U.S. patent application number 12/965443 was filed with the patent office on 2012-05-10 for communication service handover processing system for femtocells and method thereof.
This patent application is currently assigned to Askey Computer Corporation. Invention is credited to Ching-Feng Hsieh, Kuo-Wei Hung.
Application Number | 20120115461 12/965443 |
Document ID | / |
Family ID | 45688317 |
Filed Date | 2012-05-10 |
United States Patent
Application |
20120115461 |
Kind Code |
A1 |
Hsieh; Ching-Feng ; et
al. |
May 10, 2012 |
COMMUNICATION SERVICE HANDOVER PROCESSING SYSTEM FOR FEMTOCELLS AND
METHOD THEREOF
Abstract
A method for processing handover of a mobile communication
device between femtocell base stations, includes: setting
communication alert value and signal capture time period; detecting
the signal strength of the femtocell base station currently serving
the mobile communication device, and when the detected signal
strength is less than the communication alert value, performing a
timing operation to continuously capture the signal strength of the
serving femtocell base station and other femtocell base stations
that allow the mobile communication device to access thereto until
the elapsed time measured through the timing operation reaches the
signal capture time period, and creating a priority list according
to the signal strength of said other femtocell base stations; and
choosing the femtocell base station with highest priority as a
handover target when the signal strength of the serving femtocell
base station is less than that of the femtocell base station with
highest priority.
Inventors: |
Hsieh; Ching-Feng; (Wanhua
District, TW) ; Hung; Kuo-Wei; (Sanmin District,
TW) |
Assignee: |
Askey Computer Corporation
Chung-Ho
TW
|
Family ID: |
45688317 |
Appl. No.: |
12/965443 |
Filed: |
December 10, 2010 |
Current U.S.
Class: |
455/423 |
Current CPC
Class: |
H04J 11/0093 20130101;
H04W 36/0085 20180801; H04W 36/00835 20180801; H04W 36/30 20130101;
H04W 48/02 20130101; H04W 84/045 20130101 |
Class at
Publication: |
455/423 |
International
Class: |
H04W 24/00 20090101
H04W024/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 5, 2010 |
TW |
99138066 |
Claims
1. A method for processing communication service handover of a
mobile communication device between femtocell base stations through
a network device, comprising the steps of: creating in the network
device a permission list containing at least one of the femtocell
base stations that allows the mobile communication device to access
thereto in the coverage of the femtocell base stations and setting
a communication alert value and a signal capture time period;
detecting by the network device signal strength of the femtocell
base station currently connected to the mobile communication
device, and when the detected signal strength is less than the
communication alert value having the network device perform a
timing operation according to the signal capture time period so as
to continuously capture the signal strength of the femtocell base
station currently connected to the mobile communication device and
other femtocell base stations in the permission list until the
elapsed time measured through the timing operation reaches the
signal capture time period, and creating a priority list according
to the signal strength of said other femtocell base stations; and
when the signal strength of the femtocell base station currently
connected to the mobile communication device is less than that of
the femtocell base station with highest priority in the priority
list having the network device choose the femtocell base station
with highest priority as a target femtocell base station for
handover of the mobile communication device.
2. The method of claim 1, further comprising the step of
calculating average signal strength of each of the femtocell base
stations in the permission list according to the captured signal
strength thereof within the signal capture time period.
3. The method of claim 2, further comprising the step of comparing
the average signal strength of the femtocell base station currently
connected to the mobile communication device with those of the
femtocell base stations in the priority list so as to choose the
femtocell base station with highest priority as the target
femtocell base station for handover of the mobile communication
device when the average signal strength of the femtocell base
station currently connected to the mobile communication device is
less than that of the femtocell base station with highest
priority.
4. The method of claim 2, further comprising the step of creating
the priority list according to the average signal strength of said
other femtocell base stations.
5. The method of claim 4, further comprising the step of comparing
the average signal strength of the femtocell base station currently
connected to the mobile communication device with those of the
femtocell base stations in the priority list so as to choose the
femtocell base station with highest priority as the target
femtocell base station for handover of the mobile communication
device when the average signal strength of the femtocell base
station currently connected to the mobile communication device is
less than that of the femtocell base station with highest
priority.
