U.S. patent application number 15/283235 was filed with the patent office on 2017-01-26 for method and apparatus that facilitates interference reduction in wireless systems.
This patent application is currently assigned to QUALCOMM Incorporated. The applicant listed for this patent is Peter Gaal, Ravi Palanki. Invention is credited to Peter Gaal, Ravi Palanki.
Application Number | 20170026977 15/283235 |
Document ID | / |
Family ID | 42733742 |
Filed Date | 2017-01-26 |
United States Patent
Application |
20170026977 |
Kind Code |
A1 |
Gaal; Peter ; et
al. |
January 26, 2017 |
METHOD AND APPARATUS THAT FACILITATES INTERFERENCE REDUCTION IN
WIRELESS SYSTEMS
Abstract
Techniques for managing interference in a wireless communication
system are disclosed. In one aspect, one or more frequencies are
identified, where transmission by a user equipment (UE) on the one
or more frequencies would interfere with reception at the UE. An
indication is transmitted to a base station which comprises
frequency location information based on the one or more
frequencies. Additionally, the UE can receive an assignment of
frequency resources from the based station based on the
indication.
Inventors: |
Gaal; Peter; (San Diego,
CA) ; Palanki; Ravi; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gaal; Peter
Palanki; Ravi |
San Diego
San Diego |
CA
CA |
US
US |
|
|
Assignee: |
QUALCOMM Incorporated
San Diego
CA
|
Family ID: |
42733742 |
Appl. No.: |
15/283235 |
Filed: |
September 30, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12824123 |
Jun 25, 2010 |
9509543 |
|
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15283235 |
|
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61220983 |
Jun 26, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 72/0453 20130101;
H04L 25/0206 20130101; H04W 72/082 20130101; H04L 27/2647 20130101;
H04J 11/0023 20130101; H04L 25/023 20130101 |
International
Class: |
H04W 72/08 20060101
H04W072/08; H04W 72/04 20060101 H04W072/04 |
Claims
1. A method of wireless communication, comprising: identifying one
or more frequencies on which transmission by a user equipment (UE)
causes interference with reception at the UE; and transmitting an
indication to a base station, the indication comprising frequency
location information based on the one or more frequencies.
2. The method of claim 1, further comprising: receiving an
assignment of frequency resources from the base station based on
the indication.
3. The method of claim 1, wherein the interference comprises an
intermodulation product of the one or more frequencies.
4. The method of claim 3, further comprising: determining whether
the intermodulation product has a frequency location within a
frequency range of the UE reception.
5. The method of claim 4, further comprising: identifying multiple
distinct frequency intervals that collectively contain the one or
more frequencies; and calculating a frequency interval
corresponding to the intermodulation product based on the multiple
distinct frequency intervals.
6. A user equipment (UE), comprising: a transmitter configured to
transmit wireless signals; a receiver configured to receive
wireless signals; and a processor configured to: identify one or
more frequencies on which transmission by the transmitter causes
interference with reception at the receiver; and transmit, via the
transmitter, an indication to a base station, the indication
comprising frequency location information based on the one or more
frequencies.
7. The UE of claim 6, wherein the processor is further configured
to: receive, via the receiver, an assignment of frequency resources
from the base station based on the indication.
8. The UE of claim 6, wherein the interference comprises an
intermodulation product of the one or more frequencies.
9. The UE of claim 8, wherein the processor is further configured
to: determine whether the intermodulation product has a frequency
location within a frequency range of the reception at the
receiver.
10. The UE of claim 9, wherein the processor is further configured
to: identify multiple distinct frequency intervals that
collectively contain the one or more frequencies; and calculate a
frequency interval corresponding to the intermodulation product
based on the multiple distinct frequency intervals.
11. An apparatus of wireless communications, comprising: means for
identifying one or more frequencies on which transmission by a user
equipment (UE) causes interference with reception at the UE; and
means for transmitting an indication to a base station, the
indication comprising frequency location information based on the
one or more frequencies.
12. The apparatus of claim 11, further comprising: means for
receiving an assignment of frequency resources from the base
station based on the indication.
13. The apparatus of claim 11, wherein the interference comprises
an intermodulation product of the one or more frequencies.
14. The apparatus of claim 13, further comprising: means for
determining whether the intermodulation product has a frequency
location within a frequency range of the UE reception.
15. A non-transitory computer-readable medium having instructions
stored thereon, the instructions comprising codes executable to
cause a user equipment (UE) to: identify one or more frequencies on
which transmission by the UE causes interference with reception at
the UE; and transmit an indication to a base station, the
indication comprising frequency location information based on the
one or more frequencies.
16. The medium of claim 15, further comprising codes to: receive an
assignment of frequency resources from the base station based on
the indication.
17. The medium of claim 15, wherein the interference comprises an
intermodulation product of the one or more frequencies.
18. The medium of claim 17, further comprising codes to: determine
whether the intermodulation product has a frequency location within
a frequency range of the UE reception.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
Utility application Ser. No. 12/824,123, entitled "METHOD AND
APPARATUS THAT FACILITATES INTERFERENCE REDUCTION IN WIRELESS
SYSTEMS" and filed on Jun. 25, 2010, which claims the benefit of
U.S. Provisional Patent Application Ser. No. 61/220,983 entitled
"METHOD AND APPARATUS FACILITATING INTERFERENCE MITIGATION FOR
NON-CONTIGUOUS TRANSMISSIONS," which was filed Jun. 26, 2009. The
aforementioned applications are herein incorporated by reference in
entirety.
BACKGROUND
[0002] I. Field
[0003] The following description relates generally to wireless
communications, and more particularly to methods and apparatuses
that facilitate interference reduction.
[0004] II. Background
[0005] Wireless communication systems are widely deployed to
provide various types of communication content such as voice, data,
and so on. These systems may be multiple-access systems capable of
supporting communication with multiple users by sharing the
available system resources (e.g., bandwidth and transmit power).
Examples of such multiple-access systems include code division
multiple access (CDMA) systems, time division multiple access
(TDMA) systems, frequency division multiple access (FDMA) systems,
3GPP Long Term Evolution (LTE) systems, and orthogonal frequency
division multiple access (OFDMA) systems.
[0006] Generally, a wireless multiple-access communication system
can simultaneously support communication for multiple wireless
terminals. Each terminal communicates with one or more base
stations via transmissions on forward and reverse links. The
forward link (or downlink) refers to the communication link from
the base stations to the terminals, and the reverse link (or
uplink) refers to the communication link from the terminals to the
base stations. This communication link may be established via a
single-in-single-out, multiple-in-signal-out or a
multiple-in-multiple-out (MIMO) system.
[0007] A MIMO system employs multiple (N.sub.T) transmit antennas
and multiple (N.sub.R) receive antennas for data transmission. A
MIMO channel formed by the N.sub.T transmit and N.sub.R receive
antennas may be decomposed into N.sub.S independent channels, which
are also referred to as spatial channels, where N
.sub.S.ltoreq.min{N.sub.T, N.sub.R}. Each of the N.sub.S
independent channels corresponds to a dimension. The MIMO system
can provide improved performance (e.g., higher throughput and/or
greater reliability) if the additional dimensionalities created by
the multiple transmit and receive antennas are utilized.
SUMMARY
[0008] The following presents a simplified summary of one or more
embodiments in order to provide a basic understanding of such
embodiments. This summary is not an extensive overview of all
contemplated embodiments, and is intended to neither identify key
or critical elements of all embodiments nor delineate the scope of
any or all embodiments. Its purpose is to present concepts of one
or more embodiments in a simplified form as a prelude to the more
detailed description that is presented later.
