U.S. patent application number 14/591428 was filed with the patent office on 2016-07-07 for dynamic hand-over parameter control.
The applicant listed for this patent is Verizon Patent and Licensing Inc.. Invention is credited to Barry Steven Braun.
Application Number | 20160198385 14/591428 |
Document ID | / |
Family ID | 56287256 |
Filed Date | 2016-07-07 |
United States Patent
Application |
20160198385 |
Kind Code |
A1 |
Braun; Barry Steven |
July 7, 2016 |
DYNAMIC HAND-OVER PARAMETER CONTROL
Abstract
Methods and systems for dynamic parameter selection are
provided. A station receives a condition measurement report from
user equipment (UE) served by the station. The condition
measurement report includes a signal strength indication, which
includes a strength of a reference signal measured by the UE that
is received by the UE over the air from the station. The wireless
communication network includes a Long Term Evolution (LTE) network.
A parameter controller compares the signal strength indication to a
signal strength threshold, to identify a change in the strength of
the reference signal. The parameter controller selects an alternate
parameter value of a parameter associated with hand-over that is
different from a current parameter value, responsive to the
identified change in the reference signal strength. The station
sends an instruction to the UE served by the station to perform
hand-over measurement reporting using the selected alternate
parameter value.
Inventors: |
Braun; Barry Steven;
(Batavia, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Verizon Patent and Licensing Inc. |
Arlington |
VA |
US |
|
|
Family ID: |
56287256 |
Appl. No.: |
14/591428 |
Filed: |
January 7, 2015 |
Current U.S.
Class: |
455/437 |
Current CPC
Class: |
H04W 36/0058 20180801;
H04W 36/0094 20130101 |
International
Class: |
H04W 36/30 20060101
H04W036/30 |
Claims
1. A method comprising: receiving, by a station in a wireless
communication network, a condition measurement report from a user
equipment (UE) served by the station, the wireless communication
network including a Long Term Evolution (LTE) network, the
condition measurement report including signal strength information
indicating a signal strength of the station for the UE, the signal
strength information comprising information indicating a strength
of a reference signal measured by the UE, the reference signal
being received by the UE from the station; comparing, by the
station, the signal strength information to a signal strength
threshold in order to identify a change in the strength of the
reference signal received from the station by the UE; selecting, by
the station, an alternate parameter value for a parameter
associated with a hand-over of the UE, based on the change in the
strength of the reference signal, the alternate parameter value
being different than a current parameter value being utilized by
the UE for the parameter associated with the hand-over of the UE;
and sending, by the station and to the UE, an instruction
instructing the UE to perform hand-over measurement reporting based
on the alternate parameter value.
2. The method of claim 1, wherein the signal strength information
includes at least one of a reference signal receive power (RSRP)
level or a reference signal receive quality (RSRQ) level.
3. The method of claim 1, wherein the parameter associated with
hand-over includes at least one of a hysteresis or an offset.
4. The method of claim 1, wherein the selecting of the alternate
parameter value for the parameter associated with the hand-over
includes selecting a first parameter value when the signal strength
information is greater than the signal strength threshold and
selecting a second parameter value when the signal strength
information is less than or equal to the signal strength threshold,
the second parameter value being less than the first parameter
value.
5. The method of claim 4, wherein the first parameter value is
selected to reduce a hand-over likelihood in radio frequency (RF)
conditions of the station higher than the signal strength threshold
and the second parameter value is selected to increase the
hand-over likelihood in RF conditions of the station lower than the
signal strength threshold.
6. The method of claim 1, wherein the condition measurement report
includes a plurality of condition measurement reports and the
method includes comparing the signal strength information from each
of the plurality of condition measurement reports to the signal
strength threshold, to identify the change in the strength of the
reference signal received from the station.
7. The method of claim 1, wherein the receiving of the condition
measurement report includes receiving the condition measurement
report responsive to a predetermined trigger condition associated
with a current strength of the reference signal measured by the
UE.
8. The method of claim 1, wherein the signal strength threshold
includes a plurality of signal strength thresholds and the method
includes selecting the alternate parameter value by comparing the
signal strength information to the plurality of signal strength
thresholds.
9. The method of claim 1, the method further comprising sending a
further instruction from the station to the UE served by the
station, the further instruction including at least one of a
predetermined trigger condition for sending the condition
measurement report to the station, an indication of a number of
condition measurement reports to generate by the UE or a
predetermined report interval between each condition measurement
report.
10. The method of claim 1, the method further comprising, after the
sending of the instruction: repeating the steps of receiving the
condition measurement report, comparing the signal strength
information, selecting the alternate parameter value, and sending
the instruction.
11. A system comprising: a station in a wireless communication
network serving a user equipment (UE), the wireless communication
network including a Long Term Evolution (LTE) network; a database
storing at least one signal strength threshold; and a parameter
controller communicatively coupled to the station, the parameter
controller configured to: receive, via the station, a condition
measurement report from the UE served by the station, the condition
measurement report including a signal strength information
indicating a signal strength of the station for the UE, the signal
strength information comprising information indicating a strength
of a reference signal measured by the UE, the reference signal
being received by the UE from the station; compare the signal
strength information to the at least one signal strength threshold
stored in the database in order to identify a change in the
strength of the reference signal received from the station by the
UE; and select an alternate parameter value for a parameter
associated with a hand-over of the UE, based on the change in the
strength of the reference signal, the alternate parameter value
being different than a current parameter value being utilized by
the UE for the parameter associated with the hand-over of the UE,
wherein the station sends an instruction to the UE to perform
hand-over measurement reporting based on the alternate parameter
value.
12. The system of claim 11, wherein the parameter controller is
configured to select a first parameter value as the alternate
parameter value for the parameter associated with the hand-over
when the signal strength information is greater than the at least
one signal strength threshold and select a second parameter value
as the alternate parameter value for the parameter associated with
the hand-over when the signal strength information is less than or
equal to the at least one signal strength threshold, the second
parameter value being less than the first parameter value.
13. The system of claim 11, wherein the station is configured to
send a further instruction to the UE served by the station, the
further instruction including at least one of a predetermined
trigger condition for sending the condition measurement report to
the station, an indication of a number of condition measurement
reports to generate by the UE or a predetermined report interval
between each condition measurement report.
14. The system of claim 11, wherein the station is configured to
receive the condition measurement report responsive to a
predetermined trigger condition associated with a current strength
of the reference signal measured by the UE.
15. The system of claim 11, wherein the condition measurement
report includes a plurality of condition measurement reports and
the parameter controller is configured to compare the signal
strength information from each of the plurality of condition
measurement reports to the at least one signal strength threshold,
to identify the change in the strength of the reference signal
received from the station by the UE.
16. The system of claim 11, wherein the at least one signal
strength threshold includes a plurality of signal strength
thresholds and the parameter controller is configured to select the
alternate parameter value by comparing the signal strength
information to the plurality of signal strength thresholds.
17. A non-transitory computer readable medium for storing
instructions, the instructions comprising: one or more instructions
that, when executed by one or more network devices in a wireless
communication network, cause the one or more network devices to:
receive, via a network device in the wireless communication
network, at least one condition measurement report from a user
equipment (UE) served by the network device, the wireless
communication network including a Long-Term Evolution (LTE)
network, the at least one condition measurement report including
signal strength information indicating a signal strength of the
network device for the UE, the signal strength information
comprising information indicating a strength of a reference signal
measured by the UE, the reference signal being received by the UE
from the network device; compare the signal strength information in
the at least one condition measurement report to at least one
signal strength threshold in order to identify a change in the
strength of the reference signal received from the network device
by the UE; select an alternate parameter value for a parameter
associated with a hand-over of the UE, based on the change in the
strength of the reference signal, the alternate parameter value
being different than a current parameter value being utilized by
the UE for the parameter associated with the hand-over of the UE;
and send an instruction to the UE served by the network device to
perform hand-over measurement reporting based on the alternate
parameter value.
18. The non-transitory computer readable medium of claim 17,
wherein the instructions further comprise: one or more instructions
that, when executed by the one or more network devices, cause the
one or more network devices to: select a first parameter value as
the alternate parameter value for the parameter associated with the
hand-over when the signal strength information is greater than the
at least one signal strength threshold; and select a second
parameter value as the alternate parameter value for the parameter
associated with the hand-over when the signal strength information
is less than or equal to the at least one signal strength
threshold, the second parameter value being less than the first
parameter value.
19. The non-transitory computer readable medium of claim 17,
wherein the at least one signal strength threshold includes a
plurality of signal strength thresholds and the instructions
further comprise: one or more instructions that, when executed by
the one or more network devices, cause the one or more network
devices to: select the alternate parameter value for the parameter
associated with the hand-over from among two or more predetermined
parameter values by comparing the signal strength information to
the plurality of signal strength thresholds.
