The invention generally relates to wireless communications and more particularly to apparatuses, systems, and methods for changing communications systems radio coverage configuration based on available capacity of one or more compensation cells.
Many wireless communication systems employ transceiver stations or radio heads to provide service within geographical service areas, where the boundaries of a service area are determined by the radio coverage of its associated transceiver station. Wireless service is provided to user equipment (UE) devices over radio frequency carriers (carriers) within each service area, where a carrier is the modulated waveform that conveys the physical channels as specified by the associated wireless technology standard. These service areas are sometimes referred to as “cells”.
Although the term “cell” sometimes refers to the geographical area where multiple uplink and downlink resources (e.g., pairs of uplink and downlink carriers) are used, increasingly the term. “cell” is used to refer to the geographical service area where single uplink resource and a single downlink resource are used to communicate with the UE devices. For example, where Time Division Duplex (TDD) is used, a single frequency may be used for uplink and downlink at different times within the “cell”. Where Frequency Division Duplex (FDD) is used, a single uplink/downlink frequency pair (one uplink frequency and one downlink frequency) is used within a “cell”.
As discussed herein, one or more resources (carrier pairs) may be used in a service area. As a result, a service area may be a single cell or may contain multiple cells. In one common arrangement, each service area is adjacent to several other service areas to provide ubiquitous coverage over a large geographical area
Adjacent service areas may overlap slightly, but, for the following discussion, no service areas provide service within the same geographical area. In many situations, there may be an advantage'to dynamically change the configuration of the service areas, such as by selectively reducing the size of some service areas and expanding the size of one or more other service areas to provide service within the area previously serviced by the service areas that were reduced. Such dynamic coverage area configuration transitions may allow for more efficient operation of the system.
For example, a service area with only a small number of UE devices may be reduced to zero by deactivating its associated transceivers, and an adjacent service area that is serving several UE devices but has available capacity may be expanded to provide radio coverage for the UE, devices previously contained in the reduced service area. Therefore, a service area that is reduced may be referred to as an energy saving service area since the energy consumed by its associated transceivers is reduced or eliminated, and a service area that is reduced to zero may be referred to as a deactivated service area A service area that is expanded in cooperation with a service area that is reduced may be referred to, as compensation service area since its service area is expanded to compensate for a service area that is reduced.
UE devices being served by an energy saving service area may lose their connection with the network if they are not handed over to another service area before the energy saving service area is deactivated. If the energy saving service area and the compensation service area operate on the same frequency resources, UE devices being served by an energy saving service area may lose their connection with the network if the compensation service area is expanded before the UE devices are handed over to another service area because of the interference between the energy saving service area and the compensation service area. As discussed below, management techniques are needed to control the dynamic coverage area configuration transitions.
In a cellular communication system, a coverage area configuration transition is performed when it is determined that the resources allocated to a compensation service area have sufficient available capacity to serve one or more UE devices being served by an energy saving service area In reconfiguring the coverage areas of the system, the compensation service area is expanded to cover at least a portion of an energy saving service area of an energy saving cell and the energy saving service area is at least partially deactivated. A compensation communication station providing the compensation service area sends a request for a coverage area configuration transition to an energy saving communication station, and the energy saving communication station may reject the coverage area configuration transition or may accept it and send an expansion notification to the compensation communication station, where the notification at least indicates that the compensation service area can be expanded.
In a cellular communication system, a coverage area configuration transition is performed when it is determined that the resources allocated to a compensation service area have sufficient available capacity to serve one or more UE devices being served by an energy saving service area. In reconfiguring the coverage area of the system, the compensation service area (e.g., compensation communication station coverage area) is expanded to include at least a portion of an area covered by the energy saving communication station. For example, the expanded compensation service area would cover an energy saving service area of an energy saving cell and the energy saving service area is deactivated.
