U.S. patent application number 14/910568 was filed with the patent office on 2016-06-30 for communications system radio coverage reconfiguration based on available capacity of a compensation cell.
The applicant listed for this patent is Kyocera Corporation. Invention is credited to David COMSTOCK.
Application Number | 20160192262 14/910568 |
Document ID | / |
Family ID | 52449073 |
Filed Date | 2016-06-30 |
United States Patent
Application |
20160192262 |
Kind Code |
A1 |
COMSTOCK; David |
June 30, 2016 |
COMMUNICATIONS SYSTEM RADIO COVERAGE RECONFIGURATION BASED ON
AVAILABLE CAPACITY OF A COMPENSATION CELL
Abstract
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, A coverage area
configuration transition includes reducing the coverage of an
energy saving service area and expanding the coverage of a
compensation service area. A compensation communication station
providing the compensation service area sends a request for a
coverage area configuration transition to an energy saving
communication station. 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.
Inventors: |
COMSTOCK; David; (San Diego,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kyocera Corporation |
Kyoto |
|
JP |
|
|
Family ID: |
52449073 |
Appl. No.: |
14/910568 |
Filed: |
August 11, 2014 |
PCT Filed: |
August 11, 2014 |
PCT NO: |
PCT/IB2014/001947 |
371 Date: |
February 5, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61864474 |
Aug 9, 2013 |
|
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|
Current U.S.
Class: |
370/331 |
Current CPC
Class: |
H04L 43/16 20130101;
H04W 36/0069 20180801; H04W 52/346 20130101; H04W 52/34 20130101;
H04W 52/0209 20130101; H04W 36/165 20130101; H04W 72/0486 20130101;
Y02D 30/70 20200801; Y02D 70/1262 20180101; H04W 52/0206 20130101;
H04L 43/062 20130101 |
International
Class: |
H04W 36/16 20060101
H04W036/16; H04L 12/26 20060101 H04L012/26; H04W 52/34 20060101
H04W052/34; H04W 72/04 20060101 H04W072/04 |
Claims
1. A method comprising: determining a traffic load of a first
compensation communication station, if the traffic load of the
first compensation communication station is below a first threshold
level, determining a traffic load of an energy saving communication
station; determining, based at least on the traffic load of the
energy saving communication station and an available capacity of
the first compensation communication station, whether the first
compensation communication stator can serve one or more user
equipment devices (UE devices) being served by the energy saving
communication station; in response to determining that the first
compensation communication station can serve one or more UE devices
being served by the energy saving communication station,
reconfiguring the first compensation communication station such
that the first compensation communication station can serve the one
or more UE devices being served by the energy saving communication
station; handing over at least one of the UE devices from the
energy saving communication station to the first compensation
communication station; and reducing an amount of energy used by the
energy saving communication station.
2. The method of claim 1, wherein the determining whether the first
compensation communication station can serve one or more UE devices
being served by the energy saving communication station comprises:
determining whether the traffic load of the energy saving
communication station is less than or equal to the available
capacity of the first compensation communication station.
3. The method of claim 1, wherein reconfiguring the first
compensation communication station comprises: expanding a first
compensation communication station coverage area to include at
least a portion of an area covered by the energy saving
communication station.
4. The method of claim 3, wherein expanding the first compensation
communication station coverage area comprises: expanding the first
compensation communication station coverage area to include all of
the area covered by the energy saving communication station.
5. The method of claim 3, wherein one or more additional
compensation communication stations expand their respective
coverage areas to include any portion of the area covered by the
energy saving communication station that is not covered by the
expanded first compensation communication station coverage
area.
6. The method of claim 1, wherein handing over at least one of the
UE devices comprises: handing over all of the UE devices being
served by the energy saving communication station to the first
compensation communication station.
7. The method of claim 1, wherein reducing the amount of energy
used by the energy saving communication station comprises:
deactivating the energy saving communication station.
8. The method of claim 1, further comprising: if the traffic load
of the energy saving communication station is more than a capacity
threshold based on the available capacity of the first compensation
communication station, requesting that the energy saving
communication station transmits a report to the first compensation
communication station when the traffic load of the energy saving
communication station falls below a second threshold level; and
transmitting the requested report to the first compensation
communication station when the traffic load of the energy saving
communication station falls below the second threshold level.
