U.S. patent application number 14/712574 was filed with the patent office on 2015-09-03 for frequency sub-band selection in wireless communications.
This patent application is currently assigned to BROADCOM CORPORATION. The applicant listed for this patent is BROADCOM CORPORATION. Invention is credited to Seppo ROUSU, Ville VINTOLA.
Application Number | 20150249991 14/712574 |
Document ID | / |
Family ID | 45508784 |
Filed Date | 2015-09-03 |
United States Patent
Application |
20150249991 |
Kind Code |
A1 |
ROUSU; Seppo ; et
al. |
September 3, 2015 |
FREQUENCY SUB-BAND SELECTION IN WIRELESS COMMUNICATIONS
Abstract
This document discloses a solution where a network element of a
cellular communication system detects appearance of a terminal
device in the cellular communication system. In connection with
registering the terminal device in the cellular communication
system, the network element determines that a native frequency band
of the terminal device is a sub-band of an operating frequency band
of the cellular communication system and, then, allocates to the
terminal device frequency resources from the native frequency band
of the terminal device.
Inventors: |
ROUSU; Seppo; (Oulu, FI)
; VINTOLA; Ville; (Kirkkonummi, FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BROADCOM CORPORATION |
Irvine |
CA |
US |
|
|
Assignee: |
BROADCOM CORPORATION
Irvine
CA
|
Family ID: |
45508784 |
Appl. No.: |
14/712574 |
Filed: |
May 14, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13310096 |
Dec 2, 2011 |
9066346 |
|
|
14712574 |
|
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Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04W 72/0453 20130101;
H04W 60/04 20130101; H04W 88/02 20130101 |
International
Class: |
H04W 72/04 20060101
H04W072/04; H04W 60/04 20060101 H04W060/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 25, 2011 |
GB |
1120393.2 |
Claims
1. A method comprising: detecting, in a network element of a
cellular communication system, appearance of a terminal device in
the cellular communication system; determining, in connection with
registering the terminal device in the cellular communication
system, that a native frequency band of the terminal device is a
sub-band of an operating frequency band of the cellular
communication system; and allocating to the terminal device
frequency resources from the native frequency band of the terminal
device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of and is based upon and
claims the benefit of priority under 35 U.S.C. .sctn.120 for U.S.
Ser. No. 13/310,096, filed Dec. 2, 2011, the entire contents of
this application is incorporated herein by reference. U.S. Ser. No.
13/310,096 claims the benefit of priority under 35 U.S.C. .sctn.119
from United Kingdom Application No. 1120393.2, filed Nov. 25,
2011.
FIELD
[0002] The invention relates to the field of radio communications
and, particularly, to selecting an operating frequency sub-band for
a terminal device.
BACKGROUND
[0003] Different operating frequencies have been adopted for a
given cellular telecommunication system in different geographical
areas. Furthermore, different bandwidths and different carrier
aggregation component combinations may be used in different
geographical areas, which increases hardware complexity of terminal
devices.
BRIEF DESCRIPTION
[0004] According to an aspect of the present invention, there is
provided a method comprising: detecting, in a network element of a
cellular communication system, appearance of a terminal device in
the cellular communication system; determining, in connection with
registering the terminal device in the cellular communication
system, that a native frequency band of the terminal device is a
sub-band of an operating frequency band of the cellular
communication system; and allocating to the terminal device
frequency resources from the native frequency band of the terminal
device.
[0005] According to another aspect of the present invention, there
is provided a method comprising: initiating a search for a cellular
communication network in a terminal device having a split-band
radio frequency filter splitting an operating frequency band of the
terminal device into at least two sub-bands, wherein the terminal
device is configured to search for the cellular communication
network from the at least two sub-bands; detecting the cellular
communication network operating on one of the at least two
sub-bands; determining internally in the terminal device whether or
not the terminal device is allowed to operate in the cellular
communication network; and if the terminal device is allowed to
operate in the cellular communication network, selecting the
sub-band on which the cellular communication network was detected
for communication with the cellular communication network.
[0006] According to another aspect of the present invention, there
is provided an apparatus comprising means for detecting appearance
of a terminal device in the cellular communication system; means
for determining, in connection with registering the terminal device
in the cellular communication system, that a native frequency band
of the terminal device is a sub-band of an operating frequency band
of the cellular communication system; and means for allocating to
the terminal device frequency resources from the native frequency
band of the terminal device.
[0007] According to another aspect of the present invention, there
is provided an apparatus comprising means initiating a search for a
cellular communication network in a terminal device having a
split-band radio frequency filter splitting an operating frequency
band of the terminal device into at least two sub-bands, wherein
the terminal device is configured to search for the cellular
communication network from the at least two sub-bands; means for
detecting the cellular communication network operating on one of
the at least two sub-bands; means for determining internally in the
terminal device whether or not the terminal device is allowed to
operate in the cellular communication network; and means for
selecting, if the terminal device is allowed to operate in the
cellular communication network, the sub-band on which the cellular
communication network was detected for communication with the
cellular communication network.
[0008] According to another aspect of the present invention, there
is provided an apparatus comprising: at least one processor; and at
least one memory including program instructions, wherein the at
least one memory and the computer program code are configured, with
the at least one processor, to cause the apparatus to: detect
appearance of a terminal device in a cellular communication system;
determine, in connection with registering the terminal device in
the cellular communication system, that a native frequency band of
the terminal device is a sub-band of an operating frequency band of
the cellular communication system; and allocating to the terminal
device frequency resources from the native frequency band of the
terminal device.
