Apparatus and method for cell frequency change procedure signal timing selection

Abstract

A method of a network node for changing a first frequency of a first original cell, wherein one or more wireless communication devices are served by the original cell, and wherein the network node controls a plurality of other cells. The method comprises selecting one or more second frequency of an unlicensed spectrum that the network node should switch the original cell to, determining a second cell on the selected one or more second frequency as target cell and causing the target cell to maintain the same neighbor cell relations as the original cell. The method also comprises moving the one or more wireless communication devices from the original cell to the target cell, turning off the original cell when the one or more wireless communication devices have been moved from the original cell to the target cell and informing one or more neighboring network nodes of the frequency change to the one or more second frequency. Also disclosed is a computer program product, an arrangement and a network node.

Claims

1. A method of a network node for changing a first frequency of a first original cell controlled by the network node, wherein one or more wireless communication devices are served by the original cell, and wherein the network node controls a plurality of other cells, the method comprising: selecting one or more second frequency of an unlicensed spectrum that the network node should switch the original cell to; determining a second cell on the selected one or more second frequency and controlled by the network node as target cell; causing the target cell to maintain the same neighbor cell relations as the original cell, including causing the original cell and the target cell to have a same set of neighboring cells; emptying the original cell of all wireless communication devices by moving the one or more wireless communication devices from the original cell to the target cell; turning off the original cell when the one or more wireless communication devices have been moved from the original cell to the target cell; and informing one or more neighboring network nodes of the frequency change to the one or more second frequency, wherein determining the second cell on the selected one or more second frequency comprises: determining if the network node controls a maximum number of cells, and if so, moving the one or more wireless communication device from the original cell to one or more of the plurality of other cells; turning off the original cell; determining the target cell on the selected one or more second frequency by creating a new cell operating in the selected one or more second frequency and moving the one or more wireless communication device from the one or more of the plurality of other cells to the target cell.

2. The method according to claim 1, wherein determining the second cell on the selected one or more second frequency comprises: determining if there are other active cells among the plurality of other cells controlled by the network node that can continue to be operated with, and if so, determining the target cell by selecting one or more such active cells as target cell.

3. The method according to claim 1, wherein determining if the network node controls the maximum number of cells comprises: determining if the network node controls the maximum number of cells wherein all of the cells have to be turned off, and if so, moving the one or more wireless communication device from the one or more of the plurality of other cells to the target cell comprises moving the one or more wireless communication device from the plurality of other cells to the target cell; and the method comprises turning off the plurality of other cells.

4. The method according to claim 1, further comprising: determining if there is a sufficient amount of free capacity to create the target cell, and if so creating the target cell; and refraining from turning off the original cell until the target cell is created.

5. The method according to claim 1, wherein moving the one or more wireless communication device from the original cell comprises: determining if the one or more wireless communication device is in Radio Resource Control (RRC) Connected state and uses the original cell as Primary Cell, and if so, performing a handover or a release by re-directing the one or more wireless communication device from the original cell to the target cell.

6. The method according to claim 1, further comprising: determining if the one or more wireless communication device is in RRC Connected state and uses the original cell as Secondary Cell, and if so, releasing the one or more wireless communication device from the original cell; and configuring the target cell as new Secondary Cell.

7. The method according to claim 1, further comprising: determining if the one or more wireless communication device is in RRC Idle state and uses the original cell as serving cell, and if so, paging the one or more wireless communication device to force it to RRC Connected state and then moving the one or more wireless communication device from the original cell by determining if the one or more wireless communication device is in RRC Connected state and uses the original cell as Primary Cell, and if so, performing handover or a release by re-directing the one or more wireless communication device from the original cell to the target cell.

8. The method according to claim 1, further comprising: determining if the one or more wireless communication device is in RRC Idle state and uses the original cell as serving cell, and if so, moving the one or more wireless communication device while in RRC IDLE state through the steps of: updating a system information in the original cell with the target cell's frequency as a neighbor frequency, information that the original cell is barred and/or information that intra- frequency cell reselection is not allowed; and paging the one or more wireless communication device to re-read the system information of the original cell.

9. The method according to claim 1, further comprising: determining if the one or more wireless communication device is in RRC IDLE state and uses the original cell as serving cell, and if so, moving the wireless communication device while in RRC IDLE state through at least one of dedicated paging messages and broadcast information.

10. A non-transitory computer readable medium, having thereon a computer program comprising program instructions, the computer program being loadable into a data-processing unit and adapted to cause execution of a method when the computer program is run by the data-processing unit, wherein the method is of a network node for changing a first frequency of a first original cell controlled by the network node, wherein one or more wireless communication devices are served by the original cell, and wherein the network node controls a plurality of other cells, and wherein the method comprises: selecting one or more second frequency of an unlicensed spectrum that the network node should switch the original cell to; determining a second cell on the selected one or more second frequency and controlled by the network node as target cell; causing the target cell to maintain the same neighbor cell relations as the original cell, including causing the original cell and the target cell to have a same set of neighboring cells; emptying the original cell of all wireless communication devices by moving the one or more wireless communication devices from the original cell to the target cell; turning off the original cell when the one or more wireless communication devices have been moved from the original cell to the target cell; and informing one or more neighboring network nodes of the frequency change to the one or more second frequency, wherein determining the second cell on the selected one or more second frequency comprises: determining if the network node controls a maximum number of cells, and if so, moving the one or more wireless communication device from the original cell to one or more of the plurality of other cells; turning off the original cell; determining the target cell on the selected one or more second frequency by creating a new cell operating in the selected one or more second frequency and moving the one or more wireless communication device from the one or more of the plurality of other cells to the target cell.