20. The non-transitory computer readable medium of claim 17,
wherein the instructions further comprise: one or more instructions
that, when executed by the one or more network devices, cause the
one or more network devices to: send a further instruction to the
UE served by the network device, the further instruction including
at least one of a predetermined trigger condition for sending the
at least one condition measurement report to the network device, an
indication of a number of condition measurement reports to generate
by the UE or a predetermined report interval between each condition
measurement report.
Description
BACKGROUND
[0001] Consumer adoption of user equipment (UE) such as cellular
telephones, laptop computers, pagers, personal digital assistants,
and the like, is increasing. These devices can be used in a
wireless communication network for a diversity of purposes ranging
from basic communications, to conducting business transactions, to
managing entertainment media, as well as a host of other tasks.
[0002] A wireless communication network may include a number of
stations associated with a respective number of geographical areas
(also referred to herein as cells) that can support communication
coverage for a number of UEs. A UE can travel through the network
from a source cell to a neighboring cell on a single-cell network
connection basis. As the UE migrates through the network, the
existing connection to the network via the source cell is released,
and a new connection to the network is re-established on the
neighboring cell. This process is known as hand-over.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The drawing figures depict one or more implementations in
accord with the present teachings, by way of example only, not by
way of limitation. In the figures, like reference numerals refer to
the same or similar elements.
[0004] FIG. 1 is a high-level functional block diagram of an
example of a system that supports an example of a dynamic parameter
control service.
[0005] FIG. 2 is a high-level functional block diagram of an
example of a station and dynamic parameter controller shown in FIG.
1.
[0006] FIG. 3 is a signal flow diagram illustrating an example of
hand-over processing with dynamic parameter adjustment.
[0007] FIG. 4 is a flow chart diagram illustrating an example of
dynamic parameter control based on source station signal strength
information.
[0008] FIG. 5A is a flow chart diagram illustrating an example of
condition measurement report transmission and parameter value
storage at a UE.
[0009] FIG. 5B is a flow chart diagram illustrating an additional
example of dynamic parameter control.
[0010] FIG. 5C is a flow chart diagram illustrating an example of
dynamic parameter control based on two signal strength
thresholds.
[0011] FIG. 6A is a graph of RSRP for a source station and a target
station as a function of time, illustrating an example of an event
for hand-over measurement reporting based on predetermined trigger
parameters.
[0012] FIG. 6B is a graph of RSRP for a source station and a target
station as a function of time, illustrating an example of the
effect of hysteresis adjustment based on source station signal
strength on the hand-over initiation point in an event.
[0013] FIG. 7 is a high-level functional block diagram of an
example user equipment, as may be involved in generating signal
strength condition measurement reports and hand-over measurement
reports.
[0014] FIG. 8 is a simplified functional block diagram of a
computer that may be configured as a host or server, for example,
to function as the dynamic parameter controller in the system of
FIG. 1.
[0015] FIG. 9 is a simplified functional block diagram of a
personal computer or other work station or terminal device.
DETAILED DESCRIPTION OF EXAMPLES
[0016] In the following detailed description, numerous specific
details are set forth by way of examples in order to provide a
thorough understanding of the relevant teachings. However, it
should be apparent that the present teachings may be practiced
without such details. In other instances, well known methods,
procedures, components, and/or circuitry have been described at a
relatively high-level, without detail, in order to avoid
unnecessarily obscuring aspects of the present teachings.
[0017] In a Long Term Evolution (LTE) network, a UE detects
suitable neighbor cells for hand-over with and sometimes without
the assistance of a list of neighbor cells. The UE detects suitable
hand-over candidates, and a hand-over evaluation is performed by
the serving station. The UE uses parameters sent by the serving
station to determine when to perform hand-over measurements. The UE
monitors the serving cell's coverage and determines the health of
its radio link through a reference signal strength. The reference
signal strength (such as a Reference Signal Receive Power (RSRP),
typically measured in decibels (dBs)) is applied to the messaging
to and from the station to express the condition of the radio
link.
[0018] An example of hand-over for a UE that originates a call in a
coverage area of cell A is described. As the UE leaves the coverage
of cell A and enters the coverage area of neighboring cell B, the
RSRP of cell A becomes weaker, and the RSRP of cell B becomes
stronger. Eventually, the RSRP of cell B becomes stronger than cell
A; as cell B signal becomes strong enough to interfere with the
existing connection that the UE has with cell A. At this point, the
condition of the radio link between the UE and the system is
degraded, and handing the connection over to (the stronger) cell B
becomes desirable to maintain a healthy radio link with the
network.
[0019] When the UE detects a stronger neighbor and the desirability
of a hand-over, the UE sends a measurement report message to the
system about the condition. The UE sends a report message
containing the signal strength of both the serving cell (RSRP) and
the hand-over candidate cell (RSRP). (The UE may periodically scan
its own serving cell RSRP, as well as all other RSRP cells in the
neighboring system and typically reports the strongest values.) The
system evaluates the measurement report message and determines if
the conditions are right for a hand-over. When the hand-over
conditions are met, the system initiates the hand-over. Measurement
condition values, including a measurement offset value and a
measurement hysteresis value, may collectively determine if the
hand-over condition is met in order to initiate the hand-over.
[0020] The level of hysteresis (or difference in strength of
received signals, between a hand-over candidate and a current
serving station) in which the hand-over initiation determination is
made can be set by one or more dynamically controlled parameters
that the network communicates to the UE. In LTE, the event A3 is
defined as a triggering event when conditions are right for
hand-over initiation. An LTE example may use the event A3
parameters "A3-offset" and "A3-Hysteresis," which are represented
in decibels (dB).
[0021] The need for initiating a hand-over to rectify the
difference in strength between the serving cell and the better (but
interfering) candidate cell can be referred to as "hysteresis". The
hysteresis value is the predetermined difference (in dB) between
the serving cell and the neighboring cell that has to be reached
before a hand-over is initiated. For example if the system
hysteresis value is 6 dB, and a UE has a serving cell RSRP value of
-80 dBm, a measurement report message will not be sent back to the
system and a hand-over will not be initiated until a neighboring
cell's RSRP is received and qualifies for hand-over at -74 dBm.
[0022] The measurement offset value (also referred to as bias value
or sometimes the A3 offset value) is a value applied to a serving
cell or an adjacent neighbor cell to encourage or retard the
hand-over in one way or another. For example, if the neighboring
cell has an offset (bias) value of -2dB, the UE will apply that
bias value to the hand-over initiation criteria to advance or
retard the hand-over. For example, if a serving cell has an RSRP of
-80dBm, and a hand-over hysteresis of 6 dB, a neighbor cell with a
hand-over bias of -2 dB has an RSRP of -72 dBm before the hand-over
is initiated by the system. Hand-over qualification (also referred
to as event A3 in the LTE standard) may be described by the
equation: Event A3=Serving Cell RSRP measurement+Hysteresis+Serving
Cell Offset<Neighbor Cell RSRP measurement+Neighbor Cell Offset.
The event A3 is described further below with respect to FIG.
6A.
[0023] Currently, the hysteresis parameter and offset (bias)
parameter(s) for initiating hand-over measurement are fixed values.
The likelihood of hand-over is directly proportional to the
selected value for the hysteresis parameter and the offset
parameter.
[0024] A large value (for the hysteresis and/or offset) discourages
hand-overs, while a low value increases the frequency of
hand-overs. In practice, a wireless network operator determines a
"balanced" fixed value that is large enough to control the number
of hand-over attempts and manage capacity, and small enough to
allow hand-overs to occur easily enough for a smooth transition
from cell to cell.
[0025] Intentional handoff reluctance created by large hysteresis
and offset values is an effective capacity management technique as
it helps to keep demand away from capacity-strapped cells in busy
environments. (For example, UEs are discouraged from handing to
busy cells and adding to the capacity problem). However, this large
value may create a problematic hand-over environment, with poor
performance, for weak signal strength areas (e.g. by encouraging a
UE device to stay with a weak-signal capacity strapped cell even
when a cell providing a stronger signal is detected).
[0026] When the hysteresis is a fixed small value, hand-offs are
encouraged. The performance with a small value may be tolerable in
low signal strength environments (because hand-over can occur more
frequently), but capacity may not be well managed in strong signal
strength environments (because UEs are likely to jump to the
capacity-strapped cell). There is also a problem of frequent
messaging, which places a strain on system resources as well has a
higher probability of dropping the connection under frequent
hand-over conditions.