[0009] In accordance with one or more embodiments and corresponding
disclosure thereof, various aspects are described in connection
with reducing interference in wireless communication systems. In
one aspect, methods and computer program products are disclosed for
facilitating wireless communications. Such embodiments include
determining an estimated interference associated with a data
transmission over a plurality of subcarriers on an uplink, and
processing data received over at least one subcarrier on a downlink
based at least in part on the estimated interference.
[0010] Another aspect relates to an apparatus for wireless
communications. The apparatus includes a processor configured to
execute computer executable components stored in a memory. The
computer executable components include an estimation component and
a signal processing component. The estimation component is
configured to determine an estimated interference associated with a
data transmission over a plurality of subcarriers on an uplink. The
signal processing component is configured to process data received
over at least one subcarrier on a downlink based at least in part
on the estimated interference.
[0011] Additional aspects relate to an apparatus that includes
means for determining an estimated interference associated with a
data transmission over a plurality of subcarriers on an uplink. The
apparatus also includes means for processing data received over at
least one subcarrier on a downlink based at least in part on the
estimated interference.
[0012] According to another aspect, methods and computer program
products are disclosed for facilitating wireless communications at
a base station. Such embodiments include determining an estimated
interference associated with a data transmission by a wireless
device over a plurality of subcarriers, and assigning resources to
the wireless device based at least in part on the estimated
interference.
[0013] Yet another aspect relates to an apparatus for wireless
communications. The apparatus includes a processor configured to
execute computer executable components stored in a memory. The
computer executable components include an estimation component and
an assigning component. The estimation component is configured to
determine an estimated interference associated with a data
transmission by a wireless device over a plurality of subcarriers.
The assigning component is configured to assign resources to the
wireless device based at least in part on the estimated
interference.
[0014] Additional aspects relate to an apparatus that includes
means for determining an estimated interference associated with a
data transmission by a wireless device over a plurality of
subcarriers. The apparatus also includes means for assigning
resources to the wireless device based at least in part on the
estimated interference.
[0015] To the accomplishment of the foregoing and related ends, the
one or more embodiments comprise the features hereinafter fully
described and particularly pointed out in the claims. The following
description and the annexed drawings set forth in detail certain
illustrative aspects of the one or more embodiments. These aspects
are indicative, however, of but a few of the various ways in which
the principles of various embodiments can be employed and the
described embodiments are intended to include all such aspects and
their equivalents.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 shows an exemplary wireless communication system.
[0017] FIG. 2 illustrates aspects of an exemplary wireless network
environment.
[0018] FIG. 3 depicts additional aspects of a wireless
communication system.
[0019] FIG. 4 shows an exemplary user equipment and network
entity.
[0020] FIG. 5 is a block diagram of an exemplary interference
management unit.
[0021] FIG. 6 shows a first exemplary coupling of electrical
components that effectuate interference reduction in a wireless
communication system.
[0022] FIG. 7 shows a second exemplary coupling of electrical
components that effectuate interference reduction in a wireless
communication system.
[0023] FIG. 8 shows an example methodology for reducing
interference.
[0024] FIG. 9 illustrates an exemplary communication system having
multiple wireless access technologies.
[0025] FIG. 10 shows an exemplary communication system having
multiple cells.
[0026] FIG. 11 is a block diagram of an exemplary base station.
[0027] FIG. 12 is a block diagram of an exemplary wireless
terminal.
DETAILED DESCRIPTION
[0028] Various embodiments are now described with reference to the
drawings, wherein like reference numerals are used to refer to like
elements throughout. In the following description, for purposes of
explanation, numerous specific details are set forth in order to
provide a thorough understanding of one or more embodiments. It may
be evident, however, that such embodiment(s) may be practiced
without these specific details. In other instances, well-known
structures and devices are shown in block diagram form in order to
facilitate describing one or more embodiments.
[0029] Techniques for reducing interference in wireless systems are
described herein. Among other things, transmitting signals in the
presence of interference from intermodulation and/or harmonic
products of received signals is discussed. In a particular
embodiment, interference caused by the intermodulation and/or
harmonic products are estimated, wherein the estimated interference
is then used to zero out a set of log-likelihood ratio (LLR)
metrics. In another embodiment, aspects are disclosed which avoid
transmitting signals via subcarriers which may contribute to
interference to received signals from intermodulation and/or
harmonic products (hereinafter collectively referred to as
"intermodulation products").
[0030] The techniques described herein can be used for various
wireless communication systems such as code division multiple
access (CDMA), time division multiple access (TDMA), frequency
division multiple access (FDMA), orthogonal frequency division
multiple access (OFDMA), single carrier-frequency division multiple
access (SC-FDMA), High Speed Packet Access (HSPA), and other
systems. The terms "system" and "network" are often used
interchangeably. A CDMA system can implement a radio technology
such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc.
UTRA includes Wideband-CDMA (W-CDMA) and other variants of CDMA.
CDMA2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA system
can implement a radio technology such as Global System for Mobile
Communications (GSM). An OFDMA system can implement a radio
technology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband
(UMB), IEEE 802.11 (Wi-Fi.TM.), IEEE 802.16 (WiMAX), IEEE 802.20,
Flash-OFDM, etc. UTRA and E-UTRA are part of Universal Mobile
Telecommunication System (UMTS). 3GPP Long Term Evolution (LTE) is
a release of UMTS that uses E-UTRA, which employs OFDMA on the
downlink and SC-FDMA on the uplink.
[0031] Single carrier frequency division multiple access (SC-FDMA)
utilizes single carrier modulation and frequency domain
equalization. SC-FDMA has similar performance and essentially the
same overall complexity as those of an OFDMA system. A SC-FDMA
signal has lower peak-to-average power ratio (PAPR) because of its
inherent single carrier structure. SC-FDMA can be used, for
instance, in uplink communications where lower PAPR greatly
benefits access terminals in terms of transmit power efficiency.
Accordingly, SC-FDMA can be implemented as an uplink multiple
access scheme in 3GPP Long Term Evolution (LTE) or Evolved
UTRA.
[0032] High speed packet access (HSPA) can include high speed
downlink packet access (HSDPA) technology and high speed uplink
packet access (HSUPA) or enhanced uplink (EUL) technology and can
also include HSPA+ technology. HSDPA, HSUPA and HSPA+ are part of
the Third Generation Partnership Project (3GPP) specifications
Release 5, Release 6, and Release 7, respectively.
[0033] High speed downlink packet access (HSDPA) optimizes data
transmission from the network to the user equipment (UE). As used
herein, transmission from the network to the user equipment UE can
be referred to as the "downlink" (DL). Transmission methods can
allow data rates of several Mbits/s. High speed downlink packet
access (HSDPA) can increase the capacity of mobile radio networks.
High speed uplink packet access (HSUPA) can optimize data
transmission from the terminal to the network. As used herein,
transmissions from the terminal to the network can be referred to
as the "uplink" (UL). Uplink data transmission methods can allow
data rates of several Mbit/s. HSPA+ provides even further
improvements both in the uplink and downlink as specified in
Release 7 of the 3GPP specification. High speed packet access
(HSPA) methods typically allow for faster interactions between the
downlink and the uplink in data services transmitting large volumes
of data, for instance Voice over IP (VoIP), videoconferencing and
mobile office applications
[0034] Fast data transmission protocols such as hybrid automatic
repeat request, (HARQ) can be used on the uplink and downlink. Such
protocols allow a recipient to automatically request retransmission
of a packet that might have been received in error.
[0035] Various embodiments are described herein in connection with
an access terminal. An access terminal can also be called a system,
subscriber unit, subscriber station, mobile station, mobile, remote
station, remote terminal, mobile device, user terminal, terminal,
wireless communication device, user agent, user device, or user
equipment (UE). An access terminal can be a cellular telephone, a
cordless telephone, a Session Initiation Protocol (SIP) phone, a
wireless local loop (WLL) station, a personal digital assistant
(PDA), a handheld device having wireless connection capability,
computing device, or other processing device connected to a
wireless modem. Moreover, various embodiments are described herein
in connection with a base station. A base station can be utilized
for communicating with access terminal(s) and can also be referred
to as an access point, Node B, Evolved Node B (eNodeB), access
point base station, or some other terminology.
