to the 3GPP standard defined inter-frequency handover signaling and measurement mechanism. Using the method, the throughput improvement could be as much as 7.5% for the measurement gap configuration of 6 millisecond gap length in every 80 millisecond measurement gap repetition period, or 15% for the other configuration of 6 millisecond gap length in every 40 millisecond measurement gap repetition period. A secondary method is also proposed in which the spare transceiver is used to measure as many handover candidate frequencies as possible between two scheduled gaps to achieve a fast handover decision based on the congregated report of multiple frequencies.

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Page 01 of 4

Method and System for Throughput Improvement and Handover Decision Expedition in a Gap Measurement Based Inter-

Frequency Handover

Ethan Y. Chen, Mike H. Baker, Brundaban Sahoo Motorola Solutions, Inc.

ABSTRACT

  The 3GPP standard inter- frequency handover method employs a gap measurement mechanism in order for devices to take measurements by switching between the serving frequency and the handover candidate frequencies. The method suffers from throughput degradation during gaps and slow handover decision. The inter-PLMN (Public Land Mobile Network) handover solution that enables a public safety LTE (Long Term Evolution) network to use commercial carrier networks as seamless supplemental coverage is based on the standard inter- frequency handover and suffers from the same drawbacks.

  In this paper, we present a new method that takes advantage of a spare transceiver in an LTE- advanced chipset based public safety device to achieve inter- frequency measurements following the configured measurement gaps but without the throughput degradation during gaps. The method includes the notification of such public safety device capability to the base station and the customization of the scheduler to bypass measurement gaps for continuous data scheduling. The method is completely compliant to the 3GPP standard defined inter- frequency handover signaling and measurement mechanism. Using the method, the throughput improvement could be as much as 7.5% for the measurement gap configuration of 6 millisecond gap length in every 80 millisecond measurement gap repetition period, or 15% for the other configuration of 6 millisecond gap length in every 40 millisecond measurement gap repetition period.

  A secondary method is also proposed in which the spare transceiver is used to measure as many handover candidate frequencies as possible between two scheduled gaps to achieve a fast handover decision based on the congregated report of multiple frequencies.

PROBLEM

  The inter-PLMN (Public Land Mobile Network) handover solution of Motorola Solutions, Inc. uses commercial carrier LTE (Long Term Evolution) networks as seamless

© 2015 Motorola Solutions, Inc.


Page 02 of 4

supplemental coverage to a public safety LTE network and is based on the 3GPP (3Rd Generation Partnership Project) standard inter- frequency handover method. Because a mobile device cannot transmit and receive on one frequency and make measurements on another at the same time, the standard inter-frequency handover method employs a gap measurement mechanism as a solution. The base station defines measurement gaps as part of handover measurement configuration to the device. The measurement gaps are the subframes in which the LTE base station, a.k.a. eNodeB (Evolved Node B) promises not to schedule any transmissions to or from the mobile device. During these subframes, the mobile device can tune to another handover candidate frequency and make a measurement while confident it will not miss any downl...