[0027] Today, there is no existing solution for selecting the
hysteresis and offset values that takes into consideration
different, possibly variable, signal strength environments, without
an operator.
[0028] As discussed above, currently, the hysteresis and offset
values are fixed. Reduced hysteresis values make hand-overs easier
and create an increase in hand-over attempts. If UE hand-overs are
made difficult with large hysteresis values, the number of
hand-overs attempts decrease. Sometimes operators use a larger
hysteresis value to discourage hand-overs into busy (overloaded)
sectors in an effort to improve capacity and cell efficiency of the
network. If the hysteresis and offset values are too high, the UE
suffers a great amount of interference from the hand-over candidate
before the hand-over is made. Therefore, performance may suffer in
the effort to improve capacity. If the hysteresis and offset values
are too small, the UE makes the hand-over too early. Thus, slight
changes in the received signal strength could make the UE attempt
to hand back to the previous cell. If system conditions cause
serving and neighbor cells RSRP values to fluctuate slightly, the
end result could be a Ping-Pong effect as the UE hands back and
forth between competing cells. Currently, the wireless network
operator determines a "balanced" fixed value that is large enough
to control the number of hand-over attempts and manage capacity,
and small enough to allow hand-overs to occur easily enough for a
smooth transition from cell to cell.
[0029] The various methods and systems disclosed herein relate to
dynamic parameter selection methods and dynamic parameter control
systems. The parameter is a parameter associated with hand-over in
a wireless communication network including an LTE network. A
station in the wireless communication network, such as the eNodeB
in an LTE network, receives a condition measurement report from a
UE device served by the station. The condition measurement report
includes a signal strength indication of the station. The signal
strength indication represents a strength of a reference signal
measured by the UE, that is received by the UE over the air from
the station. A parameter controller in the network compares the
signal strength indication of the station to a signal strength
threshold, to identify a change in the strength of the reference
signal (received from the station by the UE). The parameter
controller selects an alternate parameter value different from a
current parameter value, responsive to the identified change in the
strength of the reference signal. The station sends an instruction
to the UE served by the station to perform hand-over measurement
reporting using the selected alternate parameter value. The
parameter controller is associated with the station (i.e., as an
internal component of the station or an external component in the
network that is communicatively coupled to the station). The
parameter associated with hand-over may include a hysteresis and/or
an offset, as well as any other suitable parameter associated
hand-over. Thus, in some examples, the parameter controller may
select two or more alternate parameter values associated with two
or more parameters (e.g., hysteresis and offset).
[0030] The source station is a station that serves the UE, to
establish and maintain a connection between the UE and the wireless
communication network. The connection may be an active connection,
where data is exchanged between the UE and the network. The
connection may also be an idle connection, in which no data is
exchanged.
[0031] In some examples, the parameter value may be used for
hand-over measurement reporting. In some examples, the parameter
value may also be used for actual initiation of hand-over to a
target station (i.e., a station not currently serving the UE). As
described further below with respect to FIGS. 3 and 6A, hand-over
measurement reporting is typically the first step in hand-over
processing, and involves a comparison of source and target station
signal strengths. The condition measurement report(s) is used to
communicate changes in reference signal strength of the source
(i.e., serving) station (as measured by the UE), in order to vary
the parameter value (for hand-over measurement reporting and/or
hand-over initiation) based on the radio link health of the source
station.
[0032] In some examples, a first parameter value is selected when
the signal strength indication is greater than the signal strength
threshold. A second parameter value that is less than the first
parameter value is selected when the signal strength indication is
less than or equal to the signal strength threshold. The first
parameter value is selected to reduce a hand-over likelihood in
radio frequency (RF) conditions of the station higher than the
signal strength threshold (i.e., better RF conditions). The second
parameter value is selected to increase the hand-over likelihood in
RF conditions of the station lower than the predetermined threshold
(i.e., poor RF conditions). In some examples, multiple condition
measurement reports are used to identify the change in a reference
signal strength of the station. In some examples, the alternate
parameter value is selected by comparing the signal strength
indication to one or more signal strength thresholds. In some
examples, a condition measurement report is sent from the UE to the
station responsive to a predetermined trigger condition.
[0033] Reference now is made in detail to the examples illustrated
in the accompanying drawings and discussed below. FIG. 1 is a
high-level functional block diagram of an example of a system of
networks/devices that provides various communications for UEs and
supports an example of the dynamic parameter control service. The
system 10 (also referred to as network 10) includes a number of
stations (referred to collectively herein as "stations 17" and
individually as "station 17"), a wireless communication network 15
and other network entities (for example, public switched telephone
network (PSTN) 19, Internet 23, other network 29, and the like). A
dynamic parameter controller 30 (also referred to herein as
controller 30) is communicatively coupled to station 17-1.
Controller 30 adjusts a parameter associated with hand-over
measurement reporting (e.g., trigger event initiation such as event
A3) based on a reference signal strength identified by a UE (e.g.,
UE 13-1 or 13-2) in a condition measurement report (described
further below with respect to FIG. 3). Although not shown, an
additional controller 30 may also be communicatively coupled to
station 17-2. In some examples, controller 30 is separate from
(i.e., external to) station 17. For example, controller 30 may be
located on a server (outside of cell 20-1, such as in network 15)
that is communicatively coupled to station 17. In other examples,
controller 30 may be part of (i.e., internal to) station 17. In
some examples, controller 30 may be part of mobility management
entity (MME) 16.
[0034] The present techniques may be implemented in any of a
variety of available wireless networks 15 and/or on any type of UE
(referred to collectively herein as "UEs 13" and individually as
"UE 13") compatible with such a network 15, and the drawing shows
only a very simplified example of a few relevant elements of
network 15 for purposes of discussion herein. Network 10 provides
communications between UEs 13 as well as communications for UEs 13
within networks and devices outside wireless communication network
15.
[0035] Network 15 allows users of UEs 13 (and other mobile devices
not shown) to initiate and receive telephone calls to each other as
well as through PSTN 19. Network 15 also typically offers a variety
of data services via Internet 23, such as downloads, web browsing,
email, etc. The carrier also operates a number of systems that
provide ancillary functions in support of the communications
services and/or application services provided through network 10,
and those elements may communicate with other nodes or elements of
network 10 via one or more private IP type packet data networks 29
(sometimes referred to as an Intranet), i.e., a private
network.
[0036] Wireless communication network 15 (i.e., a cellular network)
might be implemented as a network conforming to the 3.sup.rd
Generation Partnership Project (3GPP) LTE standard. UEs 13 are
capable of wireless communications through network 15.
[0037] Stations 17 in the examples described below are evolved node
Bs (eNodeBs or eNBs), and stations 17 and wireless communication
network 15 operate according to the LTE standard. Each station 17
is communicatively coupled to wireless network 15 and provides
wireless communications to UEs 13. Network 15 includes a mobility
management entity (MME) 16 that processes signaling between UEs 13
and network 15 (via stations 17 in cells 20) managed by MME 16.
Station 17 facilitates the establishment of a communication session
for UEs 13 by forwarding control signals to MME 16. MME 16 may
activate and deactivate bearer channels such as radio channels over
the air and/or data network bearers. A bearer is a logical channel
having particular service requirements. For example, the bearer may
be a radio bearer between UE 13-1 and station 17-1. The bearer may
also be a data bearer between station 17-1 and a serving gateway
(SGW) in network 15 or a data bearer between gateways in network
15. The MME 16 may also authenticate UEs 13, and may interface with
non-LTE radio access networks. In some examples, network 15
includes an evolved packet core (EPC), including additional
components (not shown), such as an SGW and a packet data network
(PDN) Gateway.
[0038] Each station 17 may provide communication coverage (i.e.,
communication services) for a particular geographic area (referred
to collectively herein as "geographical areas 20" and individually
as "geographical area 20", also referred to as a "cell"), which may
be a macro cell, a pico cell, a femto cell, and/or other types of
cell. In the example shown in FIG. 1, station 17-1 provides
communication coverage for geographic coverage area 20-1 and
station 17-2 provides communication coverage for geographic
coverage area 20-2. In FIG. 1, cell 20-1 represents a rural
coverage area and cell 20-2 represents a heavy demand area. Cells
20-1 and 20-2 are separated by border 21.
[0039] For example, station 17-1 communicates with UEs 13-1 and
13-2 for coverage area 20-1. Although not shown, station 17-2
communicates with any UEs for coverage area 20-2. In FIG. 1, a
solid line indicates desired transmissions between a UE 13 and a
serving station 17, (i.e., a station designated to serve the UE). A
dashed line indicates interfering transmissions between a UE and a
station (such as between station 17-2 and UE 13-2). A UE 13 may
communicate with more than one station 17 if cells 20 of stations
17 overlap. It is understood that the number of UEs 13, the number
of stations 17, the number of cells 20 and/or networks illustrated
in FIG. 1 is provided for explanatory purposes only. In practice,
there may be additional devices and/or networks, fewer devices
and/or networks, different devices and/or networks, or differently
arranged devices and/or networks than illustrated in FIG. 1.
