U.S. patent application number 13/351677 was filed with the patent office on 2012-07-19 for interference measurement method and apparatus for user equipment having multiple heterogeneous communication modules in wireless communication system.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO. LTD.. Invention is credited to Jae Hyuk JANG, Soeng Hun KIM.
Application Number | 20120182896 13/351677 |
Document ID | / |
Family ID | 46516228 |
Filed Date | 2012-07-19 |
United States Patent
Application |
20120182896 |
Kind Code |
A1 |
JANG; Jae Hyuk ; et
al. |
July 19, 2012 |
INTERFERENCE MEASUREMENT METHOD AND APPARATUS FOR USER EQUIPMENT
HAVING MULTIPLE HETEROGENEOUS COMMUNICATION MODULES IN WIRELESS
COMMUNICATION SYSTEM
Abstract
An interference measurement method and a user equipment
supporting the method are provided. The method enables the user
equipment having multiple heterogeneous communication modules for
Long Term Evolution (LTE), WiFi, Bluetooth and Global Positioning
System (GPS) to perform interference measurement so as to avoid
coexistence interference. The user equipment may perform effective
communication by identifying non-preferred frequency bands and
avoiding coexistence interference caused by the heterogeneous
communication modules.
Inventors: |
JANG; Jae Hyuk; (Suwon-si,
KR) ; KIM; Soeng Hun; (Yongin-si, KR) |
Assignee: |
SAMSUNG ELECTRONICS CO.
LTD.
Suwon-si
KR
|
Family ID: |
46516228 |
Appl. No.: |
13/351677 |
Filed: |
January 17, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61433651 |
Jan 18, 2011 |
|
|
|
Current U.S.
Class: |
370/252 |
Current CPC
Class: |
H04W 84/045 20130101;
H04W 72/0453 20130101; H04W 24/10 20130101; H04W 72/085 20130101;
H04W 8/24 20130101; H04W 88/06 20130101; H04W 12/65 20210101; H04W
28/04 20130101; Y02D 30/70 20200801 |
Class at
Publication: |
370/252 |
International
Class: |
H04W 24/00 20090101
H04W024/00; H04W 36/20 20090101 H04W036/20 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2011 |
KR |
10-2011-0139376 |
Claims
1. A measurement method for a user equipment in a wireless
communication system, the measurement method comprising:
identifying, upon detection of activation of an interfering
communication technology that potentially causes interference to
cellular communication of the user equipment, at least one
frequency that is likely to be affected by the potential
interference; sending a measurement configuration request message
including the identified frequency that is likely to be affected by
the potential interference to a base station; and performing, upon
reception of a measurement configuration message from the base
station, measurement according to measurement configurations
included in the measurement configuration message.
2. The measurement method of claim 1, wherein the received
measurement configuration message includes an indication indicating
measurement of in-device interference caused by the interfering
communication technology in the user equipment.
3. The measurement method of claim 2, wherein the performing of the
measurement according to the measurement configurations comprises
separately storing a measurement result for subframes not affected
by in-device interference and another measurement result for
subframes affected by in-device interference.
4. The measurement method of claim 1, wherein the identifying of at
least one frequency that is likely to be affected by the potential
interference comprises determining a frequency that is supported by
the user equipment and that is not separated by a preset gap or
more from the frequency of the interfering communication technology
as a frequency that is likely to be affected by the potential
interference.
5. The measurement method of claim 1, further comprising creating,
when a trigger condition specified in the measurement configuration
message is met, a measurement report message including measurement
results, and sending the measurement report message to the base
station.
6. The measurement method of claim 5, wherein the measurement
report message separately includes a measurement result for
subframes not affected by in-device interference and another
measurement result for subframes affected by in-device
interference.
7. The measurement method of claim 6, further comprising: receiving
a handover command reflecting the measurement results from the base
station; and performing handover according to the received handover
command.
8. A user equipment capable of interference measurement in a
wireless communication system, the user equipment comprising: a
transceiver unit for sending and receiving a signal to and from a
base station; and a control unit for controlling a process of
identifying, upon detection of activation of an interfering
communication technology that potentially causes interference to
cellular communication of the user equipment, at least one
frequency that is likely to be affected by the potential
interference caused by the interfering communication technology,
for sending a measurement configuration request message including
the identified list of at least one frequency that is likely to be
affected by the potential interference to the base station, and for
performing, upon reception of a measurement configuration message
from the base station, measurement according to measurement
configurations specified in the received message.