[0009] According to another aspect of the present invention, there
is provided an apparatus comprising: at least one processor; and at
least one memory including program instructions, wherein the at
least one memory and the computer program code are configured, with
the at least one processor, to cause the apparatus to: initiate a
search for a cellular communication network in a terminal device
having a split-band radio frequency filter splitting an operating
frequency band of the terminal device into at least two sub-bands,
wherein the terminal device is configured to search for the
cellular communication network from the at least two sub-bands;
detect the cellular communication network operating on one of the
at least two sub-bands; determine internally in the terminal device
whether or not the terminal device is allowed to operate in the
cellular communication network; and if the terminal device is
allowed to operate in the cellular communication network, selecting
the sub-band on which the cellular communication network was
detected for communication with the cellular communication
network.
[0010] According to yet another aspect of the present invention,
there is provided a computer program product embodied on a
non-transitory computer readable distribution medium and configured
to execute a computer process comprising: detecting, in a network
element of a cellular communication system, appearance of a
terminal device in the cellular communication system; determining,
in connection with registering the terminal device in the cellular
communication system, that a native frequency band of the terminal
device is a sub-band of an operating frequency band of the cellular
communication system; and allocating to the terminal device
frequency resources from the native frequency band of the terminal
device.
[0011] According to yet another aspect of the present invention,
there is provided a computer program product embodied on a
non-transitory computer readable distribution medium and configured
to execute a computer process comprising: initiating a search for a
cellular communication network in a terminal device having a
split-band radio frequency filter splitting an operating frequency
band of the terminal device into at least two sub-bands, wherein
the terminal device is configured to search for the cellular
communication network from the at least two sub-bands; detecting
the cellular communication network operating on one of the at least
two sub-bands; determining internally in the terminal device
whether or not the terminal device is allowed to operate in the
cellular communication network; and if the terminal device is
allowed to operate in the cellular communication network, selecting
the sub-band on which the cellular communication network was
detected for communication with the cellular communication
network.
[0012] Embodiments of the invention are defined in the dependent
claims.
LIST OF DRAWINGS
[0013] Embodiments of the present invention are described below, by
way of example only, with reference to the accompanying drawings,
in which
[0014] FIG. 1 illustrates communication between a terminal device
and a cellular telecommunication system and respective operating
frequency bands;
[0015] FIGS. 2 to 4 illustrate flow diagrams of processes for
allocating frequency resources to a roaming terminal device
according to some embodiments of the invention;
[0016] FIGS. 5 and 6 illustrate flow diagrams of processes for
network search and associated operation in the roaming terminal
device according to some embodiments of the invention; and
[0017] FIGS. 7 and 8 illustrate block diagrams of apparatuses
according to some embodiments of the invention.
DESCRIPTION OF EMBODIMENTS
[0018] The following embodiments are exemplary. Although the
specification may refer to "an", "one", or "some" embodiment(s) in
several locations, this does not necessarily mean that each such
reference is to the same embodiment(s), or that the feature only
applies to a single embodiment. Single features of different
embodiments may also be combined to provide other embodiments.
Furthermore, words "comprising" and "including" should be
understood as not limiting the described embodiments to consist of
only those features that have been mentioned and such embodiments
may contain also features/structures that have not been
specifically mentioned.
[0019] FIG. 1 illustrates a link between a base station 100 of a
cellular communication network and a terminal device 102 having a
connection in the cellular communication network. In some
embodiments terminal/device/machine/automotive may have at least
one other connection with at least one other wireless communication
device without the cellular communication network interaction. Such
a connection may be called a device-to-device, machine to machine,
vehicle to vehicle connection. Additionally, terminal device 102
may have multiple active communications with different radio
communication systems on one or multiple frequency bands. One
example of the latter is a carrier aggregation (CA) scheme where
the terminal device 102 communicates concurrently on a plurality of
radio frequency carriers. Embodiments of the CA scheme are
intra-band CA, inter-band CA, contiguous CA and non-contiguous CA
containing various combinations for uplink and downlink directions.
Cellular communication network employing the same radio
communication protocol may operate on different frequency bands in
different geographical areas. For example, one of the frequency
bands utilized in Europe by a Long-Term Evolution of Universal
Mobile Telecommunication System (UMTS LTE) is between frequencies
1805 and 1880 MHz for downlink (108 in FIG. 1) and between
frequencies 1710 and 1785 MHz for uplink (104 in FIG. 1), as shown
in FIG. 1 by the continuous lining. This is known as UMTS LTE Band
3 (or III). As another example, one of the frequency bands operated
in Japan form a sub-band of Band III between frequencies 1844.9 and
1879.9 MHz for downlink (110 in FIG. 1) and between frequencies
1749.9 and 1784.9 MHz for uplink (106 in FIG. 1), and this LTE band
9 (or IX) is shown in FIG. 1 by the dotted line. Both bands 3 and 9
are implemented as a frequency-division duplex (FDD) method. Other
FDD frequency bands are employed in the same and other geographical
areas, and some bands may form sub-bands of other bands in radio
frequency spectrum. Table 1 below illustrates as an example
frequency bands and modes of the UMTS LTE.