[0036] Referring now to the drawings, FIG. 1 illustrates a wireless
communication system in accordance with various embodiments
presented herein. System 100 comprises a base station 102 that can
include multiple antenna groups. For example, one antenna group can
include antennas 104 and 106, another group can comprise antennas
108 and 110, and an additional group can include antennas 112 and
114. Two antennas are illustrated for each antenna group; however,
more or fewer antennas can be utilized for each group. Base station
102 can additionally include a transmitter chain and a receiver
chain, each of which can in turn comprise a plurality of components
associated with signal transmission and reception (e.g.,
processors, modulators, multiplexers, demodulators, demultiplexers,
antennas, etc.), as will be appreciated by one skilled in the
art.
[0037] Base station 102 can communicate with one or more access
terminals such as access terminal 116 and access terminal 122;
however, it is to be appreciated that base station 102 can
communicate with substantially any number of access terminals
similar to access terminals 116 and 122. Access terminals 116 and
122 can be, for example, cellular phones, smart phones, laptops,
handheld communication devices, handheld computing devices,
satellite radios, global positioning systems, PDAs, and/or any
other suitable device for communicating over wireless communication
system 100. As depicted, access terminal 116 is in communication
with antennas 112 and 114, where antennas 112 and 114 transmit
information to access terminal 116 over a forward link 118 and
receive information from access terminal 116 over a reverse link
120. Moreover, access terminal 122 is in communication with
antennas 104 and 106, where antennas 104 and 106 transmit
information to access terminal 122 over a forward link 124 and
receive information from access terminal 122 over a reverse link
126. In a frequency division duplex (FDD) system, forward link 118
can utilize a different frequency band than that used by reverse
link 120, and forward link 124 can employ a different frequency
band than that employed by reverse link 126, for example. Further,
in a time division duplex (TDD) system, forward link 118 and
reverse link 120 can utilize a common frequency band and forward
link 124 and reverse link 126 can utilize a common frequency
band.
[0038] Each group of antennas and/or the area in which they are
designated to communicate can be referred to as a sector of base
station 102. For example, antenna groups can be designed to
communicate to access terminals in a sector of the areas covered by
base station 102. In communication over forward links 118 and 124,
the transmitting antennas of base station 102 can utilize
beamforming to improve signal-to-noise ratio of forward links 118
and 124 for access terminals 116 and 122. Using beamforming to
transmit to access terminals scattered randomly through an
associated coverage can also reduce interference to access
terminals in neighboring cells.
[0039] FIG. 2 shows an exemplary wireless communication system 200
having a base station 210 and an access terminal 250. For the sake
of brevity, only one base station 210 and one access terminal 250
are shown. However, it will be appreciated that system 200 can
include more than one base station and/or more than one access
terminal, wherein additional base stations and/or access terminals
can be substantially similar or different from the exemplary base
station 210 and access terminal 250 described below. In addition,
it is to be appreciated that base station 210 and/or access
terminal 250 can employ the systems and/or methods described herein
to facilitate wireless communication there between.
[0040] At base station 210, traffic data for a number of data
streams is provided from a data source 212 to a transmit (TX) data
processor 214. According to an example, each data stream can be
transmitted over a respective antenna. TX data processor 214
formats, codes, and interleaves the traffic data stream based on a
particular coding scheme selected for that data stream to provide
coded data.
[0041] The coded data for each data stream can be multiplexed with
pilot data using orthogonal frequency division multiplexing (OFDM)
techniques. Additionally or alternatively, the pilot symbols can be
frequency division multiplexed (FDM), time division multiplexed
(TDM), or code division multiplexed (CDM). The pilot data is
typically a known data pattern that is processed in a known manner
and can be used at access terminal 250 to estimate channel
response. The multiplexed pilot and coded data for each data stream
can be modulated (e.g., symbol mapped) based on a particular
modulation scheme (e.g., binary phase-shift keying (BPSK),
quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK),
M-quadrature amplitude modulation (M-QAM), etc.) selected for that
data stream to provide modulation symbols. The data rate, coding,
and modulation for each data stream can be determined by
instructions performed or provided by processor 230.
[0042] The modulation symbols for the data streams can be provided
to a TX MIMO processor 220, which can further process the
modulation symbols (e.g., for (OFDM). TX MIMO processor 220 then
provides N.sub.T modulation symbol streams to N.sub.T transmitters
(TMTR) 222a through 222t. In various embodiments, TX MIMO processor
220 applies beamforming weights to the symbols of the data streams
and to the antenna from which the symbol is being transmitted.
[0043] Each transmitter 222 receives and processes a respective
symbol stream to provide one or more analog signals, and further
conditions (e.g., amplifies, filters, and upconverts) the analog
signals to provide a modulated signal suitable for transmission
over the MIMO channel. Further, N.sub.T modulated signals from
transmitters 222a through 222t are transmitted from N.sub.T
antennas 224a through 224t, respectively.
[0044] At access terminal 250, the transmitted modulated signals
are received by N.sub.R antennas 252a through 252r and the received
signal from each antenna 252 is provided to a respective receiver
(RCVR) 254a through 254r. Each receiver 254 conditions (e.g.,
filters, amplifies, and downconverts) a respective signal,
digitizes the conditioned signal to provide samples, and further
processes the samples to provide a corresponding "received" symbol
stream.
[0045] An RX data processor 260 can receive and process the N.sub.R
received symbol streams from NR receivers 254 based on a particular
receiver processing technique to provide NT "detected" symbol
streams. RX data processor 260 can demodulate, deinterleave, and
decode each detected symbol stream to recover the traffic data for
the data stream. The processing by RX data processor 260 is
complementary to that performed by TX MIMO processor 220 and TX
data processor 214 at base station 210.
[0046] A processor 270 can periodically determine which available
technology to utilize as discussed above. Further, processor 270
can formulate a reverse link message comprising a matrix index
portion and a rank value portion.
[0047] The reverse link message can comprise various types of
information regarding the communication link (e.g., channel state
information (CSI)) and/or the received data stream. The reverse
link message can be processed by a TX data processor 238, which
also receives traffic data for a number of data streams from a data
source 236, modulated by a modulator 280, conditioned by
transmitters 254a through 254r, and transmitted to base station
210.
[0048] At base station 210, the modulated signals from access
terminal 250 are received by antennas 224, conditioned by receivers
222, demodulated by a demodulator 240, and processed by a RX data
processor 242 to extract the reverse link message transmitted by
access terminal 250. Further, processor 230 can process the
extracted message to determine which precoding matrix to use for
determining the beamforming weights.
[0049] Processors 230 and 270 can direct (e.g., control,
coordinate, manage, etc.) operation at base station 210 and access
terminal 250, respectively. Respective processors 230 and 270 can
be associated with memory 232 and 272 that store program codes and
data. Processors 230 and 270 can also perform computations to
derive frequency and impulse response estimates for the uplink and
downlink, respectively.
[0050] Referring next to FIG. 3, an exemplary wireless
communication system 300 configured to support a number of users is
illustrated, in which various disclosed embodiments and aspects may
be implemented. As shown in FIG. 3, by way of example, system 300
provides communication for multiple cells 302, such as, for
example, macro cells 302a-302g, with each cell being serviced by a
corresponding access point (AP) 304 (such as APs 304a-304g). Each
cell may be further divided into one or more sectors (e.g. to serve
one or more frequencies). Various access terminals (ATs) 306,
including ATs 306a-306k, also known interchangeably as user
equipment (UE) or mobile stations, are dispersed throughout the
system. Each AT 306 may communicate with one or more APs 304 on a
forward link (FL) and/or a reverse link (RL) at a given moment,
depending upon whether the AT is active and whether it is in soft
handoff, for example. The wireless communication system 300 may
provide service over a large geographic region, for example, macro
cells 302a-302g may cover a few blocks in a neighborhood.