11. An arrangement of a network node comprising a controller, for changing a first frequency of a first original cell controlled by the network node, wherein the original cell is configured to operate at a first frequency, wherein one or more wireless communication devices are served by the original cell, wherein the network node is configured to control a plurality of other cells, and wherein the controller is configured to cause the network node to: select one or more second frequency of an unlicensed spectrum that the network node should switch the original cell to; determine a second cell on the one or more selected second frequency and controlled by the network node as target cell; cause the target cell to maintain the same neighbor cell relations as the original cell, including to cause the original cell and the target cell to have a same set of neighboring cells; empty the original cell of all wireless communication devices by moving the one or more wireless communication devices from the original cell to the target cell; turn off the original cell when the one or more wireless communication device have been moved from the first cell to the target cell; and inform all neighbor cells of the original cell of the frequency change to the one or more second frequency, wherein the controller is further configured to cause determination of the second cell on the selected one or more second frequency by causing: determination of whether the network node controls a maximum number of cells, and if so, moving of the one or more wireless communication device from the original cell to one or more of the plurality of other cells; turning off of the original cell; determination of the target cell on the selected one or more second frequency by creating a new cell operating in the selected one or more second frequency and moving the one or more wireless communication device from the one or more of the plurality of other cells to the target cell.

12. The arrangement according to claim 11, wherein the controller is configured to cause determination of the second cell on the selected one or more second frequency by causing: determination of whether there are other active cells among the plurality of other cells controlled by the network node that can continue to be operated with, and if so, determination of the target cell by selecting one or more such active cells as target cell.

13. The arrangement according to claim 11, wherein determination of whether the network node controls the maximum number of cells comprises: determination of whether the network node controls the maximum number of cells wherein all of the cells have to be turned off, and if so, movement of the one or more wireless communication device from the one or more of the plurality of other cells to the target cell comprises movement of the one or more wireless communication device from the plurality of other cells to the target cell; and the controller is further configured to cause the network node to turn off the plurality of other cells.

14. The arrangement according to claim 11, wherein the controller is further configured to cause: determination of whether there is a sufficient amount of free capacity to create the target cell, and if so creation of the target cell; and refraining from turning off the original cell until the target cell is created.

15. The arrangement according to claim 11, wherein the controller is further configured to cause moving of the one or more wireless communication device from the original cell by causing: determination of whether the one or more wireless communication device is in Radio Resource Control (RRC) Connected state and uses the original cell as Primary Cell, and if so, performing of a handover or a release by re-directing the one or more wireless communication device from the original cell to the target cell.

16. The arrangement according to claim 11, wherein the controller is further configured to cause: determination of whether the one or more wireless communication device is in RRC Connected state and uses the original cell as Secondary Cell, and if so, release of the one or more wireless communication device from the original cell; and configuration of the target cell as new Secondary Cell.

17. The arrangement according to claim 11, wherein the controller is further configured to cause: determination of whether the one or more wireless communication device is in RRC Idle state and uses the original cell as serving cell, and if so, paging of the one or more wireless communication device to force it to RRC Connected state and then moving of the one or more wireless communication device from the original cell by determination of whether the one or more wireless communication device is in RRC Connected state and uses the original cell as Primary Cell, and if so, performing handover or a release by re-directing the one or more wireless communication device from the original cell to the target cell.

18. The arrangement according to claim 11, wherein the controller is further configured to cause: determination of whether the one or more wireless communication device is in RRC Idle state and uses the original cell as serving cell, and if so, moving of the one or more wireless communication device while in RRC IDLE state through by causing: update of a system information in the original cell with the target cell's frequency as a neighbor frequency, information that the original cell is barred and/or information that intra-frequency cell reselection is not allowed; and paging of the one or more wireless communication device to re-read the system information of the original cell.

19. The arrangement according to claim 11, wherein the controller is further configured to cause: determination of whether the one or more wireless communication device is in RRC IDLE state and uses the original cell as serving cell, and if so, moving of the wireless communication device while in RRC IDLE state through at least one of dedicated paging messages and broadcast information.