6. A system for processing communication service handover of a
mobile communication device between femtocell base stations through
a network device, comprising: a database for storing a permission
list containing at least one of the femtocell base stations that
allows the mobile communication device to access thereto within
coverage of the femtocell base stations; a setting module for
setting a communication alert value and a signal capture time
period; a detection module for detecting signal strength of the
femtocell base station currently connected to the mobile
communication device, and performing a timing operation according
to the signal capture time period when the detected signal strength
is less than the communication alert value; a capturing module for
continuously capturing the signal strength of the femtocell base
station currently connected to the mobile communication device and
other femtocell base stations in the permission list until elapsed
time measured through the timing operation reaches the signal
capture time period and creating a priority list according to the
signal strength of said other femtocell base stations; and a
switching module for comparing the signal strength of the femtocell
base station currently connected to the mobile communication device
with those of the femtocell base stations in the priority list so
as to choose the femtocell base station with highest priority as a
target femtocell base station for handover of the mobile
communication device when the signal strength of the femtocell base
station currently connected to the mobile communication device is
less than that of the femtocell base station with highest
priority.
7. The system of claim 6, wherein the capturing module further
comprises a calculating unit for calculating average signal
strength of each of the femtocell base stations in the permission
list according to the captured signal strength thereof within the
signal capture time period.
8. The system of claim 7, wherein the switching module further
comprises a comparison unit for comparing the average signal
strength of the femtocell base station currently connected to the
mobile communication device with those of the femtocell base
stations in the priority list so as to choose the femtocell base
station with highest priority as the target femtocell base station
for handover of the mobile communication device when the average
signal strength of the femtocell base station currently connected
to the mobile communication device is less than that of the
femtocell base station with highest priority.
9. The system of claim 7, wherein the capturing module creates the
priority list according to the average signal strength of said
other femtocell base stations.
10. The system of claim 9, wherein the switching module further
comprises a comparison unit for comparing the average signal
strength of the femtocell base station currently connected to the
mobile communication device with those of the femtocell base
stations in the priority list so as to choose the femtocell base
station with highest priority as the target femtocell base station
for handover of the mobile communication device when the average
signal strength of the femtocell base station currently connected
to the mobile communication device is less than that of the
femtocell base station with highest priority.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to handover techniques in the
field of wireless communication, and more particularly, to a system
and method for processing handover of a mobile communication device
between femtocell base stations.
[0003] 2. Description of Related Art
[0004] In the development of network communications, network
coverage has long been a focus of concern for communication service
providers and an important factor considered by users when choosing
communication service providers. Currently, the coverage of wide
area networks is quite stable. For example, the coverage of
macrocell base stations can reach sparsely populated regions and
fast moving users and even reach remote villages.
[0005] But in buildings of densely populated cities, the macrocell
coverage is quite poor. Therefore, femtocell base stations are
developed to extend the coverage of mobile networks so as to
overcome the above-described drawback of poor indoor coverage.
[0006] As known in the prior art, handover of a mobile
communication terminal such as a mobile phone between different
macrocell base stations is a process of signal comparison. That is,
when the mobile communication terminal detects multiple macrocell
base stations in its vicinity, it tends to select the one with
highest signal strength. Since the macrocell base stations are
connected together through optical fibers, it leads to a high
message exchange rate between the macrocell base stations and
accordingly leads to a synchronous signal comparison between the
macrocell base stations, thereby ensuring that the mobile
communication terminal is handed over to the macrocell base station
with best communication quality.
[0007] In contrary, since femtocell base stations are connected
through network cables with a significantly lower signal
transmission rate compared with that of the optical fibers, a
synchronous signal comparison cannot be achieved between the
femtocell base stations. A femtocell base station performing a
signal strength comparison cannot timely capture a signal reference
value (signal strength) from another femtocell base station, which
leads to an uncertainty in the comparison result such that the
mobile communication terminal may be handed over to a femtocell
base station with poor signal strength.
SUMMARY OF THE INVENTION
[0008] Accordingly, the present invention provides a system and
method for processing handover of a mobile communication device
between femtocell base stations so as to overcome the conventional
drawback of uncertain comparison results due to inability to timely
capture the signal strength of femtocell base stations.
