U.S. patent application number 11/237328 was filed with the patent office on 2010-04-01 for reconfigurable orthogonal frequency division multiplexing (ofdm) chip supporting single weight diversity.
Invention is credited to Pieter van Rooyen.
Application Number | 20100080314 11/237328 |
Document ID | / |
Family ID | 37564175 |
Filed Date | 2010-04-01 |
United States Patent
Application |
20100080314 |
Kind Code |
A9 |
van Rooyen; Pieter |
April 1, 2010 |
Reconfigurable orthogonal frequency division multiplexing (OFDM)
chip supporting single weight diversity
Abstract
A method and system for a reconfigurable orthogonal frequency
division multiplexing (OFDM) chip supporting single weight
diversity are provided. The reconfigurable OFDM chip may be
configured to process signals such as IEEE 802.11, 802.16, and
digital video broadcasting (DVB). The OFDM chip may generate
channel weights to be applied to signals received in receive
antennas. The weighted signals may be combined into a single
received signal and channel estimates may be generated from the
single received signal. Updated channel weights may be generated
from the generated channel estimates. Updates to the channel
weights may be performed dynamically. The configurable OFDM chip
may be utilized to provide collaborative cellular and OFDM-based
communication. The reconfigurable OFDM chip and the cellular chip
may communicate data and/or control information via a memory
coupled to a common bus.
Inventors: |
van Rooyen; Pieter; (San
Diego, CA) |
Correspondence
Address: |
MCANDREWS HELD & MALLOY, LTD
500 WEST MADISON STREET
SUITE 3400
CHICAGO
IL
60661
US
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20070071126 A1 |
March 29, 2007 |
|
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Family ID: |
37564175 |
Appl. No.: |
11/237328 |
Filed: |
September 28, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10645349 |
Aug 21, 2003 |
7148845 |
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11237328 |
Sep 28, 2005 |
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60405285 |
Aug 21, 2002 |
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Current U.S.
Class: |
375/267 |
Current CPC
Class: |
H04L 27/2647 20130101;
H04L 25/0206 20130101; H04B 7/0848 20130101; H04L 27/2649
20130101 |
Class at
Publication: |
375/267 |
International
Class: |
H04L 1/02 20060101
H04L001/02 |
Claims
1. A method for handling wireless communication, the method
comprising applying, within a single chip, at least one of a
plurality of channel weights generated within said single chip to
at least one of a plurality of signals received via a plurality of
antennas in a single orthogonal frequency division multiplexing
(OFDM) receiver.
2. The method according to claim 1, further comprising combining
said plurality of signals received via said plurality of antennas
to generate a single combined received signal.
3. The method according to claim 2, further comprising determining
a plurality of channel estimates based on said generated single
combined received signal.
4. The method according to claim 3, further comprising selecting an
integration time for determining said plurality of channel
estimates.
5. The method according to claim 3, further comprising determining
at least one of a plurality of subsequent channel weights based on
said determined plurality of channel estimates.
6. The method according to claim 1, wherein one of said plurality
of signals received via said plurality of antennas is a reference
signal.
7. The method according to claim 1, further comprising configuring
said single chip in said OFDM receiver to handle at least one of a
plurality of communication protocols based on OFDM.
8. The method according to claim 7, wherein said at least one of
said plurality of communication protocols based on OFDM is an IEEE
802.11 wireless local area network (WLAN) protocol, an IEEE 802.16
wireless metropolitan area network (WMAN) protocol, or a digital
video broadcasting (DVB) protocol.
9. The method according to claim 1, further comprising updating at
least a portion of said at least one of said plurality of channel
weights dynamically.
10. The method according to claim 1, further comprising determining
a phase and amplitude component for said at least one of said
plurality of channel weights.
11. A system for handling wireless communication, the system
comprising circuitry within a single chip that applies at least one
of a plurality of channel weights generated within said single chip
to at least one of a plurality of signals received via a plurality
of antennas in a single orthogonal frequency division multiplexing
(OFDM) receiver.
12. The system according to claim 11, wherein said circuitry within
said single chip combines said plurality of signals received via
said plurality of antennas to generate a single combined received
signal.
13. The system according to claim 12, wherein said circuitry within
said single chip determines a plurality of channel estimates based
on said generated single combined received signal.
14. The system according to claim 13, further comprising a
processor coupled to said single chip, wherein said processor
selects an integration time for determining said plurality of
channel estimates.
15. The system according to claim 13, wherein said circuitry within
said single chip determines at least one of a plurality of
subsequent channel weights based on said determined plurality of
channel estimates.
