Enhancements in Channel Reliability in Scenarios Operating on Shared Band

Abstract

The present invention proposes methods and devices for mobile communication deployed on shared bands, which enhance reliability of channels such as control channels. According to an aspect thereof, at a communication terminal, a list of channels useable for communication is maintained, information on the usability of a currently used channel is obtained, and it is switched to one of the channels of the list of useable channels if the currently used channel becomes unusable. The invention encompasses also corresponding computer products as well as methods, devices and computer products residing at a network node.

We claim: 
     
         1 . A method of configuring channels for use in communications between a network node and a communication terminal operating in a shared frequency band, the method comprising:
 constructing at the network node a list comprising a plurality of channels usable for said communications, the list comprising data indicative of bandwidth and center frequency of individual said channels, wherein at least one of the bandwidth and center frequency of individual ones of the plurality of channels are configured by the network node;   transmitting to the communication terminal data indicative of the list of the plurality of channels; and   communicating with the communication terminal via one of the plurality of channels of the list of channels.   
     
     
         2 . The method according to  claim 1 , comprising:
 obtaining, at the network node, information on the usability of a currently used channel, said currently used channel being one of said plurality of the list of channels; and   instructing the communication terminal to switch to one of the channels of the list of usable channels if the currently used channel becomes unusable.   
     
     
         3 . An apparatus for configuring channels for use in communications between the apparatus and a communication terminal operating in a shared frequency band, the apparatus comprising a processing system that includes at least one processor and at least one memory storing a computer program that is arranged to:
 construct a list comprising a plurality of channels usable for said communications, the list comprising data indicative of bandwidth and center frequency of individual said channels, wherein at least one of the bandwidth and center frequency of individual ones of the plurality of channels are configured by the apparatus;   transmit to the communication terminal data indicative of the list of the plurality of channels; and   communicate with the communication terminal via one of the plurality of channels of the list of channels.   
     
     
         4 . The apparatus according to  claim 3 , wherein the processing system is arranged to:
 obtain information on the usability of a currently used channel, said currently used channel being one of said plurality of the list of channels; and   instruct the communication terminal to switch to one of the channels of the list of usable channels if the currently used channel becomes unusable.   
     
     
         5 . The apparatus according to  claim 4 , wherein the processing system is arranged to detect that a connection to a communication terminal is lost whereby to obtain said information on the usability of said currently used channel. 
     
     
         6 . The apparatus according to  claim 3 , wherein the list of channels is associated with a validity attribute, said processing system is further arranged to re-establish a connection to the communication terminal via a predetermined channel or blindly via an arbitrary channel, in the event that the validity of the list of channels expires and a currently used channel becomes unusable. 
     
     
         7 . The apparatus according to  claim 3 , wherein the number of channels making up the plurality of channels is configured in dependence on the bandwidth of individual said channels in the list and the bandwidth of the shared frequency band. 
     
     
         8 . The apparatus according to  claim 3 , wherein at least one entry in the list comprises a code indicative of a relationship between a center frequency of a first channel of the plurality of channels and a center frequency of a second channel. 
     
     
         9 . The apparatus according to  claim 8 , wherein the code indicates that the center frequency of the first channel is the center frequency of the second channel. 
     
     
         10 . The apparatus according to  claim 9 , wherein the code indicates that the first channel has a bandwidth equal to a bandwidth of the second channel. 
     
     
         11 . The apparatus according to  claim 8 , wherein the code indicates that the first channel spans multiple adjacent channels. 
     
     
         12 . The apparatus according to  claim 3 , wherein the shared frequency band comprises a TV white space (TV WS) spectrum band. 
     
     
         13 . The apparatus according to  claim 3 , wherein the shared frequency band comprises an Industrial, Scientific, Medical (ISM) band. 
     
     
         14 . The apparatus according to  claim 3 , wherein the processing system is arranged to:
 update the list;   responsive to a change to the list, distribute the updated list of the plurality of channels to the communication terminal, wherein the processing system is arranged to at least transmit a signal to the communication terminal whereby to distribute the updated list.   
     
     
         15 . The apparatus according to  claim 14 , wherein the signal informs the communication terminal that the list has changed, and the processing system is arranged to:
 receive a request for the updated list from the communications terminal; and   transmit at least a part of the updated list to the communication terminal whereby to distribute the updated list.   
     
     
         16 . The apparatus according to  claim 14 , wherein the signal comprises a contact verification signal. 
     
     
         17 . The apparatus according to  claim 14 , wherein the contact verification signal comprises a flag bit indicating if the list has changed. 
     
     
         18 . The apparatus according to  claim 14 , wherein the processing system is arranged to update the list of channels if an update criterion is fulfilled; and
 Wherein said update criterion comprises an indication of a changed channel list to be coordinated being available at a network node other than the apparatus or an expiry of a validity attribute associated with the list of channels.   
     
     
         19 . A memory storing a computer program for use in communications between a network node and a communication terminal operating in a shared frequency band, the computer program comprising a set of instructions which, when executed by a computing system within the network node, cause the computing system to perform at least:
 constructing a list comprising a plurality of channels usable for said communications, the list comprising data indicative of bandwidth and center frequency of individual said channels, wherein at least one of the bandwidth and center frequency of individual ones of the plurality of channels are configured by the network node;   transmitting to the communication terminal data indicative of the list of the plurality of channels; and   communicating with the communication terminal via one of the plurality of channels of the list of channels.   
     
     
         20 . The memory storing the computer program according to  claim 19 , wherein the set of instructions, when executed by the computing system, cause the computing system to perform:
 obtaining information on the usability of a currently used channel, said currently used channel being one of said plurality of the list of channels; and   instructing the communication terminal to switch to one of the channels of the list of usable channels if the currently used channel becomes unusable.