TABLE-US-00001 TABLE 1 E- Uplink (UL) Downlink (DL) UTRA operating
band operating band Oper- BS receive BS transmit Du- ating UE
transmit UE receive plex Band
F.sub.UL.sub.--.sub.low-F.sub.UL.sub.--.sub.high
F.sub.DL.sub.--.sub.low-F.sub.DL.sub.--.sub.high Mode 1 1920
MHz-1980 MHz 2110 MHz-2170 MHz FDD 2 1850 MHz-1910 MHz 1930
MHz-1990 MHz FDD 3 1710 MHz-1785 MHz 1805 MHz-1880 MHz FDD 4 1710
MHz-1755 MHz 2110 MHz-2155 MHz FDD 5 824 MHz-849 MHz 869 MHz-894
MHz FDD 6.sup.1 830 MHz-840 MHz 875 MHz-885 MHz FDD 7 2500 MHz-2570
MHz 2620 MHz-2690 MHz FDD 8 880 MHz-915 MHz 925 MHz-960 MHz FDD 9
1749.9 MHz-1784.9 MHz 1844.9 MHz-1879.9 MHz FDD 10 1710 MHz-1770
MHz 2110 MHz-2170 MHz FDD 11 1427.9 MHz-1447.9 MHz 1475.9
MHz-1495.9 MHz FDD 12 699 MHz-716 MHz 729 MHz-746 MHz FDD 13 777
MHz-787 MHz 746 MHz-756 MHz FDD 14 788 MHz-798 MHz 758 MHz-768 MHz
FDD 15 Reserved Reserved FDD 16 Reserved Reserved FDD 17 704
MHz-716 MHz 734 MHz-746 MHz FDD 18 815 MHz-830 MHz 860 MHz-875 MHz
FDD 19 830 MHz-845 MHz 875 MHz-890 MHz FDD 20 832 MHz-862 MHz 791
MHz-821 MHz FDD 21 1447.9 MHz-1462.9 MHz 1495.9 MHz-1510.9 MHz FDD
22 3410 MHz-3490 MHz 3510 MHz-3590 MHz FDD 23 2000 MHz-2020 MHz
2180 MHz-2200 MHz FDD 24 1626.5 MHz-1660.5 MHz 1525 MHz-1559 MHz
FDD 25 1850 MHz-1915 MHz 1930 MHz-1995 MHz FDD . . . 33 1900
MHz-1920 MHz 1900 MHz-1920 MHz TDD 34 2010 MHz-2025 MHz 2010
MHz-2025 MHz TDD 35 1850 MHz-1910 MHz 1850 MHz-1910 MHz TDD 36 1930
MHz-1990 MHz 1930 MHz-1990 MHz TDD 37 1910 MHz-1930 MHz 1910
MHz-1930 MHz TDD 38 2570 MHz-2620 MHz 2570 MHz-2620 MHz TDD 39 1880
MHz-1920 MHz 1880 MHz-1920 MHz TDD 40 2300 MHz-2400 MHz 2300
MHz-2400 MHz TDD 41 2496 MHz 2690 MHz 2496 MHz 2690 MHz TDD 42 3400
MHz-3600 MHz 3400 MHz-3600 MHz TDD 43 3600 MHz-3800 MHz 3600
MHz-3800 MHz TDD Note .sup.1Band 6 is not applicable
[0020] Some radio communication networks may utilize a
time-division duplex (TDD) method that terminals may
correspondingly support. In TDD systems, transmission and reception
is carried out on the same allocated frequency band. Other TDD
frequency bands may be employed in the same and other geographical
areas, and some bands may form sub-bands of other bands in the
radio frequency spectrum. FDD and TDD systems may be employed in
the same geographical areas, and some TDD bands may be arranged to
be adjacent to FDD downlink and/or uplink frequency bands. In some
employment, FDD and TDD systems band allocations may overlap. All
of these non-overlapping and overlapping bands may be considered as
sub-bands in the context of the present description. In some TDD
implementations TX and RX operational frequencies are with
predefined frequency offset to improve interoperability.
[0021] For example, a frequency band of a Japanese operator AXGP
(2545-2575 MHz) overlaps partially with a frequency band of an US
operator Clearwire (2496-2620 MHz), while band 41 of the UMTS LTE
in Table 1 occupies a portion of band 38. On the same frequency
range exist a communication system for band 7 FDD and for example a
Wimax system (Worldwide Interoperability for Microwave Access).
Additionally, an LTE system occupying band 40 (TDD) and a WLAN
(Wireless Local Area Network) operating on an ISM (Industrial,
Scientific, and Medical) band may have practically zero Hz
frequency separation.
[0022] Radio communication systems allocated close to each other in
the frequency domain may generate interference problems such as
adjacent channel leakage (ACL), wide band noise, blocking,
intermodulation, cross-modulation, etc. Even when there is some
frequency separation between systems, harmonic power and ACL may
cause interference particularly on higher frequencies. Interference
victim and/or source may be a radio communication link, the same
radio communication system, the same radio terminal, an external
radio terminal, downlink/uplink transmission/reception with all
possible combinations. Additionally, interference may be generated
by the same communication link, e.g. in CA transmission harmonic
interference and/or ACL may interfere with another CA reception
band. In another example, a victim may be another radio system,
e.g. a Global Positioning System (GPS) receiver suffering from at
least one of harmonic interference, ACL interference, and wide band
noise. The interference may result in degraded quality of voice or
data, dropped link, degraded probability of connection
establishments, degraded power class, degraded data class, degraded
data throughput, and/or no connection.
[0023] In some embodiments, the support for the different operating
bands in terminal device may be implemented by applying multiple
filters on the same band. These implementations may be realized by
at least two filters, e.g. split-band filters operating on adjacent
frequency bands, or a passband may overlap between the filters. For
example, the split-band filter may be realized to operate on UMTS
LTE band 41 (2496-2690 MHz) such that the band 41 is split into
three sub-bands, wherein one filter is tuned to each sub-band. The
sub-bands of the 41 may be split into, for example, 2496-2572 MHz
(sub-band 1), 2572-2614 MHz (sub-band 2), and 2614-2690 MHz
(sub-band 3). Other splits can be done according to the
architecture and other technical and/or commercial
requirements.
[0024] As a further example, frequency bands above 3 GHz, for
example bands 33 and 34 have a broad passband, and even the broad
frequency bands may be covered by using split-band filters, each
sub-band filtercovering a sub-band of the broad frequency band.