9. The user equipment of claim 8, wherein the control unit
receives, through the transceiver unit, a measurement configuration
message including an indication indicating measurement of in-device
interference caused by the interfering communication technology in
the user equipment.
10. The user equipment of claim 9, wherein the control unit
controls an operation to separately store a measurement result for
subframes not affected by in-device interference and another
measurement result for subframes affected by in-device
interference.
11. The user equipment of claim 8, wherein the control unit
determines a frequency that is supported by the user equipment and
is not separated by a preset gap or more from the frequency of the
interfering communication technology as a frequency that is likely
to be affected by the potential interference.
12. The user equipment of claim 8, wherein the control unit
controls, when a trigger condition specified in the measurement
configuration message is met, an operation to create a measurement
report message including measurement results, and to send the
measurement report message to the base station.
13. The user equipment of claim 12, wherein the control unit sends,
through the transceiver unit, a measurement report message
separately including a measurement result for subframes not
affected by in-device interference caused by the interfering
communication technology and another measurement result for
subframes affected by in-device interference.
14. The user equipment of claim 13, wherein the control unit
controls, upon reception of a handover command reflecting the
measurement results from the base station, an operation to perform
handover according to the received handover command.
15. A system for coordinating measurement of in-device
interference, the system comprising: a base station; and a terminal
that communicates with the base station, wherein the base station
instructs the terminal to measure in-device interference if the
terminal determines that an interfering communication technology is
activated as the terminal is communicating with the base
station.
16. The system of claim 15, wherein upon detection of the
activation of the interfering communication technology, the
terminal identifies at least one frequency that is likely to be
affected by potential interference from the interfering
communication technology.
17. The system of claim 16, wherein the terminal identifies at
least one frequency that is likely to be affected by potential
interference from the interfering communication technology by
determining frequencies over which the terminal communicates that
are within a predefined threshold from the frequency over which the
interfering communication technology is capable of
communicating.
18. The system of claim 15, wherein the base station coordinates a
handover with the terminal to a frequency which will likely not
suffer interference from the interfering communication
technology.
19. The system of claim 15, wherein the terminal, upon receipt of
instructions from the base station to measure in-device
interference, transmits a message which separately indicates a
measurement result for subframes not affected by in-device
interference and a measurement result for subframes affected by
in-device interference.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(e) of a U.S. provisional application filed on Jan. 18,
2011 in the U.S. Patent and Trademark Office and assigned Ser. No.
61/433,651, and under 35 U.S.C. .sctn.119(a) of a Korean patent
application filed on Dec. 21, 2011 in the Korean Intellectual
Property Office and assigned Serial No. 10-2011-0139376, the entire
disclosures of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a wireless communication
system. More particularly, the present invention relates to an
interference measurement method that enables a user equipment
having multiple heterogeneous communication modules to avoid
coexistence interference.
[0004] 2. Description of the Related Art
[0005] In recent years, smartphones having WiFi, Bluetooth and
Global Positioning System (GPS) modules have been rapidly
popularized. With this trend, various communication technologies
(for example, Long Term Evolution (LTE)/Universal Mobile
Telecommunication System (UMTS) for cellular network communication,
WiFi for wireless local area communication, Bluetooth for
short-range wireless communication, and GNSS/GPS for location-based
services, etc.) may coexist in the same user equipment. When
heterogeneous communication technologies are simultaneously used in
the same user equipment, a problem of interference therebetween may
arise. This problem has been discussed under the name of In-Device
Coexistence (IDC) in 3GPP.
[0006] While LTE/UMTS communication operates in various frequency
bands, Bluetooth or WiFi communication operates in the Industrial
Scientific Medical (ISM) band of 2400-2483.5 MHz. In particular,
Band 40 (2300-2400 MHz) and Band 7 Uplink (2500-2570 MHz) among
multiple LTE/UMTS frequency bands are adjacent to the ISM band for
Bluetooth or WiFi communication. Hence, when LTE/UMTS communication
and Bluetooth or WiFi communication are simultaneously conducted, a
transmit signal for one communication technology may be received as
a receive signal for another communication technology, thereby
causing serious interference.
[0007] FIG. 3 illustrates 3GPP frequency bands for mobile
communication around the ISM band. As indicated by FIG. 3, use of
WiFi channel 1 while Band 40 is used for a mobile communication
cell may cause serious interference, and use of WiFi channel 13 or
14 while Band 7 is used for a mobile communication cell may cause
serious interference.
[0008] Hence, it is necessary to identify such mutual interference
through precise measurement in the event of interference.