20. A network node comprising the arrangement according to claim 11.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further objects, features and advantages will appear from the following detailed description of embodiments, with reference being made to the accompanying drawings, in which:

(2) FIG. 1 is a schematic drawing illustrating an LTE downlink physical resource;

(3) FIG. 2 illustrates an LTE time-domain structure;

(4) FIG. 3 illustrates a normal downlink subframe;

(5) FIG. 4 is an illustration of carrier aggregation;

(6) FIG. 5 is an illustration of small cell overview of on/off via SCell activation/deactivation;

(7) FIG. 6 is a schematic drawing illustrating a Listen Before Talk procedure;

(8) FIG. 7 is a schematic drawing illustrating Licensed-assisted access (LAA) to unlicensed spectrum using LTE carrier aggregation;

(9) FIG. 8 is a schematic drawing illustrating an example arrangement for use in a user equipment according to some embodiments;

(10) FIG. 9 is a schematic drawing illustrating an example arrangement for use in a base station according to some embodiments;

(11) FIG. 10 is a schematic drawing illustrating a computer program product according to some embodiments;

(12) FIG. 11 is a flow chart showing a method according to one embodiment of the teachings disclosed herein;

(13) FIG. 12 is a schematic drawing illustrating the frequency change according to one embodiment of the teachings disclosed herein;

(14) FIG. 13 is a schematic drawing illustrating the frequency change according to one embodiment of the teachings disclosed herein;

(15) FIG. 14 is a schematic drawing illustrating the frequency change according to one embodiment of the teachings disclosed herein.

(16) FIG. 15 is a schematic drawing illustrating the frequency change according to one embodiment of the teachings disclosed herein;

(17) FIG. 16 is a schematic drawing illustrating the frequency change according to one embodiment of the teachings disclosed herein; and

(18) FIG. 17 is a schematic drawing illustrating the frequency change according to one embodiment of the teachings disclosed herein.

DETAILED DESCRIPTION

(19) In the following, embodiments will be described. In the described embodiments reconfiguration of cell frequency is enabled without negatively affect user experience or network performance. The described embodiments and their equivalents may be realized in software or hardware or a combination thereof. They may be performed by general-purpose circuits associated with or integral to a communication device, such as digital signal processors (DSP), central processing units (CPU), co-processor units, field-programmable gate arrays (FPGA) or other programmable hardware, or by specialized circuits such as for example application-specific integrated circuits (ASIC). All such forms are contemplated to be within the scope of this disclosure.

(20) Embodiments may appear within an electronic apparatus (such as a wireless communication device) comprising circuitry/logic or performing methods according to any of the embodiments. The electronic apparatus may, for example, be a portable or handheld mobile radio communication equipment, a mobile radio terminal, a mobile telephone, a base station, a base station controller, a pager, a communicator, an electronic organizer, a smartphone, a computer, a notebook, a USB-stick, a plug-in card, an embedded drive, or a mobile gaming device.

(21) FIG. 8 illustrates an example arrangement for use in a user equipment (UE) for implementing a method as taught herein according to some embodiments. The UE 800 comprises a transceiver (RX/TX) 801, a controller (CNTR) 802, and a memory 803 MEM. The transceiver 801 may in some embodiments be a separate transmitter and a separate receiver. The controller 802 is configured to receive and transmit data through the transceiver, which data may be stored in the memory 803, and to execute any of the methods taught herein.

(22) FIG. 9 illustrates an example arrangement for use in a base station eNB according to some embodiments. Example eNB 900 comprises a transceiver (RX/TX) 901, a controller (CNTR) 902, and a memory (MEM) 903. The transceiver 901 may in some embodiments be a separate transmitter and a separate receiver. The controller 902 is configured to receive and transmit data through the transceiver, which data may be stored in the memory 903, and to execute any of the methods taught herein.

(23) In some embodiments, the example eNB 900 may be an arrangement of a network node for changing a frequency of a first original cell, wherein the original cell is configured to operate at a first frequency. The one or more wireless communication devices are served by the original cell, and the network node is configured to control a plurality of other cells.

(24) If the original cell for some reason no longer provides sufficient resources so that it no longer can support the one or more wireless communication devices that is attached to it, the network node may determine that the original cell may need a change of frequency. In order to realize this, the controller 902 may be configured to cause the network node to select one or more second frequency of an unlicensed spectrum that the network node should switch the original cell to, determine a second cell on the selected second frequency as target cell and cause the target cell to maintain the same neighbor cell relations as the original cell.

(25) The target cell may e.g. be configured with the same neighbor list and network parameters as the original cell.

(26) The controller 902 is further configured to cause the network node to move the one or more wireless communication devices from the original cell to the target cell, turn off the original cell when the one or more wireless communication device have been moved from the first cell to the target cell and inform all neighbor cells of the original cell of the frequency change to the selected one or more second frequency.

(27) Thus, the wireless communication devices will always be connected to a cell, which leads to that network performance is kept on an overall high level, and carrier aggregation is as much as possible maintained.

(28) In some embodiments, the arrangement may comprise means to turn on a new cell.

(29) In some embodiments, the arrangement may further comprise means to reconfigure an already existing cell.

(30) In some embodiments, the controller 902 is further configured to inform the wireless device by means of dedicated signaling. The controller 902 may e.g. cause the transceiver 901 to signal the wireless device.

(31) In some embodiments, the arrangement may further comprise dedicated signaling means configured to perform a hand over. The dedicated signaling means may e.g. be a RRCConnectionReconfiguration message.

(32) In some embodiments, the arrangement may further comprise dedicated signaling means to perform a connection release with re-direct. The dedicated signaling means may e.g. be a RRCConnectionRelease message.

(33) In some embodiments, the controller 902 is further configured to inform the wireless device using broadcast and paging messages. The controller 902 may e.g. cause the transceiver 901 to broadcast a paging message to all wireless communication devices controlled by the eNB.