Communication stations 108, 112 transmit and receive wireless signals to provide the cells 104, 106. Each communication station 108, 112, which also may be referred to as an access node, access point, eNodeB, eNB, base station, and other terms, includes a transceiver and station controller. The controller in each communication station is configured to perform the various methods and operations described herein. The transceiver, or radio head, is typically collocated with the station controller although, in some situations, the station controller may be physically separated from the radio head. The radio head at least includes radio frequency (RF) transceiver equipment such as antennas, transmitters, and receivers, for transmitting and receiving wireless signals. Typically, radio heads do not include higher level processing and control functions which are performed by the associated station controller. For the illustration of
A cellular communication system is typically required to adhere to a communication standard or specification. The communication specification defines at least a data channel and a control channel for uplink and downlink transmissions and specifies at least some timing and frequency parameters for physical downlink control channels from a base station to a wireless communication device. The Third-Generation Partnership Project Long-Term Evolution (3GPP LTE) communication specification is a specification for systems where communication stations (eNodeBs) provide service to wireless communication devices (UE devices) using orthogonal frequency-division multiplexing (OFDM) on the downlink and single-carrier frequency-division multiple access (SC-FDMA) on the uplink. Although the techniques described herein may be applied in other types of communication systems, the exemplary systems discussed herein operate in accordance with an FDD 3GPP LTE communication specification.
Therefore, for the examples herein, the compensation communication station 108 includes a wireless transceiver that transmits downlink signals 120 to one or more UE devices 114 within the compensation cell 104 in accordance with 3GPP LTE and receives uplink signals 122 from one or more UE devices 114 within the compensation cell 104 in accordance with 3GPP LTE. The energy saving communication station 112 includes a wireless transceiver that transmits downlink signals 126 and 130 to one or more UE devices 116, 118 within the energy saving cell 106 in accordance with 3GPP LTE and receives uplink signals 124 and 128 from one or more UE devices 116, 118 within the energy saving cell 106 in accordance with 3GPP LTE.
The User Equipment (UE) devices 114, 116, 118 may be referred to as mobile devices, wireless devices, wireless communication devices, and mobile wireless devices, and UEs, as well as by other terms. The wireless communication devices include electronics and code for communicating with communication stations (eNBs) and, in some cases, with other devices including other UE devices. The UE devices include devices such as smart phones, cell phones, personal digital assistants (PDAs), wireless modem cards, wireless modems, televisions with wireless communication electronics, and laptop and desktop computers, as well as other devices. The combination of wireless communication electronics with an electronic device, therefore, may form a wireless communication device. For example, a wireless communication device may include a wireless modem connected to an appliance, computer, or television.
In some instances, the compensation communication station 108 uses the same frequency channel to provide the compensation cell 104 as the energy saving communication station uses to provide the energy saving cell 106. For the example of
First, the compensation communication station 108 determines a traffic load of the compensation cell. As used herein, the term “traffic load” generally refers to an amount of communications resources of a particular cell that are being used by the UE devices that are being served by the cell. Traffic load can be expressed in an absolute terms or as a measurement relative to the total resources (e.g., capacity) of the cell.
Regardless of how the traffic load is expressed, if the traffic load of the compensation cell is below a first threshold level, the traffic load of the energy saving cell is determined. More specifically, the compensation communication station 108 transmits a request 132 for the traffic load of the energy saving communication station 112. The energy saving communication station responds by transmitting the traffic load indicator 134 that is indicative of the traffic load of the energy saving communication station to the compensation communication station 108. Based at least on the traffic load of the energy saving cell and the available capacity of the compensation cell, the compensation communication station 108 determines whether the compensation cell can serve the UE devices 116, 118 being served by the energy saving communication station 112 if the compensation service area were to be expanded to include the energy saving service area. When determining whether the compensation cell can serve the traffic load of the energy saving cell, the compensation communication station may take into consideration the amount of the energy saving cell's traffic load that could be transferred to other cells. This information could be obtained from the energy saving communication station or from a centralized traffic management server, or it might be determined by the compensation communication station based on traffic load reports received from other communication stations. In response to a determination that the compensation cell can serve the UE devices 116, 118 being served by the energy saving cell, the compensation communication station 108 initiates a transition of the radio coverage area configuration.
