U.S. patent application number 13/618197 was filed with the patent office on 2013-08-01 for low power narrowband operation by an endpoint.
This patent application is currently assigned to Fujitsu Limited. The applicant listed for this patent is Chenxi Zhu. Invention is credited to Chenxi Zhu.
Application Number | 20130194997 13/618197 |
Document ID | / |
Family ID | 48870132 |
Filed Date | 2013-08-01 |
United States Patent
Application |
20130194997 |
Kind Code |
A1 |
Zhu; Chenxi |
August 1, 2013 |
Low Power Narrowband Operation By An Endpoint
Abstract
According to one embodiment, a method includes receiving a
communication from a transceiver. An endpoint searches a search
space for one or more control signals addressed to the endpoint.
The search space includes one or more subcarrier frequencies of the
plurality of subcarrier frequencies that are located within the
narrowband portion of the frequency range and no subcarrier
frequencies located outside the narrowband portion of the frequency
range. The endpoint decodes at least one control signal addressed
to the endpoint and transmitted using at least subcarrier frequency
of the search space. The at least one decoded control signal
indicates at least one time and at least one set of subcarrier
frequencies of the plurality of subcarrier frequencies used to
transmit at least one data signal of the communication to the
endpoint. The method further includes recovering, by the endpoint,
the at least one data signal transmitted to the endpoint.
Inventors: |
Zhu; Chenxi; (Fairfax,
VA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zhu; Chenxi |
Fairfax |
VA |
US |
|
|
Assignee: |
Fujitsu Limited
Kanagawa
JP
|
Family ID: |
48870132 |
Appl. No.: |
13/618197 |
Filed: |
September 14, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61593705 |
Feb 1, 2012 |
|
|
|
Current U.S.
Class: |
370/312 |
Current CPC
Class: |
H04L 5/0053 20130101;
H04W 72/042 20130101; H04L 5/0094 20130101; H04L 5/0048 20130101;
H04W 72/1289 20130101 |
Class at
Publication: |
370/312 |
International
Class: |
H04W 4/06 20090101
H04W004/06 |
Claims
1. An endpoint comprising: an interface configured to receive a
communication from a transceiver, the communication transmitted to
a plurality of endpoints using a plurality of subcarrier
frequencies spanning a frequency range, the communication including
at least one control signal transmitted using at least one
subcarrier frequency of the plurality of subcarrier frequencies
that is outside of a narrowband portion of the frequency range; a
processor coupled to the interface and configured to: search a
search space for one or more control signals addressed to the
endpoint, the search space including one or more subcarrier
frequencies of the plurality of subcarrier frequencies that are
located within the narrowband portion of the frequency range and no
subcarrier frequencies located outside the narrowband portion of
the frequency range; decode at least one control signal addressed
to the endpoint and transmitted using at least subcarrier frequency
of the search space, the at least one decoded control signal
indicating at least one time and at least one set of subcarrier
frequencies of the plurality of subcarrier frequencies used to
transmit at least one data signal of the communication to the
endpoint; and recover the at least one data signal transmitted to
the endpoint.
2. The endpoint of claim 1, wherein the processor is further
configured to perform analog-to-digital conversion (ADC) sampling
on only the narrowband portion of the frequency range.
3. The endpoint of claim 1, wherein the processor is further
configured to perform ADC sampling on the entire frequency
range.
4. The endpoint of claim 3, wherein the at least one data signal
recovered by the endpoint is transmitted to the endpoint using at
least one set of contiguous frequencies of the plurality of
contiguous frequencies that is outside the narrowband portion of
the frequency range.
5. The endpoint of claim 1, wherein the processor is further
configured to awake from an idle or dormant state prior to
searching the search space for the one or more control signals
addressed to the endpoint.
6. The endpoint of claim 1, wherein the search space is a first
search space and the processor is further configured to: receive a
subsequent communication from the transceiver, the subsequent
communication transmitted using the same plurality of subcarrier
frequencies spanning the frequency range; and search a second
search space for one or more additional control signals addressed
to the endpoint, the second search space including one or more
subcarrier frequencies of the plurality of subcarrier frequencies
that are located outside the narrowband portion of the frequency
range.
7. The endpoint of claim 1, wherein the communication from the
transceiver includes a plurality of data signals and control
signals that are multiplexed in time using frequency division
multiplexing.
8. A method comprising: receiving, by an endpoint, a communication
from a transceiver, the communication transmitted to a plurality of
endpoints using a plurality of subcarrier frequencies spanning a
frequency range, the communication including at least one control
signal transmitted using at least one subcarrier frequency of the
plurality of subcarrier frequencies that is outside of a narrowband
portion of the frequency range; searching, by the endpoint, a
search space for one or more control signals addressed to the
endpoint, the search space including one or more subcarrier
frequencies of the plurality of subcarrier frequencies that are
located within the narrowband portion of the frequency range and no
subcarrier frequencies located outside the narrowband portion of
the frequency range; decoding, by the endpoint, at least one
control signal addressed to the endpoint and transmitted using at
least subcarrier frequency of the search space, the at least one
decoded control signal indicating at least one time and at least
one set of subcarrier frequencies of the plurality of subcarrier
frequencies used to transmit at least one data signal of the
communication to the endpoint; and recovering, by the endpoint, the
at least one data signal transmitted to the endpoint.
9. The method of claim 8, further comprising performing
analog-to-digital conversion (ADC) sampling on only the narrowband
portion of the frequency range.
10. The method of claim 8, further comprising performing ADC
sampling on the entire frequency range
11. The method of claim 10, wherein the at least one data signal
recovered by the endpoint is transmitted to the endpoint using at
least one set of contiguous frequencies of the plurality of
contiguous frequencies that is outside the narrowband portion of
the frequency range.
12. The method of claim 8, further comprising awaking from an idle
or dormant state prior to searching the search space for the one or
more control signals addressed to the endpoint.
13. The method of claim 8, wherein the search space is a first
search space and the method further comprises: receiving a
subsequent communication from the transceiver, the subsequent
communication transmitted using the same plurality of subcarrier
frequencies spanning the frequency range; and searching a second
search space for one or more additional control signals addressed
to the endpoint, the second search space including one or more
subcarrier frequencies of the plurality of subcarrier frequencies
that are located outside the narrowband portion of the frequency
range.
14. The method of claim 8, wherein the communication from the
transceiver includes a plurality of data signals and control
signals that are multiplexed in time using frequency division
multiplexing.
15. One or more non-transitory computer-readable storage media
embodying logic that when executed by a processor is configured to:
receive, at an endpoint, a communication from a transceiver, the
communication transmitted to a plurality of endpoints using a
plurality of subcarrier frequencies spanning a frequency range, the
communication including at least one control signal transmitted
using at least one subcarrier frequency of the plurality of
subcarrier frequencies that is outside of a narrowband portion of
the frequency range; search a search space for one or more control
signals addressed to an endpoint, the search space including one or
more subcarrier frequencies of the plurality of subcarrier
frequencies that are located within the narrowband portion of the
frequency range and no subcarrier frequencies located outside the
narrowband portion of the frequency range; decode at least one
control signal addressed to the endpoint and transmitted using at
least subcarrier frequency of the search space, the at least one
decoded control signal indicating at least one time and at least
one set of subcarrier frequencies of the plurality of subcarrier
frequencies used to transmit at least one data signal of the
communication to the endpoint; and recover the at least one data
signal transmitted to the endpoint.
16. The media of claim 15, the logic further configured to perform
analog-to-digital conversion (ADC) sampling on only the narrowband
portion of the frequency range.
17. The media of claim 15, the logic further configured to perform
ADC sampling on the entire frequency range.
18. The media of claim 17, wherein the at least one data signal
recovered by the endpoint is transmitted to the endpoint using at
least one set of contiguous frequencies of the plurality of
contiguous frequencies that is outside the narrowband portion of
the frequency range.