(34) The controller 902 may further be configured to cause determination of whether there are other active cells among the plurality of other cells controlled by the network node that can continue to be operated with. If such is the case the controller 902 may further cause determination of the target cell by selecting one or more such active cells as target cell.

(35) For instance, a cell may be continued to be operated with, i.e. maintained on the same frequency, if it provides acceptable network performance. The signal quality may e.g. be good, latency low etc.

(36) However, in some embodiments, the network node may determine that one or more cells has to be turned off and or have their frequency changed, but there is no spare capacity to create a new cell. In such case, the network node is already operating with a maximum number of cells.

(37) Thus, in some embodiments, the controller 902 may further be configured to cause determination of the target cell by causing the determination of whether the network node controls a maximum number of cells. If such is the case the controller 902 may cause moving of the one or more wireless communication device from the original cell to one or more of the plurality of other cells and turning off of the original cell. The controller 902 may further cause determination of the target cell on the selected one or more second frequency by creating a new cell operating in the selected one or more second frequency and moving the one or more wireless communication device from the plurality of other cells to the target cell.

(38) Thus, a cell frequency change can be made even though the node controls a maximum number of cells, since the devices are moved to the other cells prior to turning off the original cell. When the original cell has been turned off, a new cell may be created and then be configured as the target cell having the same neighbor configurations as the original cell.

(39) However, if more than one of the cell, or all of the cells controlled by the network node has to be turned off, then in some embodiments, the controller 902 may further be configured to cause determination of whether the network node controls a maximum number of cells and determine whether all of the cells has to be turned off (they may e.g. not provide sufficient signal quality or the network is to be restarted or the like). If such is the case the controller may be configured to cause the move of the one or more wireless communication device from the original cell to one or more of the plurality of other cells and the turning off of the original cell. The controller 902 may also cause determination of the target cell on the selected second frequency by creating a new cell operating in the selected second frequency and moving the one or more wireless communication device from the plurality of other cells to the target cell and the turning off the plurality of other cells.

(40) Moving the devices from the plurality of other cells may be made in steps, where a new cell is created and some of the devices are moved to this cell, then another cell is created and another group of devices are moved, until no devices are served by the old cells anymore so that they may be turned off.

(41) The controller 902 may further be configured to cause determination of whether there is a sufficient amount of free capacity to create the target cell. If such is the case the controller may cause creation of the target cell and cause the eNB to refraining from turning off the original cell until the target cell is created.

(42) If there is a sufficient amount of capacity to create a new cell as target cell, then there may be no need to first move the devices to the other cell controlled by the network node.

(43) In some embodiments, the controller may further be configured to cause moving of the one or more wireless communication device from the original cell by causing determination of whether the one or more wireless communication device is in Radio Resource Control—RRC—Connected state and uses the original cell as Primary Cell. If such is the case, the controller 902 may cause performing of a handover or a release by re-directing or moving the one or more wireless communication device from the original cell to the target cell.

(44) In some embodiments, it may be the secondary cell that needs to have a change of frequency, in such case the controller 902 may further be configured to cause determination of whether the one or more wireless communication device is in RRC Connected state and uses the original cell as Secondary Cell. If such is the case, the controller 902 may cause release of the one or more wireless communication device from the original cell; and configuration of the target cell as new Secondary Cell.

(45) Releasing the devices from the secondary cells means that they are still attached to the primary cell. It may thus not be necessary to create the target cell prior to releasing the devices from the original cell.

(46) The devices may furthermore only be moved when they are in a RRC connected state.

(47) Thus, in some embodiments, the controller 902 may further be configured to cause determination of whether the one or more wireless communication device is in RRC Idle state and uses the original cell as serving cell. If such is the case, the controller 902 may cause paging of the one or more wireless communication device to force it to RRC Connected state and then moving of the one or more wireless communication device from the original cell by causing determination of whether the one or more wireless communication device is in RRC Connected state and uses the original cell as Primary Cell. If such is the case, the controller 902 may cause performing of handover or a release by re-directing the one or more wireless communication device from the original cell to the target cell.

(48) Thus, the network node wakes the device such that it goes from camping on the cell as serving cell in IDLE state to camping on the cell as a primary cell in a Connected state.

(49) The controller 902 may further be configured to cause determination of whether the one or more wireless communication device is in RRC Idle state and uses the original cell as serving cell. If such is the case, the controller 902 may cause moving of the one or more wireless communication device while in RRC IDLE state by causing an update of a system information in the original cell with the target cell's frequency as a neighbor frequency (SIB5), information that the original cell is barred (SIB1) and/or information that intra-frequency cell reselection is not allowed (SIB1). The controller 902 may further cause paging of the one or more wireless communication device to re-read the system information of the original cell.

(50) Thus the device is forced to read the updated information and knows that when it wakes up it should look for the other cell.

(51) The controller may further be configured to cause determination of whether the one or more wireless communication device is in RRC IDLE state and uses the original cell as serving cell, and if so, moving of the wireless communication device while in RRC IDLE state through at least one of dedicated paging messages and broadcast information.

(52) In some embodiments, the arrangement may be of a network node 900 such as an eNB for changing a first frequency of a first original cell, wherein the network node controls a plurality of other cells and wherein one or more wireless communication devices are served by the original cell.