[0009] In order to achieve the above and other objects, an aspect
of the present invention provides a system for processing
communication service handover of a mobile communication device
between femtocell base stations through a network device, which
comprises: a database for storing a permission list containing at
least one of the femtocell base stations that allows the mobile
communication device to access thereto in the coverage of the
femtocell base stations; a setting module for setting a
communication alert value and a signal capture time period; a
detection module for detecting the signal strength of the femtocell
base station currently connected to the mobile communication
device, and performing a timing operation according to the signal
capture time period when the detected signal strength is less than
the communication alert value; a capturing module for continuously
capturing the signal strength of the femtocell base station
currently connected to the mobile communication device and the
other femtocell base stations in the permission list until the
elapsed time measured through the timing operation reaches the
signal capture time period and creating a priority list according
to the signal strength of said other femtocell base stations; and a
switching module for comparing the signal strength of the femtocell
base station currently connected to the mobile communication device
with that of the femtocell base station in the priority list so as
to choose the femtocell base station with highest priority as a
target femtocell base station for handover of the mobile
communication device when the signal strength of the femtocell base
station currently connected to the mobile communication device is
less than that of the femtocell base station with highest
priority.
[0010] In another aspect, the capturing module creates the priority
list according to the average signal strength of said other
femtocell base stations. Further, the switching module comprises a
comparison unit for comparing the average signal strength of the
femtocell base station currently connected to the mobile
communication device with that of the femtocell base station in the
priority list so as to choose the femtocell base station with
highest priority as the target femtocell base station for handover
of the mobile communication device when the average signal strength
of the femtocell base station currently connected to the mobile
communication device is less than that of the femtocell base
station with highest priority.
[0011] Further, an aspect of the present invention provides a
method for processing communication service handover of a mobile
communication device between femtocell base stations through a
network device, which comprises the steps of: creating in the
network device a permission list containing at least one of the
femtocell base stations that allows the mobile communication device
to access thereto in the coverage of the femtocell base stations
and setting a communication alert value and a signal capture time
period; the network device detecting the signal strength of the
femtocell base station currently connected to the mobile
communication device, and when the detected signal strength is less
than the communication alert value, the network device performing a
timing operation according to the signal capture time period so as
to continuously capture the signal strength of the femtocell base
station currently connected to the mobile communication device and
the other femtocell base stations in the permission list until the
elapsed time measured through the timing operation reaches the
signal capture time period, and creating a priority list according
to the signal strength of said other femtocell base stations; and
when the signal strength of the femtocell base station currently
connected to the mobile communication device is less than that of
the femtocell base station with highest priority in the priority
list, the network device choosing the femtocell base station with
highest priority as a target femtocell base station for handover of
the mobile communication device.
[0012] In another aspect, the method comprises the step of creating
the priority list according to the average signal strength of said
other femtocell base stations. The method further comprises the
step of comparing the average signal strength of the femtocell base
station currently connected to the mobile communication device with
that of the femtocell base station in the priority list so as to
choose the femtocell base station with highest priority as the
target femtocell base station for handover of the mobile
communication device when the average signal strength of the
femtocell base station currently connected to the mobile
communication device is less than that of the femtocell base
station with highest priority.
[0013] Therefore, when the signal strength of the femtocell base
station currently connected to the mobile communication device is
less than the preset communication alert value, the present
invention compares the signal strength of the femtocell base
station currently connected to the mobile communication device with
other femtocell base stations that allow the mobile communication
device to access thereto so as to choose the femtocell base station
with highest signal strength or highest average signal strength as
a handover target, thereby effectively overcoming the conventional
handover difficulty due to inability to timely capture the signal
reference values (signal strength) of other femtocell base
stations.
BRIEF DESCRIPTION OF DRAWINGS
[0014] FIG. 1 is a schematic block diagram illustrating the basic
architecture of a communication service handover processing system
between femtocell base stations according to the present invention;
and
[0015] FIG. 2 is a flow diagram illustrating a communication
service handover processing method between femtocell base stations
according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0016] The following illustrative embodiments are provided to
illustrate the disclosure of the present invention, these and other
advantages and effects can be apparent to those in the art after
reading this specification. The present invention can also be
performed or applied by other different embodiments. Various
modifications and variations based on different viewpoints and
applications can be made in the details of the specification
without departing from the spirit of the present invention.
