Method in a Base Station of a Communication System for Making a Handover Decision, Base Station, Computer Programs, and Computer Program Products

Abstract

The invention relates to a method in a base station of a communication system 1 for making a handover decision, the communication system 1 comprising a user equipment. The method comprises the steps of: performing a first type of mobility mechanism for the user equipment, and upon the first type of mobility mechanism fulfilling a criterion: configuring a second type of mobility mechanism for the user equipment, and making a handover decision for the user equipment based on the second type of mobility mechanism. The invention also relates to a base station, computer programs and computer program products.

What is claimed is: 
     
         1 . A method in a base station of a communication system for making a handover decision for a user equipment in the communication system, the method comprising:
 performing a first type of mobility mechanism for the user equipment; and   upon the first type of mobility mechanism fulfilling a criterion:
 configuring a second type of mobility mechanism for the user equipment and 
 making a handover decision for the user equipment based on the second type of mobility mechanism. 
   
     
     
         2 . The method as claimed in  claim 1 , wherein performing the first type of mobility mechanism comprises:
 transmitting a first type of pilot signal to the user equipment; and   receiving from the user equipment a measurement report for the first type of pilot signal.   
     
     
         3 . The method as claimed in  claim 2 , further comprising determining whether the first type of mobility mechanism fulfills the criterion by comparing the measurement report with threshold values. 
     
     
         4 . The method as claimed in  claim 2 , wherein configuring the second type of mobility mechanism comprises activating, based on the measurement report, a second type of pilot signal. 
     
     
         5 . The method as claimed in  claim 4 , wherein activating the second type of pilot signal comprises requesting the user equipment to transmit the second type of pilot signal. 
     
     
         6 . The method as claimed in  claim 4 , wherein activating a second type of pilot signal comprises requesting a target base station to signal the second type of pilot signal to the user equipment. 
     
     
         7 . The method as claimed in  claim 4 , wherein the second type of pilot signal comprises an uplink pilot signal. 
     
     
         8 . The method as claimed in  claim 4 , wherein the second type of pilot signal comprises a downlink pilot signal. 
     
     
         9 . The method as claimed in  claim 2 , wherein the first type of pilot signal comprises a downlink pilot signal and the measurement report comprises a downlink pilot signal strength measurement or a downlink pilot signal quality measurement. 
     
     
         10 . The method as claimed in  claim 2 , wherein configuring the second mobility mechanism comprises at least one of:
 activating or deactivating a downlink pilot signal transmitted by the base station to the user equipment;   changing beam-forming configuration of a downlink pilot signal transmitted by the base station to the user equipment; and   activating, deactivating or reconfiguring an uplink pilot signal measurement received from the user equipment.   
     
     
         11 . The method as claimed in  claim 1 , wherein the performing the first type of mobility mechanism comprises determining positioning information for the user equipment. 
     
     
         12 . The method as claimed in  claim 11 , further comprising determining that the first type of mobility mechanism fulfills the criterion, based on determining that the geographical location of the user equipment is within a predetermined distance from a cell border of the base station. 
     
     
         13 . The method as claimed in any  claim 1 , wherein the method is performed for user equipment having at least one of:
 an amount of uplink data above a first threshold;   an amount of downlink data above a second threshold:   a predetermined quality of service; and   a speed of movement below a predetermined speed.   
     
     
         14 . A base station configured for operation in a communication system, the base station comprising a controller configured to:
 perform a first type of mobility mechanism for a user equipment in the communication system; and   upon the first type of mobility mechanism fulfilling a criterion:
 configure a second type of mobility mechanism for the user equipment; and 
 make a handover decision for the user equipment based on the second type of mobility mechanism. 
   
     
     
         15 . A method in a first base station configured for operation in a communication network, said method comprising:
 determining whether a user equipment connected to the first base station is a candidate for handover to a second base station, based on evaluating a measurement report sent by the user equipment for a first type of pilot signal transmitted from each of the first and second base stations, or based on determining that the geographical location of the user equipment is within a predetermined distance from a cell border between the first and second base stations; and   in response to determining that the user equipment is a candidate for handover:
 activating a second type of pilot signal that is different than the first type of pilot signal and is transmitted by the second base station or the user equipment; and 
 making the handover decision based on evaluating a measurements report for the second type of pilot signal.