[0051] ATs 306 can transmit on one or more carrier frequencies
simultaneously. From the standpoint of ATs 306, parallel
transmission on the uplink can include, among other things,
non-contiguous carrier deployments or concurrent data transmission
over multiple wireless access technologies (e.g., cellular, Wi-Fi,
etc.). When an AT 306 is transmitting on frequencies f.sub.1,
f.sub.2, . . . , f.sub.n, intermodulation products are created at
A.sub.1f.sub.1+A.sub.2f.sub.2+ . . . +A.sub.nf.sub.n (e.g.,
locations, frequency locations) where A.sub.1, A.sub.2, . . . ,
A.sub.n are integers, and where A.sub.1+A.sub.2+ . . . +A.sub.n is
the intermodulation order. For example, third order products can be
created at 3f.sub.1 or at 2f.sub.1-f.sub.2. Intermodulation
products are spurious waveforms that are generated due to the
non-linearity of radio frequency (RF) elements such as a power
amplifier in the transmit chain. If only one frequency or frequency
range is involved in generating the spurious waveform, the products
are commonly referred to as harmonics, whereas the products may be
referred to generally as intermodulation products when more than
one frequency is involved. As used herein, the term
"intermodulation products" includes both harmonics and
intermodulation products.
[0052] ATs 306 can receive downlink transmissions in any of the
aforementioned frequency locations. For example, a downlink
subcarrier may be located at 2f.sub.1-f.sub.2. Intermodulation
products associated with parallel data transmission on the uplink
can interfere with and significantly degrade the signal-to-noise
ratio (SINR) of the downlink reception. It is therefore desirable
to mitigate the adverse impact of such intermodulation products on
downlink subcarriers.
[0053] Turning now to FIG. 4, another exemplary wireless
communication system 400 is illustrated. System 400 includes user
equipment 410 (e.g., an access terminal) and network entity 420
(e.g., an access point), wherein user equipment 410 provides
network entity 420 with an uplink communication, and wherein
network entity 420 provides user equipment 410 with a downlink
communication. As shown, user equipment 410 may include an
interference management unit 412. Network entity 420 may also
include an interference management unit 422. Interference
management units 412, 422 facilitate transmitting signals in the
presence of intermodulation or harmonic products of received
signals.
[0054] Consider the case in which f.sub.1 and f.sub.2 represent a
set of subcarriers used for data transmission on an uplink, and in
which the associated intermodulation products Af.sub.1+Bf.sub.2 are
in a downlink bandwidth W centered on a downlink subcarrier
f.sub.DL. [f.sub.DL-W/2, f.sub.DL+W/2]. In this example,
interference due to the intermodulation products can be high at
downlink subcarrier f.sub.DL. If unaccounted for in the decoding of
the downlink, the decoding could fail due to the spurious
log-likelihood ratios (LLRs) generated at this and other
subcarriers affected by intermodulation products.
[0055] Interference management unit 412 and/or interference
management unit 422 can be configured to estimate an interference
to one or more downlink subcarriers from intermodulation products
associated with the uplink data transmission and to compensate for
the effects of such interference. For instance, it is contemplated
that subcarriers can be identified where intermodulation products
will be generated based on known frequency locations of an uplink
data transmission. Interference management unit 412 of UE 410, for
example, may process data received on the affected subcarriers by,
among other things, zeroing log-likelihood ratios for modulation
symbols on those subcarriers On the other hand, interference
management unit 420 of network entity 420 may assign
uplink/downlink resources to UE 410 based on the estimated
interference so as to mitigate the effect of the intermodulation
products.
[0056] Note that it is also possible that neither f.sub.1 nor
f.sub.2 is an intended transmission, but are themselves unwanted
byproducts, such as a carrier leakage, an IQ image, or an
intermodulation product created by a preceding component in the
transmit chain. The location of these byproducts in a frequency may
be predictable, in which case the same method of zeroing the LLRs
or assigning resources can be applied.
[0057] Since there may be a large number of transmitted (uplink)
subcarriers, calculating the locations of all relevant
intermodulation products can be burdensome. Interference management
unit 412 and/or interference management unit 422 can simplify such
calculation by considering continuous occupied frequency intervals.
For example, assume that the transmitted (uplink) subcarriers are
confined in two distinct intervals [f.sub.1,Low . . . f.sub.1,High]
and [f.sub.2,Low . . . f.sub.2,High] also assume that
f.sub.1,High>f.sub.2,Low. In this example, third order
intermodulation products will be located, for example, at
[2f.sub.1,Low-f.sub.2,High . . . 2f.sub.1,High-f.sub.2,Low] and
[2f.sub.2,Low-f.sub.1,High . . . 2f.sub.2,High-f.sub.1,Low] and
also at [2f.sub.1,Low+f.sub.2,Low . . . 2f.sub.1,High+f.sub.2,High]
and [2f.sub.2,Low+f.sub.1,Low . . . 2f.sub.2,High+f.sub.1,High].
This approach is also applicable when at least one of the
transmitted waveforms is not orthogonal frequency-division
multiplexing (OFDM), or is not composed of a set of distinct
carriers, but rather includes a continuum of frequencies (e.g., in
the case of CDMA, or analog signals).
[0058] Additionally or alternatively, the interference management
unit 412 and/or interference management unit 422 can select a set
of uplink carriers such that associated intermodulation products do
not overlap with a received signal. For example, if when both WiFi
and LTE-A are utilized, a WiFi uplink carrier may be selected so
that the intermodulation products or harmonics do not overlap with
a downlink LTE-A carrier.
[0059] It should also be noted that estimating intermodulation
products can be performed by a base station and/or mobile device
within a communication system. In one example, a base station may
make downlink and uplink assignments to a mobile device, and based
on the uplink data transmission, the base station can schedule a
downlink assignment so as to avoid the subcarriers associated with
the intermodulation products. Different mobile devices can be
assigned to different uplink and downlink subcarriers so that
intermodulation products may be avoided for each mobile device,
while making use of the entire uplink and downlink bandwidth. In
another example, the mobile device may indicate to the base station
the locations where the intermodulation products or harmonics may
be expected (e.g. depending on the technologies it is using).
[0060] Referring next to FIG. 5, an exemplary interference
management unit that facilitates interference reduction is
illustrated. As shown, interference management unit 500 may include
processor component 510, memory component 520, reception component
530, transmission component 540, estimation component 550, signal
processing component 560, communication component 570, and
assigning component 580.
[0061] In one aspect, processor component 510 is configured to
execute computer-readable instructions related to performing any of
a plurality of functions. Processor component 510 can be a single
processor or a plurality of processors which analyze information to
be communicated from interference management unit 500 and/or
generate information that is utilized by memory component 520,
reception component 530, transmission component 540, estimation
component 550, signal processing component 560, communication
component 570, and/or assigning component 580. Additionally or
alternatively, processor component 510 may be configured to control
one or more components of interference management unit 500.
[0062] In another aspect, memory component 520 is coupled to
processor component 510 and configured to store computer-readable
instructions executed by processor component 510. Memory component
520 may also be configured to store any of a plurality of other
types of data including generated by any of reception component
530, transmission component 540, estimation component 550, signal
processing component 560, communication component 570, and/or
assigning component 580. Memory component 520 can be configured in
a number of different configurations, including as random access
memory, battery-backed memory, hard disk, magnetic tape, etc.