Other equivalents of the split band-filter arrangement include a
frequency tunable filter, a duplexer, a diplexer, wherein a
passband may be tunable to realize the sub-bands.
[0025] With respect to the terminal device 102, it typically
comprises a radio frequency (RF) filters, at least one duplexer,
low pass filters, high pass filters, and/or at least one diplexer
having a bandwidth configured according to the native operating
frequency band of the terminal device. In FDD systems, a duplexer
may be used to combine downlink and uplink paths to the same
antenna. In some radio frequency (RF) architectures, transmission
and reception may have separate antennas, so bandpass filters may
be used. In some embodiments, multiple-input-multiple-output (MIMO)
and/or diversity reception paths may be realized by multiple
filters arranged to have the same passband. Filters may also be
combined together to reduce the number of interfaces to subsequent
functional elements, e.g. a low-noise amplifier (LNA), band
switches, antenna switches, mode switches, and corresponding
special purpose elements/components. In some embodiments, the RF
filter(s) may be tunable so as to shift corner frequencies as
desired. In this manner, the RF filter(s) may be tuned from a
1.sup.st operational band to another frequency band according to
the communication requirements or network measurements.
Additionally, the tunable RF filter(s) may be adjusted according to
sub-band frequency allocation, as defined by the radio access
network, wherein a bandwidth (BW), frequency resource blocks (RB),
the number of carriers, and the number of carrier components may be
selected by the radio access network according to the designed
special purpose capability of the terminal device, needed special
purpose interfaces, special purpose controls, special purpose
control algorithms, special purpose firmware, special purpose
feedback information, special purpose memories, and special purpose
processors.
[0026] For example, if the terminal device 102 is configured to
operate on the LTE Band 9, the RF filters/duplexers of the terminal
device 102 may be tuned to provide a pass band having corner
frequencies around 1844.9 and 1879.9 MHz in downlink and around
1749.9 and 1784.9 MHz in uplink. On the other hand, if the terminal
device 102 is configured to operate on the LTE Band 3, the RF
filters/duplexers of the terminal device 102 are designed or tuned
to provide a passband having corner frequencies around 1805 and
1880 MHz for downlink and for uplink between frequencies 1710 and
1785 MHz, respectively. It should be noted that the terminal device
102 is in use allocated radio resources within this pass band, but
the pass band of the RF filter may remain fixed regardless of the
changes in the radio resource allocation. If the terminal device
102 supports operation on both bands III and IX, it may have two RF
filters, wherein one of the RF filters may be selected for example
with a switch or a frequency-selecting special purpose components,
e.g. an active/passive duplexer, a diplexer and/or a special
purpose power splitter.
[0027] In such a scenario where the native frequency band of the
terminal device 102 forms a sub-band of the operating frequency
band of the cellular communication system in which the terminal
device 102 roams, e.g. operates as a visiting terminal, the
cellular communication network may prioritize allocating to the
terminal device 102 frequencies on the native frequency band of the
terminal device 102. While some of the following examples relate to
the roaming terminal device, the described functionalities are
equally applicable to a terminal device that resides in its home
network. Let us now refer to an embodiment shown in a flow diagram
of FIG. 2. The flow diagram relates to a process that may be
carried out as a radio resource allocation algorithm in a network
element of the cellular communication network, e.g. a radio
resource allocator of the base station 100. Referring to FIG. 2,
appearance of a terminal device 102 residing in the cellular
communication system is detected in block 202. The terminal device
102 may be a roaming terminal device, or it may reside in its home
network, but let us now consider the roaming terminal device as an
example. In block 204, it is determined in connection with
registering the roaming terminal device 102 in the cellular
communication system that a native frequency band of the roaming
terminal device 102 is a sub-band of an operating frequency band of
the cellular communication system. In block 206, frequency
resources from the native frequency band of the roaming terminal
device 102 are then allocated to the terminal device 102. Block 206
may be carried out by a resource allocator comprised in the network
element or elsewhere, and the resource allocator may allocate to
the roaming terminal device 102 frequency resources exclusively
from the sub-band. In other words, the resource allocator prevents
allocating frequencies of the cellular communication system that
are outside the sub-band the terminal device supports natively.
[0028] For example, if the cellular communication system utilizes
Band 3 of the LTE while the terminal device supports communication
on Band 3 and Band 4, the network element may configure the
terminal device to use Band 4 in the communication in the cellular
communication system. In general, the network element may allocate
the terminal device to another frequency band than the nominal
frequency band of the cellular communication system, wherein the
other band forms the sub-band of the nominal frequency band of the
cellular communication system. As a consequence, the terminal
device may use the RF filter of the other, narrower frequency band,
which results in better performance. Thereafter, the network
element may configure a resource allocator of the cellular
communication system to allocate to the terminal device frequencies
only from the sub-band, e.g. the Band 4.
[0029] In an embodiment, both uplink and downlink bands of the
terminal device are allocated to form sub-bands of the nominal
uplink and downlink frequency bands of the cellular communication
system in an FDD system. In another embodiment, only one of the
uplink and downlink bands of the terminal device is allocated to
form a sub-band of the nominal uplink or downlink frequency bands
of the cellular communication system.
