Method and Apparatus for Improving a Transmission Signal Characteristic of a Downlink Signal in a TDMA Wireless Communication System

Abstract

The invention relates to improving the quality of a received downlink signal in a time division multiple access wireless cellular communications network. The method of the invention comprises measuring a signal quality characteristic at a user equipment and comparing this to a threshold to determine if a desired signal quality level exists. If so then a certain level or type of service on the downlink can be effected. If not, the method comprises identifying an interferer signal or signals and removing at least one of such interferer signals by arranging for it to either not be transmitted on the same TDMA timeslot as the downlink signal or to be transmitted at a lower power, for example, in said timeslot.

1 . A method of improving a signal characteristic of a downlink signal received at a user equipment in a time division multiple access (TDMA) wireless communications system, the method comprising:
 receiving from a user equipment at a network management element a signal conveying a signal quality characteristic of a desired downlink signal received at the user equipment in a predetermined time slot;   determining from the received signal conveying the signal quality characteristic that at least one other signal transmitted on the wireless network has contributed to the quality characteristic of the desired downlink signal not meeting at least one quality criterion; and   controlling at least one source of the at least one other signal to change a transmission characteristic of the at least one other signal so as to reduce interference to the desired downlink signal at the user equipment.   
     
     
         2 . The method of  claim 1 , wherein controlling the at least one source of the at least one other signal comprises controlling the at least one other source to suspend transmission of the at least one other signal in the predetermined time slot. 
     
     
         3 . The method of  claim 1 , wherein controlling the at least one source of the at least one other signal comprises controlling the at least one source of the at least one other signal to reduce the transmission power of the at least one other signal in the predetermined time slot. 
     
     
         4 . The method of  claim 1 , wherein controlling at least one source of the at least one other signal comprises controlling at least one base station to change the transmission characteristic of the at least one other signal, wherein the at least one other base station is the at least one source of the at least one other signal. 
     
     
         5 . The method of  claim 1 , wherein determining that at least one other signal transmitted on the wireless network has contributed to the quality characteristic of the desired downlink signal not meeting at least one quality criterion comprises comparing the signal quality characteristic to a threshold signal quality characteristic value. 
     
     
         6 . The method of  claim 5 , wherein the threshold signal quality characteristic value has a predetermined static value. 
     
     
         7 . The method of  claim 5 , wherein the threshold signal quality characteristic value has dynamically varying values. 
     
     
         8 . The method of  claim 1 , further comprising:
 receiving from the user equipment at the network management element a signal conveying signal quality characteristics of a plurality of other signals received at the user equipment in the predetermined time slot; and   determining from the signal quality characteristics of the plurality of other signals how much each of the other signals adversely affects the received signal quality characteristic of the desired downlink signal.   
     
     
         9 . The method of  claim 1 , wherein, on determining that a plurality of other signals has contributed to the quality characteristic of the downlink signal not meeting the at least one quality criterion, the method further comprises:
 determining which of the plurality of other signals most adversely affects the received signal quality characteristic; and   controlling a source of the signal which most adversely affects the received signal quality characteristic to change a transmission characteristic of the signal which most adversely affects the received signal quality characteristic so as to reduce interference to the desired downlink signal at the user equipment.   
     
     
         10 . The method of  claim 1 , wherein, on determining that a plurality of other signals has contributed to the quality characteristic of the downlink signal not meeting the at least one quality criterion, the method further comprises:
 determining an order of the plurality of other signals from most adversely affecting the received signal quality characteristic to least adversely affecting the received signal quality characteristic; and   controlling sources of the other signals from most adversely affecting the received signal quality characteristic to least adversely affecting the received signal quality characteristic to change a transmission characteristic of the other signals which most adversely affect the received signal quality characteristic until the received signal quality characteristic meets a quality criterion.   
     
     
         11 . A time division multiple access (TDMA) wireless network infrastructure operable to improve a signal characteristic of a downlink signal received at a user equipment, the infrastructure comprising:
 at least one network management element and at least one base station controlled by the network management element, the at least one network management element and the at least one base station being co-operable:   to receive from a user equipment at a network management element a signal conveying a signal quality characteristic of a desired downlink signal received at the user equipment in a predetermined time slot;   to determine from the received signal conveying the signal quality characteristic that at least one other signal transmitted on the wireless network has contributed to the quality characteristic of the desired downlink signal not meeting at least one quality criterion; and   to control at least one source of the at least one other signal to change a transmission characteristic of the at least one other signal so as to reduce interference to the desired downlink signal at the user equipment.   
     
     
         12 . The infrastructure of  claim 11 , wherein the infrastructure is operable to control the at least one source of the at least one other signal by controlling the at least one other source to suspend transmission of the at least one other signal in the predetermined time slot. 
     
     
         13 . The infrastructure of  claim 11 , wherein the infrastructure is operable to control the at least one source of the at least one other signal by controlling the at least one source of the at least one other signal to reduce the transmission power of the at least one other signal in the predetermined time slot. 
     
     
         14 . The infrastructure of  claim 11 , wherein the infrastructure is operable to control at least one source of the at least one other signal by controlling at least one base station to change the transmission characteristic of the at least one other signal, wherein the at least one other base station is the at least one source of the at least one other signal. 
     
     
         15 . The infrastructure of  claim 11 , wherein the infrastructure is operable to determine that at least one other signal transmitted on the wireless network has contributed to the quality characteristic of the desired downlink signal not meeting at least one quality criterion comprises comparing the signal quality characteristic to a threshold signal quality characteristic value. 
     
     
         16 . The infrastructure of  claim 15 , wherein the threshold signal quality characteristic value has a predetermined static value. 
     
     
         17 . The infrastructure of  claim 15 , wherein the threshold signal quality characteristic value has dynamically varying values. 
     
     
         18 . The infrastructure of  claim 11 , wherein the network management element and the at least one base station are further co-operable:
 to receive from the user equipment at the network management element a signal conveying signal quality characteristics of a plurality of other signals received at the user equipment in the predetermined time slot; and   to determine from the signal quality characteristics of the plurality of other signals how much each of the other signals adversely affects the received signal quality characteristic of the desired downlink signal.   
     
     
         19 . The infrastructure of  claim 11 , wherein, on determining that a plurality of other signals has contributed to the quality characteristic of the downlink signal not meeting the at least one quality criterion, the infrastructure is further operable:
 to determine which of the plurality of other signals most adversely affects the received signal quality characteristic; and   to control a source of the signal which most adversely affects the received signal quality characteristic to change a transmission characteristic of the signal which most adversely affects the received signal quality characteristic so as to reduce interference to the desired downlink signal at the user equipment.   
     
     
         20 . The infrastructure of  claim 11 , wherein, on determining that a plurality of other signals has contributed to the quality characteristic of the downlink signal not meeting the at least one quality criterion, the infrastructure is further operable:
 to determine an order of the plurality of other signals from most adversely affecting the received signal quality characteristic to least adversely affecting the received signal quality characteristic; and   to control sources of the other signals from most adversely affecting the received signal quality characteristic to least adversely affecting the received signal quality characteristic to change a transmission characteristic of the other signals which most adversely affect the received signal quality characteristic until the received signal quality characteristic meets a quality criterion.