(53) The arrangement comprises a controller 902 configured to cause selection of a second frequency or frequencies on an unlicensed spectrum that the network node should switch the original cell to and determining a second cell on the selected one or more second frequency as target cell.

(54) The controller 902 may also be configured to causing the target cell to maintain the same neighbor cell relations as the original cell and performing a handover or a release by re-directing the one or more wireless communication device from the original cell to the target cell, wherein the handover comprises handover message to the one or more wireless communication device. The handover message may comprise an activation time which may indicate when in time the target cell is available for the one or more wireless communication devices.

(55) The controller 902 may also be configured to cause the network node to turn off the original cell and turning on the target cell on the selected second frequency before the activation time expires and informing one or more neighboring network nodes of the frequency change to the second frequency.

(56) In some embodiments, controller 902 may further be configured to cause the turning off of the original cell on the first frequency and the turning on of the original cell on the second frequency within the activation time.

(57) Thus, the original cell may be turned off prior to turning on the target cell. The one or more wireless communication devices are informed by means of the activation time when in time the target cell will be ready for them, and may thus connect to the target cell when the activation time expires. This makes it possible to release the one or more wireless communication devices from the original cell and let them be unconnected during the activation time. The hand over or redirect is then finished when the activation time has expired and the released devices may connect to the target cell.

(58) FIG. 10 illustrates an example computer program product program according to some embodiments. According to some embodiments, computer program product comprises a computer readable medium 1000 such as, for example, a diskette or a CD-ROM. The computer readable medium may have stored thereon a computer program comprising program instructions. The computer program may be loadable into a data-processing unit 1001, which may, for example, be comprised in a mobile terminal. The data processing unit 1001 may comprise a memory (MEM) 1002 and a processor (PROC) 1003. When loaded into the data-processing unit, the computer program may be stored in the memory (MEM) 1002 associated with or integral to the data-processing unit 1001. According to some embodiments, the computer program may, when loaded into and run by the data-processing unit, cause the data-processing unit to execute method steps according to, for example, the methods disclosed herein such as those shown in any of the FIGS. 11, 12, 13 and 14, as well as any of the FIGS. 15, 16 and 17

(59) Starting when an eNB, such as the eNB of FIG. 9, shall change frequency of one or multiple cells (original cell) due to detection of high interference in the spectrum, detection of wireless system with higher access priority to the spectrum, or being ordered by an administration system to stop operating on the spectrum. A method executed by the eNB will be disclosed with simultaneous reference to FIG. 11.

(60) The eNB selects 1110 which frequency or frequencies on an unlicensed spectrum that it should switch to and determines 1120 a cell on the selected frequency as target cell. If there are other active cells configured in the same eNB that can continue to be operated with, they can also be selected as target cell. Or, if the eNB is already operating the maximum number of cells that it is capable of, and it has to stop operating on all of these cells, the eNB shall redirect the UEs from one of the cells to the others so the eNB can safely turn off the original cell and create the new target cell on the selected frequency. Or, if there is free capacity in the eNB to create the target cell it is created while keeping the original cell. A target cell is thus determined and the newly created or determined target cell shall maintain 1130 the same neighbor cell relations as the original cell.

(61) The eNB then moves 1140 UEs from the original cell. If the UE is in RRC Connected state and uses the original cell as Primary Cell, the eNB performs handover or a release with re-direct for the UE from the original cell to the target cell, see FIG. 12.

(62) If the UE is in RRC Connected state and uses the original cell as Secondary Cell, the eNB releases the UE from the original cell and configures the target cell as new Secondary Cell.

(63) If the UE is in RRC Idle state and uses the original cell as serving cell, the eNB can either: page the UE forcing it to RRC Connected state and then perform a handover or a release with re-direct for the UE from the original cell to the target cell as in the above; or move the UE while in IDLE using current signaling. Such a move is performed by: first updating the system information in the original cell with: the target cell's frequency as a neighbor frequency (SIB5), information that the original cell is barred (SIB1), and information that intra-frequency cell reselection is not allowed (SIB1), and then page the UE to re-read system information. The eNB may alternatively move the UE while in IDLE using new signaling through e.g. dedicated paging messages and/or broadcast information.

(64) When all UEs are moved the eNB turns off 1150 the original cell and the UEs complete 1170 the handover procedure on the target cell.

(65) The eNB then informs 1170 all its neighbor cells of the frequency change

(66) As an alternative, the eNB may also be configured to utilize an activation time, by 1110 selecting which frequency or frequencies on an unlicensed spectrum that it should switch to and then 1140 move UEs from the original cell.

(67) If the UE is in RRC Connected state and uses the original cell as Primary Cell, the eNB performs handover for the UE from the original cell to the target cell. The handover message includes an activation time indicating when in time the new cell is available for the UE. This gives the eNB time until activation time expires to shut off the original cell and turn it on again on the new frequency.

(68) If the UE is in RRC Connected state and uses the original cell as Secondary Cell, the eNB releases the UE from the original cell and configure the target cell as new Secondary Cell.

(69) If the UE is in RRC Idle state and uses the original cell as serving cell, the eNB can either: page the UE forcing it to RRC Connected state and then perform a handover or a release with re-direct for the UE from the original cell to the target cell as in the above but with an activation time.