Various features can also be implemented upon memory component 520,
such as compression and automatic back up (e.g., use of a Redundant
Array of Independent Drives configuration).
[0063] In a first exemplary embodiment, interference management
unit 500 may be configured to compensate signal transmissions
associated with intermodulation products which interfere with
received signals. Within such embodiment, reception component 530
may be configured to determine at least one subcarrier on a first
frequency, whereas transmission component 540 may be configured to
identify at least two subcarriers on a second frequency. For this
embodiment, a signal reception is facilitated by the at least one
subcarrier, whereas a signal transmission is facilitated by the at
least two subcarriers. In an aspect, the signal reception is
facilitated by a first air interface technology, whereas the signal
transmission is facilitated by a second air interface technology
different than the first air interface technology. It is also,
however, contemplated that the signal reception and the signal
transmission are facilitated by a common air interface
technology.
[0064] In a further aspect, signal transmissions may be facilitated
by either a set of distinct carriers and/or a continuum of
frequencies. For instance, with respect to transmissions via a set
of distinct carriers, the signal transmission may be an orthogonal
frequency-division multiplexing (OFDM) transmission. On the other
hand, for transmissions via a continuum of frequencies, the signal
transmission may be a code division multiple access (CDMA)
transmission or an analog transmission, for example.
[0065] As illustrated, interference management unit 500 may also
include estimation component 550 and signal processing component
560. Estimation component 550 may be configured to determine an
estimated interference to at least one subcarrier associated with
at least one of an intermodulation product, whereas signal
processing component 560 can be configured to process the at least
one subcarrier based on the estimated interference. Here, it should
be noted that signal processing component 560 may be configured to
utilize the estimated interference to process the at least one
sub-carrier in any of a plurality of ways. For instance, signal
processing component 560 may be configured to demodulate the at
least one subcarrier, as well as to decode the at least one
subcarrier. However, signal processing component 560 may also be
configured to reset a set of log-likelihood ratio metrics
associated with the at least one subcarrier. For example, signal
processing component 560 may be configured to set the set of
log-likelihood ratio metrics to zero.
[0066] Interference management unit 500 may be configured to avoid
transmitting signals via subcarriers which reduce interference to
received signals from intermodulation products. In one aspect,
reception component 530 may be configured to determine at least one
subcarrier on a first frequency, whereas transmission component 540
can be configured to perform a selection of at least two
subcarriers on a second frequency. The transmission component 540
can perform the selection so as to avoid an overlap between the at
least one subcarrier and at least one of an intermodulation product
or a harmonic product associated with the at least two subcarriers.
Communication component 570 can be configured to transmit on the at
least two subcarriers via an uplink communication in the case of
user equipment 410 or via a downlink communication in the case of
network entity 420. For instance, communication component 570 may
be configured to provide an uplink communication via the at least
two subcarriers, wherein the signal reception facilitated by
reception component 530 is associated with a downlink. Within such
embodiment, transmission component 540 may be configured to select
the at least two subcarriers based on an assignment provided by a
network. Alternatively, communication component 570 may be
configured to provide a downlink communication via the at least two
subcarriers, wherein the signal reception facilitated by reception
component 530 is associated with an uplink.
[0067] In a particular embodiment, interference management unit 500
resides within user equipment (e.g., user equipment 410). In one
aspect, estimation component 550 may be configured to determine an
estimated interference associated with a data transmission over a
plurality of subcarriers on an uplink, whereas signal processing
component 560 may be configured to process data received over at
least one subcarrier on a downlink based at least in part on the
estimated interference. Here, it should be noted that estimation
component 550 may be configured to ascertain the estimated
interference in any of a plurality of ways. For instance,
estimation component 550 may be configured to determine a set of
intermodulation products associated with the plurality of
subcarriers. Indeed, within such embodiment, estimation component
550 may be further configured to identify the at least one
subcarrier as having a frequency within a range of frequencies
related to the set of intermodulation products associated with the
plurality of subcarriers. For this embodiment, signal processing
component 560 may be configured to zero a log-likelihood ratio
(LLR) for modulation symbols of the at least one subcarrier.
[0068] When implementing interference management unit 500 within
user equipment (e.g., user equipment 410), it should also be noted
that communication component 570 may include any of multiple
further configurations as well. For instance, communication
component 570 may be configured to suspend the data transmission on
at least one of the plurality of subcarriers based at least in part
on the estimated interference. For this particular embodiment,
communication component 570 may be further configured to suspend
the data transmission in response to a scheduling from a base
station (e.g., network entity 420). In another embodiment,
communication component 570 may be configured to transmit a set of
information relating to the estimated interference to a base
station (e.g., network entity 420), wherein the set of information
may, for example, comprise frequency locations of intermodulation
products associated with the plurality of subcarriers.
[0069] Various other aspects directed towards implementing
interference management unit 500 within user equipment (e.g., user
equipment 410) are also contemplated. For instance, transmission
component 540 may be configured to select a subcarrier for
transmitting data on the uplink based at least in part on the
estimated interference. Also, with respect to particular subcarrier
characteristics, it should be noted that the plurality of
subcarriers may comprise a plurality of discontiguous subcarriers
available for a parallel data transmission on the uplink. It is
also contemplated that the plurality of subcarriers may comprise a
first set of subcarriers associated with a first wireless access
technology and second set of subcarriers associated with a second
wireless access technology. For example, the first wireless access
technology may comprise a long term evolution system, whereas the
second wireless access technology may comprise a code division
multiple access (CDMA) system or a wireless fidelity (WiFi) system.
In another embodiment, interference management unit 500 resides
within a network entity (e.g., network entity 420). In one aspect,
estimation component 550 may be configured to ascertain an
estimated interference associated with a data transmission by a
wireless device over a plurality of subcarriers, whereas assigning
component 580 may be configured to assign resources to the wireless
device based at least in part on the estimated interference. Here,
it should be noted that either of estimation component 550 or
assigning component 580 may have any of multiple further
configurations. For instance, estimation component 550 may be
further configured to determine a set of intermodulation products
associated with the plurality of subcarriers, and assigning
component 580 may be further configured to schedule the wireless
device on either an uplink subcarrier or a downlink subcarrier.
[0070] When implementing interference management unit 500 within a
network entity (e.g., network entity 420), it should also be noted
that communication component 570 may include any of multiple
further configurations as well. For instance, communication
component 570 may be configured to receive an indication from the
wireless device relating to frequency locations of intermodulation
products associated with the plurality of subcarriers, wherein
estimation component 550 may be configured to ascertain the
estimated interference based at least in part on the indication
received from the wireless device. For this particular embodiment,
the frequency locations of intermodulation products associated with
the plurality of subcarriers may be related to data transmissions
of the wireless device over at least a first wireless access
technology and a second wireless access technology. For instance,
the first wireless access technology may comprise a long term
evolution system, whereas the second wireless access technology may
be a code division multiple access (CDMA) system or a wireless
fidelity (WiFi) system.
[0071] Turning to FIG. 6, illustrated is a system 600 that
facilitates an interference reduction according to an embodiment.
System 600 and/or instructions for implementing system 600 can
reside within user equipment (e.g., user equipment 410). As
depicted, system 600 includes functional blocks that can represent
functions implemented by a processor using instructions and/or data
from a computer readable storage medium. System 600 includes a
logical grouping 602 of electrical components that can act in
conjunction. As illustrated, logical grouping 602 can include an
electrical component for estimating an estimated interference
associated with a data transmission over a plurality of subcarriers
on an uplink 610. Logical grouping 602 can also include an
electrical component for processing data received over at least one
subcarrier on a downlink based at least in part on the estimated
interference 612. Additionally, system 600 can include a memory 620
that retains instructions and/or data for executing functions
associated with electrical components 610 and 612. While shown as
being external to memory 620, it is to be understood that
electrical components 610 and 612 can exist within memory 620.