19. The media of claim 15, the logic further configured to awake
the endpoint from an idle or dormant state prior to searching the
search space for the one or more control signals addressed to the
endpoint.
20. The media of claim 15, wherein the search space is a first
search space and the logic is further configured to: receive a
subsequent communication from the transceiver, the subsequent
communication transmitted using the same plurality of subcarrier
frequencies spanning the frequency range; and search a second
search space for one or more additional control signals addressed
to the endpoint, the second search space including one or more
subcarrier frequencies of the plurality of subcarrier frequencies
that are located outside the narrowband portion of the frequency
range.
21. The media of claim 15, wherein the communication from the
transceiver includes a plurality of data signals and control
signals that are multiplexed in time using frequency division
multiplexing.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of priority under 35
U.S.C. .sctn.119(e) of U.S. Provisional Application Ser. No.
61/593,705, entitled "IMPROVEMENTS TO DOWNLINK CONTROL CHANNEL IN
LTE-A AND ENDPOINT POWER USAGE," filed Feb. 1, 2012, the entire
content of which is incorporated herein by reference.
TECHNICAL FIELD OF THE INVENTION
[0002] The present disclosure relates generally to methods and
apparatuses for low power narrowband operation by an endpoint.
BACKGROUND OF THE INVENTION
[0003] An antenna system may include multiple transceivers such as
transmission sites or endpoints. A transmission site may be a base
station (also known as a Radio Element Control or a Baseband Unit)
or a remote transmission site (also known as a Radio Element or a
Remote Radio Head). Transmission sites provide endpoints with
wireless network access. A transmission site may transmit control
signals, data signals, and other signals to the endpoints. The
control signals may facilitate the processing of the data signals
by the endpoints.
SUMMARY OF THE INVENTION
[0004] Various embodiments of the present disclosure relate to low
power narrowband operation by an endpoint. For example, in one
embodiment, a method includes receiving, by an endpoint, a
communication from a transceiver. The communication is transmitted
to a plurality of endpoints using a plurality of subcarrier
frequencies spanning a frequency range. The communication includes
at least one control signal transmitted using at least one
subcarrier frequency of the plurality of subcarrier frequencies
that is outside of a narrowband portion of the frequency range. The
method further includes searching, by the endpoint, a search space
for one or more control signals addressed to the endpoint. The
search space includes one or more subcarrier frequencies of the
plurality of subcarrier frequencies that are located within the
narrowband portion of the frequency range and no subcarrier
frequencies located outside the narrowband portion of the frequency
range. The endpoint decodes at least one control signal addressed
to the endpoint and transmitted using at least subcarrier frequency
of the search space. The at least one decoded control signal
indicates at least one time and at least one set of subcarrier
frequencies of the plurality of subcarrier frequencies used to
transmit at least one data signal of the communication to the
endpoint. The method further includes recovering, by the endpoint,
the at least one data signal transmitted to the endpoint.
[0005] The object and advantages of the invention will be realized
and achieved by means of the elements and combinations particularly
pointed out in the claims.
[0006] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] For a more complete understanding of particular embodiments
and their features and advantages, reference is now made to the
following description, taken in conjunction with the accompanying
drawings, in which:
[0008] FIG. 1 depicts an example system that includes an example
transmission site that communicates with an example wideband
endpoint and an example narrowband endpoint;
[0009] FIGS. 2A and 2B depicts example communication diagrams that
represent signals transmitted by the transmission site of FIG.
1;
[0010] FIG. 3 depicts an example method for transmitting control
signals, data signals, and other signals to wideband and narrowband
endpoints that may be performed by the transmission site of FIG.
1;
[0011] FIG. 4 depicts an example method for processing control
signals and data signals that may be performed by the narrowband
endpoint of FIG. 1; and
[0012] FIG. 5 depicts an example method for processing control
signals and data signals that may be performed by the narrowband
endpoint of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0013] FIG. 1 depicts an example system 100 that includes
transmission site 102 that communicates with a wideband endpoint
104a and a narrowband endpoint 104b. System 100 may include any
suitable number of transmission sites 102 and endpoints 104 that
communicate with each other. System 100 may provide wireless
coverage for any suitable number of endpoints 104 over a geographic
area, such as a cell. For example, transmission site 102 may be
used to provide wireless coverage for an entire building, a city
block, a campus, or any other area. Transmission site 102 may be
coupled to one or more networks, such as wireless service provider
(WSP) network 106 or internet service provider (ISP) network 108.
Transmission site 102 may communicate data between endpoints 104
and one or more nodes coupled to WSP network 106 or ISP network
108.
[0014] In particular embodiments, transmission site 102 is capable
of communicating with both wideband endpoints (such as 104a) and
narrowband endpoints (such as 104b). A wideband endpoint 104a is an
endpoint that is configured to decode signals transmitted using any
subcarrier frequencies within the frequency range (i.e., channel
bandwidth) of wireless transmissions (e.g., 200b) by transmission
site 102 to endpoints 104. As an example, if transmission site 102
transmits control signals, data signals, and other signals to
endpoints 104 using a Long Term Evolution (LTE) or LTE-Advanced
(LTE-A) standard (such as that described in 3rd Generation
Partnership Project (3GPP) Release 10 or beyond), the frequency
range may be 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or 20 MHz. Each
frequency range may include a plurality of contiguous subcarrier
frequencies that are equally spaced apart to reduce or eliminate
interference between signals transmitted using neighboring
subcarrier frequencies. For example, in LTE or LTE-A, contiguous
subcarrier frequencies are spaced 15 kHz apart from each other. In
contrast to a wideband endpoint 104a, a narrowband endpoint 104b is
configured to decode signals transmitted using subcarrier
frequencies that are within a portion of the frequency range
(referred to herein as the "narrowband"). Thus, narrowband endpoint
104b is only configured to decode signals transmitted using a
subset of the subcarrier frequencies (i.e., the narrowband) of the
frequency range, but is not configured to decode signals
transmitted using subcarrier frequencies outside of this subset.
Transmission site 102 may communicate with narrowband endpoints
104b by limiting the subcarrier frequencies that carry signals for
the narrowband endpoints 104b to the narrowband.
[0015] Narrowband endpoints 104b and methods used to wirelessly
communicate with them have various advantages over previous
communication schemes. During communication, a narrowband endpoint
104b may perform computations that are less complex than
computations performed by a wideband endpoint 104a. For example, a
narrowband endpoint 104b may perform smaller size Discrete Fourier
Transforms (DFTs) and use an analog to digital converter (ADC) with
a lower sampling rate when recovering the signals transmitted to
the endpoint. The reduction in computation complexity required may
result in a lower construction cost of a narrowband endpoint 104b
relative to a wideband endpoint 104a. For example, low cost
endpoints such as machine type communication (MTC) devices or
sensor nodes may function as narrowband endpoints. The lower
computation complexity also allows narrowband endpoint 104b to use
less power. In various embodiments, this may greatly increase the
battery cycle of a device. For example, an endpoint 104b may
periodically awake from an idle or dormant state to determine
whether a transmission site 102 is currently transmitting data to
the device. By only decoding in the narrowband, the endpoint may
realize power savings each time it wakes up and checks for data. In
particular embodiments, a narrowband endpoint 104b may transition
to operation as a wideband endpoint 104a upon a determination that
transmission site 102 has begun to transmit data signals to the
narrowband endpoint 104b. This may allow the endpoint 104 to
receive data at a higher rate than is possible during narrowband
operation. Operation of the transmission site 102 and narrowband
endpoint 104b are explained in greater detail below.
[0016] Transmission site 102 may be any suitable transceiver such
as a base station (also known as a Radio Element Control or a
Baseband Unit) or a remote transmission site (also known as a Radio
Element or a Remote Radio Head (RRH)). In certain situations, a
transmission site 102 that is a remote transmission site may
function as an extension of another transmission site that is a
base station. For example, the remote transmission site may send
wireless signals to endpoints 104 that are similar to wireless
signals that would be sent by the base station to the endpoint if
endpoint 104 were located close to the base station.