(70) The newly created target cell shall maintain 1130 the same neighbor cell relations as the original cell and the UEs complete the handover procedure 1160 on the target cell and the eNB shall inform 1170 all its neighbor cells of the frequency change.

(71) In some embodiments, the method of FIG. 11 may e.g. be a method of a network node for changing the frequency of a first original cell, wherein the network node controls a plurality of other cells. The method of FIG. 11 may e.g. begin with the network node selecting 1110 a second frequency or frequencies on an unlicensed spectrum that the network node should switch the original cell to.

(72) The network node may e.g. be an eNB and may determine that the original cell needs to be shut off due to e.g. inferior signal quality at the original cell, congestion, signal interference, change of network topology etc.

(73) When a second frequency has been selected the network node determines 1120 a second cell on the selected second frequency as target cell. The network node may cause 1130 the target cell to maintain the same neighbor cell relations as the original cell.

(74) The network node may e.g. configure the target cell with the same network parameters as the original cell. Thus, the target cell will function as the original cell, but on a different frequency.

(75) When the target cell has been determined the network node may move 1140 the one or more wireless communication devices from the original cell to the target cell.

(76) Thus it is made sure that the communication devices always are connected to at least one cell which leads to less probability that the network performance will be negatively affected.

(77) The network node may turn 1150 off the original cell when the one or more wireless communication devices has been moved from the original cell to the target cell; and may inform 1170 one or more neighboring network nodes of the frequency change to the second frequency.

(78) The step 1160 may in some embodiments be omitted from the method of FIG. 11.

(79) By informing the neighboring network nodes of the frequency change, it is ensured that all neighboring cells which may have some connection to the original cell is informed that the frequency of the original cell has been changed.

(80) In some embodiments, the network node may further determine if there are other cells among a plurality of cells which are controlled by the network node that may still be used for operation, i.e. may not need to be shut down. If so, the network node may determine the target cell by selecting one or more of the other cells. This is further illustrated in FIG. 15. FIG. 15 may in some embodiments correspond to FIG. 12.

(81) In FIG. 15 the X-axis denotes frequency and the Y-axis denotes time, or steps to be taken during a cell frequency shift.

(82) In step 1510 a primary cell (P) is operating on a first frequency f1, and a secondary cell (S) is operating on a second frequency f2.

(83) The network node may determine that the primary cell needs to be shut off but that the secondary cell still can be operated with. The Network node may then in step 1520 configure the secondary cell to be primary cell, and move all UEs to the new primary cell (compare to method step 1140 of the method of FIG. 11). Then the network node may shut of the original primary cell. During this time the capacity of the UEs and network performance may be slightly affected since normal operation may be carrier aggregation, and during the move it will be single carrier.

(84) However, in step 1530 the network node may have determined a second frequency f3 on which to start or create a new cell (compare with 1120 of FIG. 11). The new cell may then be configured as secondary cell to the UEs of the primary cell and carrier aggregation is again enabled.

(85) A cell frequency change has been made without affecting network performance since the UEs always are connected to a cell.

(86) The above scenario may e.g. be beneficial if the network node is controlling a maximum number of cells and does thus not have the capability to create new cells. Then if one cell needs to be shut down, the wireless communication devices can first be moved to another existing cell prior to shutting down the first cell. When the first cell has been shut off, a new cell can be created so that carrier aggregation is maintained.

(87) FIG. 16 illustrates a method according to some embodiments when the network node determines that all of its current cells need to be turned off FIG. 16 may in some embodiments correspond to FIG. 13.

(88) As in FIG. 15, the X-axis denotes the frequency, and the Y-axis denotes time or method steps.

(89) The network node controls a primary cell (P) on a first frequency f1, and a secondary cell (S) on a second frequency f2. In 1610 determines that both the primary cell and the secondary cell needs to be turned off and selects a new frequency for each cell.

(90) In 1620 the secondary cell on frequency f2 is configured to be primary cell and the UEs are moved to new primary cell (compare with FIGS. 12 and 15).

(91) In 1630 the old primary cell on frequency f1 has been shut off, while a new cell is turned on or created on the selected frequency f4 (compare with 1120 in FIG. 11). The new cell may be configured as target cell having the same neighbor relations as the original primary cell on the frequency f1 (compare with 1130 of FIG. 11).

(92) In 1640 the UEs are moved from the primary cell on frequency f2 to the target primary cell on the frequency f4 (compare with 1140 of FIG. 11). A new cell is created on frequency f3 and the former secondary and primary cell on frequency f2 is turned off (compare with 1150 of FIG. 11).

(93) In 1650 the new cell on the frequency f3 is configured as new secondary cell to the primary cell on the frequency f4 so that carrier aggregation may be continued.

(94) In some embodiments, the network node may determine that there is a sufficient amount of free capacity to create or start a new target cell, the procedure which follows after this determination is illustrated in FIG. 17.

(95) FIG. 17 illustrates an example where the eNB has free capacity to create a new cell while keeping an original cell. FIG. 17 may in some embodiments correspond to FIG. 14.

(96) As in FIGS. 15 and 16 the X-axis denotes frequency and the Y-axis denotes time or method steps.