SUMMARY OF THE INVENTION
[0009] Aspects of the present invention are to address at least the
above-mentioned problems and/or disadvantages and to provide at
least the advantages described below. Accordingly, an aspect of the
present invention is to provide a method and apparatus that enable
a user equipment having multiple heterogeneous communication
modules for LTE, WiFi, Bluetooth and GPS to perform interference
measurement so as to avoid coexistence interference.
[0010] In order to solve the above problems, a user equipment
identifies at least one frequency that is likely to be affected by
interference and notifies such frequency to a base station, so that
the base station can configure suitable measurement. The user
equipment may also notify non-preferred frequency bands to the base
station so that the base station may take actions to avoid
interference.
[0011] In accordance with an exemplary embodiment of the present
invention, a measurement method for a user equipment in a wireless
communication system is provided. The measurement method includes
identifying, upon detection of activation of an interfering
communication technology that potentially causes interference to
cellular communication of the user equipment, at least one
frequency that is likely to be affected by the potential
interference, sending a measurement configuration request message
including the identified at least one frequency that is likely to
be affected by the potential interference to a base station, and
performing, upon reception of a measurement configuration message
from the base station, measurement according to measurement
configurations included in the measurement configuration
message.
[0012] In accordance with another exemplary embodiment of the
present invention, a user equipment capable of interference
measurement in a wireless communication system is provided. The
user equipment includes a transceiver unit sending and receiving a
signal to and from a base station, and a control unit controlling a
process of identifying, upon detection of activation of an
interfering communication technology that potentially causes
interference to cellular communication of the user equipment, at
least one frequency that is likely to be affected by the potential
interference caused by the interfering communication technology,
for sending a measurement configuration request message including
the identified list of at least one frequency that is likely to be
affected by the potential interference to the base station, and for
performing, upon reception of a measurement configuration message
from the base station, measurement according to measurement
configurations specified in the received message.
[0013] In accordance with another exemplary embodiment of the
present invention, a system for coordinating measurement of
in-device interference is provided. The system comprises a base
station, and a terminal that communicates with the base station,
wherein the base station instructs the terminal to measure
in-device interference if the terminal determines that an
interfering communication technology is activated as the terminal
is communicating with the base station.
[0014] Other aspects, advantages, and salient features of the
invention will become apparent to those skilled in the art from the
following detailed description, which, taken in conjunction with
the annexed drawings, discloses exemplary embodiments of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The above and other aspects, features, and advantages of
certain exemplary embodiments of the present invention will be more
apparent from the following description taken in conjunction with
the accompanying drawings, in which:
[0016] FIG. 1 illustrates an LTE system architecture according to
an exemplary embodiment of the present invention;
[0017] FIG. 2 illustrates a hierarchy of wireless protocols in an
LTE system according to an exemplary embodiment of the present
invention;
[0018] FIG. 3 illustrates 3GPP frequency bands for mobile
communication around the ISM band according to an exemplary
embodiment of the present invention;
[0019] FIG. 4 is a message sequence chart illustrating an
interference measurement method according to an exemplary
embodiment of the present invention;
[0020] FIG. 5 is a flowchart of a procedure performed by a user
equipment such as, for example the user equipment provided in FIG.
4 according to an exemplary embodiment of the present
invention;
[0021] FIG. 6 is a message sequence chart illustrating an
interference measurement method according to an exemplary
embodiment of the present invention;
[0022] FIG. 7 is a flowchart of a procedure performed by a user
equipment such as, for example, the user equipment provided in FIG.
6 according to an exemplary embodiment of the present invention;
and
[0023] FIG. 8 is a block diagram of a user equipment according to
an exemplary embodiment of the present invention.
[0024] Throughout the drawings, it should be noted that like
reference numbers are used to depict the same or similar elements,
features, and structures.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0025] The following description with reference to the accompanying
drawings is provided to assist in a comprehensive understanding of
exemplary embodiments of the invention as defined by the claims and
their equivalents. It includes various specific details to assist
in that understanding but these are to be regarded as merely
exemplary. Accordingly, those of ordinary skill in the art will
recognize that various changes and modifications of the embodiments
described herein can be made without departing from the scope and
spirit of the invention. In addition, descriptions of well-known
functions and constructions may be omitted for clarity and
conciseness.
[0026] The terms and words used in the following description and
claims are not limited to the bibliographical meanings, but, are
merely used by the inventor to enable a clear and consistent
understanding of the invention. Accordingly, it should be apparent
to those skilled in the art that the following description of
exemplary embodiments of the present invention is provided for
illustration purpose only and not for the purpose of limiting the
invention as defined by the appended claims and their
equivalents.
