Handoff procedure in a mobile communication system

Patent metadata

Field	Value
Publication number	US-2016174124-A1
Application number	US-201414908522-A
Country	US
Kind code	A1
Filing date	Jul 29, 2014
Priority date	Jul 31, 2013
Publication date	Jun 16, 2016
Grant date	—

Abstract

The invention relates to an improved handover procedure for a mobile terminal. Under control of the target base station, the mobile terminal is to perform a handoff to a target base station, wherein it is to be configured for communication with the target base station via a target radio cell comprising a downlink carrier and an uplink carrier. The mobile terminal receives a handoff command message for the handoff to the target base station including a handoff execution condition as trigger for executing handoff to the target base station. Then, the mobile terminal determines, based on the received handoff execution condition, whether or not the mobile terminal is to trigger execution of the handoff to the target base station. In case the mobile terminal determines that it is to trigger execution of the handoff to the target base station, the mobile terminal executes the handoff to the target base station.

First claim

1 - 48 . (canceled)

49 . A mobile terminal for performing a handoff of a mobile terminal to a target base station, wherein the mobile terminal is to be configured, under control of the target base station, for communication with the target base station via a target radio cell comprising a downlink carrier and an uplink carrier, comprising:
a receiving circuit configured to receive a handoff command message for the handoff to the target base station including a handoff execution condition as trigger for executing handoff to the target base station; and a processor configured to determine, based on the received handoff execution condition included in the handoff command message, whether or not the mobile terminal is to trigger execution of the handoff to the target base station; wherein, in case the processor determines that the mobile terminal is to trigger execution of the handoff to the target base station, the mobile terminal executes the handoff to the target base station (a) by performing a random access channel, RACH, procedure with the target base station to thereby time align the uplink carrier of the target radio cell, and (b) by transmitting to the target base station a handoff complete message thereby indicating completion of the handoff to the target base station including completion of configuration of the mobile terminal for communication with the target base station via the target radio cell.

50 . The mobile terminal according to claim 49 , wherein the mobile terminal, prior to receiving the handoff command message, is configured for communication with a source base station via a source radio cell; and
the receiving circuit is configured to receive the handoff command message from the source base station via a downlink carrier of the source radio cell; and, after receiving the handoff command message, the mobile terminal is configured to detach from the source radio cell whereby communication with the source base station is stopped.

51 . The mobile terminal according to claim 49 , wherein in case the processor does not, within a first pre-configured period of time, determine that the mobile terminal is to trigger execution of the handoff to the target base station, the mobile terminal is configured to discard the received handoff command message.

52 . The mobile terminal according to claim 51 , wherein the received handoff command message includes a handoff validity timer, and
the processor is configured to re-configure the first pre-configured period of time based on the handoff validity timer.

53 . The mobile terminal according to claim 49 , wherein the handoff execution condition, included in the received handoff command message, corresponds to a timer value; and
the processor is configured to determine whether or not a timer with the timer value has expired; wherein, upon expiration of the timer with the timer value, the mobile terminal is to trigger execution of the handoff to the target base station.

54 . The mobile terminal according to claim 49 , wherein the handoff execution condition, included in the received handoff command message, corresponds to an indication to trigger execution of the handoff based on pre-configured threshold values for the signal strength or signal quality of a source and/or target radio cell; and
the processor is configured to determine whether or not the respective signal strength or signal quality of the source radio cell falls below one of the pre-configured threshold values and/or the respective signal strength or signal quality of target radio cell rises above another of the pre-configured threshold values; wherein, upon the respective signal strength or signal quality having fallen below the one of the pre-configured threshold values and/or having risen above the other of the pre-configured threshold values, the mobile terminal is to trigger execution of the handoff to the target base station.

55 . The mobile terminal according to claim 49 , wherein the handoff execution condition, included in the received handoff command message, corresponds to at least one threshold value for the signal strength or signal quality of a source and/or target radio cell; and
the processor is configured to determine whether or not the respective signal strength or signal quality of the source radio cell falls below one of the received threshold value(s) and/or the respective signal strength or signal quality of target radio cell rises above another of the received threshold value(s); wherein, upon the respective signal strength or signal quality having fallen below one of the at least one threshold value(s) and/or having risen above the other of the at least one threshold value(s), the mobile terminal is to trigger execution of the handoff to the target base station.

56 . The mobile terminal according to claim 54 , wherein the threshold value for the signal strength corresponds to a threshold value for the reference signal received power, RSRP, to be measured by the mobile terminal based on reference signals, RSs, transmitted in the source and/or target radio cell; and/or
the threshold value for the signal quality corresponds to a threshold value for the reference signal received quality, RSRQ, to be measured by the mobile terminal based on reference signals, RSs, transmitted in the source and/or target radio cell.

57 . The mobile terminal according to claim 49 , wherein the handoff execution condition, included in the received handoff command message, corresponds to an indication to trigger execution of the handoff based on out-of-sync events where a channel quality of a source radio cell falls below a pre-configured out-of-sync threshold (Qout); and
the processor is configured to determine whether or not the number of out-of-sync events exceeds the pre-configured number (N310) for the predefined period of time, wherein, in case the number of out-of-sync events exceeds the pre-configured number (N310) for the predefined period of time, the mobile terminal is to trigger execution of the handoff to the target base station.

58 . The mobile terminal according to claim 49 , wherein the handoff execution condition, included in the received handoff command message, corresponds to a counter value for out-of-sync events where a channel quality of a source radio cell falls below a pre-configured out-of-sync threshold (Qout); and
the processor is configured to determine whether or not the number of out-of-sync events exceeds the received counter value (N310-alike) for the predefined period of time, wherein, in case the number of out-of-sync events exceeds the received counter value (N310-alike) for the predefined period of time, the mobile terminal is to trigger execution of the handoff to the target base station.

59 . The mobile terminal according to claim 49 , wherein the handoff command message corresponds to a RRCConnectionReconfiguration message.

60 . The mobile terminal according to claim 49 , wherein the handoff complete message corresponds to a RRCConnectionReconfigurationComplete message.

61 . The mobile terminal according to claim 49 , wherein:
in case the processor determines, within a second pre-configured period of time, that the mobile terminal is to trigger execution of the handoff to the target base station, the mobile terminal executes the handoff to the target base station including (a) performing a contention-free RACH procedure based on a random access preamble included in the handoff command message; and in case the processor determines, after expiry of the second pre-configured period of time, that the mobile terminal is to trigger execution of the handoff to the target

Assignees

• Panasonic Ip Corp America

Inventors

• Basu Mallick Prateek
• Loehr Joachim

Classifications

• H04W74/006

  in the downlink, i.e. towards the terminal · CPC title

• H04W36/0005

  Control or signalling for completing the hand-off · CPC title

• H04W74/0833

  Random access procedures, e.g. with 4-step access · CPC title

• H04W74/0838

  using contention-free random access [CFRA] · CPC title

• H04W36/30 Primary

  by measured or perceived connection quality data · CPC title