U.S. patent number RE46,975 [Application Number 14/857,723] was granted by the patent office on 2018-07-31 for frequency hopping pattern and arrangement for sounding reference signal.
This patent grant is currently assigned to CELLULAR COMMUNICATIONS EQUIPMENT LLC. The grantee listed for this patent is CELLULAR COMMUNICATIONS EQUIPMENT LLC. Invention is credited to Kari Hooli, Kari Pajukoski, Esa Tiirola.
United States Patent |
RE46,975 |
Hooli , et al. |
July 31, 2018 |
Frequency hopping pattern and arrangement for sounding reference
signal
Abstract
A method, an apparatus, and a computer program that includes
forming frequency hopping position of the sounding reference signal
is based on a hopping pattern. The hopping pattern of the sounding
reference signal is configured to utilize a tree assignment for a
frequency allocation of the sounding reference signal and to
support at least one frequency band branch per layer. The hopping
pattern of the sounding reference signal is also configured to
provide consecutive sounding reference signals on widely separated
frequency allocations.
Inventors: |
Hooli; Kari (Oulu,
FI), Pajukoski; Kari (Oulu, FI), Tiirola;
Esa (Kempele, FI) |
Applicant: |
Name |
City |
State |
Country |
Type |
CELLULAR COMMUNICATIONS EQUIPMENT LLC |
Plano |
TX |
US |
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Assignee: |
CELLULAR COMMUNICATIONS EQUIPMENT
LLC (Plano, TX)
|
Family
ID: |
1000003152019 |
Appl.
No.: |
14/857,723 |
Filed: |
September 17, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61064690 |
Mar 20, 2008 |
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61071299 |
Apr 21, 2008 |
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61071837 |
May 20, 2008 |
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Reissue of: |
12382662 |
Mar 20, 2009 |
8537876 |
Sep 17, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L
5/0012 (20130101); H04L 5/0048 (20130101); H04L
5/0012 (20130101); H04B 1/7143 (20130101); H04B
1/7143 (20130101); H04L 5/0048 (20130101) |
Current International
Class: |
H04B
1/00 (20060101); H04L 5/00 (20060101); H04B
1/7143 (20110101) |
Field of
Search: |
;375/133,130,132,134,135,136,137 ;370/320,335,342,441
;455/39,41.2 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2193277 |
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Nov 2002 |
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RU |
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2219663 |
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Dec 2003 |
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RU |
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2005107717 |
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Dec 2006 |
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RU |
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WO 2007/075133 |
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Jul 2007 |
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WO |
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WO 2007/075133 |
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Jul 2007 |
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WO |
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2007139335 |
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Dec 2007 |
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WO |
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WO 2007/139335 |
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Dec 2007 |
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WO |
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Other References
3GPP TSG RAN WG1 Archives--Aug. 2007, Week 2 (#49), Aug. 10, 2007,
http://list.etsi.org/scripts/wa.exe?A1=ind0708b&L=3gpp_tsg_ran_wg1);
4 pp. cited by applicant .
"Assignment Scheme for Sounding Reference Signals in E-UTRA
Uplink", NTT DoCoMo, Fujitsu, Institute for Infocomm Research, 3GPP
TSG RAN WG1 Meeting #51, Jeju, Korea, Nov. 5-9, 2007, Document No.
R1-074806. cited by applicant .
Etri; "Cyclic-Shift Hopping for Uplink Sounding Reference Signal",
3GPP TSG RAN WG1 Meeting #48, R1-070748, Feb. 12-16, 2007, pp. 1-7.
cited by applicant .
NTT DoCoMo et al.; "Assignment Scheme for Sounding Reference
Signals in E-UTRA Uplink", 3GPP TSG RAN WG1 Meeting #51, R1-074806,
Nov. 5-9, 2007, pp. 1-4. cited by applicant .
Nokia Siemens Networks, Nokia; "SRS Bandwidth Selection", 3GPP TSG
RAN WG1 Meeting #52, R1-080921, Feb. 11-15, 2008, pp. 1-7. cited by
applicant .
Korean Office Action corresponding to Korean Patent Application No.
10-2010-7023333, dated Apr. 18, 2012. cited by applicant .
Official Action dated Aug. 22, 2012 issued in corresponding
Japanese Patent Application No. 2011-500222, translation, 2 pgs.
cited by applicant .
NTT DoCoMo, Fujitsu, Mitsubishi Electric, NEC, Panasonic, Sharp,
Necessity of Multiple Bandwidths for Sounding Reference Signals,
3GPP TSG-RAN WG1#47bis, R1-070090, URL:
http://www.quintillion.co.jp/3GPP/TSG_RAN/TSG_RAN2007/TSG_RAN_WG1_RL1_1.h-
tml, Sorrento, Italy, Jan. 15-19, 2007, pp. 1-10. cited by
applicant.
|
Primary Examiner: Escalante; Ovidio
Attorney, Agent or Firm: Procopio, Cory, Hargreaves &
Savitch LLP
Parent Case Text
REFERENCE TO RELATED APPLICATIONS
This application .Iadd.is a reissue of U.S. Pat. No. 8,537,876,
which was filed Mar. 20, 2009, and was assigned U.S. application
Ser. No. 12/382,662; which .Iaddend.claims priority to U.S.
Provisional Patent Application No. 61/064,690, filed on Mar. 20,
2008, U.S. Provisional Patent Application No. 61/071,299, filed on
Apr. 21, 2008, and U.S. Provisional Patent Application No.
61/071,837, filed on May 20, 2008. The disclosures of the prior
applications are hereby incorporated by reference in their
entirety.
Claims
The invention claimed is:
1. A method, comprising: forming, by a .[.processor.]. .Iadd.user
equipment.Iaddend., a frequency hopping position of .[.the.].
.Iadd.a .Iaddend.sounding reference signal based on a hopping
pattern; configuring.Iadd., at the user equipment, .Iaddend.the
hopping pattern of the sounding reference signal to utilize a tree
assignment for a frequency allocation of the sounding reference
signal and to support at least one frequency band branch per layer;
configuring.Iadd., at the user equipment, .Iaddend.the hopping
pattern of the sounding reference signal to provide consecutive
sounding reference signals on widely separated frequency
allocations; defining.Iadd., at the user equipment, .Iaddend.a
frequency-domain starting position for a hopping sounding reference
signal .[.based on a similar equation as the sounding reference
signal without frequency hopping.].; and defining.Iadd., at the
user equipment, .Iaddend.the hopping pattern in terms of n.sub.l
for tree layers 1 and above: n.sub.l=F.sub.l,t+n.sub.l,orig mod
N.sub.l, where n.sub.l,orig is a reference value of an allocation
index for tree layer .[.1.]. .Iadd.l.Iaddend., where N.sub.l is a
number of new branches per a branch on an assignment tree layer
.[.1.]. .Iadd.l.Iaddend., where t is a time index for the sounding
reference signal and is relative on a common reference frame and
subframe number and is a function of the current frame number, the
subframe number and a sounding reference signal period, n.sub.l is
the sounding reference signal frequency position index on tree
layer .[.1.]. .Iadd.l.Iaddend., and F.sub.l,t is a sounding
reference signal position.
2. The method according to claim 1, further comprising: defining a
frequency-domain starting position of k.sub.0 by '.times..times.