[0017] Transmission site 102 may include any combination of
hardware, software embedded in a computer readable medium, or
encoded logic incorporated in hardware or otherwise stored (e.g.,
firmware) to implement any number of communication protocols that
allow for wired or wireless exchange of information in system 100.
Transmission site 102 may be operable to exchange control signals,
data signals, and other signals with endpoints 104. A transmission
site 102 may also be coupled to other transmission sites 102 via
one or more wired connections. These wired connections may comprise
any suitable material, such as optical fiber. Transmission sites
102 may use any suitable technologies or protocols (e.g., Common
Public Radio Interface (CPRI)) to communicate with each other.
[0018] Transmission site 102 may communicate with endpoint 104
using wireless communication via one or more antennas 110. In
particular embodiments, transmission site 102 coordinates with one
or more other transmission sites 102 to communicate with endpoint
104. For example, transmission site 102 may coordinate with one or
more other transmission sites 102 to communicate with endpoint 104
using a MIMO transmission scheme where multiple transmitting
antennas 110 are placed at different transmission sites 102, while
one or more receiving antennas (e.g., antenna 122) are located at
the endpoint 104. Accordingly, reference herein to a single
transmission site communicating with one or more endpoints 104 may
also refer to multiple transmission sites 102 jointly communicating
with the one or more endpoints 104. Transmission site 102 may
communicate with endpoints 104 using any of a variety of different
wireless technologies, including, but not limited to, orthogonal
frequency division multiple access (OFDMA) and the LTE-A protocol
as defined in the 3GPP Release 10 or beyond.
[0019] Antennas 110, 122, and 134 may be any suitable type of
antennas capable of transmitting and receiving data or signals
wirelessly. In some embodiments, antennas 110, 122, or 134 may
comprise one or more omni-directional, sector or panel antennas
operable to transmit/receive radio signals at any suitable
frequency, such as between 2 GHz and 66 GHz. An omni-directional
antenna may be used to transmit/receive radio signals in any
direction, a sector antenna may be used to transmit/receive radio
signals from devices within a particular area, and a panel antenna
may be a line of sight antenna used to transmit/receive radio
signals in a relatively straight line.
[0020] System 100 may comprise a network that includes various
networks, such as ISP network 108 and WSP network 106. In some
embodiments, a network may comprise one or more networks, such as
the Internet, a local area network (LAN), a wide area network
(WAN), a metropolitan area network (MAN), a public switched
telephone network (PSTN), or some combination of the above. In
certain embodiments, ISP network 108 may be coupled to WSP network
106 via one or more networks, including but not limited to, the
Internet, a LAN, WAN, MAN, PSTN, or some combination of the above.
In some embodiments, an ISP may provide a network node (e.g., a
computer system) with home network access. ISP network 108 may
include modems, servers, gateways (e.g., an ISP gateway), or other
suitable components.
[0021] In particular embodiments, WSP network 106 may comprise
various servers, gateways, switches, routers, and other nodes used
in providing wireless service. In some embodiments, the servers may
comprise one or more servers, such as Operation, Administration,
Maintenance and Provisioning (OAM&P) servers, Network Access
Provider (NAP) servers, Authentication, Authorization, and
Accounting (AAA) servers, Self Organizing Network (SON) servers, or
any other servers that the WSP may need to configure/authenticate
one or more transmission sites (such as 102) and provide users with
wireless service. The WSP's gateways may comprise any hardware or
software needed to couple WSP network 106 with ISP network 108. For
example, in particular embodiments, the gateway may comprise a
security gateway and, behind the security gateway, an Access
Service Network (ASN) gateway. In some embodiments, the WSP network
106 may support or implement orthogonal frequency-division multiple
access (OFDMA).
[0022] Any of the networks coupled to transmission site 102 may be
capable of transmitting signals, data, or messages, including
signals, data, or messages transmitted through WebPages, e-mail,
text chat, voice over IP (VoIP), and instant messaging in order to
provide services and data to endpoints 104. In particular
embodiments, transmission site 102 also communicates with a base
station controller that facilitates handoffs between cells and
provides other functions.
[0023] Endpoint 104 may comprise any type of wireless device able
to send and receive data or signals to and from transmission site
102 directly or via one or more other transmission sites 102. Some
examples of endpoints 104 include desktop computers, PDAs, cell
phones, laptops, VoIP phones, MTC devices, or sensor nodes.
Endpoints 104 may provide data or network services to a user
through any combination of hardware, software embedded in a
computer readable medium, or encoded logic incorporated in hardware
or otherwise stored (e.g., firmware). Endpoints 104 may also
include unattended or automated systems, gateways, other
intermediate components or other devices that may send or receive
data or signals.
[0024] Transmission site 102, endpoints 104, and nodes of WSP
network 106 or ISP network 108 may each include one or more
portions of one or more computer systems. In particular
embodiments, one or more of these computer systems may perform one
or more steps of one or more methods described or illustrated
herein. In particular embodiments, one or more computer systems may
provide functionality described or illustrated herein. In
particular embodiments, encoded software running on one or more
computer systems may perform one or more steps of one or more
methods described or illustrated herein or provide functionality
described or illustrated herein.
[0025] The components of a transmission site 102 or endpoints 104
may comprise any suitable physical form, configuration, number,
type or layout. As an example, and not by way of limitation,
transmission site 102 or endpoint 104 may comprise an embedded
computer system, a system-on-chip (SOC), a single-board computer
system (SBC) (such as, for example, a computer-on-module (COM) or
system-on-module (SOM)), a desktop computer system, a laptop or
notebook computer system, an interactive kiosk, a mainframe, a mesh
of computer systems, a mobile telephone, a personal digital
assistant (PDA), a server, or a combination of two or more of
these. Where appropriate, transmission site 102 or endpoint 104 may
include one or more computer systems; be unitary or distributed;
span multiple locations; span multiple machines; or reside in a
cloud, which may include one or more cloud components in one or
more networks.
[0026] In the depicted embodiment, transmission site 102 or
endpoints 104 each include their own respective processors 112,
124, and 136; memory 114, 128, and 140; storage 118, 130, and 142;
interfaces 120, 132, and 144; and buses 116, 126, and 138. Although
a particular system is depicted having a particular number of
particular components in a particular arrangement, this disclosure
contemplates any suitable system 100 having any suitable number of
any suitable components in any suitable arrangement. For
simplicity, similar components of transmission site 102 and
endpoints 104 will be discussed together while referring to the
component of transmission site 102. However, it is not necessary
for these devices to have the same components, or the same type of
components. For example, processor 112 may be a general purpose
microprocessor and processor 124 may be an application specific
integrated circuit (ASIC).
[0027] Processor 112 may be a microprocessor, controller, or any
other suitable computing device, resource, or combination of
hardware, software or encoded logic operable to provide, either
alone or in conjunction with other components, (e.g., memory 114)
wireless networking functionality. Such functionality may include
providing various wireless features discussed herein. Additional
examples and functionality provided, at least in part, by processor
112 will be discussed below.
[0028] In particular embodiments, processor 112 may include
hardware for executing instructions, such as those making up a
computer program. As an example and not by way of limitation, to
execute instructions, processor 112 may retrieve (or fetch)
instructions from an internal register, an internal cache, memory
114, or storage 118; decode and execute them; and then write one or
more results to an internal register, an internal cache, memory
114, or storage 118.