[0027] It is to be understood that the singular forms "a," "an,"
and "the" include plural referents unless the context clearly
dictates otherwise. Thus, for example, reference to "a component
surface" includes reference to one or more of such surfaces.
[0028] In the description, cellular communication (or mobile
communication) is focused on the Long Term Evolution (LTE) system.
However, various exemplary embodiments of the present invention are
applicable to any type of cellular communication. As an example, an
"interfering communication technology" refers to WiFI, Bluetooth or
GPS technology (e.g., a WiFI, a Bluetooth or a GPS module) other
than LTE technology (e.g., a LTE module). An LTE terminal may be
referred to as a User Equipment (UE), and an LTE base station may
be referred to as an evolved Node B (eNB).
[0029] FIG. 1 illustrates an LTE system architecture according to
an exemplary embodiment of the present invention.
[0030] Referring to FIG. 1, an LTE radio access network is composed
of eNBs 105, 110, 115 and 120, a Mobility Management Entity (MME)
125 and a Serving-Gateway (S-GW) 130. A User Equipment (UE) 135 may
connect to an external network through at least one of the eNBs 105
to 120 and the S-GW 130.
[0031] The eNBs 105 to 120 correspond to Node Bs of the Universal
Mobile Telecommunication System (UMTS). The eNB is connected to the
user equipment 135 through a wireless channel, and may perform
complex functions in comparison to an existing Node B. With regard
to a Long Term Evolution (LTE) system, because all user traffic
including real-time services such as Voice over IP (VoIP) services
is served by shared channels, it is necessary to perform scheduling
on the basis of collected status information regarding buffers,
available transmit powers, and channels of user equipments. Each of
the eNBs 105 to 120 performs such a scheduling function. In most
cases, a single eNB controls multiple cells. To achieve a data rate
of 100 Mbps, the LTE system utilizes orthogonal frequency division
multiplexing (OFDM) in a 20 MHz bandwidth as radio access
technology. The LTE system employs adaptive modulation and coding
(AMC) to determine the modulation scheme and channel coding rate
according to channel states of user equipments. The S-GW 130
provides data bearers, and creates and removes a data bearer under
control of the MME 125. The MME 125 performs various control
functions including mobility management for user equipments, and is
connected to multiple eNBs.
[0032] FIG. 2 illustrates a hierarchy of wireless protocols in an
LTE system according to an exemplary embodiment of the present
invention.
[0033] Referring to FIG. 2, in the LTE system, a user equipment
(UE) and an eNB each include a wireless protocol stack composed of
a Packet Data Convergence Protocol (PDCP) layer 205 or 240, a Radio
Link Control (RLC) layer 210 or 235, a Medium Access Control (MAC)
layer 215 or 230, and a physical (PHY) layer 220 or 225. The PDCP
layer 205 or 240 performs compression and decompression of IP
headers. The RLC layer 210 or 235 reconfigures PDCP Protocol Data
Units (PDUs) to a suitable size to conduct, for example, Automatic
Repeat-reQuest (ARQ) operations. The MAC layer 215 or 230 is
connected to multiple RLC layer devices in a user equipment, and
multiplexes RLC PDUs into MAC PDUs or demultiplexes MAC PDUs into
RLC PDUs. The physical layer 220 or 225 converts upper layer data
into OFDM symbols by means of channel coding and modulation and
transmits the OFDM symbols through a wireless channel, or converts
OFDM symbols received through a wireless channel into upper layer
data by means of demodulation and channel decoding and forwards the
data to upper layers.
[0034] FIG. 4 is a message sequence chart illustrating an
interference measurement method according to an exemplary
embodiment of the present invention.
[0035] When an interfering communication technology causes
interference in an operating frequency band, the user equipment
needs to report such interference to a corresponding eNB. For
reporting this coexistence interference using a measurement option
defined in the standard, the eNB needs to notify the user equipment
of a suitable measurement configuration.
[0036] In LTE, an A3 measurement event is commonly used for
measurement triggering. An A3 event triggers when "Neighbor becomes
offset better than serving". That is, measurement reporting is
triggered when channel quality of a neighbor cell is better than
that of the serving cell by a preset threshold. However, the A3
measurement event is not suitable for solving a problem of
interference between interfering communication technologies
coexisting in the same user equipment. This is because an
interfering communication technology transmitting signals may
affect not only the serving cell but also neighbor cells through
interference.
