Energy-Saving Mechanisms in a Heterogeneous Radio Communication Network

Abstract

There is provided support mechanisms for at least one adding and removing a cell from operation in a heterogeneous radio network having a first type of basic cell for providing basic radio coverage and a second type of cell associated to a basic cell as a capacity enhancing cell. A capacity enhancing cell is selectively switched on and off (S 1 ); when the capacity enhancing cell is shut down the cell does not exist over the air while cell configuration information is kept and when the capacity enhancing cell is switched on the cell becomes available again over the air interface. An indication of shut-down and a wake-up call message for switch-on of the capacity enhancing cell are communicated (S 2 ) between a base station serving the capacity enhancing cell and a base station serving the basic cell. In this way energy savings can be supported without disrupting service availability.

1 . A method for at least one of adding and removing a cell from operation in a heterogeneous radio communication network having at least two different types of cells, including a first type of basic cell for providing basic radio coverage and a second type of cell associated to a basic cell as a capacity enhancing cell, said method comprising the steps of:
 selectively switching the capacity enhancing cell on and off; when the capacity enhancing cell is shut down the cell does not exist over the air while cell configuration information is kept and when the capacity enhancing cell is switched on cell defining information is retransmitted and the cell becomes available again over the air interface; and   communicating an indication of shut-down and a wake-up call message for switch-on of the capacity enhancing cell between a base station serving the capacity enhancing cell and a base station serving the basic cell.   
     
     
         2 . The method of  claim 1 , wherein said step of communicating is performed on the Radio Network Layer (RNL) in the X2 Application Protocol. 
     
     
         3 . A method of operating a base station serving a basic cell providing basic radio coverage, said basic cell having a neighbour cell relation to an associated capacity enhancing cell served by another base station, said method comprising the steps of:
 the base station serving the basic cell receiving an indication that the associated capacity enhancing cell is shut down over the air for energy saving purposes, and keeping corresponding cell configuration information;   the base station serving the basic cell sending a wake-up call message to the base station serving the associated capacity enhancing cell when it is decided that the base station serving the basic cell needs the capacity enhancing cell to return operational.   
     
     
         4 . The method of  claim 3 , wherein said steps of receiving an indication and sending a wake-up call message are performed on the Radio Network Layer (RNL) in the X2AP protocol. 
     
     
         5 . The method of  claim 3 , wherein the base station serving the basic cell indicates that it needs the capacity enhancing cell(s) to return operational via said wake-up call message in the X2AP protocol. 
     
     
         6 . The method of  claim 5 , wherein said wake-up call message is a Cell Activation Request. 
     
     
         7 . The method of  claim 3 , wherein said indication is received in the eNB Configuration Update procedure of the X2AP protocol. 
     
     
         8 . The method of  claim 7 , wherein the reason for shut-down as an action due to energy-saving purposes is indicated in the eNB Configuration Update procedure. 
     
     
         9 . The method of  claim 3 , wherein the base station serving the basic cell is making a wake-up decision for activation of the capacity enhancing cell based on load-related parameters of the basic cell so that the decision to switch on the capacity enhancing cell is neighbour-induced. 
     
     
         10 . The method of  claim 9 , wherein said wake-up decision for activation of the capacity-enhancing cell is based on statistics on at least one of load in the basic cell and load balancing actions the basic cell triggers towards the capacity enhancing cell. 
     
     
         11 . The method of  claim 3 , wherein the basic cell and the capacity enhancing cell represent different types of cells in a heterogeneous radio communication network. 
     
     
         12 . The method of  claim 11 , wherein the heterogeneous radio communication network has a Hierarchical Cell Structure (HCS), and the basic cell is a cell on a lower HCS layer and the capacity enhancing cell is a cell on a higher HCS layer. 
     
     
         13 . The method of  claim 3 , wherein the base station serving the basic cell and the base station serving the associated capacity enhancing cell are radio network elements of different radio access technologies. 
     
     
         14 . The method of  claim 3 , further comprising the step of the base station serving the basic cell receiving an indication that handover of user equipment is performed from the capacity enhancing cell because the capacity enhancing cell is going to be switched off. 
     
     
         15 . The method of  claim 3 , further comprising the step of the base station serving the basic cell receiving an indication that handover of user equipment to the capacity enhancing cell has failed because the capacity enhancing cell is off. 
     
     
         16 . A method of operating a base station serving a capacity enhancing cell, said capacity enhancing cell having a neighbour cell relation to an associated basic cell, providing basic radio coverage, served by another base station, said method comprising the steps of:
 the base station serving the capacity enhancing cell shutting down the capacity enhancing cell over the air for energy saving purposes, while keeping cell configuration information; and   the base station serving the capacity enhancing cell sending an indication that the capacity enhancing cell is shut down for energy saving purposes to the base station serving the basic cell.   
     
     
         17 . The method of  claim 16 , wherein said step of sending an indication is performed on the Radio Network Layer (RNL) in the X2AP protocol. 
     
     
         18 . The method of  claim 16 , wherein shut-down of the capacity enhancing cell is indicated in the eNB Configuration Update procedure of the X2AP protocol. 
     
     
         19 . The method of  claim 18 , wherein the reason for shut-down as an action due to energy-saving purposes is indicated in the eNB Configuration Update procedure. 
     
     
         20 . The method of  claim 16 , wherein said step of shutting down the cell is self-triggered, and the base station serving the capacity enhancing cell is making a decision to shut down the capacity enhancing cell based on load in the capacity enhancing cell. 
     