[0029] In particular embodiments, processor 112 may include one or
more internal caches for data, instructions, or addresses. This
disclosure contemplates processor 112 including any suitable number
of any suitable internal caches, where appropriate. As an example
and not by way of limitation, processor 112 may include one or more
instruction caches, one or more data caches, and one or more
translation lookaside buffers (TLBs). Instructions in the
instruction caches may be copies of instructions in memory 114 or
storage 118 and the instruction caches may speed up retrieval of
those instructions by processor 112. Data in the data caches may be
copies of data in memory 114 or storage 118 for instructions
executing at processor 112 to operate on; the results of previous
instructions executed at processor 112 for access by subsequent
instructions executing at processor 112, or for writing to memory
114, or storage 118; or other suitable data. The data caches may
speed up read or write operations by processor 112. The TLBs may
speed up virtual-address translations for processor 112. In
particular embodiments, processor 112 may include one or more
internal registers for data, instructions, or addresses. Depending
on the embodiment, processor 112 may include any suitable number of
any suitable internal registers, where appropriate. Where
appropriate, processor 112 may include one or more arithmetic logic
units (ALUs); be a multi-core processor; include one or more
processors 112; or any other suitable processor.
[0030] Memory 114 may be any form of volatile or non-volatile
memory including, without limitation, magnetic media, optical
media, random access memory (RAM), read-only memory (ROM), flash
memory, removable media, or any other suitable local or remote
memory component or components. In particular embodiments, memory
114 may include random access memory (RAM). This RAM may be
volatile memory, where appropriate. Where appropriate, this RAM may
be dynamic RAM (DRAM) or static RAM (SRAM). Moreover, where
appropriate, this RAM may be single-ported or multi-ported RAM, or
any other suitable type of RAM or memory. Memory 114 may include
one or more memories 114, where appropriate. Memory 114 may store
any suitable data or information utilized by transmission site 102.
For example, memory 114 may include logic 115. Logic 115 may
include software embedded in a computer readable medium, or encoded
logic incorporated in hardware or otherwise stored (e.g.,
firmware). In particular embodiments, logic 115 may be executed to
perform the functions of transmission site 102. Similarly, logic
129 and 141 may be executed to perform the functions of wideband
endpoint 104a and narrowband endpoint 104b respectively. In
particular embodiments, memory 114 may include main memory for
storing instructions for processor 112 to execute or data for
processor 112 to operate on. In particular embodiments, one or more
memory management units (MMUs) may reside between processor 112 and
memory 114 and facilitate accesses to memory 114 requested by
processor 112.
[0031] As an example and not by way of limitation, transmission
site 102 may load instructions from storage 118 or another source
(such as, for example, another computer system, another base
station, or a remote transmission site) to memory 114. Processor
112 may then load the instructions from memory 114 to an internal
register or internal cache. To execute the instructions, processor
112 may retrieve the instructions from the internal register or
internal cache and decode them. During or after execution of the
instructions, processor 112 may write one or more results (which
may be intermediate or final results) to the internal register or
internal cache. Processor 112 may then write one or more of those
results to memory 114. In particular embodiments, processor 112 may
execute only instructions in one or more internal registers or
internal caches or in memory 114 (as opposed to storage 118 or
elsewhere) and may operate only on data in one or more internal
registers or internal caches or in memory 114 (as opposed to
storage 118 or elsewhere).
[0032] In particular embodiments, storage 118 may include mass
storage for data or instructions. As an example and not by way of
limitation, storage 118 may include a hard disk drive (HDD), a
floppy disk drive, flash memory, an optical disc, a magneto-optical
disc, magnetic tape, or a Universal Serial Bus (USB) drive or a
combination of two or more of these. Storage 118 may include
removable or non-removable (or fixed) media, where appropriate.
Storage 118 may be internal or external to transmission site 102,
where appropriate. In particular embodiments, storage 118 may be
non-volatile, solid-state memory. In particular embodiments,
storage 118 may include read-only memory (ROM). Where appropriate,
this ROM may be mask-programmed ROM, programmable ROM (PROM),
erasable PROM (EPROM), electrically erasable PROM (EEPROM),
electrically alterable ROM (EAROM), or flash memory or a
combination of two or more of these. Storage 118 may take any
suitable physical form and may comprise any suitable number or type
of storage. Storage 118 may include one or more storage control
units facilitating communication between processor 112 and storage
118, where appropriate.
[0033] In particular embodiments, interface 120 may include
hardware, encoded software, or both providing one or more
interfaces for communication (such as, for example, packet-based
communication) between transmission sites 102, endpoints 104, any
networks, any network devices, or any other computer systems. As an
example and not by way of limitation, communication interface 120
may include a network interface controller (NIC) or network adapter
for communicating with an Ethernet or other wire-based network or a
wireless NIC (WNIC) or wireless adapter for communicating with a
wireless network.
[0034] In some embodiments, interface 120 comprises one or more
radios coupled to one or more antenna ports 110. In such an
embodiment, interface 120 receives digital data that is to be sent
out to wireless devices, such as endpoints 104, via a wireless
connection. The radio may convert the digital data into a radio
signal having the appropriate center frequency, bandwidth
parameters, and transmission power. Similarly, the radios may
convert radio signals received via one or more receiving antennas
into digital data to be processed by, for example, processor
112.
[0035] Depending on the embodiment, interface 120 may be any type
of interface suitable for any type of network for which system 100
is used. As an example and not by way of limitation, system 100 may
communicate with an ad-hoc network, a personal area network (PAN),
a LAN, a WAN, a MAN, or one or more portions of the Internet or a
combination of two or more of these. One or more portions of one or
more of these networks may be wired or wireless. As an example,
system 100 may communicate with a wireless PAN (WPAN) (such as, for
example, a BLUETOOTH WPAN), a WI-FI network, a WI-MAX network, an
LTE network, an LTE-A network, a cellular telephone network (such
as, for example, a Global System for Mobile Communications (GSM)
network), or any other suitable wireless network or a combination
of two or more of these. Transmission site 102 may include any
suitable interface 120 for any one or more of these networks, where
appropriate.
[0036] In some embodiments, interface 120 may include one or more
interfaces for one or more I/O devices. One or more of these I/O
devices may enable communication between a person and transmission
site 102. As an example and not by way of limitation, an I/O device
may include a keyboard, keypad, microphone, monitor, mouse,
printer, scanner, speaker, still camera, stylus, tablet,
touchscreen, trackball, video camera, another suitable I/O device
or a combination of two or more of these. An I/O device may include
one or more sensors. Particular embodiments may include any
suitable type or number of I/O devices and any suitable type or
number of interfaces 120 for them. Where appropriate, interface 120
may include one or more drivers enabling processor 112 to drive one
or more of these I/O devices. Interface 120 may include one or more
interfaces 120, where appropriate.
[0037] Bus 116 may include any combination of hardware, software
embedded in a computer readable medium, or encoded logic
incorporated in hardware or otherwise stored (e.g., firmware) to
couple components of transmission site 102 to each other. As an
example and not by way of limitation, bus 116 may include an
Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced
Industry Standard Architecture (EISA) bus, a front-side bus (FSB),
a HYPERTRANSPORT (HT) interconnect, an Industry Standard
Architecture (ISA) bus, an INFINIBAND interconnect, a low-pin-count
(LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a
Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X)
bus, a serial advanced technology attachment (SATA) bus, a Video
Electronics Standards Association local (VLB) bus, or any other
suitable bus or a combination of two or more of these. Bus 116 may
include any number, type, or configuration of buses 116, where
appropriate. In particular embodiments, one or more buses 116
(which may each include an address bus and a data bus) may couple
processor 112 to memory 114. Bus 116 may include one or more memory
buses.
[0038] Herein, reference to a computer-readable storage medium
encompasses one or more tangible computer-readable storage media
possessing structures. As an example and not by way of limitation,
a computer-readable storage medium may include a
semiconductor-based or other integrated circuit (IC) (such, as for
example, a field-programmable gate array (FPGA) or an
application-specific IC (ASIC)), a hard disk, an HDD, a hybrid hard
drive (HHD), an optical disc, an optical disc drive (ODD), a
magneto-optical disc, a magneto-optical drive, a floppy disk, a
floppy disk drive (FDD), magnetic tape, a holographic storage
medium, a solid-state drive (SSD), a RAM-drive, a SECURE DIGITAL
card, a SECURE DIGITAL drive, a flash memory card, a flash memory
drive, or any other suitable tangible computer-readable storage
medium or a combination of two or more of these, where
appropriate.