[0072] Referring next to FIG. 7, illustrated is another exemplary
system 700 that facilitates interference reduction. System 700
and/or instructions for implementing system 700 can physically
reside within a network entity (e.g., network entity 420), for
instance, wherein system 700 includes functional blocks that can
represent functions implemented by a processor using instructions
and/or data from a computer readable storage medium. System 700
includes a logical grouping 702 of electrical components that can
act in conjunction similar to logical grouping 602 in system 600.
As illustrated, logical grouping 702 can include an electrical
component for estimating an estimated interference associated with
a data transmission by a wireless device over a plurality of
subcarriers 710. Logical grouping 702 can also include an
electrical component for assigning resources to the wireless device
based at least in part on the estimated interference 712.
Additionally, system 700 can include a memory 720 that retains
instructions and/or data for executing functions associated with
electrical components 710 and 712. While shown as being external to
memory 720, it is to be understood that electrical components 710
and 712 can exist within memory 720.
[0073] Referring next to FIG. 8, an example process is shown for
facilitating an interference reduction in wireless communications.
As illustrated, process 800 includes a series of operations that
may be performed by a wireless terminal or network entity. For
instance, process 800 may be implemented by employing a processor
to execute computer executable instructions stored on a computer
readable storage medium to implement the series of operations.
[0074] In an aspect, process 800 begins with a signal being
received at 810. At 820, intermodulation or harmonic products
within the received signal are identified. Once the intermodulation
or harmonic products have been identified, process 800 determines,
at 830, whether intermodulation or harmonic products may cause
interference that should be avoided in a subsequent signal
transmission.
[0075] If the interference is to be avoided, processing proceeds to
840 where candidate alternative sub-carriers for transmission are
ascertained. In one aspect, sub-carriers which do not overlap with
the intermodulation or harmonic products of the received signal are
identified. Once the candidate sub-carriers are identified,
particular sub-carriers are selected for transmission at 850. At
860, a signal is transmitted using the selected sub-carriers.
[0076] However, if it is determined at 830 that the interference is
not to be avoided by selection of sub-carriers, processing proceeds
to 835 where the interference caused by the intermodulation or
harmonic products is estimated. The received signal is then
processed at 845 based at least in part on the estimated
interference and at 860 a signal is transmitted. Here, it should be
noted that such processing may, for example, include demodulating
and/or decoding the received signal according to the estimated
interference. The processing may also include resetting a set of
log-likelihood ratio metrics associated with the received signal,
wherein the resetting comprises setting the set of log-likelihood
ratio metrics to zero.
[0077] In a particular aspect, it should be noted that
intermodulation products and/or harmonics may result from
multicarrier communications involving different types of wireless
networks. In FIG. 9, an exemplary system is illustrated in which
user equipment 910 transmits uplink communications to each of long
term evolution (LTE) network 920 and Wi-Fi network 930. For this
particular example, the uplink communication transmitted to long
term evolution (LTE) network 920 is transmitted via a first
frequency f.sub.1, whereas the uplink communication transmitted to
WiFi network 930 is transmitted via a second frequency f.sub.2. As
illustrated, such uplink transmissions may create intermodulation
products and/or harmonics A.sub.1f.sub.1+A.sub.2f.sub.2, which may
interfere with downlink communications received from either of long
term evolution (LTE) network 920 or wireless fidelity (WiFi)
network 930.
Exemplary Communication System
[0078] Referring next to FIG. 10, an exemplary communication system
1000 having multiple cells (e.g., cell 1002, cell 1004) is
illustrated. Here, it should be noted that neighboring cells 1002,
1004 overlap slightly, as indicated by cell boundary region 1068,
thereby creating potential for signal interference between signals
transmitted by base stations in neighboring cells. Each cell 1002,
1004 of system 1000 includes three sectors. Cells which have not
been subdivided into multiple sectors (N=1), cells with two sectors
(N=2) and cells with more than 3 sectors (N>3) can also be
utilized. Cell 1002 includes a first sector, sector I 1010, a
second sector, sector II 1012, and a third sector, sector III 1014.
Each sector 1010, 1012, and 1014 has two sector boundary regions;
each boundary region is shared between two adjacent sectors.
[0079] Interference between signals transmitted by base stations in
neighboring sectors can occur in boundary regions. Line 1016
represents a sector boundary region between sector I 1010 and
sector II 1012; line 1018 represents a sector boundary region
between sector II 1012 and sector III 1014; line 1020 represents a
sector boundary region between sector III 1014 and sector I 1010.
Similarly, cell M 1004 includes a first sector, sector I 1022, a
second sector, sector II 1024, and a third sector, sector III 1026.
Line 1028 represents a sector boundary region between sector I 1022
and sector II 1024; line 1030 represents a sector boundary region
between sector II 1024 and sector III 1026; line 1032 represents a
boundary region between sector III 1026 and sector I 1022. Cell I
1002 includes a base station (BS), base station I 1006, and a
plurality of end nodes (EN.sub.S) in each sector 1010, 1012, 1014.
Sector I 1010 includes EN(1) 1036 and EN(X) 1038 coupled to BS 1006
via wireless links 1040, 1042, respectively; sector II 1012
includes EN(1') 1044 and EN(X') 1046 coupled to BS 1006 via
wireless links 1048, 1050, respectively; sector III 1014 includes
EN(1'') 1052 and EN(X'') 1054 coupled to BS 1006 via wireless links
1056, 1058, respectively. Similarly, cell M 1004 includes base
station M 1008, and a plurality of end nodes (EN.sub.S) in each
sector 1022, 1024, and 1026. Sector I 1022 includes EN(1) 1036' and
EN(X) 1038' coupled to BS M 1008 via wireless links 1040', 1042',
respectively; sector II 1024 includes EN(1') 1044' and EN(X') 1046'
coupled to BS M 1008 via wireless links 1048', 1050', respectively;
sector III 1026 includes EN(1'') 1052' and EN(X'') 1054' coupled to
BS 1008 via wireless links 1056', 1058', respectively.
[0080] System 1000 also includes a network node 1060 which is
coupled to BS I 1006 and BS M 1008 via network links 1062, 1064,
respectively. Network node 1060 is also coupled to other network
nodes, e.g., other base stations, AAA server nodes, intermediate
nodes, routers, etc. and the Internet via network link 1066.
Network links 1062, 1064, 1066 may be, e.g., fiber optic cables.
Each end node, e.g. EN 1 1036 may be a wireless terminal including
a transmitter as well as a receiver. The wireless terminals, e.g.,
EN(1) 1036 may move through system 1000 and may communicate via
wireless links with the base station in the cell in which the EN is
currently located. The wireless terminals, (WTs), e.g. EN(1) 1036,
may communicate with peer nodes, e.g., other WTs in system 1000 or
outside system 1000 via a base station, e.g. BS 1006, and/or
network node 1060. WTs, e.g., EN(1) 1036 may be mobile
communications devices such as cell phones, personal data
assistants with wireless modems, etc. Respective base stations
perform tone subset allocation using a different method for the
strip-symbol periods, from the method employed for allocating tones
and determining tone hopping in the rest symbol periods, e.g., non
strip-symbol periods. The wireless terminals use the tone subset
allocation method along with information received from the base
station, e.g., base station slope ID, sector ID information, to
determine tones that they can employ to receive data and
information at specific strip-symbol periods. The tone subset
allocation sequence is constructed, in accordance with various
aspects to spread inter-sector and inter-cell interference across
respective tones. Although the subject system was described
primarily within the context of cellular mode, it is to be
appreciated that a plurality of modes may be available and
employable in accordance with aspects described herein.