9. The method of claim 1, further comprising: transmitting a
request to initiate a transition of a cell coverage configuration,
transmitting a response to the request to initiate a transition of
the cell coverage configuration; and if the response is an
acceptance, initiating a transition of the cell coverage
configuration.
10. A compensation communication station, comprising: a controller
configured to determine a traffic load of the compensation
communication station; and a transmitter configured to transmit a
request for a traffic load of an energy saving communication
station if the traffic load of the compensation communication
station is below a first threshold level, wherein the controller is
further configured to: determine, based on at least the traffic
load of the energy saving communication station and an available
capacity of the compensation communication station, whether the
compensation communication station can serve one or more user
equipment devices (UE devices) being served by the energy saving
communication station, in response to determining that the
compensation communication station can serve one or more UE devices
being served by the energy saving communication station,
reconfigure the compensation communication station such that the
compensation communication station can serve one or more UE devices
being served by the energy saving communication station, and
receive at least one of the UE devices being handed over from the
energy saving communication station to the compensation
communication station.
11. The compensation communication station of claim 10, wherein the
controller is configured to determine that the compensation
communication station can serve one or more UE devices being served
by the energy saving communication station if the traffic load of
the energy saving communication station is less than or equal to
the available capacity of the compensation communication
station.
12. The compensation communication station of claim 10, wherein the
controller is further configured to: expand a compensation
communication station coverage area to include at leas a portion of
an area covered by the energy saving communication station.
13. The compensation communication station of claim 12 wherein the
controller is further configured to: expand the compensation
communication station coverage area to include a the area covered
by the energy saving communication station.
14. The compensation communication station of claim 10, wherein the
controller is further configured to: receive all of the UE devices
being handed over from the energy saving communication station to
the compensation communication station.
15. The compensation communication station of claim 10, wherein the
controller is further configured to: if the traffic load of the
energy saving communication station is more than a capacity
threshold based on the available capacity of the compensation
communication station, request that the energy saving communication
station transmits a report to the compensation communication
station when the traffic load of the energy saving communication
station falls below a second threshold level.
16. A system, comprising: a compensation communication station,
comprising: a controller configured to determine a traffic load of
the compensation communication station, and a transmitter; and an
energy saving communication station, comprising: a receiver
configured to receive a request, transmitted by the compensation
communication station, for a traffic load of the energy saving
communication station if the traffic load of the compensation
communication. station is below a first threshold level, and a
transmitter configured to transmit the traffic load of the energy
saving communication station to the compensation communication
station, wherein the controller is further configured to:
determine, based on at least the traffic load of the energy saving
communication station and an available capacity of the compensation
communication station, whether the compensation communication
station can serve one or more user equipment devices (UE devices)
being served by the energy saving communication station, in
response to determining that the compensation communication station
can serve one or more UE devices being served by the energy saving
communication station, reconfigure the compensation communication
station such that the compensation communication station can serve
one or more UE devices being served by the energy saving
communication station, and receive at least one of the UE devices
being handed over from the energy saving communication station to
the compensation communication station.
17. The system of claim 16, wherein the controller is configured to
determine that the compensation communication station can serve one
or more UE devices being served by the energy saving communication
station if the traffic load of the energy saving communication
station is less than or equal to the available capacity of the
compensation communication station.
18. The system of claim 16, wherein the controller is further
configured to expand a compensation communication station coverage
area to include at least a portion of an area covered by the energy
saving communication station.
19. The system of claim 18, wherein the controller is further
configured to: expand the compensation communication station
coverage area to include all of the area covered by the energy
saving communication station.
20. The system of claim 18, wherein one or more additional
compensation communication stations expand their respective
coverage areas to include any portion of the area covered by the
energy saving communication station that is not covered by the
expanded compensation communication station coverage area.
21. The system of claim 16, wherein the controller is further
configured to: receive all of the UE devices being handed over from
the energy saving communication station to the compensation
communication station.
22. The system of claim 16, wherein the energy saving communication
station is configured to deactivate after handing over at least one
of the UE devices.