[0039] Particular embodiments may include one or more
computer-readable storage media implementing any suitable storage.
In particular embodiments, a computer-readable storage medium
implements one or more portions of processor 112 (such as, for
example, one or more internal registers or caches), one or more
portions of memory 114, one or more portions of storage 118, or a
combination of these, where appropriate. In particular embodiments,
a computer-readable storage medium implements RAM or ROM. In
particular embodiments, a computer-readable storage medium
implements volatile or persistent memory. In particular
embodiments, one or more computer-readable storage media embody
encoded software.
[0040] Herein, reference to encoded software may encompass one or
more applications, bytecode, one or more computer programs, one or
more executables, one or more instructions, logic, machine code,
one or more scripts, or source code, and vice versa, where
appropriate, that have been stored or encoded in a
computer-readable storage medium. In particular embodiments,
encoded software includes one or more application programming
interfaces (APIs) stored or encoded in a computer-readable storage
medium. Particular embodiments may use any suitable encoded
software written or otherwise expressed in any suitable programming
language or combination of programming languages stored or encoded
in any suitable type or number of computer-readable storage media.
In particular embodiments, encoded software may be expressed as
source code or object code. In particular embodiments, encoded
software is expressed in a higher-level programming language, such
as, for example, C, Perl, or a suitable extension thereof. In
particular embodiments, encoded software is expressed in a
lower-level programming language, such as assembly language (or
machine code). In particular embodiments, encoded software is
expressed in JAVA. In particular embodiments, encoded software is
expressed in Hyper Text Markup Language (HTML), Extensible Markup
Language (XML), or other suitable markup language.
[0041] Although FIG. 1 has been described above as including
particular components, the system of FIG. 1 may include any
combination of any of the described components and any of the
options or features described herein, as would be understood by one
of ordinary skill in the art. For example, any of the options or
features described herein may be utilized in combination with the
illustrated embodiments of FIG. 1 or any number of the other
options or features also described herein as would be understood by
one of ordinary skill in the art.
[0042] While various implementations and features are discussed
with respect to multiple embodiments, it should be understood that
such implementations and features may be combined in various
embodiments. For example, features and functionality discussed with
respect to a particular figure, such as FIG. 1, may be used in
connection with features and functionality discussed with respect
to another such figure, such as FIG. 2, 3, 4 or 5, according to
operational needs or desires.
[0043] FIGS. 2A and 2B depict example communication diagrams that
illustrate communications 200 used by transmission site 102 to
transmit information to one or more wideband endpoints 104a and one
or more narrowband endpoints 104b. The diagram of FIG. 2A depicts
communication 200a used to transmit information to wideband
endpoints 104a while the diagram of FIG. 2B depicts communication
200b used to transmit information to wideband endpoints 104a and
narrowband endpoints 104b. The horizontal axis of each diagram is
time and the vertical axis is frequency.
[0044] Communication 200a is divided into units of time (subframes
202) and frequency sets 204, that each include one or more
subcarrier frequencies. In the embodiment depicted, each subframe
202 represents the amount of time required to transmit twelve
symbols (e.g., 1 ms in an LTE-A transmission scheme) and each
frequency set 204a represents twelve contiguous subcarrier
frequencies. The subcarrier frequencies may be equally spaced apart
to reduce or eliminate interference between signals transmitted
using neighboring subcarrier frequencies. By way of example, a set
of contiguous subcarrier frequencies may include 3.000060 GHz,
3.000075 GHz, 3.000090 GHz, 3.000105 GHz, and so on. The
aggregation of frequency sets 204 represents the frequency range of
the communication 200a. That is, the frequency range spans from the
lowest frequency of set 204a to the highest frequency of set 204p
and includes each subcarrier frequency in between these two
frequencies.
[0045] In particular implementations, a set 204 of contiguous
subcarrier frequencies used to transmit one or more signals for a
particular amount of time may form a block. A block may include any
suitable number of subcarrier frequencies and any suitable number
of data symbols. For example, in an LTE-A communication scheme,
twelve contiguous subcarrier frequencies each transmitting six or
seven data symbols in a given amount of time (e.g., 0.5 ms) form a
physical resource block (PRB). Accordingly, the area of
communication 200a bounded by subframe 202a and frequency set 204a
may represent two PRBs.
[0046] A data symbol is a complex number with real or imaginary
components that map a group of bits to one or more modulation
characteristics of a carrier wave transmitted at a particular
subcarrier frequency. Groups of bits of data signals, control
signals, or other signals to be transmitted may be encoded into
data symbols associated with the signals. The data symbols may be
transmitted (generally after one or more processing steps) to one
or more endpoints 104 via carrier waves with modulated
characteristics defined by the data symbols (or the data symbols
that result from the processing of the original data symbols). As
an example, a data symbol may define a phase modulation or an
amplitude modulation of a carrier wave. The modulation
characteristics defined by the data symbol are determined by the
bits of the data signals, control signals, or other signals.
Particular embodiments may use quadrature phase-shift keying
(QPSK), quadrature amplitude modulation (QAM)16, or QAM64
modulation to generate data symbols from the bits of the
signals.
[0047] Various types of information may be sent between
transmission site 102 and endpoints 104. Examples of information
types include data signals 212, control signals 210, and other
signals. Data signals 212 are carried over a connection between a
transmission site 102 and an endpoint 104. For example and not by
way of limitation, data signals 212 may include information that
transmission site 102 receives from a network coupled to the
transmission site 102 (such as WSP network 106 or ISP network 108)
or from another endpoint 104 located in the same cell or a
different cell. In a particular embodiment, data signals 212 are
sent from a transmission site 102 to an endpoint 104 via a physical
downlink shared channel (PDSCH) as defined in the LTE-A
protocol.
[0048] Control signals 210 and other signals (such as
synchronization signals 206 and broadcast channel signals 208) sent
from a transmission site 102 to an endpoint 104 may be used to
setup and maintain a connection between the transmission site 102
and the endpoint 104. Control signals 210 may also include
information (e.g., scheduling or demodulation information) that
allows endpoint 104 to recover data signals 112 sent to the
endpoint 104. In particular embodiments, at least some of the
control signals 210 and other signals may conform to the LTE-A
standard. For example, in the embodiment depicted, synchronization
signals 206 may include primary synchronization signals (PSS) and
secondary synchronization signals (SSS), broadcast channel signals
208 may include physical broadcast channel (PBCH) signals, and
control signals 210 may include physical control format indicator
channel (PCFICH) signals and physical downlink control channel
(PDCCH) signals.
[0049] Synchronization signals 206 may include one or more
sequences that are known to endpoints 104. In the embodiment
depicted, synchronization signals 206 are transmitted in the first
subframe 202a and the sixth subframe 202f. In particular
embodiments, the transmission of synchronization signals 206 may be
repeated periodically (e.g., twice every ten subframes). When an
endpoint 104 begins receiving signals from transmission site 102
(e.g., upon powering on or entering a range of the transmission
site 102), the endpoint may search for synchronization signals 206
to determine a reference point in order to synchronize to the
communication from the transmission site 102. In particular
embodiments, the synchronization signals 206 are transmitted using
only a portion of the frequency range of the communication. For
example, the synchronization signals 206 may be transmitted using
subcarrier frequencies located in the narrowband. In the embodiment
depicted, synchronization signals 206 are transmitted using
frequency sets 204f-204k.
[0050] Broadcast channel signals 208 may also be transmitted
periodically using subcarrier frequencies located in the
narrowband. In the embodiment depicted, broadcast channel signals
208 are transmitted using the same subcarrier frequencies as the
synchronization signals 206. The broadcast channel signals 208 may
include configuration information of transmission site 102 and may
indicate how particular signals from transmission site 102 should
be decoded. Broadcast channel signals 208 may include information
that is common to all endpoints, such as the frequency range used
by the transmission site 102.
[0051] Control signals 210 facilitate decoding of data signals 212.