Exemplary Base Station
[0081] FIG. 11 illustrates an example base station 1100. Base
station 1100 implements tone subset allocation sequences, with
different tone subset allocation sequences generated for respective
different sector types of the cell. Base station 1100 may be used
as any one of base stations 1006, 1008 of the system 1000 of FIG.
10. The base station 1100 includes a receiver 1102, a transmitter
1104, a processor 1106, e.g., CPU, an input/output interface 1108
and memory 1110 coupled together by a bus 1109 over which various
elements 1102, 1104, 1106, 1108, and 1110 may interchange data and
information.
[0082] Sectorized antenna 1103 coupled to receiver 1102 is used for
receiving data and other signals, e.g., channel reports, from
wireless terminals transmissions from each sector within the base
station's cell. Sectorized antenna 1105 coupled to transmitter 1104
is used for transmitting data and other signals, e.g., control
signals, pilot signal, beacon signals, etc. to wireless terminals
1200 (see FIG. 12) within each sector of the base station's cell.
In various aspects, base station 1100 may employ multiple receivers
1102 and multiple transmitters 1104, e.g., an individual receivers
1102 for each sector and an individual transmitter 1104 for each
sector. Processor 1106, may be, e.g., a general purpose central
processing unit (CPU). Processor 1106 controls operation of base
station 1100 under direction of one or more routines 1118 stored in
memory 1110 and implements the methods. I/O interface 1108 provides
a connection to other network nodes, coupling the BS 1100 to other
base stations, access routers, AAA server nodes, etc., other
networks, and the Internet. Memory 1110 includes routines 1118 and
data/information 1120.
[0083] Data/information 1120 includes data 1136, tone subset
allocation sequence information 1138 including downlink
strip-symbol time information 1140 and downlink tone information
1142, and wireless terminal (WT) data/info 1144 including a
plurality of sets of WT information: WT 1 info 1146 and WT N info
1160. Each set of WT info, e.g., WT 1 info 1146 includes data 1148,
terminal ID 1150, sector ID 1152, uplink channel information 1154,
downlink channel information 1156, and mode information 1158.
[0084] Routines 1118 include communications routines 1122 and base
station control routines 1124. Base station control routines 1124
includes a scheduler module 1126 and signaling routines 1128
including a tone subset allocation routine 1130 for strip-symbol
periods, other downlink tone allocation hopping routine 1132 for
the rest of symbol periods, e.g., non strip-symbol periods, and a
beacon routine 1134.
[0085] Data 1136 includes data to be transmitted that will be sent
to encoder 1114 of transmitter 1104 for encoding prior to
transmission to WTs, and received data from WTs that has been
processed through decoder 1112 of receiver 1102 following
reception. Downlink strip-symbol time information 1140 includes the
frame synchronization structure information, such as the superslot,
beaconslot, and ultraslot structure information and information
specifying whether a given symbol period is a strip-symbol period,
and if so, the index of the strip-symbol period and whether the
strip-symbol is a resetting point to truncate the tone subset
allocation sequence used by the base station. Downlink tone
information 1142 includes information including a carrier frequency
assigned to the base station 1100, the number and frequency of
tones, and the set of tone subsets to be allocated to the
strip-symbol periods, and other cell and sector specific values
such as slope, slope index and sector type.
[0086] Data 1148 may include data that WT1 1200 has received from a
peer node, data that WT 1 1200 desires to be transmitted to a peer
node, and downlink channel quality report feedback information.
Terminal ID 1150 is a base station 1100 assigned ID that identifies
WT 1 1200. Sector ID 1152 includes information identifying the
sector in which WT1 1200 is operating. Sector ID 1152 can be used,
for example, to determine the sector type. Uplink channel
information 1154 includes information identifying channel segments
that have been allocated by scheduler 1126 for WT1 1200 to use,
e.g., uplink traffic channel segments for data, dedicated uplink
control channels for requests, power control, timing control, etc.
Each uplink channel assigned to WT1 1200 includes one or more
logical tones, each logical tone following an uplink hopping
sequence. Downlink channel information 1156 includes information
identifying channel segments that have been allocated by scheduler
1126 to carry data and/or information to WT1 1200, e.g., downlink
traffic channel segments for user data. Each downlink channel
assigned to WT1 1200 includes one or more logical tones, each
following a downlink hopping sequence. Mode information 1158
includes information identifying the state of operation of WT1
1200, e.g. sleep, hold, on.
[0087] Communications routines 1122 are utilized by base station
1100 to perform various communications operations and implement
various communications protocols. Base station control routines
1124 are used to control the base station 1100 to perform basic
base station functional tasks, e.g., signal generation and
reception, scheduling, and to implement the steps of the method of
some aspects including transmitting signals to wireless terminals
using the tone subset allocation sequences during the strip-symbol
periods.
[0088] Signaling routine 1128 controls the operation of receiver
1102 with its decoder 1112 and transmitter 1104 with its encoder
1114. The signaling routine 1128 is responsible controlling the
generation of transmitted data 1136 and control information. Tone
subset allocation routine 1130 constructs the tone subset to be
used in a strip-symbol period using the method of the aspect and
using data/info 1120 including downlink strip-symbol time info 1140
and sector ID 1152. The downlink tone subset allocation sequences
will be different for each sector type in a cell and different for
adjacent cells. The WTs 1200 receive the signals in the
strip-symbol periods in accordance with the downlink tone subset
allocation sequences; the base station 1100 uses the same downlink
tone subset allocation sequences in order to generate the
transmitted signals. Other downlink tone allocation hopping routine
1132 constructs downlink tone hopping sequences, using information
including downlink tone information 1142, and downlink channel
information 1156, for the symbol periods other than the
strip-symbol periods. The downlink data tone hopping sequences are
synchronized across the sectors of a cell. Beacon routine 1134
controls the transmission of a beacon signal, e.g., a signal of
relatively high power signal concentrated on one or a few tones,
which may be used for synchronization purposes, e.g., to
synchronize the frame timing structure of the downlink signal and
therefore the tone subset allocation sequence with respect to an
ultra-slot boundary.
Exemplary Wireless Terminal
[0089] FIG. 12 illustrates an example wireless terminal (end node)
1200 which can be used as any one of the wireless terminals (end
nodes), e.g., EN(1) 1036, of the system 1000 shown in FIG. 10.
Wireless terminal 1200 implements the tone subset allocation
sequences. The wireless terminal 1200 includes a receiver 1202
including a decoder 1212, a transmitter 1204 including an encoder
1214, a processor 1206, and memory 1208 which are coupled together
by a bus 1210 over which the various elements 1202, 1204, 1206,
1208 can interchange data and information. An antenna 1203 used for
receiving signals from a base station (and/or a disparate wireless
terminal) is coupled to receiver 1202. An antenna 1205 used for
transmitting signals, e.g., to a base station (and/or a disparate
wireless terminal) is coupled to transmitter 1204.
[0090] The processor 1206, e.g., a CPU controls the operation of
the wireless terminal 1200 and implements methods by executing
routines 1220 and using data/information 1222 in memory 1208.
[0091] Data/information 1222 includes user data 1234, user
information 1236, and tone subset allocation sequence information
1250. User data 1234 may include data, intended for a peer node,
which will be routed to encoder 1214 for encoding prior to
transmission by transmitter 1204 to a base station, and data
received from the base station which has been processed by the
decoder 1212 in receiver 1202. User information 1236 includes
uplink channel information 1238, downlink channel information 1240,
terminal ID information 1242, base station ID information 1244,
sector ID information 1246, and mode information 1248. Uplink
channel information 1238 includes information identifying uplink
channels segments that have been assigned by a base station for
wireless terminal 1200 to use when transmitting to the base
station. Uplink channels may include uplink traffic channels,
dedicated uplink control channels, e.g., request channels, power
control channels and timing control channels. Each uplink channel
includes one or more logic tones, each logical tone following an
uplink tone hopping sequence. The uplink hopping sequences are
different between each sector type of a cell and between adjacent
cells. Downlink channel information 1240 includes information
identifying downlink channel segments that have been assigned by a
base station to WT 1200 for use when the base station is
transmitting data/information to WT 1200. Downlink channels may
include downlink traffic channels and assignment channels, each
downlink channel including one or more logical tone, each logical
tone following a downlink hopping sequence, which is synchronized
between each sector of the cell.