[0040] Each UE 13 may be stationary or mobile. A UE 13 may also be
referred to as a terminal, a mobile station, a subscriber unit, a
station, or the like. A UE 13 may be a cellular phone, a personal
digital assistant (PDA), a wireless modem, a wireless communication
device, a handheld device, a laptop computer, a personal computer
(PC), a cordless phone, a tablet, or the like. In FIG. 1, UE 13-1
represents a device (mobile or stationary) that is within cell 20-1
and experiences minimal interference from station 17-2. UE 13-2
represents a mobile device that is roaming from cell 20-1 towards
cell 20-2, and experiences some interference from cell 20-2.
[0041] Dynamic parameter controller 30 monitors a signal strength
indication(s) from reference signal strength measurement(s) of the
source station (such as station 17-1) determined by a UE (such as
UE 13-2) (described below with respect to FIGS. 3 and 4). The
reference signal strength measurement(s) are sent from UE 13 (e.g.,
UE 13-2) in one or more signal strength condition measurement
reports (also referred to herein as condition measurement reports)
as a signal strength indication(s). The signal strength indication
represents a measured strength (such as an RSRP level) of a
reference signal received (and measured) by the UE 13 (e.g., UE
13-2) that is sent over the air from source station 17-1.
Controller 30 compares the signal strength indication of station
17-1 to a signal strength threshold, to determine whether a
parameter associated with hand-over should be changed from a
current value to a different value (e.g., from a first value to a
second predetermined value). When it is determined that the
parameter should be adjusted, controller 30 instructs the UE 13
that sent the condition measurement report (e.g., UE 13-2), to set
the parameter to the newly selected predetermined value (described
further below with respect to FIG. 4). Dynamic parameter controller
30 is described further below with respect to FIG. 2.
[0042] FIG. 2 is a diagram of example functional components of
station 17 and dynamic parameter controller 30. Station 17 includes
transceivers 202, processing system 204 and network interface 206
for communication with network 15 (FIG. 1). Processing system 204
may control the operation of station 17. Processing system 204
includes processing unit 208 and memory 210. Controller 30
determines whether to adjust a parameter associated with hand-over
for a specific UE 13 (such as UE 13-2), based on a reference signal
strength of station 17 as measured by the corresponding UE 13
(e.g., UE 13-2). Controller 30 selects an alternate value and
indicates to processing unit 208 to change to the alternate value.
Responsive to the indication from controller 30, processing system
204 instructs the corresponding UE 13 (e.g., UE 13-2) (via
transceivers 202) to initiate hand-over measurement reports using
the alternate value. Processing system 204 sends the instructions
as a radio resource control (RRC) connection reconfiguration
message to the UE 13-2.
[0043] Processing unit 208 of station 17 includes one or more
processors, microprocessors, application specific circuits (ASICs),
field programmable gate arrays (FPGAs), or the like. Processing
unit 208 processes information received via transceivers 202 and
network interface 206. The processing may include, for example,
data conversion, forward error correction (FEC), rate adaptation,
Wideband Code Division Multiple Access (WCDMA),
spreading/despreading, quadrature phase shift keying (QPSK)
modulation, etc. In addition, processing unit 208 may transmit
control messages and/or data messages, and cause those control
messages and/or data messages to be transmitted via transceivers
202 and/or network interface 206. Processing unit 208 may also
process control messages and/or data messages received from
transceivers 202 and/or network interface 206.
[0044] Example memory 210 includes a random access memory (RAM), a
read-only memory (ROM) and/or another type of non-transitory memory
to store data and instructions that may be used by processing unit
208. In some examples, memory 210 stores predetermined signal
strength conditions that are used by controller 30 to determine
whether to adjust the parameter (examples of which are described
further below with respect to FIGS. 5A-5C).
[0045] In FIG. 2, processing unit 208 is illustrated as being
communicatively coupled to controller 30. In some examples,
controller 30 may be located on a server (not shown in the network
10). In some examples, controller 30 may be a separate component
internal to station 17. In some examples, processing system 204 is
configured to perform at least some or all of the processing
performed by controller 30.
[0046] Dynamic parameter controller 30 may include signal strength
comparator 212 and parameter value selector 214. Dynamic parameter
controller 30 is also communicatively coupled to database 216 that
stores predetermined signal strength conditions, such as
predetermined signal strength thresholds and predetermined
parameter values. In some examples, database 216 may be located in
network 10. In other examples, database 216 may be located internal
to station 17. As discussed above, in some examples, memory 210 may
also store one or more predetermined signal strength thresholds
and/or predetermined parameter values. The predetermined parameter
values may be associated with any parameter associated with
hand-over including, but not limited to, at least one of hysteresis
or offset. In some examples, database 216 and/or memory 210 stores
additional information such as predetermined trigger condition(s),
a predetermined report interval and/or a predetermined number of
condition measurement reports to generate. This additional
information may be included in an instruction to a UE 13 (e.g., UE
13-2), in order for the UE 13 to generate condition measurement
reports.
[0047] In some examples, different signal strength thresholds
and/or parameter values may be assigned to different UEs 13 served
by cell 20 (e.g., cell 20-1). In some examples, all UEs 13 served
by the same cell 20 may have the same signal strength threshold(s)
and/or parameter values. In some examples, different cells may be
associated with different signal strength thresholds and/or
parameter values. For example, rural cell 20-1 may be associated
with a first (higher) signal strength threshold and/or parameter
values, whereas heavy demand cell 20-2 may be associated with a
second (lower) signal strength threshold and/or parameter values.
In other examples, all cells 20 in network 10 may have the same
signal strength threshold(s) and/or parameter values.
[0048] Signal strength comparator 212 obtains signal strength
indication(s) from one or more condition measurement reports sent
by a UE 13, via processing system 204. Signal strength comparator
212 compares the signal strength indication (e.g., RSRP level) with
one or more predetermined signal strength thresholds stored in
database 216, to identify a change in reference signal strength of
station 17 (as measured by UE 13). The change in reference signal
strength is used determine whether an alternate predetermined
parameter value (different from the current parameter value) should
be selected.
[0049] Parameter value selector 214 receives the signal strength
indication from signal strength comparator 212 and selects an
alternate parameter value for hand-over processing. Parameter value
selector 214 sends an indication of the selected parameter value to
processing unit 208 of processing system 204. Processing unit 208
sends an instruction to the UE 13 that sent the condition
measurement report (e.g., UE 13-2), via transceivers 202, to use
the newly selected parameter value for hand-over measurement report
generation. The instruction may be sent to the UE 13 as an RRC
connection reconfiguration message. The example illustrates
changing a parameter value for one parameter (e.g., hysteresis or
offset) based on the signal strength indication. In some examples,
a parameter value for each of multiple parameters associated with
hand-over (e.g., hysteresis and offset) may be altered based on the
signal strength.
[0050] As discussed above, dynamic parameter controller 30 relies
on reference signal strength information of station 17 as captured
by the UE 13, to identify a change in the reference signal strength
of station 17 and adjust the parameter value. Next, a brief
description of LTE hand-over initiation (e.g., event A3) and its
relationship to the hand-over measurement parameters (including
hysteresis and offset parameters) is provided, prior to describing
example dynamic parameter value adjustment by controller 30. In the
description below, station 17-1 represents a source station,
station 17-2 represents a target station, and UE 13-2 represents
the UE that performs hand-over measurements and communicates with
source station 17-1. Although the signal strength measurement is
described in terms of RSRP level, UE 13-2 may also measure a
reference signal receive quality (RSRQ) level for the event
procedure.
[0051] In an LTE network (such as network 15), UE 13-2 uses
parameters sent by source station 17-1 to determine when to perform
hand-over measurements. UE 13-2 performs hand-over measurements on
source station 17-1 and neighboring stations (such as target
station 17-2). The hand-over measurements by UE 13-2 begin when the
signal strength (e.g., RSRP level) of source station 17-1 becomes
less than a predetermined value (typically referred to as an
sMeasure parameter). UE 13-2 detects neighboring stations 17 via
intra frequency searches.
[0052] As discussed above, in an LTE network, the event A3 is
defined as a triggering event for hand-over initiation. The event
A3 is triggered when the RSRP level of a neighbor station (e.g.,
target station 17-2) becomes greater than source station 17-1 by a
predetermined bias value.