##EQU00007## where k'.sub.0 is an offset in sub-carriers related to
a used repetition factor comb, L.sub.SRS is the index of the
assigned sounding reference signal bandwidth value, B.sub.l is the
sounding reference signal bandwidth in subcarriers on tree layer
.[.1, and n.sub.l is the sounding reference signal frequency
position index on tree layer 1.]. .Iadd.l.Iaddend..
3. The method according to claim 1, further comprising: defining
F.sub.l,t as
.times..times..times..times.'.times..times.''.times..times.'.times..times-
..times.'.times..times.'.times.'.times..times.' ##EQU00008## when
N.sub.l is even; and defining F.sub.l,t as F.sub.l,t=.left
brkt-bot.N.sub.l/2.right brkt-bot..left
brkt-bot.t/.PI..sub.l'=0.sup.l-1N.sub.l'.right brkt-bot. when
N.sub.l is odd.
4. The method according to claim 1, further comprising: defining
the frequency hopping of sounding reference signal only for tree
layers .[.1.]. .Iadd.l.Iaddend..sub.min and above; and defining the
hopping pattern in terms of n.sub.l for tree layers .[.1.].
.Iadd.l.Iaddend..sub.min and above:
n.sub.l=F.sub.l,t+n.sub.l,origmod N.sub.l, where n.sub.l,orig is a
reference value of an allocation index for tree layer .[.1.].
.Iadd.l.Iaddend., where N.sub.l is a number of new branches per a
branch on an assignment tree layer .[.1.]. .Iadd.l.Iaddend., where
t is a time index for the sounding reference signal and is relative
on a common reference frame and subframe number and is a function
of the current frame number, the subframe number and a sounding
reference signal period.
5. The method according to claim 4, further comprising: defining
F.sub.l,t as F.sub.l,t=0 when .[.1.]. .Iadd.l.Iaddend.<.[.1.].
.Iadd.l.Iaddend..sub.min; defining F.sub.l,t as
.times..times..times..times.'.times..times.'.times..times..times..times..-
times.'.times..times..times.'.times..times. ##EQU00009## when
.[.1.]. .Iadd.l .Iaddend.is equal to or larger than .[.1.].
.Iadd.l.Iaddend..sub.min and when N.sub.l even; and defining
F.sub.l,t as .times.'.times..times. ##EQU00010## when .[.1.].
.Iadd.l .Iaddend.is equal to or larger than .[.1.].
.Iadd.l.Iaddend..sub.min and when N.sub.l odd, where N.sub.l is a
number of new branches per a branch on an assignment tree layer
.[.1.]. .Iadd.l.Iaddend., except for .[.1.].
.Iadd.l.Iaddend..sub.min-1 for which N.sub.l.sub.min.sub.-1=1
regardless of the number of new branches on tree layer .[.1.].
.Iadd.l.Iaddend..sub.min-1.
6. The method according to claim 1, further comprising: receiving a
selection between .[.the.]. .Iadd.a .Iaddend.frequency hopping and
.[.the.]. .Iadd.a .Iaddend.non-frequency hopping sounding reference
signal, wherein the sounding reference signal is configured with
the frequency hopping or without the frequency hopping, wherein the
selection of the frequency hopping and the non-frequency hopping
sounding reference signal is specific to a user equipment or to all
user equipments within a cell.
7. The method according to claim 1, further comprising: receiving a
radio resource control signal from an apparatus, the radio resource
control signal is a sounding reference signal configuration
signalling; transmitting an uplink message to the apparatus
including an allocated sounding reference signal based on data in
the radio resource control signal.
.[.8. An apparatus, comprising: a processor configured to process
frequency hopping position of the sounding reference signal based
on a hopping pattern, wherein the hopping pattern of the sounding
reference signal is configured to utilize a tree assignment for a
frequency allocation of the sounding reference signal and to
support at least one frequency band branch per layer, to provide
consecutive sounding reference signals on widely separated
frequency allocations, to define a frequency-domain starting
position for a hopping sounding reference signal based on a similar
equation as the sounding reference signal without frequency
hopping, and to define the hopping pattern in terms of n.sub.l for
tree layers 1 and above: n.sub.l=F.sub.l,t+n.sub.l,origmod N.sub.l,
where n.sub.l,orig is a reference value of an allocation index for
tree layer l, where N.sub.l is a number of new branches per a
branch on an assignment tree layer l, where t is a time index for
the sounding reference signal and is relative on a common reference
frame and subframe number and is a function of the current frame
number, the subframe number and a sounding reference signal period,
n.sub.l is the sounding reference signal frequency position index
on tree layer l and F.sub.l,t is a sounding reference signal
position..].
.[.9. The apparatus according to claim 8, wherein the processor is
further configured to define a frequency-domain starting position
of k.sub.0 by '.times..times. ##EQU00011## where k'.sub.0 is an
offset in sub-carriers related to a used repetition factor comb,
L.sub.SRS is the index of the assigned sounding reference signal
bandwidth value, B.sub.l is the sounding reference signal bandwidth
in subcarriers on tree layer l, and n.sub.l is the sounding
reference signal frequency position index on tree layer l..].
.[.10. The apparatus according to claim 8, wherein the processor is
further configured to define F.sub.l,t as
.times..times..times..times.'.times..times.''.times..times.'.times..times-
..times.'.times..times.'.times.'.times..times.' ##EQU00012## when
N.sub.l is even; and define F.sub.l,t as F.sub.l,t=.left
brkt-bot.N.sub.l/2.right brkt-bot..left
brkt-bot.t/.PI..sub.l'=0.sup.l-1N.sub.l'.right brkt-bot. when
N.sub.l is odd..].
.[.11. The apparatus according to claim 8, wherein the processor is
further configured to define the frequency hopping of sounding
reference signal only for tree layers l.sub.min and above; and
define the hopping pattern in terms of n.sub.l for tree layers
l.sub.min and above: n.sub.l=F.sub.l,t n.sub.l,origmod N.sub.l,
where n.sub.l,orig is a reference value of an allocation index for
tree layer l, where N.sub.l is a number of new branches per a
branch on an assignment tree layer l, where t is a time index for
the sounding reference signal and is relative on a common reference
frame and subframe number and is a function of the current frame
number, the subframe number and a sounding reference signal
period..].
.[.12. The apparatus according to claim 11, wherein the processor
is further configured to define F.sub.l,t as F.sub.l,t=0 when
l<l.sub.min; define F.sub.l,t as
.times..times..times..times.'.times..times.''.times..times.'.times..times-
..times.'.times..times.'.times.'.times..times.' ##EQU00013## when l
is equal to or larger than l.sub.min and when N.sub.l even; and
define as F.sub.l,t as F.sub.l,t=.left brkt-bot.N.sub.l/2.right
brkt-bot..left
brkt-bot.t/.PI..sub.l'=l.sub.min.sub.-1.sup.l-1N.sub.l'.right
brkt-bot. when l is equal to or larger than l.sub.min and when
N.sub.l odd, where N.sub.l is a number of new branches per a branch
on an assignment tree layer l, except for l.sub.min-1 for which
N.sub.l.sub.min.sub.-1=1 regardless of the number of new branches
on tree layer l.sub.min-1..].