Control signals 210 may indicate which blocks of a communication
(e.g., a subframe 202) from transmission site 102 include data
signals 212 transmitted to each endpoint 104. For example, the
control signals 210 transmitted in a particular subframe 202a may
indicate particular blocks of the subframe 202a that include data
signals for a particular endpoint 104. Control signals 210 may also
indicate a modulation and code rate of any of the blocks that
include data signals 212. Control signals 210 may also include
information regarding a transmission scheme used by transmission
site 102, such as spatial multiplex, transmission diversity, open
loop MIMO, or closed loop MIMO. A portion of control signals 210
may indicate the length (e.g., number of data symbols) of another
portion of control signals 210. For example, in an LTE-A scheme, a
PCFICH signal included in control signals 210 may indicate the
length of a PDCCH signal included in control signals 210.
[0052] In the embodiment depicted, control signals 210 are
transmitted in wideband. That is, control signals 210 are
transmitted using subcarrier frequencies that span the entire
frequency range of the communication. Accordingly, only a wideband
endpoint 104a that is configured to sample the entire frequency
range and decode signals transmitted using any subcarrier frequency
of the frequency range may properly recover the control signals 210
and use the control signals 210 to recover the data signals 212
sent to the wideband endpoint 104a. Accordingly, the method of
communication depicted in communication 200a is not compatible with
narrowband endpoints 104b.
[0053] Communication 200b represents a type of communication that
is compatible with both wideband endpoints 104a and narrowband
endpoints 104b. Similar to communication 200a, communication 200b
is divided into units of time (subframes 222) and frequency sets
224. Communication 200b may have any suitable characteristics of
communication 200a described above.
[0054] Similar to communication 200a, communication 200b depicts
the periodic transmission of synchronization signals 206 and
broadcast channel signals 208 using subcarrier frequencies within
the narrowband. In the embodiment depicted, the narrowband includes
frequency sets 224f-224k. Communication 200b also includes wideband
enhanced control signals multiplexed with data signals 214 and
narrowband enhanced control signals multiplexed with data signals
216.
[0055] The enhanced control signals present in signals 214 and 216
may include any suitable information, such as that described above
with respect to control signals 210. Communication methods
utilizing these enhanced control signals may provide various
advantages over communication schemes that are limited to
transmission of control signals 210. For example, the enhanced
control signals may allow transmission site 102 to communicate with
a narrowband endpoint 104b. As other examples, the enhanced control
signals may support increased control channel capacity and improved
spatial reuse of control channel resources relative to
communication schemes using only control signals 210. The enhanced
control signals may also support frequency-domain inter-cell
interference coordination (ICIC), beamforming, or diversity. In
particular embodiments, the enhanced control signals present in
signals 214 and 216 may implement one or more features of the
enhanced PDCCH set forth in 3GPP LTE-A Release 11.
[0056] Signals 216 include narrowband enhanced control signals
multiplexed with data signals using frequency division
multiplexing. That is, at any particular time, some subcarrier
frequencies within the narrowband may be transmitting enhanced
control signals and some may be transmitting data signals. In
particular embodiments, these signals are multiplexed according to
blocks of two or more subcarrier frequencies. For example, the
subcarrier frequencies of a particular block (such as a PRB) may
each carry the same type of signal--either an enhanced control
signal or a data signal. Signals 214 are multiplexed in a similar
manner, but these signals are transmitted using subcarrier
frequencies that are outside of the narrowband.
[0057] A control signal (such as a control signal 210 or an
enhanced control signal) may be addressed to one or more particular
endpoints 104 or it may be addressed to all of the endpoints 104
that transmission site 102 communicates with. A control signal may
be addressed to one or more endpoints 104 in any suitable manner.
In particular embodiments, a control signal may explicitly identify
the one or more endpoints to which the control signal is addressed.
A control signal may alternatively include a portion that is based
on the particular endpoint or endpoints that the control signal is
addressed to. For example, in a particular embodiment, cyclic
redundancy check (CRC) data of the control signal may be determined
based on an identifier of the destination endpoint. Accordingly,
the endpoint 104 may detect that the control signal is addressed to
the endpoint by analyzing the CRC data of the control signal in
combination with the identifier of the endpoint 104. The identifier
may be any suitable information, such as a physical address of the
endpoint 104. In particular embodiments, a control signal may be
implicitly addressed to one or more endpoints 104 by sending a
message prior to the sending of the control signal that indicates
the subcarrier frequencies and times that will be used to send the
control signal. As another example, endpoints 104 may be
preconfigured to expect a particular control signal that is sent to
all endpoints 104 using a particular set of frequencies and
times.
[0058] To facilitate the processing of control signals, one or more
search spaces may be defined for the endpoints 104. A common search
space is a group of subcarrier frequencies that are designated to
transmit control signals that are common to all endpoints 104. An
endpoint-specific search space is a group of subcarrier frequencies
that are designated for the transmission of control signals to a
particular endpoint 104. Accordingly, each endpoint 104 may locate
control signals that are addressed to the endpoint 104 by searching
the common search space and its own endpoint-specific search space.
The search spaces may be identified by the endpoints 104 in any
suitable manner. For example, the endpoints 104 may be
preconfigured with one or more of the search spaces or the search
spaces may be transmitted to the endpoints by transmission site
102. Because a common search space is broadcast in nature,
transmission site 102 may communicate control signals using
subcarrier frequencies in the common search space using
space-frequency block coding (SFBC) or open-loop MIMO, while
avoiding beamforming or closed loop MIMO.
[0059] The narrowband portion of the frequency range that includes
the narrowband enhanced control signals multiplexed with data
signals 216 may be located anywhere within the frequency range.
Because a narrowband endpoint 104b should be able to sample and
decode a frequency range that includes synchronization signals 206
and broadcast channel signals 208 to operate properly, in
particular embodiments the narrowband includes the frequencies at
which the synchronization signals 206 and broadcast channel signals
208 are transmitted. For example, in the embodiment depicted, the
narrowband includes the frequencies within frequency sets
224f-224k. However, the narrowband portion may be widened to
include additional frequencies or narrowed to include less
frequencies. Although the narrowband is centered around the middle
of the frequency range, the narrowband portion may be located
anywhere within the frequency range. For example, the narrowband
may include frequency sets 224a-224f, 224k-224p, or any other
suitable combination of contiguous subcarrier frequencies.
[0060] FIG. 3 depicts an example method for transmitting control
signals, data signals, and other signals to wideband endpoints 104a
and narrowband endpoints 104b that may be performed by transmission
site 102. For purposes of simplicity, the illustrated steps of the
method of FIG. 3 are described from the perspective of a
transmission site 102 though they could be performed by any
suitable transceiver or multiple transceivers. The method begins at
step 302, where at least one search space is assigned for the
narrowband endpoints in the narrowband portion of the frequency
range. For example, transmission site 102 may designate one or more
subcarrier frequencies for transmission of control signals that are
addressed to the narrowband endpoints 104b. These subcarrier
frequencies are located within the narrowband. The search spaces
may be endpoint-specific search spaces designated for control
signals that are addressed to one or more particular narrowband
endpoints 104b or common search spaces for control signals
addressed to all of the endpoints 104b (assuming that the
transmission site 102 communicates with at least one narrowband
endpoint 104b). In particular embodiments, the search spaces
applicable to a particular narrowband endpoint 104b (i.e., the
subcarrier frequencies that will transmit control signals addressed
to the narrowband endpoint 104b) may be communicated to the
narrowband endpoint 104b by transmission site 102 before a
communication 200b including data for the narrowband endpoint 104b
is sent to narrowband endpoint 104b.