[0053] Referring to FIG. 6A, an example event A3 is shown, for
source station signal strength (Ms 602) and target station signal
strength (Mt 604). The event A3 is based on several predetermined
hand-over parameters, including an offset parameter 606 (typically
referred to as a3offset), a hysteresis parameter 608 (typically
referred to as hysteresisa3) and a time to trigger parameter 614
(typically referred to as timetoTriggera3). The parameters 606,
608, 614 trigger hand-overs based on a strength of existing and
potential radio connections and a time delay.
[0054] Offset parameter 606 is a value used to favorably bias the
current Ms 602 of source station 17-1 compared to the current Mt
604 of target station 17-2. In general, offset parameter 606 may be
used to manipulate and bias hand-over towards source station 17-1
or target station 17-2, on a system-wide basis or in special
hand-over pair cases. Hysteresis parameter 608 may bias the Mt 604
of target station 17-2 such that the signal strength appears to be
worse than actually measured. The biasing by hysteresis parameter
608 may be used to ensure that the signal strength Mt 604 of target
station 17-2 really is stronger than the signal strength Ms 602 of
source station 17-1, before UE 13-2 decides to send a measurement
report to initiate hand-over. Hysteresis parameter 608 is a general
hand-over "hurdle" used to isolate cells in hand-over initiation.
Time to trigger parameter 614 is a time delay used to avoid a
Ping-Pong effect for event triggering.
[0055] UE 13-2 uses offset parameter 606 and hysteresis parameter
608 to determine whether to trigger an event A3. In general, event
A3 triggers when:
Mt-Hysteresis>Ms+offset (1)
Event A3 onset point 610 illustrates the relationship shown in
equation 1. At the onset of time to trigger 614 (provided that UE
13-2 does not receive a hand-over command from source station
17-1), UE 13-2 starts report interval timer 620, and sends
measurement report 618 to source station 17-1. If the conditions
(equation 1) are still met (and source station 17-1 has not
responded), timer 620 is initiated again, and another measurement
report 618 is sent to source station 17-1 at the expiration of
timer 620. Measurement reports 618 are sent periodically while the
event A3 condition (equation 1) is active.
[0056] UE 13-2 uses the same offset parameter 606 and hysteresis
parameter 608 to determine when to leave event A3 (e.g., when
source station 17-1 improves in signal quality relative to target
station 17-2). UE 13-2 leaves event A3 when:
Mt+Hysteresis<Ms+offset. (2)
Event A3 end point 612 illustrates the relationship shown in
equation 2.
[0057] Referring to FIGS. 1 and 6A, currently, both offset 606 and
hysteresis 608 are fixed values. Typically, a predetermined (fixed)
offset value 606 and a high (fixed) hysteresis value 608 are
applied to prevent traffic from handing over from cell 20-1 to cell
20-2. Offset value 606 and hysteresis value 608 are selected for
capacity management purposes (i.e., to keep traffic from unloaded
cell 20-1 away from busy cell 20-2). In relatively good radio
frequency (RF) conditions (e.g., outdoor conditions), UEs 13
artificially biased to cell 20-1 in cell boundary 21 (e.g., UE
13-2) may easily sustain a substantial level of interference from
cell 20-2 without dropping the call.
[0058] However, if the hand-over parameters (e.g., offset 606 and
hysteresis 608) are tuned to good outdoor conditions, a large
(fixed) hand-over hysteresis value 608 may cause difficult and
problematic hand-overs for indoor conditions (i.e., where the RSRP
coverage level is close to a minimal RSRP coverage required to
sustain a call (e.g., about -120 dBm)). With a high hysteresis
value 608, UEs 13 (such as UE 13-2) may sustain a considerable
amount of interference in very poor coverage conditions before a
hand-over to a better serving cell is triggered. For example,
matched RSRP boundary outdoor levels may be about -85 dBm. With
about 30 dB in-building loss, the same matched boundary level is
about -115 dBm. If in-building penetration loss substantially
reduces the RSRP level of both candidate cell 20-2 and serving cell
20-1, a large hysteresis value (e.g., about 4-6 dB) may push the
RSRP hand-over trigger 610 of serving cell 20-1 close to the edge
of functionality before the hand-over can be initiated. This
situation may cause serious performance issues, such as slow
throughput, choppy voice call audio and/or an excessive number of
dropped connections.
[0059] Dynamic parameter controller 30 provides a dynamic (i.e.,
variable) parameter value (such as hysteresis value 608 and/or
offset value 606) that considers the signal strength of source cell
20-1 as measured by a UE (such as UE 13-2). Referring to FIG. 6B,
an example of hysteresis adjustment by controller 30 is shown. In
particular, FIG. 6B illustrates source station signal strength Ms
602, target station signal strength Mt 604, first hysteresis values
632-1, second hysteresis value 632-2, first hand-over initiation
point 634-1 (corresponding to first hysteresis value 632-1), second
hand-over initiation point 634-2 (corresponding to second
hysteresis value 632-2), and signal strength threshold 630. To
simplify the discussion, in FIG. 6B, offset 606 (FIG. 6A) is not
shown. Although offset 606 is not shown in FIG. 6B, it is
understood that hand-over initiation point 610 (FIG. 6A) may also
be a function of any offset value 606 (see equation 1). Although
parameter adjustment is described in FIG. 6B with respect to
hysteresis 632, it is also understood that offset 606 may be
similarly adjusted. In other examples, both the offset 606 and
hysteresis 632 may be adjusted based on the source station signal
strength Ms602 with respect to signal strength threshold 630.
[0060] In the example shown in FIG. 6B, controller 30 uses a
dynamic hysteresis value (e.g., first hysteresis value 632-1 or
second hysteresis value 632-2) to restrict frequent and
capacity-consequential hand-overs in good (i.e., high) signal
strength conditions (for capacity purposes), and to release
hand-over prevention in poor (i.e., low) signal strength conditions
(for performance purposes). For capacity purposes, controller 30
selects first (higher) hysteresis value 632-1 in good signal
strength conditions (i.e., when MS 602 is greater than signal
strength threshold 630). For performance purposes, controller 30
selects second (lower) hysteresis value 632-2 in poor signal
strength conditions (i.e., when MS 602 is less than or equal to
signal strength threshold 630).
[0061] For example, first hysteresis value 632-1 may be set to 6
dB, resulting in hand-over initiation point 634-1, when Ms 602 is
-118 dBm and Mt 604 is -112 dBm. Second hysteresis value 632-2 may
be set to 2 dB, resulting in hand-over initiation point 643-2, when
Ms 602 is -116 dBm and Mt 604 is -114 dBm. Signal strength
threshold 630 may be set to -100 dBm.
[0062] If Ms 602 (as measured by UE 13-2) is greater than signal
strength threshold 630 (e.g., -100 dBm), controller 30 considers
source cell 20-1 as having good (i.e., high) RF conditions, and
selects first hysteresis value 632-1 (e.g., 6 dB) to initiate
hand-over. If Ms 602 (as measured by UE 13-2) drops below signal
strength threshold 630 (e.g., -100 dBm), controller 30 considers
source cell 20-1 as having poor (i.e., low) RF conditions, and
changes (i.e., reduces) first hysteresis value 632-1 (e.g., 6 dB)
to second hysteresis value 632-2 (e.g., 2 dB). By changing first
hysteresis value 632-1 (6 dB) to second hysteresis value 632-2 (2
dB), the hand-over difference between source cell 20-1 and target
cell 20-2 is reduced in poor signal strength conditions.
[0063] FIG. 6B illustrates one example of dynamic parameter control
by changing between two different hysteresis values 632-1, 632-2
based on one threshold 630. It is understood that controller 30 is
not limited to a single threshold and two parameter values (e.g.,
two hysteresis values). In some examples, controller 30 may use two
or more thresholds to select between two or more parameter values.
An example of using two thresholds to select between two parameter
values is described with respect to FIG. 5C.
[0064] FIG. 3 is a signal flow diagram illustrating an example of
hand-over processing with dynamic parameter adjustment by dynamic
parameter controller 30. In FIG. 3, the signal flow includes an
interaction between UE 13-2, controller 30, source station 17-1 and
target station 17-2. These applications were described in detail
with respect to FIGS. 1, 2 and 7. Therefore, for the sake of
brevity, they are not described here in more detail. As discussed
above, controller 30 may be an internal component of source station
17-1 or may be an external component communicatively coupled to
station 17-1. Although steps 306 and 312 are illustrated as being
performed sequentially, it is understood that steps 306 and 312 may
be performed in a different order than shown in FIG. 3, including
being performed simultaneously.