.[.13. The apparatus according to claim 8, further comprising: a
receiver configured to receive a selection between the frequency
hopping and the non-frequency hopping sounding reference signal,
wherein the sounding reference signal is configured with the
frequency hopping or without the frequency hopping, wherein the
selection of the frequency hopping and the non-frequency hopping
sounding reference signal is specific to a user equipment or to all
user equipments within a cell..].
.[.14. The apparatus according to claim 8, further comprising: a
receiver configured to receive a receiving a radio resource control
signal from another apparatus, the radio resource control signal is
a sounding reference signal configuration signalling; a transmitter
configured to transmit an uplink message to the other apparatus
including an allocated sounding reference signal based on data in
the radio resource control signal..].
15. A non-transitory computer-readable medium including a computer
program, wherein the computer program is configured to control a
processor to perform a method, comprising: forming a frequency
hopping position of .[.the.]. .Iadd.a .Iaddend.sounding reference
signal based on a hopping pattern.Iadd.;.Iaddend. configuring the
hopping pattern of the sounding reference signal to utilize a tree
assignment for a frequency allocation of the sounding reference
signal and to support at least one frequency band branch per layer;
configuring the hopping pattern of the sounding reference signal to
provide consecutive sounding reference signals on widely separated
frequency allocations; defining a frequency-domain starting
position for a hopping sounding reference signal .[.based on a
similar equation as the sounding reference signal without frequency
hopping.].; and defining the hopping pattern in terms of n.sub.l
for tree layers 1 and above: n.sub.l=F.sub.l,t+n.sub.l,orig mod
N.sub.l, where n.sub.l,orig is a reference value of an allocation
index for tree layer .[.1.]. .Iadd.l.Iaddend., where N.sub.l is a
number of new branches per a branch on an assignment tree layer
.[.1.]. .Iadd.l.Iaddend., where t is a time index for the sounding
reference signal and is relative on a common reference frame and
subframe number and is a function of the current frame number, the
subframe number and a sounding reference signal period,
.[.n.sub.1.]. .Iadd.n.sub.l .Iaddend.is the sounding reference
signal frequency position index on tree layer .[.1.]. .Iadd.l
.Iaddend.and F.sub.l,t is a sounding reference signal position.
.[.16. An apparatus, comprising: forming means for forming a
frequency hopping position of the sounding reference signal based
on a hopping pattern; configuring means for configuring the hopping
pattern of the sounding reference signal to utilize a tree
assignment for a frequency allocation of the sounding reference
signal, to support at least one frequency band branch per layer,
and to provide consecutive sounding reference signals on widely
separated frequency allocations; defining means for defining a
frequency-domain starting position for a hopping sounding reference
signal based on a similar equation as the sounding reference signal
without frequency hopping and for defining the hopping pattern in
terms of n.sub.l for tree layers 1 and above:
n.sub.1=F.sub.l,t+n.sub.l,origmod N.sub.l, where n.sub.l,orig is a
reference value of an allocation index for tree layer l, where
N.sub.l is a number of new branches per a branch on an assignment
tree layer l, where t is a time index for the sounding reference
signal and is relative on a common reference frame and subframe
number and is a function of the current frame number, the subframe
number and a sounding reference signal period, n.sub.l is the
sounding reference signal frequency position index on tree layer l
and F.sub.l,t is a sounding reference signal position..].
17. A method, comprising: forming, by a .[.processor.]. .Iadd.user
equipment.Iaddend., a frequency hopping position of .[.the.].
.Iadd.a .Iaddend.sounding reference signal based on a hopping
pattern; configuring.Iadd., at the user equipment, .Iaddend.the
hopping pattern of the sounding reference signal to utilize a tree
assignment for a frequency allocation of the sounding reference
signal and to support at least one frequency band branch per layer;
configuring.Iadd., at the user equipment, .Iaddend.the hopping
pattern of the sounding reference signal to provide consecutive
sounding reference signals on widely separated frequency
allocations; defining.Iadd., at the user equipment, .Iaddend.a
frequency-domain starting position for a hopping sounding reference
signal .[.based on a similar equation as the sounding reference
signal without frequency hopping.].; defining.Iadd., at the user
equipment, .Iaddend.the hopping pattern in terms of n.sub.l for
tree layers 1 and above: n.sub.l=F.sub.l,t+n.sub.l,origmod N.sub.l,
where n.sub.l,orig is a reference value of an allocation index for
tree layer .[.1.]. .Iadd.l.Iaddend., where N.sub.l is a number of
new branches per a branch on an assignment tree layer .[.1.].
.Iadd.l.Iaddend., where t is a time index for the sounding
reference signal and is relative on a common reference frame and
subframe number and is a function of the current frame number, the
subframe number and a sounding reference signal period, n.sub.l is
the sounding reference signal frequency position index on tree
layer .[.1.]. .Iadd.l.Iaddend., and F.sub.l,t is a sounding
reference signal position; receiving.Iadd., at the user equipment,
.Iaddend.a radio resource control signal from an apparatus, the
radio resource control signal is a sounding reference signal
configuration signalling; and transmitting.Iadd., at the user
equipment, .Iaddend.an uplink message to the apparatus including an
allocated sounding reference signal based on data in the radio
resource control signal.
.[.18. An apparatus, comprising: a processor configured to process
frequency hopping position of the sounding reference signal based
on a hopping pattern, wherein the hopping pattern of the sounding
reference signal is configured to utilize a tree assignment for a
frequency allocation of the sounding reference signal and to
support at least one frequency band branch per layer, to provide
consecutive sounding reference signals on widely separated
frequency allocations, to define a frequency-domain starting
position for a hopping sounding reference signal based on a similar
equation as the sounding reference signal without frequency
hopping, and to define the hopping pattern in terms of n.sub.l for
tree layers 1 and above: n.sub.1=F.sub.1,t+n.sub.l,origmod N.sub.l,
where n.sub.l,orig is a reference value of an allocation index for
tree layer l, where N.sub.l is a number of new branches per a
branch on an assignment tree layer l, where t is a time index for
the sounding reference signal and is relative on a common reference
frame and subframe number and is a function of the current frame
number, the subframe number and a sounding reference signal period,
n.sub.l is the sounding reference signal frequency position index
on tree layer l, and F.sub.l,t is a sounding reference signal
position; a receiver configured to receive a receiving a radio
resource control signal from another apparatus, the radio resource
control signal is a sounding reference signal configuration
signalling; and a transmitter configured to transmit an uplink
message to the other apparatus including an allocated sounding
reference signal based on data in the radio resource control
signal..].
Description
FIELD
Some embodiments generally relate to communications, especially
wireless communications. In particular, some of the embodiments
relate to an uplink (UL) transmission of the universal mobile
telecommunications system (UMTS) terrestrial radio access network
(UTRAN) long term evolution (LTE). More specifically, certain
embodiments relate to sounding reference signal (SRS) transmission
and configuration.
BACKGROUND
Wireless communication networks are well known and constantly
evolving. For example, UMTS is one of third-generation (3G) cell
phone technologies. Currently, the most common form of UMTS uses
wideband code division multiple access (W-CDMA) as the underlying
air interface, as standardized by the 3GPP (3G partnership
project).
Currently, UMTS networks worldwide are being upgraded to increase
data rate and capacity for downlink packet data. In order to ensure
a further competitiveness of UMTS, various concepts for UMTS long
term evolution (LTE) have been investigated to achieve a
high-data-rate, low-latency and packet optimized radio access
technology.