[0037] Hence, it is necessary to configure measurement settings in
consideration of an A2 measurement event ("Serving becomes worse
than threshold"). In other words, it is necessary to trigger
measurement reporting when signal quality of the serving cell
becomes worse than a preset threshold.
[0038] As a precondition for measurement configuration based on an
A2 measurement event, it is necessary for the user equipment to
report activation of an interfering communication technology to the
eNB. Upon reception of the activation report, the eNB notifies the
user equipment of appropriate measurement objects and a reporting
configuration.
[0039] Referring to FIG. 4, the UE 401 detects activation of an
interfering communication technology at step 405. Here, the UE 401
may detect activation of or an activation request for an
interfering communication module. The UE 401 needs to detect
activation of an interfering communication technology that may
potentially interfere with cellular communication like LTE
operation. To achieve this, the UE 401 may detect activation of a
GPS module, a WiFi module, or a Bluetooth module by the user, or
may detect potential interference while measuring quality of a
received signal from a base station.
[0040] The UE 401 checks possibility of interference caused by the
interfering communication technology, and identifies, when the
interfering communication technology may cause interference, at
least one frequency that is likely to be affected by the
interfering communication technology at step 407. Among frequencies
supported by the UE 401 (including the serving frequency), a
frequency supported by the system that is not sufficiently
separated from the frequency of the interfering communication
technology may be regarded as a frequency that is likely to be
affected by interference. For example, a frequency that is likely
to be affected by interference indicates a frequency that may
disrupt communication of a user equipment at present or in the near
future if used by the user equipment.
[0041] For step 407, the eNB 403 uses system information blocks
(SIB) to provide information regarding frequencies supported by the
system to the UE 401. For example, SIB 5 may include information on
frequencies used by neighbor E-UTRA (LTE) cells or other E-UTRA
cells; SIB 6 may include information on frequencies used by
neighbor UTRA (3G) cells or other UTRA cells; SIB 7 may contain
information on frequencies used by neighbor GERAN (2G) cells or
other GERAN cells; and SIB 8 may include information on frequencies
used by neighbor CDMA2000 cells or other CDMA2000 cells.
[0042] A reason for examining those frequencies supported by the
system among the frequencies supported by the user equipment is
that it is possible for the user equipment in motion to perform
handover to one of the frequencies supported by the system. Here,
sufficiency of separation to avoid coexistence interference depends
upon a filtering capability of the user equipment.
[0043] When at least one frequency that is likely to be affected by
interference is present, the UE 401 sends a measurement
configuration request message to the eNB 403 at step 409. Here, the
measurement configuration request message is an RRC message
including a list of frequencies that are likely to be affected by
interference, and requests the eNB 403 to specify measurement
objects and reporting configurations. As an example, entries of the
list of frequencies that are likely to be affected by interference
may correspond to frequencies to be specified as a measurement
object.
[0044] Upon reception of the RRC message (e.g., the measurement
configuration request message), the eNB 403 determines necessity of
measurement configuration for the UE 401 in consideration of the
frequencies that are likely to be affected by interference at step
411. When the serving frequency of the UE 401 is a frequency that
is likely to be affected by interference, the eNB 403 may configure
measurement based on an A2 measurement event.
[0045] When a measurement configuration is necessary, the eNB 403
sends a measurement configuration message to the UE 401 at step
413. Here, the measurement configuration message is an RRC message
including information on a measurement configuration. More than one
measurement may be configured. The measurement configuration may
include an indication indicating measurement of in-device
interference caused by an interfering communication technology in
the UE 401.
[0046] The UE 401 performs measurement according to the measurement
configuration specified by the eNB 403 at step 415.
[0047] In WiFi or Bluetooth communication, as uplink transmission
is not continuous, some (e.g., not all) LTE subframes may be
affected by interference caused by WiFi or Bluetooth transmission.
If the UE 401 produces a measurement result by averaging
measurement values for all subframes, the eNB 403 may not receive
an appropriate measurement result. In other words, the eNB 403 may
receive only a measurement result obtained by averaging measurement
values for all subframes, but such a measurement result does not
indicate severity and frequency of interference.
[0048] In an exemplary embodiment, to solve the above problem, if
an indication indicating measurement of in-device interference
caused by an interfering communication technology is received from
the eNB 403, then the UE 401 maintains two measurement results: one
measurement result for subframes not affected by in-device
interference and another measurement result for subframes affected
by in-device interference.