[0065] The process for hand-over processing begins at step 302,
with UE 13-2 and source station 17-1 being in an RRC-connected
state (i.e., to permit communication of data between UE 13-2 and
source station 17-1).
[0066] At step, 304, source station 17-1 sends RRC measurement
control parameters (e.g., offset value 606, a hysteresis value
(e.g., first hysteresis value 632-1 or second hysteresis value
632-2), TimetoTrigger 614, etc.) to UE 13-2. In one example, the
measurement control parameters (step 304) sets an initial
hysteresis value to first hysteresis value 632-1 (i.e., a higher
hysteresis value). The measurement control parameters set
thresholds for sending hand-over measurement reports (step 312) for
initiating hand-over.
[0067] The measurement control parameters (step 304) may also set
any parameters for performing condition measurement reports (step
306). For example, UE 13-2 may be instructed (in step 304 and/or in
step 310) to send a predetermined number of condition measurement
reports, to periodically send condition measurement reports at a
predetermined report interval and/or to send condition measurement
report(s) responsive to one or more trigger conditions (e.g., a
predetermined change in the source signal strength Ms 602).
[0068] At step 306, UE 13-2 sends one or more condition measurement
reports to controller 30. Each condition measurement report 306
indicates a signal strength (e.g., RSRP level) of source station
17-1, as measured by UE 13-2 from a strength of a reference signal
sent from source station 17-1. In some examples, the condition
measurement report may also indicate a signal strength of one or
more target stations (such as target station 17-2). At step 308,
responsive to the condition measurement report(s) (step 306),
controller 30 determines whether to change the current parameter
value to an alternate value. For example, controller 30 may
determine to change the hysteresis value from first hysteresis
value 632-1 to second hysteresis value 632-2 (or vice versa). In
another example, controller 30 may determine to change the offset
value to an alternate value. In another example, controller 30 may
determine to change both the hysteresis value and the offset value
to alternate values. Step 308 is described further below with
respect to FIG. 4.
[0069] When controller 30 selects an alternate parameter value in
step 308, controller 30 sends an RRC connection reconfiguration
message, at step 310, to UE 13-2 via source station 17-1. The RRC
connection reconfiguration message (step 310) includes instructions
for UE 13-2 to send condition measurement report(s) (step 306)
using the alternate parameter value selected by controller 30. In
some examples, the RRC connection reconfiguration message may also
include instructions regarding how many condition measurement
reports to send, how often to send condition measurement report(s)
and/or any trigger conditions for sending condition measurement
report(s).
[0070] Although not shown in FIG.3, controller 30, at step 308, may
determine to maintain the current parameter value. When controller
30 determines to maintain the current parameter value, step 310 is
not performed, and no RRC connection reconfiguration message is
sent to UE 13-2. In some examples, steps 306-310 may be repeated
multiple times, for example, when the signal strength of source
station 17-1 fluctuates around signal strength threshold 630 (FIG.
6B) and no hand-over (HO) decision (step 314) occurs.
[0071] At step 312, UE 13-2 is triggered to send one or more
hand-over measurement reports to source station 17-1, as described
above with respect to FIG. 6A, based on the currently selected
parameter value. At step 314, source station 17-1 determines
whether to initiate a hand-over, based on the hand-over measurement
report(s) received at step 312. Source station 17-1 may also
consider other information to make a hand-over decision, such as
load and/or service information of target station 17-2.
[0072] When source station 17-1 determines to initiate the
hand-over (step 314), source station 17-1, at step 316, sends a
hand-over request message to target station 17-2. At step 318,
target station 17-2 performs admission control, responsive to the
hand-over request message (step 316). During admission control,
target station 17-2 performs a validation process to determine
whether its current resources are sufficient for the proposed
connection.
[0073] At step 320, target station 17-2 sends a hand-over request
acknowledgement message to source station 17-2, responsive to the
admission control (step 318). At 322, source station 17-1 sends a
hand-over command to UE 13-2, responsive to the received hand-over
request acknowledgement message (step 320). The hand-over command
includes information for UE 13-2 to set up a connection to target
station 17-2.
[0074] At step 324, UE 13-2 performs synchronization to target
station 17-2 and accesses target station 17-2 via a resources
access channel (RACH) procedure. At step 326, target station 17-2
sends uplink allocation and timing adjustment information to UE
13-2, responsive to the synchronization and RACH access in step
324.
[0075] At step 328, a hand-over confirm message is sent from UE
13-2 to target station 17-2, responsive to the uplink allocation
(in step 326). At step 330, source station 17-1 flushes its buffer
and releases its resources relating to UE 13-2. In some examples,
UE 13-2 may be placed in an RRC idle state after source station
17-1 sends the hand-over command (step 322) to UE 13-2.
[0076] At step 332, signaling between UE 13-2 and target station
17-2 commences, and UE 13-2 is no longer connected to source
station 17-1.
[0077] FIG. 4 is a flow chart diagram illustrating an example of
dynamic parameter control (step 308 in FIG. 3) by controller 30,
based on signal strength information of source station 17-1. At
step 402, the current signal strength indication of source station
17-1 is received from UE 13-2, for example, in one or more
condition measurement reports (step 306) via transceivers 202 (FIG.
2) of source station 17-1. The condition measurement report(s) may
be sent from station 17-1 to signal strength comparator 212 (FIG.
2) of dynamic parameter controller 30. The condition measurement
report(s) indicate the current strength of a received reference
signal from source station 17-1 as measured by UE 13-2.
[0078] At step 404, the received current signal strength indication
of source station 17-1 is compared with a signal strength threshold
630 (FIG. 6B), for example, by signal strength comparator 212 (FIG.
2), to identify whether there is a change in the strength of the
reference signal received by UE 13-2 from source station 17-1
(i.e., significant enough to change the currently selected
parameter value, such as hysteresis value 632). In one example,
comparator 212 compares the current signal strength indication and
a previously received signal strength indication with threshold 630
(stored in database 216) to identify a change in the reference
signal strength. In another example, comparator 212 compares the
current signal strength to threshold 630, and determines whether or
not the comparison corresponds to the currently selected parameter
value. The change in signal condition may represents a change from
a high RF condition to a low RF condition (i.e., where the signal
strength drops below threshold 630) or from a low RF condition to a
high RF condition (i.e., where the signal strength increases above
threshold 630).
[0079] At step 406, it is determined whether there is a change in
the signal strength condition, for example, by signal strength
comparator 212 (FIG. 2). When signal strength comparator 212
determines, at step 406, that there is no change in the signal
strength, step 406 proceeds to step 408. At step 408, the current
parameter value is maintained (and no instruction is sent to UE
13-2).
[0080] When it is determined (e.g., by signal strength comparator
212), at step 406, that the signal strength is changed, step 406
proceeds to step 410. At step 410, it is determined (e.g., by
parameter value selector 214) whether the current signal strength
indication is greater than signal strength threshold 630.
[0081] When it is determined, at step 410, that the signal strength
indication is greater than predetermined threshold 630, step 410
proceeds to step 412, and parameter value selector 214 selects a
first (higher) parameter value (e.g., hysteresis value 632-1 shown
in FIG. 6B). When it is determined, at step 410, that the signal
strength indication is less than or equal to predetermined
threshold 630, step 410 proceeds to step 414, and parameter value
selector 214 selects a second (lower) parameter value (e.g.,
hysteresis value 632-2 shown in FIG. 6B).
[0082] At step 416, an instruction is sent to UE 13-2 with the
selected (alternate) parameter value, as determined by parameter
value selector 214 in step 412 or step 414. For example, controller
30 (FIG. 2) may instruct processing system 204 to send the
instruction to UE 13-2.
[0083] Processing system 204 may send the instruction (including
the selected parameter value) to UE 13-2 in an RRC connection
reconfiguration message (step 310 in FIG. 3) via transceiver
202.
[0084] FIG. 5A is a flow chart diagram illustrating an example of
condition measurement report transmission and parameter value
storage, at a UE such as UE 13-2. At step 500, UE 13-2 measures the
current strength of a reference signal received from source station
17-1. At step 502, UE 13-2 sends an indication of the measured
signal strength (such as an RSRP level or an RSRQ level) in a
condition measurement report (e.g., step 306 of FIG. 3) to source
station 17-1.
[0085] In one example, UE 13-2 sends a condition measurement report
responsive to a trigger condition. For example, UE 13-2 compares
the currently measured reference signal strength (or a change in
reference signal strength) to a predetermined trigger condition.
The trigger condition may include a trigger threshold having a same
value or a different value from signal strength threshold 630 (FIG.
6B). The trigger condition may also include two or more different
thresholds for sending a condition report to source station 17-1.