3GPP LTE (long term evolution) is the name given to a project
within the third generation partnership project to improve the UMTS
mobile phone standard to cope with future requirements. Goals of
the project include improving efficiency, lowering costs, improving
services, making use of new spectrum opportunities, and better
integration with other open standards. The LTE project is not a
standard, but it is expected to result in the new evolved release 8
of the UMTS standard, including mostly or wholly extensions and
modifications of the UMTS system.
A characteristic of evolved UMTS is that it is fundamentally based
upon transmission control protocol/internet protocol (TCP/IP), the
core protocol of the Internet, with built-on higher level services
such as voice, video, and messaging.
In modern wireless networks, a sounding reference signal (SRS) is
typically transmitted with a wide bandwidth for a base station, or
node B, to find a best resource unit (RU), also known as a resource
block (RB) or physical resource block (PRB) in the LTE standard for
a transmitting from a user equipment (UE), such as a mobile device.
However, due to the restrictions on the maximum UE transmission
power, the channel quality indication (CQI) measurement accuracy is
degraded when the received power of the SRS signal is degraded,
such as when a UE located near edge of the cell transmits the SRS.
This degradation of the SRS may cause errors to arise in the
optimum RU assignment and in the modulation and coding scheme (MCS)
selection. Therefore, improvements in the transmission of the SRS
from the UE help to achieve the maximum user throughput.
Accordingly, the SRS is designed to enable channel aware scheduling
and fast link adaptation for PUSCH for UL data transmissions. The
SRS is also used as a reference (RS) for closed loop power control
(PC) for both physical uplink shared channel (PUSCH) and a physical
uplink control channel (PUCCH).
Furthermore, SRS can be used to improve/enable the channel aware
download (DL) scheduling in time division duplex (TDD) mode. TDD is
the application of time-division multiplexing to separate outward
and return signals. In particular, TDD emulates full duplex
communication over a half duplex communication link and provides
benefits where the asymmetry of the uplink and downlink data speed
is variable.
SUMMARY
The present invention has been developed in response to the present
state of the art, and in particular, in response to the problems
and needs in the art that have not yet been fully solved by
currently available communication system technologies. Accordingly,
the present invention has been developed to provide a sounding
reference signal frequency hopping pattern apparatus, method, and a
computer program embodied on a computer-readable medium.
According to one embodiment, a method may be provided to include
forming, by a processor, a frequency hopping position of the
sounding reference signal based on a hopping pattern. The method
may also include configuring the hopping pattern of the sounding
reference signal to utilize a tree assignment for a frequency
allocation of the sounding reference signal and to support at least
one frequency band branch per layer. The method may include
configuring the hopping pattern of the sounding reference signal to
provide consecutive sounding reference signals on widely separated
frequency allocations.
According to another embodiment, an apparatus may be provided to
include a processor configured to process frequency hopping
position of the sounding reference signal based on a hopping
pattern. The hopping pattern of the sounding reference signal may
be configured to utilize a tree assignment for a frequency
allocation of the sounding reference signal and to support at least
one frequency band branch per layer, and to provide consecutive
sounding reference signals on widely separated frequency
allocations.
According to another embodiment, computer program may be provided
to be embodied on a computer-readable medium. The computer program
may be configured to control a processor to perform a method. The
computer program includes forming a frequency hopping position of
the sounding reference signal based on a hopping pattern. The
computer program may also include configuring the hopping pattern
of the sounding reference signal to utilize a tree assignment for a
frequency allocation of the sounding reference signal and to
support at least frequency band branch per layer. The computer
program may also include configuring the hopping pattern of the
sounding reference signal to provide consecutive sounding reference
signals on widely separated frequency allocations.
In accordance with another embodiment, an apparatus may be provided
to include a forming means for forming a frequency hopping position
of the sounding reference signal based on a hopping pattern. The
apparatus may also include a configuring means for configuring the
hopping pattern of the sounding reference signal to utilize a tree
assignment for a frequency allocation of the sounding reference
signal, to support at least one frequency band branch per layer,
and to provide consecutive sounding reference signals on widely
separated frequency allocations.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the advantages of the invention will be readily
understood, a more particular description of the invention briefly
described above will be rendered by reference to specific
embodiments that are illustrated in the appended drawings.
Understanding that these drawings depict only typical embodiments
of the invention and are not therefore to be considered to be
limiting of its scope, the invention will be described and
explained with additional specificity and detail through the use of
the accompanying drawings, in which:
FIG. 1 is a high level schematic diagram of a UMTS system;
FIG. 2 is a high level schematic diagram of a user equipment in
accordance with some embodiments;
FIG. 3 illustrates steps in a sounding reference signal frequency
hopping pattern and arrangement method in accordance with at least
one embodiment;
FIG. 4 illustrates a process flow diagram for SRS bandwidth
allocation configuration in accordance with at least one
embodiment;
FIG. 5 illustrates a tree based SRS frequency hopping;
FIG. 6 illustrates an exemplary SRS frequency position
configuration with tree structure in accordance with at least one
embodiment;
FIG. 7A illustrates an exemplary SRS frequency hopping pattern in
accordance with at least one embodiment;
FIG. 7B illustrates an exemplary SRS arrangements with dynamically
changing PUCCH region in accordance with at least one
embodiment;
FIG. 8 illustrates steps in a method for forming a hopping SRS in
accordance with at least one embodiment;
FIG. 9 illustrates an exemplary SRS that has been scheduled with
frequency hopping for a second UE and without frequency hopping for
other depicted UEs in accordance with at least one embodiment;
and
FIG. 10 is a high-level, schematic diagram that illustrates
components of a cell system in accordance with some
embodiments.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It will be readily understood that the components of the present
invention, as generally described and illustrated in the figures
herein, may be arranged and designed in a wide variety of different
configurations. Thus, the following more detailed description of
the embodiments of the apparatus, system, and method of the present
invention, as represented in the attached figures, is not intended
to limit the scope of the invention, as claimed, but is merely
representative of selected embodiments of the invention.
The features, structures, or characteristics of the invention
described throughout this specification may be combined in any
suitable manner in one or more embodiments. For example, reference
throughout this specification to "certain embodiments," "some
embodiments," or similar language means that a particular feature,
structure, or characteristic described in connection with the
embodiment is included in at least one embodiment of the present
invention. Thus, appearances of the phrases "in certain
embodiments," "in some embodiment," "in other embodiments," or
similar language throughout this specification do not necessarily
all refer to the same group of embodiments and the described
features, structures, or characteristics may be combined in any
suitable manner in one or more embodiments.
In addition, while the terms, data, packet, and/or datagram have
been used in the description of the present invention, the
invention has import to many types of network data. For purposes of
this invention, the term data includes packet, cell, frame,
datagram, bridge protocol data unit packet, packet data and any
equivalents thereof.