23. The system of claim 16, wherein the controller is further
configured to: if the traffic load of the energy saving
communication station is more than a capacity threshold based on
the available capacity of the compensation communication station,
request that the energy saving communication station transmits a
report to the compensation communication station when the traffic
load of the energy saving communication station falls below a
second threshold level; and receive the requested report when the
traffic load of the energy saving communication station falls below
the second threshold level.
Description
PRIORITY
[0001] 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.
FIELD
[0002] 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.
BACKGROUND
[0003] 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".
[0004] 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".
[0005] 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
[0006] 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.
[0007] 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.
[0008] 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.
SUMMARY
[0009] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is an illustration of coverage areas in a cellular
communication system.
[0011] FIG. 2 is an illustration of a coverage transition where the
energy saving service area (ES SA) is deactivated and the
compensation service area (Comp. SA) is expanded to provide
wireless service within the geographical region of the energy
saving service area.
[0012] FIG. 3 includes illustrations of a coverage area transition
where the compensation service area is expanded to cover more than
one energy saving service area.
[0013] FIG. 4 is a message flow diagram between the compensation
communication station, the energy saving communication station, and
the UE devices.
[0014] FIG. 5 is a method of operating the system shown in FIG.
1.
DETAILED DESCRIPTION
[0015] 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.
[0016] FIG. 1 is an illustration of coverage areas in a cellular
communication system 100 where coverage area transitions are based
on the available capacity of a compensation cell. For the example
of FIG. 1, an energy saving communication station provides wireless
service within a geographical service area represented by a
circular area of an energy saving cell and a compensation
communication station provides wireless service within a
geographical service area represented by a circular area of a
compensation cell. In typical implementations of the cellular
communication system 100, several adjacent cells cover larger
geographical regions. In the interest of brevity and clarity,
however, FIG. 1 shows only two cells 104, 106. The circular shapes
representing the service areas of the cells generally illustrate
the relationships between the cells and do not necessarily depict
the actual shapes of the service areas. The coverage area
configuration transition management techniques discussed with
reference to FIG. 1 may be applied to numerous coverage area
configuration transition scenarios. For example, several energy
saving cells may be deactivated and a compensation cell may be
expanded to cover the geographical service areas of the multiple
energy saving cells in accordance with the techniques discussed
herein. The cells may have any of several shapes and sizes.
[0017] 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 FIG. 1, the radio heads are
near a station controller where both the radio head and the
controller may be implemented within a single apparatus. Since the
location, shape, and size of the cell is determined at least in
part by wireless transmission and reception with the communication
station, the cell's location and coverage area is determined by the
location and operation of the radio head. The compensation
communication station 108 provides the compensation cell 104 and an
energy saving communication station 112 provides the energy saving
cell 106. Each communication station 108, 112, therefore, provides
wireless communication services to wireless communication user
equipment devices (UE devices) 114, 116, 118 within the cell where
each cell covers a geographical service area Communication stations
typically provide several cells, but in the interest of brevity and
clarity, communication stations 108 and 112 provide one cell and
the full radio and data processing capacity of communication
stations 108 and 112 are applied to the service of the cell they
provide. Accordingly, for the example shown in FIG. 1, the
available capacity of a cell is equivalent to the available
capacity of the communication station that provides the cell. As
discussed herein, a communication station includes the equipment
such as a station controller and radio head that provides a single
cell. Accordingly, a communication station can be configured or
adjusted to establish the size and shape of the service area of the
cell. Several communication stations are typically interconnected
through a backhaul (not shown) and to a network (not shown) to
provide several service areas to cover large areas. The backhaul
may include any combination of wired, optical, and/or wireless
communication channels. For the examples herein, the network
includes the functionality of the Mobility Management Entity (MME)
and the Packet Gateway (P-GW).
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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 FIG. 1 the same set
of downlink/uplink frequency channel pairs may be assigned for the
compensation cell 104 and the energy saving cell 106. In the cell
configuration shown in FIG. 1, communications in the compensation
cell do not interfere with communications in energy saving cell 106
when both cells use the same frequency channel since the service
areas of the cells do not overlap. When the compensation cell and
energy saving cell use the same frequency channel and the service
area of the compensation cell is expanded as discussed below, the
compensation cell will interfere with the UE devices served by the
energy saving cell if not managed in some manner.