[0030] In an embodiment, the algorithm reallocates at least one of
the other terminal devices operating on the native frequency band
of the roaming terminal device 102 to make room for the roaming
terminal device on its native frequency band. The reallocation may
comprise moving at least one other terminal device from the native
frequency band of the roaming terminal device 102 to a frequency
band out of the native frequency band. Accordingly, the native
frequency band of the roaming terminal device 102 is freed to make
room for the roaming terminal device 102. Such another terminal
device may be a terminal device having the cellular communication
network as a home network. Such another terminal device may
alternatively be another roaming terminal device, and the
reallocation may be provide the network with a more suitable
allocated frequency distribution in terms of interference and
filtering capability
[0031] Allocating the frequency resources, e.g. one or more
carriers, that are within the native frequency band of the terminal
device 102 allows the terminal device to utilize its narrowband RF
filter in the communication with the cellular communication
network. This has several advantages: the lower bandwidth results
in better efficiency of the RF filter by reducing insertion losses
in transmission and/or reception, for example, thus allowing to use
lower transmit power to achieve the same result. This reduces power
consumption in the transmitter and the amount of interference in a
radio interface when compared to a situation where the base station
allocates to the roaming terminal device 102 arbitrary frequency
resources within its own operating frequency band. It also allows a
terminal device 102 dedicated to operate on its native frequency
band to communicate with the base station 100. Further advantage is
that there is no need to equip the terminal device with a separate
RF filters/duplexers for the two operating frequency bands so as to
support roaming. The above-mentioned frequency resources may refer
to uplink and/or downlink resources.
[0032] The network element may determine the operating frequency
band and other operational parameters of the terminal device 102
from a terminal classification communicated from the terminal
device 102 to the network element in connection with registering
the terminal device 102 in the cellular network. For example, the
native frequency band, the supported frequency band, and any other
operational parameters of the terminal device 102 may be
communicated from the terminal device 102 to the network element in
UECapabilityInformation which is an UMTS LTE information element
comprising an ue-CapabilityRAT-Container carrying an
UE-EUTRA-Capability Information Element. This information element
carries RF Parameters and MeasParameters fields used by the
terminal device to indicate the frequency bands it supports and any
necessary measurement parameters. The terminal device 102 may
report supported frequency bands of any other radio access scheme,
e.g. GSM (Global System for Mobile Communications) or another 2G
system, W-CDMA (Wideband Code Division Multiple Access) or another
3G system.
[0033] In an embodiment, the terminal device 102 is equipped with
at least two RF filters providing different bandwidths or, in other
words, a sub-band within a broader band, and the network element
may be configured to prioritize the between bandwidths, e.g. by
preferring the narrower bandwidth whenever possible. The terminal
device 102 may thus carry out at least some of the special purpose
communication with the cellular communication network by using the
RF filter having the lower bandwidth. The selection of the
appropriate RF filter may be triggered autonomously in the terminal
device 102 upon identifying the cellular communication network in
which the terminal device 102 is capable to roam. Thus, the
terminal device 102 may deduce from the cellular communication
network type whether or not the network supports the feature of
utilizing the native frequency band of the terminal device 102. In
another embodiment, the base station 100 or another network element
of the cellular communication network may transmit a signal
triggering the terminal device 102 to select the appropriate RF
filter. FIG. 3 illustrates an embodiment of the process where the
prioritization is used. Referring to FIG. 3, it is determined in
block 302 that the roaming terminal device supports, in addition to
its native frequency band, also the operating frequency band of the
cellular communication system having a higher bandwidth than the
bandwidth of the native frequency band. For example, when the
terminal device 102 has the LTE Band 9 as the native frequency
band, block 302 comprises detecting that the terminal device 102 is
capable of operating also on the LTE Band 3. This information may
also be derived from the terminal device classification. The
terminal device classification may comprise a special purpose
information element indicating this capability, or the information
may be contained in another special purpose information element
used to convey another special purpose operational parameter of the
terminal device. These operational parameters may include a power
class, a downlink (DL) MIMO Class, an uplink (UL) MIMO class, data
class, the number of antennas, and/or a terminal category. In block
304, the native frequency band of the roaming terminal device is
prioritized over the other frequency bands of the operating
frequency band of the cellular communication system when allocating
frequency resources to the roaming terminal device. In an
embodiment, if frequency resources are available for allocation on
the native frequency band and outside the native frequency band,
the frequency resources on the native frequency band are allocated
to the roaming terminal device 102. On the other hand, if only
frequency resources outside the native frequency band are
available, the radio resource allocator may still allocate such
frequencies to the roaming terminal device 102.
[0034] Above, there has been considered embodiments where frequency
resources on at least one carrier are allocated to the terminal
device. Carrier aggregation (CA) is a topic developed to provide
bandwidths wider than a basic bandwidth of a single carrier
aggregation component of the cellular communication system. The
carrier aggregation component may have a bandwidth up to 20 MHz or
even larger in UMTS LTE-Advanced, and the carrier aggregation
component may carry a plurality of sub-carriers according to
Orthogonal Frequency Division (OFDM) and/or Single-Carrier
Frequency-Division Multiple Access (SC-FDMA) of the 3GPP
specification for the UMTS. In the CA, the effective bandwidth
delivered to a user terminal is expanded through concurrent
utilization of frequency resources on multiple carrier aggregation
components. In other words, a plurality of component carrier
aggregation components is aggregated to provide the terminal device
with a larger overall bandwidth in downlink and/or uplink. FIG. 4
illustrates a flow diagram of an embodiment for arranging a CA
configuration of the terminal device 102 according to the CA
capability of the terminal device. Referring to FIG. 4, an
apparatus comprised in the network element and arranging the CA
configurations, may determine in block 402 whether or not the
roaming terminal device 102 supports carrier aggregation. The
supported CA configurations of the terminal device may also be
determined, e.g. from the terminal classification. For example, the
supported frequency bands of the roaming terminal device 102 may be
determined. In block 404, the apparatus allocates to the terminal
device frequency resources of at least one carrier aggregation
component from the native frequency band of the roaming terminal
device 102. When the terminal device 102 supports operation only on
its native frequency band which is the subset of the operating
frequency band of the cellular communication system, the apparatus
may be configured to allocate the multiple carrier aggregation
components only from the native frequency band of the terminal
device 102. On the other hand, upon determining that the roaming
terminal device 102 supports, in addition to its native frequency
band, also the operating frequency band of the cellular
communication system in the carrier aggregation, the apparatus may
prioritize in block 404 the native frequency band over the other
frequency bands of the operating frequency band of the cellular
communication system when allocating additional carrier aggregation
components to the roaming terminal device. However, the additional
carriers outside the native frequency band of the terminal device
102 may also be allocated to the terminal device 102 under some
circumstances. Then, the terminal device 102 may switch the
operating band from the native band to the broader operating band
of the cellular communication system by switching to the
appropriate transmission and reception paths.