The following list of certain abbreviations is used in the current
specification:
TABLE-US-00001 BTS Base Transceiver Station BW Bandwidth DM
Demodulation LTE Long Term Evolution PUCCH Physical Uplink Control
Channel PUSCH Physical Uplink Shared Channel RB Resource Block (180
kHz, 12 subcarriers) RPF Repetition factor RRC Radio Resource
Control RS Reference Signal SRS Sounding Reference Signal TDD Time
Division Duplexing UE User Equipment UTRAN Universal Terrestrial
Radio Access Network WMCDA Wideband Code Division Multiple
Access
In the current LTE, SRS signaling is controlled by a node B 110 and
SRS parameters are configured per UE 120. For example, aspects of
the SRS are semi-statically configurable per UE 120, for example as
part of a radio resource control (RRC) signaling. In particular,
the UE 120 may specify various attributes as part of an uplink
communications to the node B 110. In addition, when the SRS is
changed, the bandwidth (BW) used by a UE 120 may be adjusted by
transmitting a configuration for a given operating bandwidth. When
adjusting the bandwidth, the SRS transmission ideally should not
puncture the PUCCH region, or PUSCH region containing persistent
resource allocations.
The UE 120 may also adjust the duration of the SRS transmissions
based on the RRC signaling made by node B 110. For example, the SRS
transmissions may be defined as being either "one shot"
transmissions or an indefinite periodic transmissions that are
valid until otherwise disabled or until the session ends. The UE
120 may further adjust the period for the SRS transmissions. For
example, the period may be 2, 5, 10, 20, 40, 80, 160 or 320 ms. The
SRS is typically defined to include a repetition factor (RPF) of 2.
The UE 120 may further adjust the SRS to include a cyclic shift
signaled with 3 bits, as described in greater detail below.
Frequency hopping SRS may be a beneficial arrangement for sounding
a large bandwidth with limited SRS overhead, although at a cost of
delaying channel quality information (CQI) measurement.
To provide an efficient assignment of SRSs with different
transmission bandwidths, one scheme presents a bandwidth assignment
based on a tree structure resembling orthogonal variable spreading
factor (OVSF) code assignment with a tree structure. In other
words, there is always exactly two branches on each layer. Although
the present discussion refers to OVSF code tree, it should be
appreciated that other tree-based assignments exist and may used in
the alternative.
For example, referring to FIG. 5, an exemplary scheme for frequency
hopping for SRSs with different bandwidths may be based on OVSF
code tree structure. In FIG. 5, a branch of the OVSF code tree 500
is switched based on a pre-determined pattern. Hence, by using the
hopping method, efficient frequency hopping of SRSs with different
bandwidths can be achieved while maintaining the OVSF code tree
based SRS assignment.
OVSF and other tree-based SRS assignment may support both
hopping-based and localized-based multiplexing for SRSs with a
narrower transmission bandwidth than the system bandwidth in order
to maximize the user throughput performance in various cell
deployment scenarios. Moreover, the scheme of FIG. 5 may be adapted
to achieve an efficient SRS hopping method based on the switching
of branches of the OVSF code tree. However, the other scheme does
not take into account the current SRS assumptions made in 3GPP. For
example, the scheme may not work properly if the SRS transmission
punctures either the PUCCH region or persistent PUSCH. Also, OVSF
code tree with two branches per layer may not work if certain BW
options are allowed for SRS. OVSF code tree, therefore, lacks a
concrete SRS frequency hopping arrangement that functions within
the current 3GPP specifications for the LTE.
Various schemes for SRS bandwidths are known. For example, co-owned
provisional application Nos. 60/006,634 filed on Jan. 8, 2008 and
60/006,901 filed on Feb. 5, 2008, the subject matter of which is
hereby incorporated by reference in full. These and other known
schemes for SRS bandwidths do not disclose any SRS frequency
hopping patterns.
FIG. 1 illustrates a UMTS system 100 in accordance with some
embodiments. In particular, the UMTS system 100 may include one or
more node B 110 (known in the LTE as enhanced node B or eNB) that
define one or more cells 101, and multiple user equipments (UE) 120
associated with one or more of the cells. The radio interface
between the UE and the Node-B is called Uu 130.
The node B 110, also known as a BTS (base transceiver station) in
GSM, may use wideband code division multiple access (WCDMA) as air
transport technology. The node B 110 include radio frequency
transmitter(s) and the receiver(s) to communicate directly with the
mobile stations (e.g. UE 120), which move freely around it. In this
type of cellular networks, the UE 120 may not communicate directly
with each other but may have to communicate with the nodes B
110.
Traditionally, the node Bs 110 have minimum functionality, and are
controlled by an RNC (radio network controller) 111. However, this
is changing with the emergence of high speed downlink packet access
(HSDPA), where some logic (e.g. retransmission) is handled on the
node B 110 for lower response times.
The utilization of WCDMA technology may allow cells belonging to
the same or different node Bs 110 and even controlled by different
RNC to overlap and still use the same frequency. in fact, the whole
network can be implemented with just one frequency pair to achieve
soft handovers between the cells.
Since WCDMA often operates at higher frequencies than global system
mobile communications (GSM), the cell range is considerably smaller
compared to GSM cells. Unlike in GSM, the size of the cells may not
be constant, in a phenomenon known as cell breathing. This
configuration may require a larger number of Node-Bs 110 and
careful planning in 3G (UMTS) networks. However, the power
requirements on the node Bs 110 and the UE 120 (user equipment) are
usually much lower.
The node B 110 typically includes an antenna (not depicted)
connected to several components, including power amplifiers and
digital signal processors (also not depicted). The node B 110 can
serve several cells 101, also called sectors, depending on the
configuration and type of antenna.
Continuing with FIG. 1, the UE 120 roughly corresponds to the
mobile station in GSM systems and may be any device used directly
by an end user to communicate. For example, the UE 120 may be a
hand-held telephone, a card in a laptop computer, or other device.
The UE 120 connects to the base station, the above-described node B
110. It roughly corresponds to the mobile station in GSM
systems.
Furthermore, the UE 120 transmits and receives several messages to
and from the node 110 B. One of the messages being transmitted
includes an SRS 102. The SRS 102 may be configured based on data
received from the node B 110 or by a user interface or both. As a
result, the message including the configured SRS 102 can be
transmitted to the node Bs 110 from the UEs 120.
The UE 120 may handle the tasks toward the core network, including:
mobility management, call control, session management, and identity
management. Generally, the corresponding protocols are transmitted
transparently via a node B 110, such that the node B 110 does not
change, use or understand the protocol information. The UMTS
back-end becomes accessible via a variety of means, such as a
GSM/UMTS radio network (GSM EDGE radio access network (GERAN), UMTS
terrestrial radio access network (UTRAN), and evolved universal
terrestrial radio access network (E-UTRAN)), WiFi, ultra mobile
broadcast (UMB) and worldwide interoperability microwave access
(WiMAX). Users of non-UMTS radio networks may be provided with an
entry-point into the IP network, with different levels of security
depending on the trustworthiness of the network being used to make
the connection. Users of GSM/UMTS networks may use an integrated
system where all authentication at every level of the system is
covered by a single system, while users accessing the UMTS network
via WiMAX and other similar technologies would handle the WiMAX
connection one way, for example, authenticating themselves via a
media access control (MAC) address or electronic serial number
(ESN) address, and the UMTS link-up another way.
In LTE Release 8, an air interface called the evolved universal
terrestrial radio access (E-UTRA) may be used by UMTS operators
deploying wireless networks. The current E-UTRA systems use OFDMA
for the downlink (tower to handset) and single carrier frequency
division multiple access (SC-FDMA) for the uplink and employs
multiple-input/multiple-output (MIMO) with up to four antennas per
station. The channel coding scheme for transport blocks is turbo
coding and a contention-free quadratic permutation polynomial (QPP)
turbo code internal interleaver.