In one example, if the reference signal strength (or change in
reference signal strength) is less than the trigger condition, a
condition measurement report is sent to source station 17-1. In
another example, if the reference signal strength (or change in
reference signal strength) is greater than the trigger condition, a
condition measurement report is sent to source station 17-1. In
another example, if the reference signal strength (or change in
reference signal strength) is between a first threshold and a
second threshold, a condition measurement report is sent to source
station 17-1.
[0086] At optional step 504, UE 13-2 periodically repeats steps
500-502 at a predetermined report interval. Any instructions
regarding a number of reference signal strength measurements to
obtain, a predetermined report interval between signal strength
measurements and/or trigger condition(s) for generating and sending
condition measurement reports may be received in a measurement
control message (step 304 in FIG. 3) and/or an RRC connection
reconfiguration message step 310) from source station 17-1.
[0087] At step 506, UE 13-2 receives an RRC connection
reconfiguration message including an instruction to use the
selected (alternate) parameter value in the instruction for
hand-over measurement reporting (step 312 in FIG. 3). At step 508,
the selected parameter value in the RRC connection reconfiguration
message is stored at UE 13-2. Steps 500-508 may be repeated until a
hand-over decision is reached (step 314), for example, if the
signal strength Ms 602 of source station 17-1 fluctuates around
signal strength threshold 630.
[0088] FIG. 5B is a flow chart diagram illustrating an additional
example of dynamic parameter control that may be performed by
controller 30. At step 510, UE 13-2 measures the current reference
signal strength of source station 17-1. At step 512, UE 13-2 sends
an indication of the measured reference signal strength in a
condition measurement report (e.g., step 306 of FIG. 3) to source
station 17-1, responsive to a trigger condition(s).
[0089] At step 514, controller 30 performs steps 404-406 (FIG. 4),
responsive to the condition measurement report of step 512. At step
516, controller 30, via source station 17-1, sends an instruction
to UE 13-2 to perform a set of signal strength measurements when
controller 30 determines that there is a change in the signal
strength (in step 406 of FIG. 4). Source station 17-1 may send the
instruction to UE 13-2 in an RRC connection reconfiguration
message. At step 518, controller 30 (via source station 17-1)
receives a set of measurements from UE 13-2, responsive to the
instruction (step 516). UE 13-2 may send the set of signal strength
measurements to controller 30 (via source station 17-1) in one or
more condition measurement reports.
[0090] At step 520, controller 30 determines whether there is a
change in the signal strength of source station 17-1, based on the
set of signal strength measurements received from UE 13-2.
[0091] When it is determined, by controller 30 at step 520, that
the signal strength is changed, step 520 proceeds to step 522. At
step 522, controller 30 performs steps 410-416 (FIG. 4), to select
an alternate parameter value.
[0092] When it is determined, by controller 30 at step 520, that
the signal strength is not changed, step 520 proceeds to step 524.
At step 524, controller 30 performs step 408 (FIG. 4), to maintain
the current parameter value.
[0093] By using the trigger condition(s) (step 512) and the set of
measurements (steps 516-520), a variability of the parameter value
(e.g., between first hysteresis value 632-1 and second hysteresis
value 632-2) may be reduced for conditions where the signal
strength fluctuates around signal strength threshold 630. The
example method may also reduce alteration of the parameter value
for errant signal strength values that may trigger a condition
measurement report (step 512).
[0094] FIG. 5C is a flow chart diagram illustrating an example of
dynamic parameter control based on two signal strength thresholds
that may be performed by controller 30. In FIG. 5C, it is assumed
that steps 402-406 (FIG. 4) have been performed. At step 530,
controller 30 compares the signal strength to a first threshold
(when it is determined in step 406 that the signal strength has
changed).
[0095] When controller 30 determines that the signal strength is
greater than the first threshold, step 530 proceeds to step 532. At
step 532, controller 30 selects the first (higher) parameter value
(e.g., hysteresis value 632-1). Step 532 proceeds to step 540. At
step 540, controller 30 performs step 416, sending an instruction
to UE 13-2 to use the selected parameter value for hand-over
measurement reporting.
[0096] When controller 30 determines that the signal strength is
less than or equal to the first threshold, step 530 proceeds to
step 534. At step 534, controller 30 compares the signal strength
to a second threshold that is less than the first threshold.
[0097] When controller 30 determines that the signal strength is
less than the second threshold, step 534 proceeds to step 536. At
step 536, controller 30 selects second (lower) parameter value
(e.g., hysteresis value 632-2). Step 536 proceeds to step 540, and
controller 30 performs step 416.
[0098] When controller 30 determines, at step 534, that the signal
strength is greater than or equal to the second threshold (and less
than or equal to the first signal strength), step 534 proceeds to
step 538. At step 538, controller 30 performs steps 516-524, to
determine whether to change the parameter value.
[0099] Although FIG. 5C illustrates two thresholds, it is
understood that more than two thresholds may be used to select
between parameter values. Although FIG. SC illustrates selecting
between two parameter values, controller 30 may select between two
or more parameter values. For example, in FIG. 5C, step 538 may be
used to select a third parameter value between the first and second
parameter values (as opposed to performing additional
measurements).
[0100] FIG. 7 is a block diagram of an example UE 13 (e.g., 13-1 or
13-2). In general, UE 13-1, 13-2 may be implemented as any portable
computing device capable of generating condition measurement
reports (for parameter adjustment), as well as hand-over
measurement reports (for initiation of hand-over).
[0101] The example UE 13 shown in FIG. 7 includes display 702 and
touch sensor 704 controlled by display driver 706 and sense control
circuit 708 respectively. UE 13 may also include keys 710 that
provide additional input. Of course other user interface hardware
components may be used in place of or instead of the display, touch
sensor and keys, depending on the expected types of data
applications used by UE 13.
[0102] The UE 13 includes one or more processor circuits
implementing a CPU functionality for data processing and
operational control of UE 13, including for operations involved in
the condition measurement reports under consideration here (such as
the functions shown in FIG. 3, 5A and 5B). Although a
microcontroller or other type of processor circuit may be used, in
the example, the CPU processor of UE 13 takes the form of a
microprocessor 712.
[0103] Programs and data for microprocessor 712 are stored in
memory 714. Memory 714 may include flash type program memory for
storage of various "software" or "firmware" program routines and
configuration settings, such as mobile directory number (MDN), an
international mobile subscriber identity (IMSI) and/or a mobile
identification number (MIN), etc. The UE 13 may also include a
non-volatile random access memory for a working data processing
memory. Of course, other storage devices or configurations may be
added to or substituted for those in the example. In some examples,
memory 714 may include both random access memory and flash
memory.
[0104] The UE 13 includes transceiver (XCVR) 716 coupled to antenna
718, for digital wireless communications. The concepts discussed
here encompass embodiments of UE 13 utilizing any digital
transceivers that conform to current or future developed digital
wireless communication standards. The UE 13 may also be capable of
analog operation via a legacy network technology. Transceiver 716
provides two-way wireless communication of information, in
accordance with the technology of the network 10. Transceiver 716
also sends and receives a variety of signaling messages in support
of the various data services provided via UE 13 and the
communication network 15.
[0105] Keys 710, display driver 706, sense control circuit 708,
transceiver 716 and memory 714 are all coupled to microprocessor
712. Operation of UE 13 is controlled by microprocessor 712
execution of programming from memory 714.
[0106] As shown by the above discussion, functions relating to the
dynamic parameter control service may be implemented on computers
connected for data communication via the components of a packet
data network, operating as various servers and/or user terminals,
as shown in FIG. 1. Although special purpose devices may be used
for servers operating as a dynamic parameter controller, such
devices also may be implemented using one or more hardware
platforms intended to represent a general class of data processing
device commonly used to run "server" programming so as to implement
the dynamic parameter control functions discussed above, albeit
with an appropriate network connection for data communication. UEs
such as 13-1 and 13-2 similarly may be implemented on general
purpose computers, albeit with appropriate user interface elements
and programming.
[0107] As known in the data processing and communications arts, a
general-purpose computer typically comprises a central processor or
other processing device, an internal communication bus, various
types of memory or storage media (RAM, ROM, EEPROM, cache memory,
disk drives etc.) for code and data storage, and one or more
network interface cards or ports for communication purposes. The
software functionalities involve programming, including executable
code as well as associated stored data, e.g., files used for the
dynamic parameter control service. For each of the various server
platforms, the software code is executable by the general-purpose
computer that functions as a server and/or that functions as a
terminal device. In operation, the code is stored within the
general-purpose computer platform. At other times, however, the
software may be stored at other locations and/or transported for
loading into the appropriate general-purpose computer system.