[0061] At step 304, at least one search space is assigned for the
wideband endpoints within the frequency range. For example,
transmission site 102 may designate one or more subcarrier
frequencies for transmission of control signals that are addressed
to the wideband endpoints 104a. These subcarrier frequencies may be
located anywhere within the frequency range, including the
narrowband if frequencies are available. These search spaces may be
designated for control signals that are addressed to one or more
particular wideband endpoints 104a (e.g., the search spaces may be
endpoint-specific search spaces). In particular embodiments, the
search space applicable to a particular wideband endpoint 104a
(i.e., the subcarrier frequencies that will transmit control
signals addressed to the wideband endpoint 104a) may be
communicated to the wideband endpoint 104a by transmission site 102
before a communication 200b including data for the wideband
endpoint 104a is sent to wideband endpoint 104a.
[0062] At step 306, wideband control signals, narrowband
synchronization signals, and narrowband broadcast channel signals
are scheduled. Scheduling a signal may include determining one or
more subcarrier frequencies that will transmit the signal and one
or more times at which the designated subcarrier frequencies will
transmit the signal. As an example of step 302, transmission site
102 may schedule control signals 210, synchronization signals 206,
and broadcast signals 208. A wideband control signal refers to a
control signal that is transmitted using at least one subcarrier
frequency located outside of the narrowband portion of the
frequency range. A narrowband synchronization signal refers to a
synchronization signal that is transmitted using subcarrier
frequencies that are each inside of the narrowband. Similarly, a
narrowband broadcast channel signal refers to a broadcast channel
signal that is transmitted using subcarrier frequencies that are
each inside of the narrowband.
[0063] At step 308, enhanced control signals are scheduled for
transmission in appropriate search spaces. For example, in an
enhanced control signal is addressed to all endpoints 104, it is
placed in a common search space in the narrowband. As another
example, if an enhanced control signal is addressed to one or more
particular narrowband endpoints 104b, then the enhanced control
signal is scheduled within the appropriate endpoint-specific search
space(s) in the narrowband. As yet another example, if an enhanced
control signal is addressed to one or more particular wideband
endpoints 104a, then it may be placed within the appropriate
endpoint-specific search space(s) in either the narrowband or the
outside of the narrowband.
[0064] At step 310, data is scheduled for narrowband endpoints
within the narrowband portion of the frequency range. As an
example, transmission site 102 may schedule data signals for
transmission to one or more narrowband endpoints 104b using blocks
with subcarrier frequencies located within the narrowband that are
not used for the transmission of other signals, such as
synchronization signals 206, broadcast channel signals 208, or
enhanced control signals. In particular embodiments, transmission
site 102 may schedule data signals for transmission to one or more
narrowband endpoints 104b using blocks with subcarrier frequencies
located outside the narrowband if the narrowband endpoint 104b is
capable of decoding these data signals using control signals
transmitted using subcarrier frequencies in the narrowband as
illustrated in further detail in FIG. 5.
[0065] At step 312, data is scheduled for wideband endpoints within
the frequency range. As an example, transmission site 102 may
schedule data signals for transmission to one or more wideband
endpoints 104a using any available blocks that are not used for the
transmission of other signals, such as synchronization signals 206,
broadcast channel signals 208, or enhanced control signals.
[0066] At step 314, wideband control signals are transmitted. For
example, transmission site 102 may transmit control signals 210 via
subcarrier frequencies that span the entire frequency range. As
depicted in communication diagram 200b, the control signals 210 are
sent at the beginning of each subframe 222.
[0067] At step 316, multiplexed data and enhanced control signals
are transmitted. For example, transmission site 102 may transmit
wideband enhanced control signals multiplexed with data signals 214
and narrowband enhanced control signals multiplexed with data
signals 216. The enhanced control signals and the data signals may
be multiplexed using frequency division multiplexing. Accordingly,
at any given time, particular subcarrier frequencies may transmit
data signals while other subcarrier frequencies may transmit
enhanced control signals. At a different point in time, a different
set of subcarrier frequencies may transmit data signals while other
subcarrier frequencies transmit enhanced control signals.
[0068] At step 318, narrowband synchronization signals are
transmitted. For example, transmission site may transmit
synchronization signals 206 using subcarrier frequencies within the
narrowband. Simultaneously with this transmission, wideband
enhanced control signals multiplexed with data signals 214 may be
transmitted outside of the narrowband. In embodiments, where the
narrowband includes subcarrier frequencies that are not utilized
during transmission of synchronization signals 206, these
subcarrier frequencies may be used to transmit narrowband enhanced
control signals multiplexed with data signals 216 simultaneously
with the transmission of synchronization signals 206.
[0069] At step 320, narrowband broadcast channel signals are
transmitted and the method ends. For example, transmission site may
transmit broadcast channel signals 208 using subcarrier frequencies
within the narrowband. Simultaneously with this transmission,
wideband enhanced control signals multiplexed with data signals 214
may be transmitted outside of the narrowband. In embodiments, where
the narrowband includes subcarrier frequencies that are not
utilized during transmission of broadcast channel signals 208,
these subcarrier frequencies may be used to transmit narrowband
enhanced control signals multiplexed with data signals 216
simultaneously with the transmission of broadcast channel signals
208.
[0070] Some of the steps illustrated in FIG. 3 may be combined,
modified or deleted where appropriate, and additional steps may
also be added to the flowchart. Any of the steps may be repeated.
Additionally, steps may be performed in any suitable order without
departing from the scope of particular embodiments. Moreover, two
or more of the steps of the method may be performed simultaneously
in particular embodiments. Although, the steps of FIG. 3 have been
described with respect to a transmission site 102, they may be
performed by any suitable transceiver.
[0071] FIG. 4 depicts an example method for processing control
signals and data signals that may be performed by narrowband
endpoint 104b. For purposes of simplicity, the illustrated steps of
the method of FIG. 4 are described from the perspective of an
endpoint 104 although they could be performed by any suitable
transceiver. The method begins at step 402 in which narrowband
endpoint 104b enters an idle or dormant state. When endpoint 104b
is in an idle state, it does not transmit or receive data, and thus
operates in a power conserving mode. The endpoint 104b may
periodically wake up and analyze a communication from transmission
site 102 to determine whether the communication includes a paging
message for the endpoint 104b that indicates that data is to be
transmitted to the endpoint. If a paging message is not present,
the endpoint 104b may return to the idle state until it is
scheduled to wake up and check again for a paging message. In the
idle state, endpoint 104b may not have an active connection to a
transmission site 102, so the endpoint 104b may need to perform a
random access procedure to establish a connection with transmission
site 102 before transmitting or receiving data signals. When
endpoint 104b is in a dormant state, it does not transmit or
receive data, and thus operates in a power conserving mode.
However, a dormant endpoint 104b is connected to at least one
transmission site 102 and wakes up more often than an idle
endpoint. Upon waking up, the endpoint 104b may check to see if a
communication from a transmission site 102 includes data signals
for the endpoint 104b. If the communication does not, endpoint 104b
will go back to a dormant state. If a dormant endpoint has not
received data for a predetermined period of time, it may enter an
idle state.
[0072] At step 404, the endpoint waits a predetermined period of
time before waking up. As an example and not by way of limitation,
a dormant endpoint may wait five seconds and an idle endpoint may
wait two hundred milliseconds. At step 406, endpoint 104b wakes up
and performs baseband sampling at the narrow bandwidth (i.e., in
the narrowband). That is, endpoint 104b samples a transmission from
transmission site 102 at a sufficient rate to recover the
narrowband portion of the frequency range. The sampling rate of an
ADC that samples at the narrowband may be lower than the sampling
rate required that samples at the entire frequency range. The
narrowband sampling also results in a reduction of the amount of
memory required to store the samples.
[0073] At step 408, narrowband processing is performed in the
common search space and the endpoint-specific search space
associated with the endpoint 104b to decode enhanced control
signals. Processing may include any suitable operations that
facilitate decoding of the enhanced control signals. For example,
processing may include filtering the sampled signals, performing
discrete Fourier transforms (DFT) on the sampled signals,
demodulation of the sampled signals, or other suitable processing.