The use of OFDM, a system where the available spectrum may be
divided into thousands of very thin carriers, each on a different
frequency, each carrying a part of the signal, enables E-UTRA to be
much more flexible in its use of spectrum than the older CDMA based
systems used in the 3G protocols. CDMA networks may require large
blocks of spectrum to be allocated to each carrier, to maintain
high chip rates, and thus maximize efficiency. OFDM has a link
spectral efficiency that is greater than CDMA, and when combined
with modulation formats such as 64 QAM and techniques as MIMO,
E-UTRA is typically more efficient than W-CDMA with HSDPA and
HSUPA.
In the LTE, release 8, the subcarrier spacing in the OFDM downlink
is 15 kHz and there is a maximum of 2048 subcarriers available.
Mobile devices may be capable of receiving all 2048 subcarriers but
a base station typically supports transmitting only 72 subcarriers,
in the minimum configuration. The number of subcarriers in DL
depends on the channel BW, and the 2048 subcarriers can be achieved
with a 20 MHZ BW. The exact number of subcarriers scales down with
the BW. The transmission is divided in time into time slots of
duration 0.5 ms and subframes of duration 1.0 ms. A radio frame is
10 ms long. Supported modulation formats on the downlink data
channels are quadrature phase-shift keying (QPSK), 16 quadrature
amplitude modulation (QAM), and 64 QAM.
Continuing with the current specification for the uplink,
multiplexing SC-FDMA may be used, and QPSK or 16 QAM (64 QAM
optional) modulation. SC-FDMA is used because it has a low
peak-to-average power ratio (PAPR). Each mobile device has at least
one transmitter. Through virtual MIMO/spatial division multiple
access (SDMA), system capacity in the uplink direction can be
increased depending on the number of antennas at the base
station.
In particular, LTE uplink transmission scheme uses SC-FDMA. While
OFDMA is seen optimum to fulfill the LTE requirements in downlink,
OFDMA properties are less favorable for the uplink. This is mainly
due to weaker peak-to-average power ratio (PAPR) properties of an
OFDMA signal, resulting in worse uplink coverage. Thus, the LTE
uplink transmission scheme for FDD and TDD mode is based on SC-FDMA
with cyclic prefix. SC-FDMA signals have better PAPR properties
compared to an OFDMA signal, and the PAPR characteristics are
important for cost-effective design of UE power amplifiers. Still,
SC-FDMA signal processing has some similarities with OFDMA signal
processing, so parameterization of downlink and uplink can be
harmonized.
There are different possibilities how to generate an SC-FDMA
signal. For example, discrete fourier transform-spread-orthogonal
frequency division multiplexing (DFT-s-OFDM) has been selected for
E-UTRA. For DFT-s-OFDM, a size-M DFT may be first applied to a
block of M modulation symbols. Then, QPSK, 16 QAM and 64 QAM may be
used as uplink E-UTRA modulation schemes, the latter being optional
for the UE. The DFT may transform the modulation symbols into the
frequency domain. The result may be mapped onto the available
sub-carriers. In E-UTRA uplink, only localized transmission on
consecutive sub-carriers may be allowed. An N point inverse fast
fourier transform (IFFT) where N>M is then performed as in OFDM,
followed by addition of the cyclic prefix and parallel to serial
conversion.
The DFT processing is, therefore, a fundamental difference between
SCFDMA and OFDMA signal generation, as indicated by the term
DFT-spread-OFDM. In a SC-FDMA signal, each sub-carrier used for
transmission contains information of all transmitted modulation
symbols, since the input data stream has been spread by the DFT
transform over the available sub-carriers. In contrast to this,
each sub-carrier of an OFDMA signal only carries information
related to specific modulation symbols.
Similarly, in SC-FDMA parameterization, the E-UTRA uplink structure
can be similar to the downlink. For example, an uplink radio frame
may consist of 20 slots of 0.5 ms each, and 1 subframe consists of
2 slots. In uplink, data is allocated in multiples of one resource
block. Uplink resource block size in the frequency domain is
currently 12 sub-carriers, the same as in downlink However, not all
integer multiples are usually allowed in order to simplify the DFT
design in uplink signal processing, and typically, only factors 2,
3, and 5 are allowed. These restrictions are cited as examples.
Similarly, the uplink transmission time interval is 1 ms (same as
downlink).
User data can be carried on the physical uplink shared channel
(PUSCH) that may be determined by the transmission bandwidth and
the possible frequency hopping pattern. The physical uplink control
channel (PUCCH) can carry uplink control information in the absence
of UL data, e.g., CQI reports and ACK/NACK information related to
data packets received in the downlink (in the presence of UL data,
control signals can be transmitted on PUSCH time multiplexed with
UL data). The PUCCH can be transmitted on a reserved frequency
region in the uplink.
In the uplink reference signal structure, uplink reference signals
may be used for channel estimation in the node B 110 receiver in
order to demodulate control and data channels. On the other hand,
the reference signals may provide channel quality information (CQI)
as a basis for scheduling decisions in the base station, also
called channel sounding. The uplink reference signals can be based
on CAZAC (constant amplitude zero auto correlation) sequences or
computer search based ZAC (zero auto correlation) sequences.
For uplink physical layer procedures with E-UTRA, the uplink
physical layer procedures may be needed. For example, with
non-synchronized random access, the random access may be used to
request initial access, as part of handover, when transiting from
idle to connected, or to reestablish uplink synchronization.
Similarly, if multiple random access channels can be defined in the
frequency domain within one access period in order to provide a
sufficient number of random access opportunities.
The random access procedure can use open loop power control with
power ramping similar to WCDMA. After sending the preamble on a
selected random access channel, the UE waits for the random access
response message. If no response is detected then another random
access channel is selected and a preamble is sent again.
For uplink scheduling, the scheduling of uplink resources can be
done by node B 110. The node B 110 can assign certain
time/frequency resources to the UEs 120 and informs UEs 120 about
which transmission formats to use. Scheduling decisions affecting
the uplink can be communicated to the UEs 120 via the PDCCH in the
downlink The scheduling decisions may be based on quality of
service (QoS) parameters, UE buffer status, uplink channel quality
measurements, UE capabilities, UE measurement gaps, etc.
As uplink link adaptation methods, transmission power control,
adaptive modulation and channel coding rate, as well as adaptive
transmission bandwidth can be used. Similarly, uplink timing
control may be needed to time align the transmissions from
different UEs 120 with the receiver window of the node B 110. The
node B 110 sends the appropriate timing-control commands to the UEs
120 in the downlink, commanding the UEs 120 to adapt respective
transmit timing. For hybrid automatic repeat request (HARQ), the
node B 120 may request retransmissions of incorrectly received data
packets.
The 3.9-generation mobile telephone technology provides a digital
mobile phone system that is based on 3G but with expanded
capabilities close to the expectations of 4G. Feasibility and
standardization are being studied with the objective of achieving a
smooth transitional link between the current 3G and future 4G.