[0022] 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.
[0023] 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.
[0024] In the example shown in FIG. 1, the coverage area
configuration transition consists of expanding the compensation
service area, handing over the UE devices being served by the
energy saving cell, and deactivating the energy saving cell. In
general, all of the UE devices being served by the energy saving
cell are handed over to one or more compensation cells (or
neighboring cells that do not expand their coverage area) before
the energy saving cell reduces the amount of energy being used, and
the compensation coverage area is expanded to include the entire
area of the energy saving service area. However, in other
instances, the energy saving cell's activity may only be partially
reduced and a compensation service area may be expanded to include
only a part of the energy saving service area. The energy saving
cell may hand over one or more UE devices and still continue to
serve one or more remaining UE devices. When the energy saving cell
hands over all of its UE devices, the reduction of energy will
generally include switching off or deactivating the energy saving
cell 106. In other circumstances, the reduction of energy could
include: reducing the size of the service area being served by the
energy saving cell 106, reducing the broadcast strength of the
signals 126, 130 being transmitted by the energy saving
communication station 112, and/or reducing the number of UE devices
being served by the energy saving cell 106.
[0025] FIG. 2 is an illustration of a coverage transition where the
energy saving service area (ES SA) 106 is deactivated and the
compensation service area (Comp. SA) 104 is expanded to provide
wireless service within the geographical region of the energy
saving service area 106. In the example of FIG. 2, a coverage
transition within the system of FIG. 1 is shown progressing through
three stages. In the interests of clarity and brevity, two UE
devices 116, 118, are shown in the example.
[0026] 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.
[0027] In FIG. 2, when it is determined that the compensation
cell's traffic load may be sufficiently low to allow the
deactivation of the energy saving cell 106, the compensation
communication station 108 obtains the current traffic load of the
energy saving cell 106. The compensation communication station 108
may already have this information because of previously received
traffic load information or it may request the information based on
existing methods. When the level of the traffic load of the energy
saving cell 106 does not exceed the available capacity of the
resources allocated to the compensation coverage area 104, the
compensation communication station 108 sends a message to the
energy saving communication station 112 to request a cell coverage
configuration transition. The energy saving communication station
112 sends a response message that indicates whether the request is
accepted or not For the purpose of this illustration, the cell
coverage configuration transition would consist of the expansion of
the coverage area 104 of the compensation cell to include the
energy saving coverage area 106 and the deactivation of the energy
saving service area 106.
[0028] 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.
[0029] 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.
[0030] FIG. 3 includes illustrations 300, 301 of a coverage area
transition where the compensation service area is expanded to cover
more than one energy saving service area. The circular shapes
representing the service areas generally illustrate the
relationships between the service areas and do not necessarily
depict the actual shapes of the service areas. In addition, the
service areas may overlap in some regions more than in other
regions. The open areas shown between the circular shaped service
areas in the figure do not necessarily indicate that no service is
available in these areas and are merely a product of illustration
utilizing simple shapes to represent a more complicated
relationship between service areas. Further, the service areas may
contain. holes of coverage where service is unavailable. In the
interests of clarity and brevity, such features are not illustrated
in the figures.
[0031] For the example of FIG. 3, the region 102 includes the
geographical areas of several smaller service areas 104, 106, 302,
304, 306, 308, 310 including the compensation service area 104 and
three energy saving service areas 106, 302, 304. In state 300
before the compensation area is expanded, the energy saving service
areas 106, 302, 304 have coverage areas adjacent to the
compensation service area 104. In state 301 after the compensation
service area is expanded, the compensation service area 312 has a
coverage area that includes the original coverage area of the
compensation service area 104 and at least portions of the coverage
areas of the energy saving service areas 106, 302, 304. The
expanded compensation service area 312, therefore, is the
compensation service area 104 with a larger coverage area The
energy saving service areas are shown with dashed lines in the
coverage state 301 to illustrate that the service areas have been
deactivated. The coverage area transition procedure for multiple
energy saving service areas is similar to the transition procedure
for a single energy saving service area discussed above. In one
example, the compensation service area expands to cover each energy
saving service area serially. In other words, the compensation
service area is expanded to cover a first energy saving service
area before a second energy service area. In such an example, all
UE devices in the first energy saving service area are handed over
to the compensation service area, the compensation service area is
expanded to cover the first energy saving service area, and the UE
devices are transferred to the compensation service area prior to
the procedure being performed for next energy saving service area
in the examples discussed below, however, the compensation service
area is expanded to cover multiple energy saving service area areas
in a single coverage area transition procedure. In this example,
all UE devices from all energy saving service areas are handed over
to the compensation service area, the compensation service area is
expanded, and all the UE devices complete the handovers to the
compensation service area. In some circumstances, some UE devices
may be transferred to neighboring small service areas (306, 310)
instead of the compensation service area. In these instances, the
small service areas 306, 310 may act as additional compensation
communication stations and may remain the same size or may
expand/reduce their respective compensation service areas, as
needed.