In the example shown in
In the first stage 202, the UE devices 116, 118 are communicating over wireless communication links 204, 206 with the communication station 112 of the energy saving service area 106. For the example, the UE devices 116, 118 are at least receiving control signals and may also be transmitting control signals and exchanging data with the communication station 112 prior to the coverage transition. The coverage transition may be initiated in response to a determination that the energy saving service area 106 should be deactivated and the compensation service area 104 should be expanded. Such a determination may be based on any number of several factors and circumstances where some examples include the resource load on the energy saving service area 106 and the compensation service area 104. For example, the resource load of the energy saving service area may at least partly be based on the amount of time and frequency resources being used by all of the UE devices 116, 118 within the service area. The determination for deactivating the energy saving service area 106 may be based on whether the resources allocated to the compensation service area 104 have sufficient available capacity to provide service to the UE devices 116, 118 within the ES service area 106. As another example, the determination for deactivating an energy saving service area 106 may be based on a particular time, day, month, etc., where an operator has determined that the traffic load at this time can be managed without the energy saving service area 106. In response to the determination that the energy saving service area 106 should be deactivated, the coverage transition is initiated.
In
When the compensation communication station 108 receives a response message from the energy saving communication station 112 with an “accept” indication, the coverage transition may be initiated, which is the second stage 208. The compensation communication station 108 initiates the expansion of the compensation service area and the energy saving communication station 112 initiates the handover procedures for the UE devices 116, 118 currently receiving wireless service from the energy saving communication station 112. The UE devices 116, 118 are handed over from the energy saving cell to other cells according to the typical LTE handover procedures. UE devices 116, 118 may be handed over to the compensation cell 104 when the compensation cell's coverage of the energy saving service area 106 allows it to be a suitable handover target for the UE.
After the compensation cell expansion is complete, the compensation communication station 108 notifies the energy saving communication station 112. After the energy saving communication station 112 receives notification that the compensation cell expansion is complete and all of the UE devices 116, 118 are handed over to other cells, at the third stage 210 of the transition procedure, the energy saving service area 106 is deactivated. The circle representing the energy saving service area 106 is shown with a dashed line to indicate that the cell is no longer active. As a result, the energy saving communication station (eNB) 112 does not provide wireless service within the energy saving service area 106 by transmitting or receiving wireless signals. For the example herein, the energy saving communication station 112 is turned off and consumes little or no power, and the UE devices 116, 118 are communicating over wireless communication links 212, 214 with the compensation communication station 112 of the expanded compensation service area 104.
For the example of
In some situations, a first compensation service area (e.g., first compensation communication coverage area) is only expanded to cover a portion of the energy saving service area, and one or more additional compensation communication stations each expand their respective coverage areas to include any portion of the energy saving service area that is not covered by the expanded first compensation communication station coverage area.
For the example shown in
If it is determined that the compensation communication station 108 can serve the UE devices 116, 118 being served by the energy saving cell, the compensation communication station 108 sends a request to the energy saving communication station 112 to initiate a transition of the cell coverage configuration for the energy saving cell. In the example shown in
A part of the transition of the cell coverage configuration is that the compensation cell is reconfigured such that its coverage area is expanded to include the coverage area being served by the energy saving cell. The expansion of the compensation service area is initiated by the compensation communication station 108 after receiving the Cell Status Change Response 408 with an indication that the energy saving communication station 112 accepts the request for a transition of the cell coverage configuration for the energy saving cell. The compensation communication station 108 increases transmission power and performs other known techniques for expanding the compensation service area to cover the energy saving service area For example, techniques such as antenna tilting and antenna beam forming may be used to provide an expanded service area of the compensation cell that covers the original service area of the energy saving service area as well as the original service area of the compensation service area.
Where multiple energy saving service areas are deactivated, the compensation service area is expanded to cover those service areas. In one example, the parameters for establishing the expanded coverage area are determined at the time of equipment deployment. For example, signal quality measurements may be made and the parameters may be determined using the, signal measurements at the time of or after equipment installation. Accordingly, the compensation communication station applies stored values or values it has received from an Operations and Maintenance (OAM) system to expand the service area to cover the areas of the energy saving service areas that have been deactivated.