Execution of such code by a processor of the computer platform
enables the platform to implement the methodology for the dynamic
parameter control service, in essentially the manner performed in
the implementations discussed and illustrated herein.
[0108] FIGS. 8 and 9 provide functional block diagram illustrations
of general purpose computer hardware platforms. FIG. 8 illustrates
a network or host computer platform, as may typically be used to
implement a server, including the dynamic parameter controller 30.
FIG. 9 depicts a computer with user interface elements, as may be
used to implement a personal computer or other type of work station
or terminal device, although the computer of FIG. 9 may also act as
a server if appropriately programmed. It is believed that the
general structure and general operation of such equipment as shown
in FIGS. 8 and 9 should be self-explanatory from the high-level
illustrations.
[0109] A server, for example, includes a data communication
interface for packet data communication. The server also includes a
central processing unit (CPU), in the form of one or more
processors, for executing program instructions. The server platform
typically includes an internal communication bus, program storage
and data storage for various data files to be processed and/or
communicated by the server, although the server often receives
programming and data via network communications. The hardware
elements, operating systems and programming languages of such
servers are conventional in nature. Of course, the server functions
may be implemented in a distributed fashion on a number of similar
platforms, to distribute the processing load.
[0110] A computer type user terminal device, such as a PC or tablet
computer, similarly includes a data communication interface CPU,
main memory and one or more mass storage devices for storing user
data and the various executable programs (see FIG. 9). A mobile
device type user terminal may include similar elements, but will
typically use smaller components that also require less power, to
facilitate implementation in a portable form factor. The various
types of user terminal devices will also include various user input
and output elements. A computer, for example, may include a
keyboard and a cursor control/selection device such as a mouse,
trackball, joystick or touchpad; and a display for visual outputs.
A microphone and speaker enable audio input and output. Some
smartphones include similar but smaller input and output elements.
Tablets and other types of smartphones utilize touch sensitive
display screens, instead of separate keyboard and cursor control
elements. The hardware elements, operating systems and programming
languages of such user terminal devices also are conventional in
nature.
[0111] Hence, aspects of the dynamic parameter control service
outlined above may be embodied in programming. Program aspects of
the technology may be thought of as "products" or "articles of
manufacture" typically in the form of executable code and/or
associated data that is carried on or embodied in a type of machine
readable medium. "Storage" type media include any or all of the
tangible memory of the computers, processors or the like, or
associated modules thereof, such as various semiconductor memories,
tape drives, disk drives and the like, which may provide
non-transitory storage at any time for the software programming.
All or portions of the software may at times be communicated
through the Internet or various other telecommunication networks.
Such communications, for example, may enable loading of the
software from one computer or processor into another. Thus, another
type of media that may bear the software elements includes optical,
electrical and electromagnetic waves, such as used across physical
interfaces between local devices, through wired and optical
landline networks and over various air-links. The physical elements
that carry such waves, such as wired or wireless links, optical
links or the like, also may be considered as media bearing the
software. As used herein, unless restricted to non-transitory,
tangible "storage" media, terms such as computer or machine
"readable medium" refer to any medium that participates in
providing instructions to a processor for execution.
[0112] Hence, a machine readable medium may take many forms.
Non-volatile storage media include, for example, optical or
magnetic disks, such as any of the storage devices in any
computer(s) or the like, such as may be used to implement the
aspects shown in the drawings. Volatile storage media include
dynamic memory, such as main memory of such a computer platform.
Common forms of computer-readable media therefore include for
example: a floppy disk, a flexible disk, hard disk, magnetic tape,
any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other
optical medium, punch cards paper tape, any other physical storage
medium with patterns of holes, a RAM, a PROM and EPROM, a
FLASH-EPROM, any other memory chip or cartridge. Many of these
forms of non-transitory computer readable media may be involved in
carrying one or more sequences of one or more instructions to a
processor for execution.
[0113] While the foregoing has described what are considered to be
the best mode and/or other examples, it is understood that various
modifications may be made therein and that the subject matter
disclosed herein may be implemented in various forms and examples,
and that the teachings may be applied in numerous applications,
only some of which have been described herein. It is intended by
the following claims to claim any and all applications,
modifications and variations that fall within the true scope of the
present teachings.
[0114] Unless otherwise stated, all measurements, values, ratings,
positions, magnitudes, sizes, and other specifications that are set
forth in this specification, including in the claims that follow,
are approximate, not exact. They are intended to have a reasonable
range that is consistent with the functions to which they relate
and with what is customary in the art to which they pertain.
[0115] The scope of protection is limited solely by the claims that
now follow. That scope is intended and should be interpreted to be
as broad as is consistent with the ordinary meaning of the language
that is used in the claims when interpreted in light of this
specification and the prosecution history that follows and to
encompass all structural and functional equivalents.
Notwithstanding, none of the claims are intended to embrace subject
matter that fails to satisfy the requirement of Sections 101, 102,
or 103 of the Patent Act, nor should they be interpreted in such a
way. Any unintended embracement of such subject matter is hereby
disclaimed.
[0116] Except as stated immediately above, nothing that has been
stated or illustrated is intended or should be interpreted to cause
a dedication of any component, step, feature, object, benefit,
advantage, or equivalent to the public, regardless of whether it is
or is not recited in the claims.
[0117] It will be understood that the terms and expressions used
herein have the ordinary meaning as is accorded to such terms and
expressions with respect to their corresponding respective areas of
inquiry and study except where specific meanings have otherwise
been set forth herein. Relational terms such as first and second
and the like may be used solely to distinguish one entity or action
from another without necessarily requiring or implying any actual
such relationship or order between such entities or actions. The
terms "comprises," "comprising," or any other variation thereof,
are intended to cover a non-exclusive inclusion, such that a
process, method, article, or apparatus that comprises a list of
elements does not include only those elements but may include other
elements not expressly listed or inherent to such process, method,
article, or apparatus. An element proceeded by "a" or "an" does
not, without further constraints, preclude the existence of
additional identical elements in the process, method, article, or
apparatus that comprises the element.
[0118] The Abstract of the Disclosure is provided to allow the
reader to quickly ascertain the nature of the technical disclosure.
It is submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims. In addition,
in the foregoing Detailed Description, it can be seen that various
features are grouped together in various embodiments for the
purpose of streamlining the disclosure. This method of disclosure
is not to be interpreted as reflecting an intention that the
claimed embodiments require more features than are expressly
recited in each claim. Rather, as the following claims reflect,
inventive subject matter lies in less than all features of a single
disclosed embodiment. Thus the following claims are hereby
incorporated into the Detailed Description, with each claim
standing on its own as a separately claimed subject matter.
Appendix: Acronym List
[0119] The description above has a large number of acronyms to
refer to various devices, messages and system components. Although
generally known, use of several of these acronyms is not strictly
standardized in the art. For the convenience of the reader, the
following list correlates terms to acronyms, as used by way of
example in the detailed description above.
[0120] ASIC--Application Specific Circuit
[0121] CD-ROM--Compact Disk Read Only Memory
[0122] CPU --Central Processing Unit
[0123] DVD--Digital Video Disk
[0124] DVD-ROM--Digital Video Disk Read Only Memory
[0125] eNB, eNodeB--Evolved Node B
[0126] EPC--Evolved Packet Core
[0127] EEPROM--Electrically Erasable Programmable Read Only
Memory
[0128] EPROM--Erasable Programmable Read Only Memory
[0129] FEC--Forward Error Correction
[0130] FLASH-EPROM--Flash Erasable Programmable Read Only
Memory
[0131] FPGA--Field Programmable Gate Array
[0132] HO--Hand-over
[0133] IMSI--International Mobile Subscriber Identity
[0134] IP--Internet Protocol
[0135] LTE--Long Term Evolution
[0136] MDN--Mobile Directory Number
[0137] MIN--Mobile Identification Number
[0138] MME--Mobility Management Entity
[0139] PC--Personal Computer
[0140] PDA--Personal Digital Assistant
[0141] PDN--Packet Data Network
[0142] PROM--Programmable Read Only Memory
[0143] PSTN--Public Switched Telephone Network
[0144] QPSK--Quadrature Phase Shift Keying
[0145] RACH--Resources Access Channel
[0146] RAM--Random Access Memory
[0147] RF--Radio Frequency
[0148] ROM--Read Only Memory
[0149] RRC--Radio Resource Control
[0150] RSRP--Reference Signal Receive Power
[0151] RSRQ--Reference Signal Receive Quality
[0152] SGW--Serving Gateway
[0153] UE--User Equipment
[0154] WCDMA--Wideband Code Division Multiple Access
[0155] 3GPP--3.sup.rd Generation Partnership Project
* * * * *