     
         21 . The method of  claim 16 , wherein the base station serving the capacity enhancing cell is receiving a wake-up call message from the base station serving the basic cell requesting the capacity enhancing cell to return operational, and switching the capacity enhancing cell on based on the wake-up call message. 
     
     
         22 . The method of  claim 16 , wherein the basic cell and the capacity enhancing cell represent different types of cells in a heterogeneous radio communication network. 
     
     
         23 . The method of  claim 22 , wherein the heterogeneous radio communication network has a Hierarchical Cell Structure (HCS), and the basic cell is a cell on a lower HCS layer and the capacity enhancing cell is a cell on a higher HCS layer. 
     
     
         24 . The method of  claim 16 , further comprising the step of the base station serving the capacity enhancing cell sending an indication that handover of user equipment is performed from the capacity enhancing cell because the capacity enhancing cell is going to be switched off. 
     
     
         25 . The method of  claim 16 , further comprising the step of the base station serving the capacity enhancing cell sending an indication that handover of user equipment to the capacity enhancing cell has failed because the capacity enhancing cell is off. 
     
     
         26 . A base station having a radio coverage unit configured to serve a basic cell providing basic radio coverage, and a neighbour cell relation unit configured to manage a neighbour cell relation between said basic cell and an associated capacity enhancing cell served by another base station, wherein said base station comprises:
 a cell configuration information unit configured to receive an indication that the associated capacity enhancing cell is shut down over the air for energy saving purposes, and to keep corresponding cell configuration information; and   a wake-up call unit configured to send a wake-up call message to a base station serving the associated capacity enhancing cell when it is decided that the base station serving the basic cell needs the capacity enhancing cell to return operational.   
     
     
         27 . The base station of  claim 26 , wherein said base station is configured to receive said indication and to send said wake-up call message on the Radio Network Layer (RNL) in the X2AP protocol. 
     
     
         28 . The base station of  claim 26 , wherein said wake-up call unit is configured to indicate that it needs the capacity enhancing cell(s) to return operational via said wake-up call message in the X2AP protocol. 
     
     
         29 . The base station of  claim 28 , wherein said wake-up call message is a Cell Activation Request. 
     
     
         30 . The base station of  claim 26 , wherein said cell configuration information unit is configured to receive said indication in the eNB Configuration Update procedure of the X2AP protocol. 
     
     
         31 . The base station of  claim 30 , wherein said base station is configured to receive an indication of the reason for shut-down as an action due to energy-saving purposes in the eNB Configuration Update procedure. 
     
     
         32 . The base station of  claim 26 , wherein said a wake-up call unit comprises a wake-up decision unit configured to make a wake-up decision for activation of the capacity-enhancing cell based on load-related parameters of the basic cell so that the decision to switch on the capacity enhancing cell is neighbour-induced. 
     
     
         33 . The base station of  claim 32 , wherein said wake-up decision unit is configured to make said wake-up decision for activation of the capacity-enhancing cell based on statistics on at least one of load in the basic cell and load balancing actions the basic cell triggers towards the capacity enhancing cell. 
     
     
         34 . The base station of  claim 26 , wherein said base station is further configured to-receive an indication that handover of user equipment is performed from the capacity enhancing cell because the capacity enhancing cell is going to be switched off. 
     
     
         35 . The base station of  claim 26 , wherein said base station is further configured to receive an indication that handover of user equipment to the capacity enhancing cell has failed because the capacity enhancing cell is off. 
     
     
         36 . A base station having a radio coverage unit configured to serve a capacity enhancing cell, and a neighbour cell relation unit configured to manage a neighbour cell relation between said capacity enhancing cell and an associated basic cell, providing basic radio coverage, served by another base station, wherein said base station comprises:
 a shut-down unit configured to shut down the capacity enhancing cell over the air for energy saving purposes;   a cell configuration information unit configured to keep corresponding cell configuration information;   
       wherein said shut-down unit is configured to send an indication that the capacity enhancing cell is shut down for energy saving purposes to the base station serving the basic cell. 
     
     
         37 . The base station of  claim 36 , wherein said shut-down unit is configured to send said indication on the Radio Network Layer (RNL) in the X2AP protocol. 
     
     
         38 . The base station of  claim 36 , wherein said shut-down unit is configured to indicate shut-down of the capacity enhancing cell in the eNB Configuration Update procedure of the X2AP protocol. 
     
     
         39 . The base station of  claim 38 , wherein said shut-down unit is configured to indicate the reason for shut-down as an action due to energy-saving purposes in the eNB Configuration Update procedure. 
     
     
         40 . The base station of  claim 36 , wherein said shut-down unit is configured to make a decision to shut down the capacity enhancing cell based on load in the capacity enhancing cell. 
     
     
         41 . The base station of  claim 36 , wherein said base station comprises a switch-on unit configured to receive a wake-up call message from the base station serving the basic cell requesting the capacity enhancing cell to return operational, and to switch the capacity enhancing cell on based on the wake-up call message. 
     
     
         42 . The base station of  claim 36 , wherein said base station is further configured to send an indication that handover of user equipment is performed from the capacity enhancing cell because the capacity enhancing cell is going to be switched off. 
     
     
         43 . The base station of  claim 36 , wherein said base station is further configured to send an indication that handover of user equipment to the capacity enhancing cell has failed because the capacity enhancing cell is off.