[0035] Above, there have been described embodiments where the
native frequency band of the roaming terminal device 102 is a
sub-band of the operating frequency band of the cellular
communication system, e.g. a situation where a Japanese terminal
roams in Europe. Let us now consider an opposite situation where
the native frequency band of the roaming terminal device is broader
than the operating frequency band of the cellular communication
system in which the terminal device roams, e.g. a European Band III
terminal device roams in Japan and in a Japanese cellular
communication network operating on Band IX.
[0036] FIG. 5 illustrates a flow diagram of an embodiment of a
process for discovering a cellular communication network and
configuring operation in the cellular communication network. The
process may be carried out in the terminal device 102 that roams as
a visiting device in a cellular communication network. Upon being
powered up or in response to another activation event, the terminal
device 102 initiates in block 502 a search for a cellular
communication network. The terminal device may search for a pilot
signal or any broadcast signal transmitted by cellular networks.
The terminal device 102 may have a split-band RF filter splitting
an operating frequency band of the roaming terminal device into at
least two sub-bands, and the roaming terminal device 102 may be
configured to search for the cellular communication network from
the at least two sub-bands in block 502. The split-band filter may
be realized by providing at least two RF filters configured with
different pass band frequencies. For example, Bands 2 and 25 of
Table 1 may be realized by using a split-band filter, wherein one
portion of the split-band filter forms Band 2 which is the sub-band
of Band 25, while another portion of the split-band filter is tuned
to cover the remaining 5 MHz band of Band 25. As another example,
let us assume that the cellular communication system operates Band
10, while the terminal device supports at least Bands 1 and 4. Even
if the terminal device does not support Band 10 directly, the
network element may configure the terminal device to tune the
reception band of the terminal device to Band 1, which corresponds
to the reception band of Band 1 (FDD). The network element may
configure the terminal device to tune the reception band of the
terminal device to Band 1, which corresponds to the reception band
of Band 10 (FDD). The network element may further configure the
terminal device to tune the transmission band of the terminal
device to Band 4, which forms a sub-band of the transmission band
of Band 10 (FDD). As long as the resource allocator of the cellular
communication system allocates to the terminal device transmission
resources within that sub-band (Band 4), the network element may
allocate to the terminal device a transmission band which is
nominally different but having overlapping frequencies with the
nominal band of the cellular communication system (Band 10 in this
case). The same principles may be applied to the reception
band.
[0037] There may be provided a switching mechanism to switch
between the different RF filters, wherein the switching mechanism
may be realized by frequency selectable filters, one switch or
multiple switches in common nodes of reception/transmission paths
containing the RF filters Switches are typically needed to combine
different galvanic paths to common galvanic paths in the
transmitter/receiver architecture. The switches may be understood
as selecting a transmission (TX) and/or a reception (RX) path in
the transmitter/receiver circuitry of the terminal device. In
architecture where there are no common paths, the switches may be
omitted. The terminal device may have split-band implementations in
FDD and/or TDD frequency allocation systems.
[0038] In block 504, the cellular communication network operating
on one of the at least two sub-bands is detected. Upon network
discovery, the terminal device 102 may determine in block 506
internally whether or not it is allowed to operate in the cellular
communication network. The broader frequency band of the terminal
device 102 may cause certain problems related to inter-system
crosstalk and inter-system interference, for example, and in order
to avoid such undesired features the terminal device may check
whether it is allowed to operate in the cellular network and, if it
is allowed, the special conditions (if any) under which it is
allowed to operate. As mentioned above, the decision may be made
internally in the terminal device 102 upon recognizing the cellular
network. The terminal device may store a database defining a
mapping between the allowability and the different cellular
networks or any other information related to the cellular networks,
e.g. communication systems, continent, country, operator, or area
codes. This database may be stored beforehand in the terminal
device and, therefore, the terminal device only needs to identify
the cellular communication network on some level to carry out block
506. Such identification may be made from a broadcast special
purpose signal received from the cellular network. If the terminal
device 102 determines that it is not allowed to roam in the
detected cellular network, it may instantly prevent any
communication with the cellular network. On the other hand, if the
roaming terminal device is allowed to operate in the cellular
communication network, it may determine the conditions under which
it is allowed to operate in the cellular communication network. For
example, the operation may require that the terminal device
restricts its operative frequency band by selecting an appropriate
RF filter or adjust a tunable filter to have predefined corner
frequencies/frequency division. As a consequence, the terminal
device 102 may select in block 506 the sub-band or sub-bands on
which the cellular communication network was detected for
communication with the cellular communication network.
[0039] If the terminal device detects no cellular communication
network from any frequency band it scans in block 502, it may
execute a sub-routine of FIG. 6. Referring to FIG. 6, the terminal
device may execute block 602 in response to the detection of no
cellular communication networks. In block 602, the terminal device
extends the search to frequency bends outside the pass band(s) of
the RF filter(s) already executed. Prior to the new search, the
terminal device may adjust corner frequencies of the
frequency-tunable filters and, thereafter, execute the search.