(97) A first original cell is primary cell (P) on a first frequency f1. In 1710 the network node may determine that the original cell needs to be shut off, and may thus select a second frequency which the network node should move the original cell to.

(98) In 1720 a target cell is created on a second frequency f3 (compare with 1120 of FIG. 11). The target cell is configured with the same parameters as the original cell so as to keep the same neighbor relations (compare with 1130 of FIG. 11). The target cell may e.g. be configured with the same cell ID or the same neighbor list or the like.

(99) In 1730 the network node moves the UEs that were served by the original cell to the target cell on the second frequency f3 (compare with 1140 of FIG. 11), and in 1740 when all UEs have been moved, the original cell on the first frequency f1 is shut off (compare with 1150 of FIG. 11).

(100) When moving a wireless communication device, the network node can either initiate a handover to another cell or inform the device that is should move to the other cell.

(101) For instance, the network node may determine if the one or more wireless communication device is in Radio Resource Control—RRC—Connected state and uses the original cell as Primary Cell, and if so, the network node may perform a handover or a release by re-directing the one or more wireless communication device from the original cell to the target cell.

(102) Or, the network node may determine if the one or more wireless communication device is in RRC Idle state and uses the original cell as serving cell. If such is the case, the network node may move the one or more wireless communication device while in RRC IDLE state through the steps of updating a system information in the original cell with the target cell's frequency as a neighbor frequency (SIB5), information that the original cell is barred (SIB1) and/or information that intra-frequency cell reselection is not allowed (SIB1) and paging the one or more wireless communication device to re-read the system information of the original cell.

(103) Thus, when a terminal in idle mode wakes up it will read the new system information and know that it should connect to the cell on another frequency.

(104) A person skilled in the art realizes that the term Primary cell is used for UEs in RRC connected mode, and the term serving cell is used for UEs in RRC IDLE mode, since the UE when in IDLE mode is only connected to one cell. When the UE is in connected mode it may have both a primary and a secondary cell, which both acts as serving cells.

(105) The network node could also, if the wireless communication device is in IDLE state, page the device in order to force it wake up so that a hand over may be performed.

(106) In IDLE state the terminal is typically inactive but does monitor paging and performs measurements on its serving cell and neighboring cells.

(107) In some embodiments, if the original cell is a secondary cell, then the network node may release the wireless communication device from the original cell, and configure the target cell as new secondary cell. In this case it is not crucial that there already exists a new cell when the original cell is shut off, since the wireless device will be connected to a primary cell.

(108) In some embodiments, a handover between cells may be performed with the aid of an activation time. The network node may e.g. transmit a handover message to the one or more wireless communication devices served by a cell, wherein the handover message comprises an activation time indicating when in time the target cell is available for the one or more wireless communication devices.

(109) The network node may then release the UEs even though there isn't a new cell for them to connect to yet. However, the handover message will inform the UEs where there will be a cell ready for them and when.

(110) Thus, the one or more wireless communication device will know when in time there will be a cell ready for it which it may connect to at that time.

(111) In some embodiments, the network node may turn off the original cell and turn it on again on the selected second frequency before the activation time expires. It is to be noted that it is not the exact same cell that is turned on again on the selected frequency, but another cell having the same cell ID, or same network parameters as the original cell.

(112) The activation time enables a handover or redirect without the need of an overlap of cells. This method may e.g. be beneficial if it is not possible to create a new cell in the network while still keeping the old cell, e.g. if maximum capacity has been reached or if the above described method for some reason fails. The network node may for that reason use the activation time if the method as described in conjunction with FIG. 11 for some reason fails.

(113) Then, handover or a release may be performed by re-directing the one or more wireless communication device from the original cell to the target cell with an activation time. I.e. the devices may receive a handover message comprising an activation time, the devices may then be released from the original cell and connect to the target cell on or after the expiry of the activation time.

(114) In some embodiments, the network node may further determine if the one or more wireless communication device is in RRC Connected state and uses the original cell as Primary Cell. If so, the network node may perform handover of the one or more wireless communication device from the original cell to the target cell, wherein the hand over comprises a handover message comprising an activation time indicating when in time the new cell is available for the one or more wireless communication device.

(115) The network node may deactivate the original cell, and activates it again on the selected second frequency before expiration of the activation time.

(116) In some embodiments, the network node may determine if the one or more wireless communication device is in RRC Idle state and uses the original cell as serving cell, and if so page the one or more wireless communication device in order to force it into RRC Connected state and determine if the UE is in RRC Connected state and uses the original cell as Primary Cell. If such is the case the network node may perform handover or a release by re-directing the one or more wireless communication device from the original cell to the target cell with an activation time.

Embodiments

(117) One embodiment relates to a method implemented in a network node for changing the frequency of a cell, the method comprising:

(118) determining a target frequency;

(119) providing a cell on the target frequency;

(120) moving wireless devices from the original frequency to the target frequency;

(121) turning off the cell on the original frequency; and

(122) informing neighbor cells about the frequency change.

(123) One embodiment relates to an arrangement, such as a network node, for changing the frequency of a cell, the arrangement being configured to

(124) determine a target frequency;

(125) provide a cell on the target frequency;

(126) move wireless devices from the original frequency to the target frequency;

(127) turn off the cell on the original frequency; and

(128) inform neighbor cells about the frequency change.