[0049] In the event that LTE downlink signal reception is affected
by in-device interference caused by an interfering communication
technology, the UE 401 starts to conduct inter-frequency
measurement even though signal quality of the serving cell is
greater than an "s-Measure" value received from the eNB 403. The UE
401 determines necessity of reporting based on an A2 measurement
event by comparing the measurement result for subframes affected by
the interfering communication technology with a threshold received
from the eNB 403.
[0050] When the trigger condition for measurement as to the
interfering communication technology is met, the UE 401 sends a
measurement report message including a measurement report to the
eNB 403 at step 417. Here, the measurement report includes a
measurement result for subframes affected by in-device interference
and another measurement result for subframes not affected by
in-device interference.
[0051] In an exemplary embodiment, the measurement report may
include a ratio of subframes affected by in-device interference to
subframes not affected by in-device interference. The measurement
report may include a measurement result for all subframes without
classifying subframes according to in-device interference. The
measurement report may further include measurement results for
available frequencies (e.g., inter-frequency measurement).
Specifically, the measurement report may include measurement
results for N cells exhibiting best signal qualities corresponding
to available frequencies.
[0052] Upon reception of the measurement report, the eNB 403
determines necessity of handover of the UE 401. If handover of the
UE 401 is necessary, then the eNB 403 determines a target cell to
which the UE 401 is to be handed over, performs operations
necessary for handover, and sends a handover command to the UE 401
at step 419.
[0053] FIG. 5 is a flowchart of a procedure performed by an UE 401
such as, for example, the user equipment provided in FIG. 4
according to an exemplary embodiment of the present invention.
[0054] Referring to FIG. 5, the UE 401 detects activation of an
interfering communication technology at step 503. Upon detection of
activation of an interfering communication technology, the UE 401
identifies at least one frequency that is likely to be affected by
the interfering communication technology at step 505. If at least
one frequency that is likely to be affected by interference is
present, then the UE 401 sends a measurement configuration request
message to the eNB 403 at step 507. Here, the measurement
configuration request message is an RRC message including a list of
frequencies that are likely to be affected by interference, and
requests the eNB 403 to specify measurement objects and measurement
configurations.
[0055] Thereafter, the UE 401 receives a measurement configuration
message including information on measurement objects and
measurement configurations from the eNB 403 at step 509. The UE 401
performs measurement according to the measurement configurations
specified in the measurement configuration message at step 511.
[0056] When a trigger condition is met during measurement, the UE
401 sends a measurement report message to the eNB 403 at step
513.
[0057] If a handover command message is received from the eNB 403,
then the UE 401 performs handover according to the handover command
message at step 515.
[0058] The UE 401 starts the interfering communication technology
if necessary at step 517. Thereafter, the UE 401 returns to step
503 and performs requested operations (such as detection of
activation or stoppage of interfering communication
technologies).
[0059] FIG. 6 is a message sequence chart illustrating an
interference measurement method according to an exemplary
embodiment of the present invention.
[0060] Referring to FIG. 6, a UE 601 performs a procedure for RRC
connection setup with an eNB 603 through a network access process
at step 605. The UE 601 detects activation of or an activation
request for an interfering communication technology that may affect
LTE communication or may be affected by LTE communication through
coexistence interference at step 607. As previously described in
connection with FIG. 4, the UE 601 needs to detect activation of an
interfering communication technology that may potentially interfere
with cellular communication like LTE operation. To achieve this,
the UE 601 may sense activation of a GPS module, a WiFi module, a
Bluetooth module, or the like by the user or may detect potential
interference while measuring quality of a received signal from a
base station.
[0061] The UE 601 communicates with the eNB 603 so as not to use an
LTE frequency band that may potentially interfere with the
interfering communication technology. To achieve this, the UE 601
selects a preferred frequency that does not interfere with the
interfering communication technology, and sends an RRC message to
the eNB 603 to notify the same of the preferred frequency at step
609.
[0062] In step 609, the UE 601 identifies the operating frequency
(or frequency band) of the interfering communication technology.
This frequency (or frequency band) is referred to as frequency A
(or frequency band A).
[0063] The UE 601 also identifies the frequency (or frequency band)
supported by the current cellular system (e.g., LTE, UMTS or GSM)
among frequencies supported by the UE 601. The frequency (or
frequency band) supported by the system is referred to as frequency
B (or frequency band B).