16. The system according to claim 11, wherein one of said plurality
of signals received via said plurality of antennas is a reference
signal.
17. The system according to claim 11, further comprising a
processor coupled to said single chip, wherein said processor
configures said single chip in said OFDM receiver to handle at
least one of a plurality of communication protocols based on
OFDM.
18. The system according to claim 17, wherein said at least one of
said plurality of communication protocols based on OFDM is an IEEE
802.11 wireless local area network (WLAN) protocol, an IEEE 802.16
wireless metropolitan area network (WMAN) protocol, or a digital
video broadcasting (DVB) protocol.
19. The system according to claim 11, wherein said circuitry within
said single chip updates at least a portion of said at least one of
said plurality of channel weights dynamically.
20. The system according to claim 11, wherein said circuitry within
said single chip determines a phase and amplitude component for
said at least one of said plurality of channel weights.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY
REFERENCE
[0001] This application makes reference to: [0002] U.S. application
Ser. No. ______ (Attorney Docket No. 16847US01) filed Sep. 28,
2005; and [0003] U.S. application Ser. No. ______ (Attorney Docket
No. 16848US01) filed Sep. 28, 2005.
[0004] Each of the above stated applications is hereby incorporated
by reference in its entirety.
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0005] [Not Applicable]
MICROFICHE/COPYRIGHT REFERENCE
[0006] [Not Applicable]
FIELD OF THE INVENTION
[0007] Certain embodiments of the invention relate to processing of
signals in communication systems. More specifically, certain
embodiments of the invention relate to a reconfigurable orthogonal
frequency division multiplexing (OFDM) chip supporting single
weight diversity.
BACKGROUND OF THE INVENTION
[0008] Mobile communications has changed the way people communicate
and mobile phones have been transformed from a luxury item to an
essential part of every day life. The use of mobile devices is
today dictated by social situations, rather than hampered by
location or technology. While voice connections fulfill the basic
need to communicate, and mobile voice connections continue to
filter even further into the fabric of every day life, the mobile
Internet is the next step in the mobile communication revolution.
The mobile Internet and/or mobile video are poised to become a
common source of everyday information, and easy, versatile mobile
access to this data will be taken for granted.
[0009] Third generation (3G) cellular networks, for example, have
been specifically designed to fulfill these future demands of the
mobile devices. As these services grow in popularity and usage,
factors such as cost efficient optimization of network capacity and
quality of service (QoS) will become even more essential to
cellular operators than it is today. These factors may be achieved
with careful network planning and operation, improvements in
transmission methods, and advances in receiver techniques. To this
end, carriers need technologies that will allow them to increase
downlink throughput and, in turn, offer advanced QoS capabilities
and speeds that rival those delivered by cable modem and/or DSL
service providers. In this regard, networks based on wideband CDMA
(WCDMA) technology may make the delivery of data to end users a
more feasible option for today's wireless carriers. The GPRS and
EDGE technologies may be utilized for enhancing the data throughput
of present second generation (2G) systems such as GSM. Moreover,
HSDPA technology is an Internet protocol (IP) based service,
oriented for data communications, which adapts WCDMA to support
data transfer rates on the order of 10 megabits per second
(Mbits/s).
[0010] In addition to cellular technologies, technologies such as
those developed under the IEEE 802.11 and 802.16 standards, and/or
the digital video broadcasting (DVB) standard, may also be utilized
to fulfill these future demands of the mobile devices. For example,
wireless local area networks (WLAN), wireless metropolitan area
networks (WMAN), and DVB networks may be adapted to support mobile
Internet an/or mobile video applications, for example. The digital
video broadcasting (DVB) standard, for example, is a set of
international open standards for digital television maintained by
the DVB Project, an industry consortium, and published by a Joint
Technical Committee (JTC) of European Telecommunications Standards
Institute (ETSI), European Committee for Electrotechnical
Standardization (CENELEC) and European Broadcasting Union (EBU).
The DVB systems may distribute data by satellite (DVB-S), by cable
(DVB-C), by terrestrial television (DVB-T), and by terrestrial
television for handhelds (DVB-H). The standards may define the
physical layer and data link layer of the communication system. In
this regard, the modulation schemes used may differ in accordance
to technical and/or physical constraints. For example, DVB-S may
utilize QPSK, DVB-C may utilize QAM, and DVB-T and DVB-H may
utilize OFDM in the very high frequency (VHF)/ultra high frequency
(UHF) spectrum.