[0032] 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.
[0033] FIG. 4 is a message flow diagram 400 between the
compensation communication station 108, the energy saving
communication station 112, and the UE devices 116, 118. For the
example, the communication stations are eNBs that communicate
through the backhaul over an X2 link in accordance with LTE
communication standards. Other communication techniques can be used
in some circumstances. More specifically, the communication
stations could communicate wirelessly in some circumstances.
[0034] For the example shown in FIG. 4, in response to determining
that the traffic load of the compensation cell is below a first
threshold level, the compensation communication station
(compensation cell eNB) 108 sends a request 402 to the energy
saving communication station (ES eNB) 112 for the traffic load of
the energy saving cell. In response to the request, the energy
saving communication station 112 transmits 404 a traffic load
indicator (e.g., indicator 134 from FIG. 1) indicative of its
current traffic load 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 controller of
the compensation communication station 108 determines whether the
compensation cell can serve the UE devices 116, 118 that are being
served by the energy saving communication station 112.
[0035] 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 FIG. 4, this request is
a Cell Status Change Request 406. The energy saving communication
station 112 sends a response to the compensation communication
station 108 accepting or rejecting the request to initiate a
transition of the cell coverage configuration for the energy saving
cell. In this example, the response is a Cell Status Change
Response 408. The Cell Status Change Response 408 is an example of
the Expansion Notification and indicates to the compensation
communication station 108 that the compensation service area can be
expanded. In one example, the Cell State Change messages 406/408
are part of a dedicated procedure for this feature that is added to
a standard specification. In other circumstances, the Cell State
Change messages 406/408 functions may be incorporated into
messaging structures and procedures currently defined by a
communication, standard, such as the Load Management or eNB
Configuration Update procedures contained in the LTE communication
standard. In either case, modifications of the LTE communication
standard can facilitate the communication.
[0036] 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.
[0037] 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.
[0038] 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 FIG. 4, handover messages 410 for the first UE
device 116 are exchanged between the communication stations 108,
112 and handover messages 412 for the nth UE device 116 are
exchanged between the communication stations 108, 112. 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. As discussed herein, a service area is
"deactivated" when it no longer transmits downlink signals to UE
devices and does not receive or process uplink signals from UE
devices. Therefore, a deactivated service area cannot provide
wireless service to UE devices. The communication station that
provides the energy saving service area still includes active
functions and is not turned off. For example, the communication
station is still capable of communicating with other communication
stations and/or the network.
[0039] 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).
[0040] 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.
[0041] FIG. 5 illustrates a method 500 of operating system 100. At
step 502, a controller of the compensation communication station
108 determines a traffic load of the compensation cell. At step
504, if the traffic load of the compensation communication station
108 is below a first threshold level, 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 112 responds by transmitting the
traffic load indicator 134 indicative of the traffic load of the
energy saving communication station 112 to the compensation
communication station 108.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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 FIG. 1, the reduction of energy includes switching off or
deactivating the energy saving cell 106. In other situations, the
reduction of energy includes: reducing the size of the service area
being served by the energy saving cell 106, reducing the broadcast
strength of the signals 126, 130 being transmitted by the energy
saving communication station 112, and/or reducing the number of UE
devices being served by the energy saving cell 106.
[0046] 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.
* * * * *