[0064] The UE 601 may obtain information on frequency B from the
cellular system, and may receive information on supported
frequencies therefrom. More specifically, if a measurement object
is configured for the UE 601 in the current cell, then the UE 601
may consider the frequency associated with the measurement object
as frequency B. When SIB 5 including an inter-frequency carrier
frequency list (InterFreqCarrierFreqList) is received from the
cellular system and stored, the UE 601 may consider a frequency
included in the inter-frequency carrier frequency list among
downlink carrier frequencies (dl-CarrierFreq) supported by the UE
601 as frequency B. UTRA frequencies belonging to a UTRA-FDD
carrier frequency list (carrierFreqListUTRA-FDD) or UTRA-TDD
carrier frequency list (carrierFreqListUTRA-TDD) included in SIB 6
may be considered as frequency B if such frequencies are supported
by the UE 601. GSM frequencies included in SIB 7 may also be
considered as frequency B if such frequencies are supported by the
UE 601.
[0065] The UE 601 selects preferred frequencies among those
frequencies regarded as frequency B (i.e., among frequencies
supported by both the UE 601 and the system) in consideration of
those frequencies regarded as frequency A. For example, the UE 601
may select one of the frequencies regarded as frequency B that is
sufficiently separated from frequency A as a preferred frequency.
Alternatively, the UE 601 may select one of the frequencies
regarded as frequency B that is not sufficiently separated from
frequency A as a non-preferred frequency. For example, sufficiency
of separation to avoid coexistence interference depends upon a
filtering capability of the UE 601.
[0066] Thereafter, the UE 601 creates a preferred frequency list
(or a non-preferred frequency list) according to the above
described scheme. The UE 601 sends an RRC message including the
preferred frequency list (or the non-preferred frequency list) to
the eNB 603 at step 609.
[0067] Upon reception of the RRC message, the eNB 603 stores the
preferred frequency list (or the non-preferred frequency list)
included in the RRC message. The eNB 603 checks whether the
frequency currently used by the UE 601 is on the preferred
frequency list.
[0068] If the frequency currently used by the UE 601 is not on the
preferred frequency list, then the eNB 603 instructs the UE 601 to
conduct handover to one frequency of the preferred frequency list
at step 611.
[0069] If the frequency currently used by the UE 601 is on the
preferred frequency list, then the eNB 603 may not instruct the UE
601 to conduct immediate handover. Later, when handover is
requested, the eNB 603 may instruct the UE 601 to conduct handover
to another eNB using a frequency on the preferred frequency list,
which has been stored.
[0070] In other words, if the current operating frequency of the UE
601 is not a preferred frequency, the eNB 603 checks possibility of
handover of the UE 601 to a preferred frequency and initiates a
handover procedure when handover of the UE 601 to a preferred
frequency is possible.
[0071] If handover of the UE 601 to a preferred frequency is not
possible (for example, lack of resources in eNBs using preferred
frequencies, or absence of neighbor eNBs using preferred
frequencies), the eNB 603 may send an RRC message to the UE 601 to
notify of impossibility of handover to a preferred frequency. Upon
reception of the RRC message, the UE 601 may provide the RRC
message to the user, so that the user may decide whether to start
the interfering communication technology if it is not yet
started.
[0072] After handover to a preferred frequency (or while already
using a preferred frequency), the UE 601 starts the interfering
communication technology at step 613. Here, two collocated
communication technologies (for example, LTE and Bluetooth) may
operate simultaneously.
[0073] When stoppage or turning off of the interfering
communication technology is detected at step 615, the UE 601 sends
an RRC message to the eNB 603 to notify stoppage of the interfering
communication technology or an updated preferred frequency list (or
non-preferred frequency list) at step 617. Upon reception of the
RRC message, the eNB 603 removes restrictions on the corresponding
frequency and stores the updated preferred frequency list (or
non-preferred frequency list) for later use.
[0074] FIG. 7 is a flowchart of a procedure performed by an UE such
as, for example, the UE 601 provided in FIG. 6 according to an
exemplary embodiment of the present invention.
[0075] Referring to FIG. 7, the UE 701 detects activation of an
interfering communication technology at step 703. Upon detection of
activation of an interfering communication technology, the UE 701
identifies at least one frequency that is likely to be affected by
the interfering communication technology at step 705.
[0076] If at least one frequency that is likely to be affected by
interference is present, then the UE 701 sends an RRC message
including a list of frequencies that are likely to be affected by
interference to the eNB at step 707.
[0077] The eNB may send a handover command. When a handover command
message is received from the eNB, the UE 701 performs handover
according to the handover command message at step 709.
[0078] The UE 701 starts the interfering communication technology
if necessary at step 711. Thereafter, the UE 701 returns to step
703 and performs requested operations (such as detection of
activation or stoppage of interfering communication
technologies).