[0011] These networks may be based on frequency division
multiplexing (FDM). The use of FDM systems may result in higher
transmission rates by enabling the simultaneous transmission of
multiple signals over a single wireline or wireless transmission
path. Each of these signals may comprise a carrier frequency
modulated by the information to be transmitted. In this regard, the
information transmitted in each signal may comprise video, audio,
and/or data, for example. The orthogonal FDM (OFDM) spread spectrum
technique may be utilized to distribute information over many
carriers that are spaced apart at specified frequencies. The OFDM
technique may also be referred to as multi-carrier or discrete
multi-tone modulation. The spacing between carriers prevents the
demodulators in a radio receiver from seeing frequencies other than
their own. This technique may result in spectral efficiency and
lower multi-path distortion, for example.
[0012] In both cellular and OFDM-based networks, the effects of
multipath and signal interference may degrade the transmission rate
and/or quality of the communication link. In this regard, multiple
transmit and/or receive antennas may be utilized to mitigate the
effects of multipath and/or signal interference on signal reception
and may result in an improved overall system performance. These
multi-antenna configurations may also be referred to as smart
antenna techniques. It is anticipated that smart antenna techniques
may be increasingly utilized both in connection with the deployment
of base station infrastructure and mobile subscriber units in
cellular systems to address the increasing capacity demands being
placed on those systems. These demands arise, in part, from a shift
underway from current voice-based services to next-generation
wireless multimedia services that provide voice, video, and data
communication.
[0013] The utilization of multiple transmit and/or receive antennas
is designed to introduce a diversity gain and to suppress
interference generated within the signal reception process. Such
diversity gains improve system performance by increasing received
signal-to-noise ratio, by providing more robustness against signal
interference, and/or by permitting greater frequency reuse for
higher capacity. In communication systems that incorporate
multi-antenna receivers, a set of M receive antennas may be
utilized to null the effect of (M-1) interferers, for example.
Accordingly, N signals may be simultaneously transmitted in the
same bandwidth using N transmit antennas, with the transmitted
signal then being separated into N respective signals by way of a
set of N antennas deployed at the receiver. Systems that utilize
multiple transmit and receive antennas may be referred to as
multiple-input multiple-output (MIMO) systems. One attractive
aspect of multi-antenna systems, in particular MIMO systems, is the
significant increase in system capacity that may be achieved by
utilizing these transmission configurations. For a fixed overall
transmitted power, the capacity offered by a MIMO configuration may
scale with the increased signal-to-noise ratio (SNR). For example,
in the case of fading multipath channels, a MIMO configuration may
increase system capacity by nearly M additional bits/cycle for each
3-dB increase in SNR.
[0014] However, the widespread deployment of multi-antenna systems
in wireless communications, particularly in wireless handset
devices, has been limited by the increased cost that results from
increased size, complexity, and power consumption. Providing
separate RF chain for each transmit and receive antenna is a direct
factor that increases the cost of multi-antenna systems. Each RF
chain generally comprises a low noise amplifier (LNA), a filter, a
downconverter, and an analog-to-digital converter (A/D). In certain
existing single-antenna wireless receivers, the single required RF
chain may account for over 30% of the receiver's total cost. It is
therefore apparent that as the number of transmit and receive
antennas increases, the system complexity, power consumption, and
overall cost may increase. This poses problems for mobile system
designs and applications.
[0015] Further limitations and disadvantages of conventional and
traditional approaches will become apparent to one of skill in the
art, through comparison of such systems with some aspects of the
present invention as set forth in the remainder of the present
application with reference to the drawings.
BRIEF SUMMARY OF THE INVENTION
[0016] A system and/or method is provided for a reconfigurable
orthogonal frequency division multiplexing (OFDM) chip supporting
single weight diversity, substantially as shown in and/or described
in connection with at least one of the figures, as set forth more
completely in the claims.
[0017] These and other features and advantages of the present
invention may be appreciated from a review of the following
detailed description of the present invention, along with the
accompanying figures in which like reference numerals refer to like
parts throughout.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0018] FIG. 1A is a block diagram illustrating an exemplary
cellular and OFDM collaboration system with single channel weight
diversity, in accordance with an embodiment of the invention.
[0019] FIG. 1B is a flow chart illustrating exemplary steps for
cellular and OFDM collaboration, in accordance with an embodiment
of the invention.
[0020] FIG. 1C is a block diagram illustrating an exemplary
reconfigurable OFDM chip with single channel weight diversity, in
accordance with an embodiment of the invention.
[0021] FIG. 2A is a block diagram of an exemplary two-transmit
(2-Tx) and two-receive (2-Rx) antennas wireless communication
system with receiver channel estimation, in accordance with an
embodiment of the invention.