[0017] It should be noted that the drawings are simplified
schematic diagrams illustrating the basic idea of the present
invention. In practice, the layout of components may be far more
intricate.
[0018] FIG. 1 is a schematic block diagram illustrating the basic
architecture of a communication service handover processing system
according to the present invention. Referring to FIG. 1, the system
5 is used for processing communication service handover of a mobile
communication device 3 between femtocell base stations 40, 41, 42
that allow the mobile communication device 3 to access thereto and
utilize communication services thereof. The system 5 can be a
network device, such as a server, built up by a communication
service provider for providing mobile communication services. The
system 5 comprises a database 51, a setting module 52, a detection
module 53, a capturing module 54 and a switching module 55.
[0019] The database 51 is used for storing a permission list
containing at least one of the femtocell base stations 41, 42, 43
that allows the mobile communication device 3 to access thereto in
the coverage of the femtocell base stations 41, 42, 43. In
practice, the database 51 can further store cell ID and IP address
of each of the femtocell base stations. In the following
embodiment, it is exemplified that the femtocell base station 41
first allows the mobile communication terminal 3 to access thereto
and utilize communication services thereof.
[0020] The setting module 52 is used for setting a communication
alert value and a signal capture time period. The communication
alert value is set according to a communication threshold value
specified in base station communication standards. In particular,
the communication alert value is greater than the communication
threshold value so as to avoid communication interruption when the
femtocell base station 41 currently connected to the mobile
communication device 3 has a signal strength lower than the
communication alert value. Therefore, both the communication alert
value and communication threshold value are preset signal strength
parameters. Since the femtocell base stations are connected
together through network cables, there exists a time delay in
signal comparison between the femtocell base stations. Therefore,
in a preferred embodiment, the signal capture time period is
greater than the length of the time delay. Particularly, the signal
capture time period is the time period for capturing signal
strength.
[0021] The detection module 53 is used for detecting the signal
strength of the femtocell base station 41 currently connected to
the mobile communication terminal 3, and performing a timing
operation according to the signal capture time period when the
detected signal strength is less than the communication alert
value. In a preferred embodiment, the detection module 53 detects
the signal strength of communication between the femtocell base
station 41 and the mobile communication device 3, and when the
signal strength is less than the communication alert value preset
by the setting module 52, the detection module 53 starts to perform
a timing operation according to the signal capture time period.
[0022] Meanwhile, the capturing module 54 continuously captures the
signal strength of the other femtocell base stations 40, 42 in the
permission list that allow the mobile communication device to
access thereto, and a calculating unit 541 of the capturing module
54 calculates the average signal strength of the femtocell base
stations 40, 42 based on the captured signal strength of the
femtocell base stations 40, 42 until the elapsed time measured
through the timing operation reaches the signal capture time
period. Further, the capturing module 54 creates a priority list
according to the average signal strength of the femtocell base
stations 40, 42. For example, if the average signal strength of the
femtocell base station 42 is greater than that of the femtocell
base station 40, the femtocell base station 42 is set with highest
priority in the priority list.
[0023] Further, the capturing module 54 continuously captures the
signal strength of the femtocell base station 41 within the signal
capture time period and the calculating unit 541 calculates the
average signal strength of the femtocell base station 41 within the
signal capture time period.
[0024] When the elapsed time measured through the timing operation
of the detection module 53 reaches the signal capture time period
set by the setting module 52, the timing operation is ended, and
the switching module 55 compares the average signal strength of the
femtocell base station 41 with that of the femtocell base stations
in the priority list through a comparison unit 551. In particular,
when the average signal strength of the femtocell base station 41
is less than that of the femtocell base station with highest
priority in the priority list, the femtocell base station with
highest priority is chosen as a target femtocell base station for
handover of the mobile communication.
[0025] On the other hand, when the average signal strength of the
femtocell base station 41 is greater than or equal to that of the
femtocell base station with highest priority in the priority list,
the mobile communication device 3 maintains the connection with the
femtocell base station 41 and communicates therewith.
[0026] Therefore, before the signal strength comparison of the
femtocell base station 41 with the other femtocell base stations
40, 42, the signal reference values of the femtocell base stations
40, 42 are obtained in advance so as to effectively overcome the
conventional handover difficulty due to inability to timely capture
the signal reference values of other femtocell base stations.