Adjusting the frequency-tunable filters and the search may be
continued until detection of a cellular communication network. In
an alternative embodiment e.g for ad hoc networks the terminal
device 102 may tune its frequency synthesizer to attempt the
discovery of the network from out-band. Even though the band is on
the transition or even stop band of the RF filter, if the terminal
device 102 is close to a base station, an access point, a router, a
relay, a modem, and/or a device, the network discovery is possible
and the terminal device 102 may be able to proceed in the process
of FIG. 5 and even establish a communication connection for the
purpose of data transfer. Network discovery cover all wireless
communications including device-to-device (D2D), machine-to-machine
(M2M), connected cars or vehicles V2V, etc.
[0040] Block 604 comprises another embodiment for improving means
for network discovery, and block 604 may be carried out in addition
to block 602 or instead of block 602, and their respective order
may be reversed from what is shown in FIG. 6. Block 604 may also be
carried out when the terminal device does not detect a cellular
communication network. However, the terminal device 102 may have
detected another wireless network, e.g. an IEEE 802.11 (WiFi or
Wireless Local Area Network, WLAN) network, femtocell, picocell,
other device or machine, automotive with wired connections etc. It
may be envisaged that upon constantly improving wireless network
cooperation, flexible spectrum utilization, and cognitive radio
features, different wireless network will be developed with
capability of communicating with each other. As a consequence, upon
discovery of such another network, the terminal device 102 may
request the other network to mediate a contact with a cellular
communication system. The request may comprise the above-mentioned
terminal classification or another identifier that enables the
cellular communication network to identify the operating frequency
of the terminal device. Upon receiving such a notification from the
other wireless network, a network element of the cellular
communication system may tune, if allowed, to a native operating
frequency of the terminal device 102 for the purpose of providing
the terminal device 102 with wireless communication services. The
network element may establish, for example, a new component carrier
on the native operating frequency of the terminal device 102.
[0041] FIG. 7 illustrates an embodiment of an apparatus comprising
means for carrying out the above-mentioned functionalities of the
radio resource allocator apparatus and/or the network element of
the cellular communication system The apparatus may be a base
station or another network element of the cellular communication
system. In another embodiment, the apparatus is comprised in such a
communication apparatus, e.g. the apparatus may comprise a physical
circuitry, e.g. a chip, a processor, a micro controller, or a
combination of such circuitries in the communication apparatus.
[0042] The apparatus may comprise a communication controller
circuitry 10 configured to control the communications in the
apparatus. The communication controller circuitry 10 may comprise a
control part 12 handling control signalling communication with
respect to transmission, reception, and extraction of control
frames, e.g. transmission of pilot signals, reception of terminal
registration signals from terminal devices in connection with
registering the terminal devices in the cellular communication
system, and any radio resource signalling. The communication
controller circuitry 10 may further comprise a data part 16 that
handles transmission and reception of payload data with the
terminal devices. The communication controller circuitry 10 may
further comprise a radio resource allocator circuitry 14 configured
to allocate at least frequency resources to the terminal devices.
The resource allocation may be dynamic, semi-static, or static.
With respect to the roaming terminal devices, the radio resource
allocator circuitry 14 may receive from the control part 12
information on the roaming terminal devices and their native
operating frequencies. On the basis of such information, the radio
resource allocator circuitry 14 may prioritize allocating to the
roaming terminal devices frequencies on their native frequency
bands, if the native frequency bands form at least one sub-band of
the operating frequency band of the cellular communication system.
The frequency allocation may comprise allocating frequency resource
blocks of a single component carrier but, in some embodiments, the
frequency allocation may comprise allocating additional component
carriers to the roaming terminal devices according to CA
principles.
[0043] The circuitries 12 to 16 of the communication controller
circuitry 10 may be carried out by the one or more physical
circuitries or processors. In practice, the different circuitries
may be realized by different computer program modules. Depending on
the specifications and the design of the apparatus, the apparatus
may comprise some of the circuitries 12 to 16 or all of them.
[0044] The memory 20 may further store computer programs (software)
configuring the apparatus to perform the above-described
functionalities of the apparatus. The memory 20 may also store
communication parameters and other information needed for the radio
resource allocation, e.g. the database storing information mapping
terminal classifications to native operating frequency bands. The
apparatus may further comprise radio interface components 22 and
antenna systems providing the apparatus with radio communication
capabilities with the terminal devices and, optionally, with other
elements of the cellular communication system and/or with other
wireless networks. The radio interface components 22 may comprise
standard well-known components such as amplifier, filter, switch,
isolator, coupler, antenna tuner, frequency-converter,
(de)modulator, and encoder/decoder circuitries and one or more
antennas.
[0045] In an embodiment, the apparatus carrying out the embodiments
of the invention in the communication apparatus comprises at least
one processor and at least one special purpose memory or/and one
special purpose software (SW) executable memory including a
computer program code, wherein the at least one memory and the
computer program code are configured, with the at least one
processor, to cause the apparatus to carry out the functionality of
the radio resource allocator and/or the network element in any one
of the processes of FIGS. 2 to 4. Accordingly, the at least one
processor, the memory, and the computer program code form
processing means for carrying out embodiments of the present
invention in the network element.
[0046] FIG. 8 illustrates an embodiment of an apparatus comprising
means for carrying out the above-mentioned functionalities of the
terminal device configured to operate also in visited cellular
networks in a roaming mode. The apparatus may be a computer (PC), a
laptop, a tablet computer, a cellular phone, a palm computer, or
any other apparatus provided with radio communication capability.
In another embodiment, the apparatus is comprised in such a
communication apparatus, e.g. the apparatus may comprise a physical
circuitry, e.g. a chip, a processor, a micro controller, or a
combination of such circuitries in the communication apparatus.