[0079] FIG. 8 is a block diagram of a user equipment according to
an exemplary embodiment of the present invention.
[0080] Referring to FIG. 8, the user equipment may include a
transceiver unit 801, a mux/demux unit 803, an upper layer unit
805, a control message handler 807, a control unit 809, an
interfering technology detector/determiner 811, and an interfering
communication module 813.
[0081] In the user equipment, data is sent and received through the
upper layer unit 805, and control messages are sent and received
through the control message handler 807. For transmission, data is
multiplexed by the mux/demux unit 803 and sent through the
transceiver unit 801 under control of the control unit 809. For
reception, a message signal received by the transceiver unit 801 is
demultiplexed by the mux/demux unit 803 and forwarded to the upper
layer unit 805 or the control message handler 807 according to the
message type, under control of the control unit 809.
[0082] As an example, the interfering communication module 813 may
directly send notification of a power on or start of operation to
the interfering technology detector/determiner 811. The interfering
technology detector/determiner 811 may already be aware of the
interfering communication module 813. When a transmit signal 815
sent by the interfering communication module 813 is received by the
transceiver unit 801 as a strong interference signal 817, the
control unit 809 may recognize this situation and notify the
interfering technology detector/determiner 811 of in-device
interference.
[0083] To avoid in-device interference, the interfering technology
detector/determiner 811 notifies the control message handler 807 of
information on the interfering communication module 813. Then, the
control message handler 807 creates an RRC message including a
measurement configuration request and a preferred frequency list
(or a non-preferred frequency list, and sends the RRC message to a
corresponding eNB.
[0084] When a measurement configuration message is received as a
control message from the eNB, the control unit 809 controls an
operation to perform measurement according to the measurement
configuration. When a handover command message is received as a
control message from the eNB, the control unit 809 controls an
operation to perform handover according to the handover command.
After successfully performing handover, the control unit 809
notifies the interfering technology detector/determiner 811 of
handover completion so as to start the interfering communication
module 813 if not yet started. Thereafter, the control unit 809
controls an operation to detect activation or stoppage of
interfering communication technologies, and the user equipment may
repeat the above process.
[0085] Although the user equipment is depicted as including
multiple blocks having different functions in the above
description, it is not necessarily limited to such a
configuration.
[0086] For example, the user equipment may be composed of a
transceiver unit to send and receive a signal to and from an eNB,
and a control unit to control interference measurement.
[0087] In this case, the control unit may control a process of
identifying, upon detection of activation of an interfering
communication technology, those frequencies that are likely to be
affected by interference caused by the interfering communication
technology, sending a measurement configuration request message
including a list of frequencies that are likely to be affected by
interference to a corresponding eNB, and performing, upon reception
of a measurement configuration message from the eNB, measurement
according to measurement configurations specified in the received
message.
[0088] For example, the measurement configuration message may
include an indication indicating measurement of in-device
interference caused by an interfering communication technology in
the user equipment.
[0089] The control unit may control an operation to separately
store a measurement result for subframes not affected by in-device
interference and another measurement result for subframes affected
by in-device interference. The control unit may regard a frequency
that is supported by the user equipment and is not separated by a
preset gap or more from the frequency of the interfering
communication technology as a frequency that is likely to be
affected by interference.
[0090] When a trigger condition in the measurement configuration
message is met, the control unit may control an operation to send a
measurement report message including measurement results to the
eNB. Here, the measurement report message may separately include a
measurement result for subframes not affected by in-device
interference and another measurement result for subframes affected
by in-device interference.
[0091] When a handover command based on the transmitted measurement
results is received from the eNB, the control unit may control an
operation to perform handover according to the handover
command.
[0092] As described above, a user equipment supporting the proposed
method may perform effective measurement as to a present or
potential interference factor, report measurement results to a
corresponding base station, and perform handover to another cell so
as to reduce in-device interference. Hence, the user equipment may
conduct smooth communication while avoiding coexistence
interference caused by an interfering communication technology.
[0093] In a feature of various exemplary embodiments of the present
invention, a user equipment supporting the proposed method may
provide information regarding a frequency band that can be affected
by interference to a corresponding base station, which is then
recommended to send a command for guiding interference avoidance to
the user equipment. Hence, it is possible for the user equipment to
perform smooth communication by reducing interference between
communication modules.
[0094] While the invention has been shown and described with
reference to certain exemplary embodiments thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the invention as defined by the appended claims and
their equivalents.
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