[0022] FIG. 2B is a block diagram of an exemplary two-transmit
(2-Tx) and multiple-receive (M-Rx) antennas wireless communication
system with receiver channel estimation, in accordance with an
embodiment of the invention.
[0023] FIG. 3A is a flow diagram illustrating exemplary steps for
channel estimation in a 2-Tx and M-Rx antennas wireless
communication system, in accordance with an embodiment of the
invention.
[0024] FIG. 3B illustrates an exemplary periodic phase rotation for
an in-phase (I) signal received in one of the additional receive
antennas, in accordance with an embodiment of the invention.
[0025] FIG. 4A is a block diagram of an exemplary single weight
baseband generator (SWBBG) that may be utilized in a 2-Tx and 2-Rx
antennas system, in accordance with an embodiment of the
invention.
[0026] FIG. 4B is a block diagram of an exemplary single weight
baseband generator (SWBBG) that may be utilized in a 2-Tx and M-Rx
antennas system, in accordance with an embodiment of the
invention.
[0027] FIG. 4C is a block diagram of an exemplary RF phase and
amplitude controller, in accordance with an embodiment of the
invention.
[0028] FIG. 5 is a flow diagram illustrating exemplary steps in the
operation of the single weight baseband generator (SWBBG) that may
be utilized for channel estimation in a 2-Tx and M-Rx antennas
system, in accordance with an embodiment of the invention.
[0029] FIG. 6 is a block diagram of an exemplary channel estimator
for a 2-Tx and 2-Rx antennas system, in accordance with an
embodiment of the invention.
[0030] FIG. 7 is a flow diagram illustrating exemplary steps for
channel estimation based on complex multiplication and integration
of a first and second baseband combined channel estimates, in
accordance with an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Certain embodiments of the invention may be found in a
system and/or method for a reconfigurable orthogonal frequency
division multiplexing (OFDM) chip supporting single weight
diversity. In accordance with various embodiments of the invention,
the reconfigurable OFDM chip may be configured to process signals
such as IEEE 802.11, 802.16, and digital video broadcasting (DVB).
The OFDM chip may generate channel weights to be applied to signals
received in receive antennas. The weighted signals may be combined
into a single received signal and channel estimates may be
generated from the single received signal. Updated channel weights
may be generated from the generated channel estimates. Updates to
the channel weights may be performed dynamically. The configurable
OFDM chip may be utilized to provide collaborative cellular and
OFDM-based communication. The reconfigurable OFDM chip and the
cellular chip may communicate data and/or control information via a
memory coupled to a common bus.
[0032] FIG. 1A is a block diagram illustrating an exemplary
cellular and OFDM collaboration system with single channel weight
diversity, in accordance with an embodiment of the invention.
Referring to FIG. 1A, there is shown a mobile terminal 150 that may
comprise a cellular block 152, an OFDM block 154, a processor 156,
a memory 158, and a common bus 160. The OFDM block 154 may comprise
a plurality of registers 157. The mobile terminal 150 may be
utilized for receiving and/or transmitting cellular and/or
OFDM-based information, such as DVB-H information for example. The
cellular block 152 may comprise suitable logic, circuitry, and/or
code that may be adapted to process cellular information. The
cellular block 152 may be adapted to transmit cellular information
via at least one transmit antenna. In this regard, there are shown
K transmit antennas 153a (Tx.sub.--0), . . . , 153b (Tx_K-1). When
K>1 the cellular block 152 may support transmit diversity
techniques, for example. The cellular block 152 may also be adapted
to receive cellular information via at least one receive antenna.
In this regard, there are shown L receive antennas 153c
(Rx.sub.--0), . . . , 153d (Rx_L-1). When L>1 the cellular block
152 may support receive diversity techniques, for example. The
cellular block 152 may be adapted to support at least one of a
plurality of cellular technologies such as CDMA, WCDMA, HSDPA, GSM,
and/or UMTS, for example.
[0033] The cellular block 152 may be adapted to transfer data
and/or control information to the OFDM block 154 via the common bus
160. In some instances, the cellular block 152 may transfer data
and/or control information to the OFDM block 154 via the common bus
160 directly. In other instances, the data and/or control
information may be first transferred from the cellular block 152 to
the memory 156 via the common bus 160 and then transferred from the
memory 156 to the OFDM block 154 via the common bus 160.
[0034] The OFDM block 154 may comprise suitable logic, circuitry,
and/or code that may be adapted to process information communicated
by OFDM modulation techniques. The OFDM block 154 may be adapted to
transmit information via at least one transmit antenna. In this
regard, there are shown R transmit antennas 155a (Tx.sub.--0), . .