[0027] FIG. 2 is a flow diagram illustrating a communication
service handover processing method between femtocell base stations
according to the present invention. Referring to FIG. 2, the method
is used for processing communication service handover of a mobile
communication device between different femtocell base stations 40,
41, 42 through a network device.
[0028] The method at least comprises the following steps.
[0029] First, at step S1, a permission list containing at least one
of the femtocell base stations 41, 42, 43 that allows the mobile
communication device 3 to access thereto in the coverage of the
femtocell base stations 41, 42, 43 is created in the network
device. Then, the process goes to step S2.
[0030] At step S2, a communication alert value and a signal capture
time period are set in the network device. The communication alert
value is set according to a communication threshold value specified
in base station communication standards. In particular, the
communication alert value is greater than the communication
threshold value so as to avoid communication interruption when the
signal strength of communication between the mobile communication
device and the femtocell base station currently connected to the
mobile communication device is less than the communication alert
value. Both the communication alert value and communication
threshold value are preset signal strength parameters. Since the
femtocell base stations are connected together through network
cables, there exists a time delay in signal comparison between the
femtocell base stations. Therefore, in a preferred embodiment, the
signal capture time period is greater than the length of the time
delay. Then, the process goes to step S3.
[0031] At step S3, the network device detects the signal strength
of the femtocell base station currently connected to the mobile
communication device, and performs a timing operation according to
the signal capture time period when the signal strength of the
femtocell base station currently connected to the mobile
communication device is less than the communication alert value. In
a preferred embodiment, the network device detects the signal
strength of communication between the mobile communication device
and the serving femtocell base station, and when the signal
strength is less than the preset communication alert value, the
process goes to step S4.
[0032] At step S4, when the timing operation of step S3 starts to
operate, the network device continuously captures the signal
strength of the femtocell base stations in the permission list that
allow the mobile communication device to access thereto as well as
the signal strength of the femtocell base station currently
connected to the mobile communication device until the elapsed time
measured through the timing operation reaches the signal capture
time period. Then, the process goes to step S5.
[0033] At step S5, a priority list is created based on the
continuously captured signal strength of the femtocell base
stations within the signal capture time period. Then, the process
goes to step S6.
[0034] At step S6, the network device compares the signal strength
of the femtocell base stations. Then, the process goes to step
S7.
[0035] At step S7, when the signal strength of the femtocell base
station currently connected to the mobile communication device is
less than that of the femtocell base station with highest priority
in the priority list, the femtocell base station with highest
priority is chosen as a target femtocell base station for handover
of the mobile communication device. Since the mobile communication
device is in the coverage of both the original femtocell base
station and the target femtocell base station, before handover, the
target femtocell base station can obtain the signal reference value
of the original femtocell base station so as to faciliate the
handover.
[0036] Further, in step S7, when the signal strength of the
femtocell base station currently connected to the mobile
communication device is greater than or equal to that of the
femtocell base station with highest priority in the priority list,
the mobile communication device maintains the connection with the
original femtocell base station.
[0037] Further, at step S5, the network device can calculate the
average signal strength of each of the femtocell base stations
based on the continuously captured signal strength thereof so as to
create the priority list according to the average signal strength
of the femtocell base stations. As such, the network device
compares the average signal strength of the femtocell base stations
at step S6, and at step S7, the network device chooses the
femtocell base station with highest priority in the priority list
as the target femtocell base station for handover when the average
signal strength of the femtocell base station currently connected
to the mobile communication device is less than the femtocell base
station with highest priority.
[0038] Therefore, when the signal strength of the femtocell base
station currently connected to the mobile communication device is
less than the preset communication alert value, the present
invention compares the signal strength of the femtocell base
station currently connected to the mobile communication device with
other femtocell base stations that allow the mobile communication
device to access thereto so as to choose the femtocell base station
with highest signal strength or highest average signal strength as
a handover target, thereby effectively overcoming the conventional
handover difficulty due to inability to timely capture the signal
reference values (signal strength) of other femtocell base
stations.
[0039] The above-described descriptions of the detailed embodiments
are intended to illustrate the preferred implementation according
to the present invention but are not intended to limit the scope of
the present invention. Accordingly, all modifications and
variations completed by those with ordinary skill in the art should
fall within the scope of present invention defined by the appended
claims.
* * * * *