(129) In one embodiment the arrangement further comprises means to turn on a new cell.

(130) In one embodiment the arrangement further comprises means to reconfigure an already existing cell.

(131) In one embodiment of the arrangement the move means are further configured to inform the wireless device using dedicated signaling

(132) In one embodiment the arrangement further comprises dedicated signaling means to perform a hand over

(133) In one embodiment the arrangement further comprises dedicated signaling means to perform a connect release with re-direct.

(134) In one embodiment of the arrangement the move means are further configured to inform the wireless device using broadcast and paging messages

(135) In one embodiment of the arrangement the move is performed within an activation time.

(136) One embodiment relates to a method for use in a node for changing the frequency of a cell, the method comprising:

(137) selecting which frequency or frequencies on an unlicensed spectrum that it should switch to;

(138) determining a cell on the selected frequency as target cell;

(139) causing the target cell to maintain the same neighbor cell relations as the original cell;

(140) moving UEs from the original cell;

(141) turning off the original cell when all UEs are moved;

(142) causing the UEs to complete the handover procedure on the target cell; and

(143) informing all its neighbor cells of the frequency change

(144) In one embodiment of the method determining a cell on the selected frequency as target cell comprises

(145) determining if there are other active cells configured in the same eNB that can continue to be operated with, and if so such active cells can also be selected as target cell.

(146) In one embodiment of the method determining a cell on the selected frequency as target cell comprises

(147) determining if a maximum number of cells is already operating on, and if operating on all of these cells has to be stopped, redirecting the UEs from one of the cells to the others so the original cell can safely be turned off and

(148) creating the new target cell on the selected frequency.

(149) In one embodiment of the method determining a cell on the selected frequency as target cell comprises

(150) determining if there is free capacity in to create the target cell it is created while keeping the original cell.

(151) In one embodiment of the method moving UEs from the original cell comprises

(152) determining if the UE is in RRC Connected state and uses the original cell as Primary Cell, then performing handover or a release with re-direct for the UE from the original cell to the target cell.

(153) In an embodiment of the embodiment above wherein the handover message includes an activation time indicating when in time the new cell is available for the UE to give the node time until activation time expires to shut off the original cell and turn it on again on the new frequency.

(154) In one embodiment of the method moving UEs from the original cell comprises

(155) determining if the UE is in RRC Connected state and uses the original cell as Secondary Cell, then releasing the UE from the original cell and configuring the target cell as new Secondary Cell.

(156) In one embodiment of the method moving UEs from the original cell comprises

(157) determining if the UE is in RRC Idle state and uses the original cell as serving cell, then page the UE forcing it to RRC Connected state and then moving UEs from the original cell by

(158) determining if the UE is in RRC Connected state and uses the original cell as Primary Cell, then performing handover or a release with re-direct for the UE from the original cell to the target cell.

(159) In one embodiment where the UE is in RRC Idle state and uses the original cell as serving cell, wherein moving UEs from the original cell by determining if the UE is in RRC Connected state and uses the original cell as Primary Cell, then performing handover or a release with re-direct for the UE from the original cell to the target cell is performed but with an activation time.

(160) In one embodiment of the method, moving UEs from the original cell comprises

(161) determining if the UE is in RRC Idle state and uses the original cell as serving cell, then move the UE while in IDLE using current signaling through the steps of:

(162) updating the system information in the original cell with: the target cell's frequency as a neighbor frequency (SIB5), information that the original cell is bared (SIB1) and/or information that intra-frequency cell reselection is not allowed (SIB1); and

(163) paging the UE to re-read system information.

(164) In one embodiment of the method, moving UEs from the original cell comprises

(165) determining if the UE is in RRC Idle state and uses the original cell as serving cell, then moving the UE while in IDLE using new signaling through e.g. dedicated paging messages and/or broadcast information.

(166) In one alternative embodiment the eNB is configured to

(167) select which frequency or frequencies on an unlicensed spectrum that it should switch to,

(168) move UEs from the original cell;

(169) Cause the newly created target cell to maintain the same neighbor cell relations as the original cell;

(170) complete the handover procedure on the target cell; and

(171) inform all its neighbor cells of the frequency change

(172) In one embodiment moving the cell comprises determining if the UE is in RRC Connected state and uses the original cell as Primary Cell, the eNB performs handover for the UE from the original cell to the target cell, wherein the handover message includes an activation time indicating when in time the new cell is available for the UE to give the node time until activation time expires to shut off the original cell and turn it on again on the new frequency.

(173) In one embodiment moving the cell comprises determining if the UE is in RRC Connected state and uses the original cell as Secondary Cell, the eNB releases the UE from the original cell and configure the target cell as new Secondary Cell.

(174) In one embodiment moving the cell comprises determining if the UE is in RRC Idle state and uses the original cell as serving cell, and determining if the UE is in RRC Connected state and uses the original cell as Primary Cell, then performing handover or a release with re-direct for the UE from the original cell to the target cell is performed but with an activation time are performed but with an activation time.

Apparatus and method for cell frequency change procedure signal timing selection

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H04W36/22

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H04W36/0022

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H04W16/14

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Abstract

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Description