[0047] The apparatus may comprise a communication controller
circuitry 10 configured to control the communications in the
communication apparatus. The communication controller circuitry 50
may comprise a control part 52 handling control signalling
communication with respect to transmission, reception, and
extraction of control frames including the pilot signals and any
message exchanged in connection with registering the terminal
device in a visited network, as described above. The communication
controller circuitry 50 may further comprise a data part 56 that
handles transmission and reception of payload data in frequency
resources allocated by the cellular communication network.
[0048] The apparatus may further comprise radio interface
components 62 providing the apparatus with radio communication
capabilities within the BSS and/or with other BS Ss. The radio
interface components 62 may comprise standard well-known components
such as amplifier, filter such as the above-mentioned RF filter(s),
frequency-converter comprising a frequency synthesizer,
(de)modulator, and encoder/decoder circuitries, switch, isolator,
antenna connector, other special purposes RF component(s) and/or
modules and one or more antennas/antenna systems and antenna system
control signals to set antennas for selected configuration.
[0049] The communication controller circuitry 50 may further
comprise a network search unit 54 configured to search for cellular
communication networks during as a response to powering the
terminal device up, for example. In connection with the network
search, the network search unit 54 may consecutively select
different RF filters in connection with network search until a
cellular communication network has been discovered. The network
search unit 54 may also tune the frequency synthesizer of the radio
interface components 62 to tune to an out-band upon discovery of no
cellular communication system within the operating band(s) of the
terminal device. Upon discovery of another network with the
capability of mediating connection with the cellular communication
system, the network search unit 54 may also communicate with the
other network in connection with requesting a connection with a
cellular communication system, as described above. Upon discovering
the cellular communication network, the network search unit 54 may
configure the control part 52 to establish a registration procedure
in which the terminal device is registered in the cellular
communication system. In connection with the registration, the
control part 52 may inform an operation control circuitry 58 about
the network, and the operation control circuitry 58 may select
appropriate operational parameters, e.g. an appropriate RF filter,
needed for radio spectrum filtering in the communication with the
cellular communication system, as described above.
[0050] The circuitries 52 to 58 of the communication controller
circuitry 50 may be carried out by the one or more physical
circuitries or processors. In practice, the different circuitries
may be realized by different computer program modules. Depending on
the specifications and the design of the apparatus, the apparatus
may comprise some of the circuitries 52 to 58 or all of them.
[0051] The apparatus may further comprise a memory 60 to store
computer programs (software) configuring the apparatus to perform
the above-described functionalities of the communication apparatus.
The memory 20 may also store communication parameters and other
information needed for the wireless communications, e.g. the
database storing information on the cellular communication systems
with which the communication is allowed and, if so, under what
conditions. The apparatus may further comprise a user interface
enabling interaction with the user of the communication device. The
user interface may comprise a display, a keypad or a keyboard, a
loudspeaker, mouse, touch screen, voice, gestures etc.
[0052] In an embodiment, the apparatus carrying out the embodiments
of the invention in the communication apparatus comprises at least
one processor and at least one memory including a computer program
code, wherein the at least one memory and the computer program code
are configured, with the at least one processor, to cause the
apparatus to carry out the functionality of the terminal device in
any one of the processes of FIGS. 5 and 6.
[0053] Accordingly, the at least one processor, the memory, and the
computer program code form processing means for carrying out
embodiments of the present invention in the apparatus functioning
in the terminal device.
[0054] As used in this application, the term `circuitry` refers to
all of the following: (a) hardware-only circuit implementations,
such as implementations in only analog and/or digital circuitry,
and (b) to combinations of circuits and software (and/or firmware),
such as (as applicable): (i) a combination of processor(s) or (ii)
portions of processor(s)/software including digital signal
processor(s), software, and memory(ies) that work together to cause
an apparatus to perform various functions, and (c) to circuits,
such as a microprocessor(s) or a portion of a microprocessor(s),
that require software or firmware for operation, even if the
software or firmware is not physically present.
[0055] This definition of `circuitry` applies to all uses of this
term in this application. As a further example, as used in this
application, the term "circuitry" would also cover an
implementation of merely a processor (or multiple processors) or
portion of a processor and its (or their) accompanying software
and/or firmware. The term "circuitry" would also cover, for example
and if applicable to the particular element, a baseband integrated
circuit or applications processor integrated circuit for a mobile
phone or a similar integrated circuit in server, a cellular network
device, or other network device.
[0056] The processes or methods described in FIGS. 2 to 6 may also
be carried out in the form of a computer process defined by a
computer program. The computer program may be in source code form,
object code form, or in some intermediate form, and it may be
stored in some sort of transitory or a non-transitory carrier,
which may be any entity or device capable of carrying the program.
Such carriers include a record medium, computer memory, read-only
memory, electrical carrier signal, telecommunications signal, and
software distribution package, for example. Depending on the
processing power needed, the computer program may be executed in a
single electronic digital processing unit or it may be distributed
amongst a number of processing units.
[0057] The present invention is applicable to cellular or mobile
telecommunication systems defined above, e.g. UMTS LTE and
LTE-Advanced, but also to other suitable telecommunication systems,
e.g. WiMAX (Worldwide Interoperability for Microwave Access), IMT
(International Mobile Telecommunications), or IMT-Advanced. The
protocols used, the specifications of cellular communication
systems, their network elements and subscriber terminals, develop
rapidly. Such development may require extra changes to the
described embodiments. Therefore, all words and expressions should
be interpreted broadly and they are intended to illustrate, not to
restrict, the embodiment. It will be obvious to a person skilled in
the art that, as technology advances, the inventive concept can be
implemented in various ways. The invention and its embodiments are
not limited to the examples described above but may vary within the
scope of the claims.
* * * * *