[0092] User info 1236 also includes terminal ID information 1242,
which is a base station-assigned identification, base station ID
information 1244 which identifies the specific base station that WT
has established communications with, and sector ID info 1246 which
identifies the specific sector of the cell where WT 1200 is
presently located. Base station ID 1244 provides a cell slope value
and sector ID info 1246 provides a sector index type; the cell
slope value and sector index type may be used to derive tone
hopping sequences. Mode information 1248 also included in user info
1236 identifies whether the WT 1200 is in sleep mode, hold mode, or
on mode.
[0093] Tone subset allocation sequence information 1250 includes
downlink strip-symbol time information 1252 and downlink tone
information 1254. Downlink strip-symbol time information 1252
include the frame synchronization structure information, such as
the superslot, beaconslot, and ultraslot structure information and
information specifying whether a given symbol period is a
strip-symbol period, and if so, the index of the strip-symbol
period and whether the strip-symbol is a resetting point to
truncate the tone subset allocation sequence used by the base
station. Downlink tone info 1254 includes information including a
carrier frequency assigned to the base station, the number and
frequency of tones, and the set of tone subsets to be allocated to
the strip-symbol periods, and other cell and sector specific values
such as slope, slope index and sector type.
[0094] Routines 1220 include communications routines 1224 and
wireless terminal control routines 1226. Communications routines
1224 control the various communications protocols used by WT 1200.
Wireless terminal control routines 1226 controls basic wireless
terminal 1200 functionality including the control of the receiver
1202 and transmitter 1204. Wireless terminal control routines 1226
include the signaling routine 1228. The signaling routine 1228
includes a tone subset allocation routine 1230 for the strip-symbol
periods and an other downlink tone allocation hopping routine 1232
for the rest of symbol periods, e.g., non strip-symbol periods.
Tone subset allocation routine 1230 uses user data/info 1222
including downlink channel information 1240, base station ID info
1244, e.g., slope index and sector type, and downlink tone
information 1254 in order to generate the downlink tone subset
allocation sequences in accordance with some aspects and process
received data transmitted from the base station. Other downlink
tone allocation hopping routine 1232 constructs downlink tone
hopping sequences, using information including downlink tone
information 1254, and downlink channel information 1240, for the
symbol periods other than the strip-symbol periods. Tone subset
allocation routine 1230, when executed by processor 1206, is used
to determine when and on which tones the wireless terminal 1200 is
to receive one or more strip-symbol signals from the base station
1100. The uplink tone allocation hopping routine 1232 uses a tone
subset allocation function, along with information received from
the base station, to determine the tones in which it should
transmit on.
[0095] In one or more exemplary embodiments, the functions
described may be implemented in hardware, software, firmware, or
any combination thereof. If implemented in software, the functions
may be stored on or transmitted over as one or more instructions or
code on a computer-readable medium. Computer-readable media
includes both computer storage media and communication media
including any medium that facilitates transfer of a computer
program from one place to another. A storage media may be any
available media that can be accessed by a computer. By way of
example, and not limitation, such computer-readable media can
comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage,
magnetic disk storage or other magnetic storage devices, or any
other medium that can be used to carry or store desired program
code in the form of instructions or data structures and that can be
accessed by a computer. Also, any connection is properly termed a
computer-readable medium. For example, if the software is
transmitted from a website, server, or other remote source using a
coaxial cable, fiber optic cable, twisted pair, digital subscriber
line (DSL), or wireless technologies such as infrared, radio, and
microwave, then the coaxial cable, fiber optic cable, twisted pair,
DSL, or wireless technologies such as infrared, radio, and
microwave are included in the definition of medium. Disk and disc,
as used herein, includes compact disc (CD), laser disc, optical
disc, digital versatile disc (DVD), floppy disk and blu-ray disc
where disks usually reproduce data magnetically, while discs
reproduce data optically with lasers. Combinations of the above
should also be included within the scope of computer-readable
media.
[0096] When the embodiments are implemented in program code or code
segments, it should be appreciated that a code segment can
represent a procedure, a function, a subprogram, a program, a
routine, a subroutine, a module, a software package, a class, or
any combination of instructions, data structures, or program
statements. A code segment can be coupled to another code segment
or a hardware circuit by passing and/or receiving information,
data, arguments, parameters, or memory contents. Information,
arguments, parameters, data, etc. can be passed, forwarded, or
transmitted using any suitable means including memory sharing,
message passing, token passing, network transmission, etc.
Additionally, in some aspects, the steps and/or actions of a method
or algorithm can reside as one or any combination or set of codes
and/or instructions on a machine readable medium and/or computer
readable medium, which can be incorporated into a computer program
product.
[0097] For a software implementation, the techniques described
herein can be implemented with modules (e.g., procedures,
functions, and so on) that perform the functions described herein.
The software codes can be stored in memory units and executed by
processors. The memory unit can be implemented within the processor
or external to the processor, in which case it can be
communicatively coupled to the processor via various means as is
known in the art.
[0098] For a hardware implementation, the processing units can be
implemented within one or more application specific integrated
circuits (ASICs), digital signal processors (DSPs), digital signal
processing devices (DSPDs), programmable logic devices (PLDs),
field programmable gate arrays (FPGAs), processors, controllers,
micro-controllers, microprocessors, other electronic units designed
to perform the functions described herein, or a combination
thereof.
[0099] What has been described above includes examples of one or
more embodiments. It is, of course, not possible to describe every
conceivable combination of components or methodologies for purposes
of describing the aforementioned embodiments, but one of ordinary
skill in the art may recognize that many further combinations and
permutations of various embodiments are possible. Accordingly, the
described embodiments are intended to embrace all such alterations,
modifications and variations that fall within the spirit and scope
of the appended claims. Furthermore, to the extent that the term
"includes" is used in either the detailed description or the
claims, such term is intended to be inclusive in a manner similar
to the term "comprising" as "comprising" is interpreted when
employed as a transitional word in a claim.
[0100] As used herein, the term to "infer" or "inference" refers
generally to the process of reasoning about or inferring states of
the system, environment, and/or user from a set of observations as
captured via events and/or data. Inference can be employed to
identify a specific context or action, or can generate a
probability distribution over states, for example. The inference
can be probabilistic--that is, the computation of a probability
distribution over states of interest based on a consideration of
data and events. Inference can also refer to techniques employed
for composing higher-level events from a set of events and/or data.
Such inference results in the construction of new events or actions
from a set of observed events and/or stored event data, whether or
not the events are correlated in close temporal proximity, and
whether the events and data come from one or several event and data
sources.
[0101] Furthermore, as used in this application, the terms
"component," "module," "system," and the like are intended to refer
to a computer-related entity, either hardware, firmware, a
combination of hardware and software, software, or software in
execution. For example, a component can be, but is not limited to
being, a process running on a processor, a processor, an object, an
executable, a thread of execution, a program, and/or a computer. By
way of illustration, both an application running on a computing
device and the computing device can be a component. One or more
components can reside within a process and/or thread of execution
and a component can be localized on one computer and/or distributed
between two or more computers. In addition, these components can
execute from various computer readable media having various data
structures stored thereon. The components can communicate by way of
local and/or remote processes such as in accordance with a signal
having one or more data packets (e.g., data from one component
interacting with another component in a local system, distributed
system, and/or across a network such as the Internet with other
systems by way of the signal).
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