FIG. 3 illustrates a method 300 for sounding reference signal
frequency hopping pattern and arrangement. In step 310, information
about the RBs in which the SRS transmission may not be allowed
(i.e., PUCCH region or PUCCH-resource-size) is broadcasted. Then,
in step 315, the SRS frequency hopping position may be formed
according to a hopping pattern, and in step 320, the SRS may be
truncated in the case when SRS overlaps the bandwidth not
supporting the SRS transmission. As described below, the UE 120 may
perform the truncation autonomously without additional UE 120
specific signalling. In particular, the SRS may be truncated
towards the maximum allowed SRS BW in step 330. Continuing with
method 300, the outermost SRS signals may be truncated in step 340
so that the truncation impacts neither one of the configured SRS BW
nor the applied tree based SRS frequency band assignment.
FIG. 6 illustrates an exemplary SRS frequency position
configuration 600 with tree structure. In particular, the
frequency-domain starting position of (non-frequency hopping) SRS,
k.sub.0, may be given in sub-carries and may be defined by
'.times..times..times. ##EQU00001## where k'.sub.0 is an offset (in
sub-carriers) related, e.g., to the PUCCH region and the used RPF
comb, L.sub.SRS is the assignment tree layer depth in the SRS
position assignment, corresponding to the assigned SRS bandwidth,
(L.sub.SRS can also be seen as the number of the assigned SRS
bandwidth value) B.sub.l is the SRS bandwidth (in subcarriers) on
tree layer l (i.e. B.sub.l=RPF.times.the length of the SRS sequence
on layer l) and n.sub.l is the SRS frequency position assignment
index on tree layer l.
FIG. 7A illustrates an exemplary SRS frequency hopping pattern 700
utilizes a tree assignment for SRS frequency allocation and
supports multiple frequency band branches per layer. The SRS
frequency hopping pattern 700 further provides consecutive SRS
signals on widely separated frequency allocations, thus, maximizing
frequency diversity in consecutive channel quality indicator (CQI)
measurements. Moreover, as described below, the SRS frequency
hopping pattern 700 further prevents frequency hopping SRS from
puncturing the PUCCH and the persistent PUSCH regions.
As described above, the LTE standards indicate that that the SRS
should not puncture PUCCH region. The condition may also be true
for the PUSCH region of persistent allocations. These condition
should be preserved when the PUCCH and/or the persistent PUSCH
regions dynamically varies. To better ensure this desired outcome,
some of the embodiments define SRS frequency hopping pattern
depending on the handling of the dynamic PUCCH region. For example,
at a change of PUCCH region, the SRS transmissions impacted may be
reconfigured.
Information on current PUCCH RBs (or more exactly, on RBs not
allowed for SRS transmission) is broadcasted and UEs will modify
their SRS transmissions as illustrated in FIG. 3. The drawback is
that occasionally when a narrow SRS transmission hops into PUCCH
region, it is dropped. In other words, there may be instances in
the hopping pattern when SRS may be not transmitted.
However, the frequency-domain starting position for hopping SRS can
be defined with the same equation as for the SRS without frequency
hopping. Then, the proposed frequency hopping pattern can be
defined in terms of n.sub.l for tree layers 1 and above:
n.sub.l=F.sub.l,t+n.sub.l,orig mod N.sub.l (Eq. 2) where:
n.sub.l,orig is the reference value of allocation index for tree
layer l. In other words, it gives the allocation index value for a
common reference frame & subframe number+subframe offset from
dedicated RRC signaling,
.times..times..times..times..times.'.times..times.''.times..times.'.times-
..times..times..times.'.times..times.'.times.'.times..times.'.times..times-
..times..times..times..times..times. ##EQU00002##
.times.'.times..times.'.times..times..times..times..times..times..times.
##EQU00003## where N.sub.l is the number new branches per a branch
on the assignment tree layer l. For example, on an OVSF code tree,
N.sub.l=2. t is the time index for the SRS, and is relative on
common reference frame & subframe number and it is function of
current frame number, subframe number, SRS subframe offset and SRS
period. Essentially it is a running index of SRS occurrences
relative to a common time reference, obtaining values {0, 1, 2, . .
. }. For example, t may be given, e.g, as t=[10.times.(frame
number-reference frame number)+subframe number-reference subframe
number-subframe offset]/SRS period.
In one embodiment, F.sub.l,t can be simplified as indicated
below:
.times..times..times..times..times..times..times..times..times..times..ti-
mes..times..times..times..times..times..times..times. ##EQU00004##
F.sub.l,t=.left brkt-bot.N.sub.l/2.right brkt-bot..left
brkt-bot.t/2.sup.l-1.right brkt-bot. (Eq. 6) if N.sub.l odd
FIG. 8 illustrates a method 800 for forming a hopping SRS. After
calculation of SRS position, UE 120 checks if SRS overlaps the
bandwidth not supporting the SRS transmission (i.e., current PUCCH
region broadcasted by eNB) in step 810. Typically, UE 120 may
perform the truncation autonomously without additional UE 120
specific signalling. The length of the SRS hopping pattern is given
by number of branches on the tree layer corresponding to the
allocated SRS bandwidth as given below in equation 7.
.PI..sub.l=0.sup.L.sup.SRSN.sub.l. (Eq. 7) Alternatively, frequency
hopping may be applied only to some tree layers. As an example,
frequency hopping may be applied to tree layers l.sub.min and but
may not be applied to tree layers from 0 to l.sub.min-1. As a
result, the proposed frequency hopping pattern can be defined by
(Eq. 1) where: F.sub.l,t=0 (Eq. 8) if l<l.sub.min; If l is equal
to or larger than l.sub.min,
.times..times..times..times.'.times..times.''.times..times.'.times..times-
..times.'.times..times.'.times.'.times..times.'.times.
##EQU00005##
.times.'.times..times.'.times..times..times..times..times..times..times.
##EQU00006## Differing from previous notation,
N.sub.l.sub.min.sub.-1=1 in (Eq. 9) and (Eq. 10) regardless of the
number of new branches on tree layer l.sub.min-1.
Continuing with FIG. 8, if the SRS overlaps, SRS may be truncated
towards the maximum allowed SRS BW in step 820. For example, FIG.
7B illustrates an exemplary SRS arrangement 750 with dynamically
changing PUCCH region, in which the SRS has been truncated to
adjust for the PUCCH region. If truncation is not possible, SRS
transmission is dropped in step 830.
Alternatively, eNB 110 may facilitate for PUCCH region changes by
broadcasting the SRS tree structure parameters (e.g. number of
layers, N.sub.l, and associated SRS bandwidths). When PUCCH region
or, alternatively, allowed SRS region changes, the broadcasted SRS
tree structure parameters are changed. In another embodiment, at
the change of broadcasted SRS tree structure parameters, the
existing SRS allocations are autonomously mapped in UE 120 and eNB
110 onto allocations on the current SRS tree according to
predefined allocation re-mapping rules. The number of SRS
allocations may be reduced in the SRS tree reconfiguration. In that
case, certain UEs 120 identified by the predefined allocation
re-mapping rules will autonomously stop their SRS transmissions
until they receive new UE 120 specific SRS configuration via higher
layer signaling. The hopping pattern is always defined according
the currently broadcasted SRS tree and, thus, covering the whole
SRS region currently allowed. This embodiment allows for
reconfiguration of SRS tree with minimal UE 120 specific signaling.
It should be appreciated that the presented SRS allocation
re-mapping can be applied for SRS allocations with and without
frequency hopping.
As a result, the hopping SRS forming method 800 illustrated in FIG.