The processed signals are then analyzed to determine whether any of
these signals include an enhanced control signal addressed to the
endpoint 104b. In particular embodiments, this analysis may include
checking a CRC value of an enhanced control signal in combination
with a physical address of the endpoint 104b to determine whether
the enhanced control signal is addressed to the endpoint 104. As
other examples, this analysis may involve a determination that an
enhanced control signal is a control signal addressed to all
endpoints 104 because it was transmitted using a particular block
or because it includes information indicating that it is addressed
to all endpoints 104.
[0074] At step 410, the control signals addressed to the endpoint
104b are decoded and it is determined whether the communication
from transmission site 102 includes data for endpoint 104b. For
example, the communication may include at least a portion of a
paging message or one or more data signals sent to the endpoint
104b. If there is no data present, endpoint 104b returns to an idle
or dormant state at step 402. If data for the endpoint 104b is
present, the endpoint performs narrowband processing to decode the
data at step 412. That is, the endpoint may perform processing on
information transmitted using subcarrier frequencies that are
within the narrowband. The processing performed to decode the data
signals may be similar to the processing performed to decode the
enhanced control signals. In particular embodiments, the enhanced
control signals may specify which blocks of the transmission
include data signals for the endpoint 104b. The endpoint 104b may
use this information to decode these blocks to recover the data
signals.
[0075] At step 414, endpoint 104b determines whether wideband
operation should be performed. That is, endpoint 104b determines
whether it should change its configuration to operate as a wideband
endpoint 104a. If endpoint 104b determines that it should not
change its configuration, then it continues processing
communications from transmission site 102 in a narrowband mode.
That is, endpoint 104b will perform sampling at the narrowband
portion and will only decode control signals transmitted via
subcarrier frequencies located in the narrowband. If endpoint 104b
determines that it should change its configuration, then the
endpoint samples and processes future communications from
transmission site 102 in a wideband mode at step 418. That is,
endpoint 104 may perform sampling on the entire frequency range and
may decode control signals transmitted via any of the subcarrier
frequencies of the frequency range, including those outside of the
narrowband. Such functionality allows endpoint 104 to conserve
power by operating in a narrowband mode as it repeatedly wakes up
from an idle or dormant state to check a communication for data and
then to reconfigure to a wideband mode to receive data more quickly
when data is being transmitted to the endpoint 104. If a narrowband
endpoint 104b is only capable of operating in a narrowband mode,
steps 414 and 418 may be omitted from the method. In particular
embodiments, transmission site 102 may be operable to detect that a
narrowband endpoint 104b is configured to switch to a wideband mode
and thus only limits control signals and data signals to the
narrowband portion on the first communication (e.g., subframe),
while the control signals and data signals may be transmitted using
any suitable subcarrier frequencies within the frequency range in
subsequent communications.
[0076] Some of the steps illustrated in FIG. 4 may be combined,
modified or deleted where appropriate, and additional steps may
also be added to the flowchart. Any of the steps may be repeated.
Additionally, steps may be performed in any suitable order without
departing from the scope of particular embodiments. Moreover, two
or more of the steps of the method may be performed simultaneously
in particular embodiments. Although, the steps of FIG. 4 have been
described with respect to an endpoint 104, they may be performed by
any suitable transceiver.
[0077] FIG. 5 depicts an example method for processing control
signals and data signals that may be performed by the narrowband
endpoint 104b. Steps 502 and 504 are similar to steps 402 and 404
of FIG. 4. At step 506, endpoint 104b performs baseband sampling at
full bandwidth. That is, endpoint 104b samples a transmission from
transmission site 102 at a sufficient rate to recover the entire
frequency range. While this may require a faster ADC sampling rate
and additional memory to store the samples as compared to baseband
sampling at the narrowband, this method allows data signals sent to
the endpoint 104b to be included in the wideband portion of the
frequency range on the first transmission, as explained in greater
detail below.
[0078] At step 508, narrowband processing in the common search
space and the endpoint-specific search space is performed to decode
enhanced control signals transmitted using subcarrier frequencies
within the narrowband. This step may be similar to step 408 of FIG.
4. At step 510, it is determined whether data for the endpoint 104b
is included in the communication. If there is no data present, the
method returns to step 502. If there is data present, endpoint 104b
determines whether the data is limited to the narrowband portion of
the frequency range. That is, endpoint 104b may determine whether
data signals for the endpoint are transmitted using only subcarrier
frequencies in the narrowband. If so, step 514, which is similar to
step 412, is performed. If at least one data signal is transmitted
using subcarrier frequencies outside of the narrowband, then
wideband processing is performed to decode the data signals. The
wideband processing may include any suitable operations that
facilitate decoding of the data signals. For example, processing
may include filtering the sampled signals, performing discrete
fourier transforms (DFT) on the sampled signals, demodulation of
the sampled signals, or other suitable processing. Wideband
processing may include more complex processing than narrowband
processing. For example, wideband processing may include performing
larger DFTs on the sampled signals. Wideband processing results in
the recovery of data signals transmitted using subcarrier
frequencies that are outside of the narrowband portion of the
frequency range. In particular embodiments, enhanced control
signals located within the narrowband portion of the frequency
range may specify blocks outside of the narrowband that include
data signals for the endpoint 104b. The endpoint 104b may use this
information to decode these blocks to recover the data signals.
[0079] At step 518, endpoint 104b determines whether wideband
operation should be performed. This step may be similar to step 414
of FIG. 4. If endpoint 104b determines that it should not change
its configuration to wideband operation, endpoint 104b maintains
its sampling and processing procedure at step 520. For example,
endpoint 104b may continue processing communications in the manner
described in steps 502-516. If endpoint 104b determines that it
should change its configuration to wideband operation, then the
endpoint samples and processes future communications from
transmission site 102 in a wideband mode. That is, endpoint 104
will perform sampling on the entire frequency range and will decode
signals transmitted via any of the subcarrier frequencies of the
frequency range, including those outside of the narrowband.
[0080] The method of FIG. 5 allows data signals to be transmitted
using subcarrier frequencies outside of the narrowband to an
endpoint that is only configured to decode control signals
transmitted via subcarrier frequencies located in the narrowband.
Such embodiments may speed up the data transfer process.
[0081] Some of the steps illustrated in FIG. 5 may be combined,
modified or deleted where appropriate, and additional steps may
also be added to the flowchart.
[0082] Any of the steps may be repeated. Additionally, steps may be
performed in any suitable order without departing from the scope of
particular embodiments. Moreover, two or more of the steps of the
method may be performed simultaneously in particular embodiments.
Although, the steps of FIG. 5 have been described with respect to
an endpoint 104, they may be performed by any suitable
transceiver.
[0083] Various embodiments of the present disclosure may provide
one or more technical advantages. Technical advantages of
particular embodiments include performing less complex computations
when sampling and processing a communication from a transmission
site. Another technical advantage may include a decreased cost for
manufacturing an endpoint. Another technical advantage may include
less power consumption. Other technical advantages will be readily
apparent to one of ordinary skill in the art from the following
figures, descriptions, and claims. Moreover, while specific
advantages have been enumerated above, various embodiments may
include all, some, or none of the enumerated advantages.
[0084] Although particular embodiments have been described in
detail, it should be understood that various other changes,
substitutions, and alterations may be made hereto without departing
from the spirit and scope of particular embodiments. For example,
although an embodiment has been described with reference to a
number of elements included within transmission site 102 and
endpoints 104 such as a processors, memories, storages, interfaces,
and buses, these elements may be combined, rearranged or positioned
in order to accommodate particular wireless architectures or needs.
In addition, any of these elements may be provided as separate
external components to transmission site 102, endpoints 104, or
each other where appropriate. Particular embodiments contemplate
great flexibility in the arrangement of these elements as well as
their internal components.
[0085] Numerous other changes, substitutions, variations,
alterations and modifications may be ascertained by those skilled
in the art and it is intended that particular embodiments encompass
all such changes, substitutions, variations, alterations and
modifications as falling within the spirit and scope of the
appended claims.
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