The UE devices 116, 118 are handed over from the energy saving cell to other cells according to the typical LTE handover procedures. A UE device may be handed over to the compensation cell when the compensation cell's coverage of the energy saving service area allows it to be a suitable handover target for the UE. As illustrated in
In some circumstances, a communication station configuration update message may be sent from the energy saving communication station 112 to other communications stations indicating that the energy saving service area is no longer active. The other communication stations include at least the neighbor stations of the energy saving service area and may include other communication stations that require information regarding the status of the energy saving service area For example, this functionality could be added to the LTE X2 interface eNB Configuration Update message that communication stations use to notify other communication stations about configuration changes of their service areas (cells).
Also, in some circumstances, a communication station configuration update message may be sent from the compensation communication station 108 to the other communications stations indicating that the compensation service area has been expanded. The other communication stations include at least the neighbor stations of the energy saving service area and the compensation service area and may include other communication stations that require information regarding the status of the compensation service area. For example, this functionality could be added to the LTE X2 interface eNB Configuration Update message that communication stations use to notify other communication stations about configuration changes of their service areas.
At step 506, based at least on the traffic load of the energy saving cell and the available capacity of the compensation cell, the compensation communication station 108 determines if the compensation cell can serve the UE devices 116, 118 being served by the energy saving cell. In some circumstances, determining whether the compensation cell can serve one or more of the UE devices 116, 118 being served by the energy saving cell includes determining whether the traffic load of the energy saving cell is less than or equal to the available capacity of the compensation cell.
If it is determined that the compensation cell cannot serve the UE devices 116, 118 being served by the energy saving cell, the compensation communication station 108 transmits a request to the energy saving communication station 112 that the energy saving communication station 112 transmits a traffic load report or other indication to the compensation communication station 108 when the traffic load of energy saving cell falls below a second threshold level.
In some situations, the determination that the compensation cell cannot serve the UE devices 116, 118 being served by the energy saving cell includes determining that the traffic load of the energy saving cell is more than a capacity threshold based on the available capacity of the compensation cell. For example, the capacity threshold could be 80% of the available capacity of the compensation cell. Of course, the capacity threshold could be any suitable threshold amount, based on system capabilities, requirements, expected traffic demands, and any other pertinent criteria. When it is determined that the traffic load of the energy saving cell is more than the capacity threshold based on the available capacity of the compensation cell, the compensation communication station 108 transmits the request to the energy saving communication station 112 that the energy saving communication station 112 transmits a report to the compensation communication station 108 when the traffic load of the energy saving cell falls below a second threshold level. In some situations, the second threshold level may be updated as the traffic load of the compensation cell changes.
Regardless of the exact method used to determine that the compensation cell cannot serve the UE devices 116, 118 being served by the energy saving cell, the energy saving communication station 112 transmits, at step 508, the requested report to the compensation communication station 108 when the traffic load of the energy saving cell falls below the second threshold level. In response to a determination that the compensation cell can serve the UE devices 116, 118 being served by the energy saving cell and the energy saving communication station 112 accepting the request for a transition of the cell coverage configuration for the energy saving cell, the compensation cell is reconfigured, at step 510, such that its coverage is expanded to include the coverage area being served by the energy saving cell. The UE devices 116, 118 are handed over from the energy saving cell to other cells according to the typical LTE handover procedures. A UE device may be handed over to the compensation cell when the compensation cell's coverage of the energy saving service area allows it to be a suitable handover target for the UE. When all of the UE devices 116, 118 are handed over to other cells and the compensation cell has completed its coverage expansion to include the energy saving service area, the energy saving service area 106 is deactivated. In the example shown in
Clearly, other modifications and manners of practicing this invention will occur readily to those of ordinary skill in the art in view of these teachings. The above description is illustrative and not restrictive. This invention is to be limited only by the following claims, which include all such modifications and manners of practice when viewed in conjunction with the above specification and accompanying drawings. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.
The present application claims priority to Provisional Application No. 61/864,474 entitled “Methods for Managing Resources for Transitions Between Cell Coverage Configurations”, filed Aug. 9, 2013, assigned to the assignee hereof, and hereby expressly incorporated by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/IB2014/001947 | 8/11/2014 | WO | 00 |
Number | Date | Country | |
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61864474 | Aug 2013 | US |