8 may utilize a tree assignment for SRS frequency allocation and
may support multiple frequency band branches per tree layer. Also,
the hopping SRS forming method 800 illustrated in FIG. 8 provides
consecutive SRS signals on widely separated frequency allocations,
thus, maximizing frequency diversity in consecutive CQI
measurements. Furthermore, the hopping SRS forming method 800
illustrated in FIG. 8 may prevent frequency hopping SRS from
puncturing the PUCCH (persistent PUSCH) region. The hopping SRS
forming method 800 illustrated in FIG. 8 may further allow
minimization of the signalling burden related to frequency hopping
SRS: frequency hopping can be made cell-specific parameter which
only requires one bit from the system information block (SIB)
message.
It should be appreciated that the SRS may be scheduled with or
without frequency hopping. For example, referring to FIG. 1, the
selection between frequency hopping and non-hopping SRS may be
specific to a cell 101 and is then broadcasted to all of the UEs
120 within the cell 101. Alternatively, the hopping/non-hopping
selection may be specific to each UE 120, and may be configured
with dedicated radio resource controller (RRC) 111. The separation
of frequency hopping and non-hopping SRS is then implemented at the
node B 110 (or enhanced node B, eNB). For example, the hopping and
non-hopping SRS can be separated with a repetition factor (RPF)
comb or with subframe offsets.
For example, as illustrated in FIG. 9, an exemplary transmission
block 900 includes frequency hopping SRS and non-hopping SRS that
are multiplexed into same SRS symbol (or SC-FDMA symbol) when the
period of non-hopping SRS is longer than the one of hopping
SRS.
With frequency hopping SRS, multiple SRS periods may potentially
cause additional restrictions on the SRS configurations. Typically,
all frequency hopping SRS preferably have the same period on each
particular SRS symbol and comb combination. For example, 2 ms and 5
ms periods can be used simultaneously for frequency hopping SRS in
a cell if they are allocated on different combs.
Similarly, configuration of a one shot SRS is relatively
straightforward by adapting previous techniques, whereby the SRS
can be configured either with or without frequency hopping.
Referring again to FIG. 1, a cell may include multiple antennas 112
to provide antenna diversity. Transmission antenna diversity can be
a closed loop transmission, wherein up-link channel information is
fed back from a mobile station. With closed loop antenna selection,
the transmitting antennas typically alternate between consecutive
SRS transmissions. Similarly, the transmitting antennas would also
typically alternate in the case of frequency hopping SRS. However,
in order to transmit the same frequency from both antennas,
consecutive SRSs are preferably transmitted from the same antenna
only once in the same frequency hopping period. For example, the
first SRS of the hopping period may be transmitted from the same
antenna as the last SRS of the hopping period.
Referring now to FIG. 4, a process flow diagram 400 in accordance
with some embodiments is now presented. In particular, the flow
diagram 400 illustrates the interaction between a node B 110 and a
UE 120. The UE 120 may receive RRC signaling 440, which is SRS
configuration signaling. The UE 120 uses data from the RRC
signaling 440 to create an uplink message 460 to the node B 110
including a SRS allocated as disclosed herein. The node B 110 may
then respond with the UL scheduling grant signaled via DL 470, such
as a PDCCH, in reply to the request by the UE 120 in the uplink
message 460. In response to the UL scheduling grant in the UL
message 460, the UE 120 may forward to the node B 110 UL data
transmission 480 for which the link adaptation/scheduling decisions
have been performed based on transmitted SRS.
Referring now to FIG. 2, a UE 120 in accordance with certain
embodiments is now provided. The UE 120 includes a processor 210
configured to access stored data in a storage device 230 to form an
uplink message that includes the SRS. The storage device 230 may
store, for example, data related to the DM RS and SRS signals, a
desired maximum cyclic shift separation, and details to support a
tree-based band assignment. Similarly, the storage device 230 may
store data as needed for the processor 220 to determine sufficient
bandwidth to reserve for PUCCH and Persistent PUSCH and the
corresponding desired DFT and RPF sizes for the SRS band and
bandwidth allocation. This information stored in the storage 230
may be provided, for example, by a user interface 210 or is
received from an outside source via a receiver 250. The processor
220 may then form the uplink message that includes the SRS on
allocated band with allocated bandwidth and forward this uplink
message to a transmitter 240 for transmission to an outside device,
such as a node B.
As described above, the SRS transmission should not "puncture" the
PUCCH region or otherwise attempt to transmit over a RB reserved
for the PUCCH. Similarly, it is possible to configure the PUCCH
bandwidth-parameter in such a way that the SRS is not overlapping
with the (majority of) persistent PUSCH allocations. Accordingly,
one embodiment relates to fulfilling this requirement that the SRS
transmission should not puncture the PUCCH regions even in cases in
which the PUCCH bandwidth (BW), including persistent PUSCH, varies
dynamically.
As depicted in FIG. 10, each of the UE 120 in a cell may include a
processor 1011, memory 1012, and input and output devices
1013-1014. The source 1010 may further include software 1015 and
related hardware 1016 to perform the functions related to forming
and transmitting an appropriate SRS message, as disclosed in the
some embodiments. For example, the source 120 may receive and store
configuration criteria for the SRS to be transmitted, access the
memory and form the SRS messages using the stored parameters, and
then remove the stored parameters from memory after receiving
confirmation that the transmitted SRS message was received by the
base station 110. Thus, the processing of the SRS messages to be
transmitted may be performed, as needed by circuitry in the
hardware 1016 or software 1015.
Likewise, the Node B 110 may include a processor 1021, memory 1022,
and input and output devices 1023-1024. The base station (e.g. node
110) may further include software 1025 and related hardware 1026
for performing the functions related to the receiving and decoding
of the transmitted SRS signals, as disclosed in the present
application. Also, the Node B 110 may include logic in the hardware
1026 or the software 1025 to form a configuration message defining
the criteria for the SRS message for a particular node B 110 or for
all of the node Bs 110 in a cell.
A computer program embodied on a computer-readable medium, a
compute-readable medium encoded with a computer program, or similar
language may be embodied as a tangible data storage device storing
computer software programs configured to control a processor,
digital processing device, central processing unit (CPU), or the
like, to perform one or more operations or execute one or more
software instructions. A tangible data storage device may be
embodied as a volatile memory device or a nonvolatile memory
device, and/or a combination of a volatile memory device and a
nonvolatile memory device. Accordingly, some of the embodiments
provide for a computer-readable medium encoded with a computer
program, where the computer program is configured to perform
operations.
It should be noted that reference throughout this specification to
features, advantages, or similar language does not imply that all
of the features and advantages that may be realized with the
embodiments described above should be or are in any single
embodiment. Rather, language referring to the features and
advantages is understood to mean that a specific feature,
advantage, or characteristic described in connection with an
embodiment is included in at least one embodiment described above.
Thus, discussion of the features and advantages, and similar
language, throughout this specification may, but do not
necessarily, refer to the same embodiment.
Furthermore, the described features, advantages, and
characteristics of the invention may be combined in any suitable
manner in one or more embodiments. One skilled in the relevant art
will recognize that the invention can be practiced without one or
more of the specific features or advantages of a particular
embodiment. In other instances, additional features and advantages
may be recognized in certain embodiments that may not be present in
all embodiments.
* * * * *
References