. , 155b (Tx_R-1). When R>1 the OFDM block 154 may support
transmit diversity techniques, for example. An exemplary diversity
technique that may be utilized by the OFDM block 154 for
transmission is single weight diversity. The OFDM block 154 may
also be adapted to receive information via at least one receive
antenna. In this regard, there are shown P receive antennas 155c
(Rx.sub.--0), . . . , 155d (Rx_P-1). When P>1 the OFDM block 154
may support receive diversity techniques, for example. An exemplary
diversity technique that may be utilized by the OFDM block 154 for
reception is single weight diversity. U.S. application Ser. No.
11/173,964, U.S. application Ser. No. 11/173,252, U.S. application
Ser. No. 11/174,252 provide a detailed description of channel
estimation and single weight generation and are hereby incorporated
herein by reference in their entirety. The OFDM block 154 may be
adapted to support at least one of a plurality of OFDM-based
technologies such as wireless local area networks (WLANs) based on
IEEE 802.11, wireless metropolitan area networks (WMANs) based on
802.16, and digital video broadcasting for handhelds (DVB-H), for
example.
[0035] The OFDM block 154 may be adapted to transfer data and/or
control information to the cellular block 152 via the common bus
160. In some instances, the OFDM block 154 may transfer data and/or
control information to the cellular block 155 via the common bus
160 directly. In other instances, the data and/or control
information may be first transferred from the OFDM block 154 to the
memory 156 via the common bus 160 and then transferred from the
memory 156 to the OFDM block 154 via the common bus 160.
[0036] The OFDM block 154 may be a configurable device and at least
a portion of the OFDM block 154 may be configured in accordance
with one of the OFDM technologies that may be supported. For
example, certain aspects in the OFDM block 154 that may be
configured may comprise forward error correction (FEC), parsing,
interleaving, mapping, fast Fourier transformations (FFTs), and/or
guard interval insertion. Other aspects of the OFDM block 154 that
may be configured may comprise operating bandwidth, auto detection
of multiple preambles, channel estimation, and/or header cyclic
redundancy check (CRC) length, for example. In this regard, the
plurality of registers 157 may comprise suitable logic, circuitry,
and/or code that may be adapted to store values and/or parameters
that correspond to the configurable aspects of the OFDM block 154.
To configure the OFDM block 154, the values and/or parameters to be
stored in the plurality of registers 157 may be transferred from
the memory 158 via the common bus 160 based on at least one control
signal generated by the processor 156, for example.
[0037] The processor 156 may comprise suitable logic, circuitry,
and/or code that may be adapted to perform control and/or
management operations for the mobile terminal 150. In this regard,
the processor 156 may be adapted to generate at least one signal
for configuring the OFDM block 154. Moreover, the processor 156 may
be adapted to arbitrate and/or schedule communications between the
cellular block 152 and the OFDM block 154 when collaborative
communication is to be utilized. In some instances, the arbitration
and/or scheduling operation may be performed by logic, circuitry,
and/or code implemented separately from the processor 156. The
processor 156 may also be adapted to control single weight
diversity operations in the OFDM block 154. For example, the
processor 156 may control the integration time utilized when
generating channel weights for receive and/or transmit antennas in
the OFDM block 154. The memory 158 may comprise suitable logic,
circuitry, and/or code that may be adapted to store information
that may be utilized by the cellular block 152, the OFDM block 154,
and/or the processor 156. In this regard, the memory 158 may store
parameters associated with the various configurations supported by
the OFDM block 154.
[0038] In operation, when an OFDM configuration mode has been
selected, the processor 156 may generate at least one signal to
transfer configuration information from the memory 156 to the
plurality of registers 157 in the OFDM block 154 via the common bus
160. In this regard, exemplary OFDM configuration modes may
comprise WLAN modes, WMAN modes, and DVB-H modes. The OFDM block
154 may receive and transmit information in accordance to the OFDM
configuration mode currently supported. Similarly, the cellular
block 152 may receive and/or transmit cellular information. When
single weight diversity is supported by the transmit and/or receive
operations of the OFDM block 154, appropriate channel weights may
be generated by the OFDM block 154 to at least one of the transmit
antennas 155a (Tx.sub.--0), . . . , 155b (Tx_R-1) and/or at lest
one of the receive antennas 155c (Rx.sub.--0), . . . , 155d
(Rx_P-1).
[0039] When cellular communication may be more efficiently
performed via the OFDM block 154, the processor 156 may coordinate
the transfer of information from the cellular block 152 to the OFDM
block 154. In this regard, information from the cellular block 152
may be transferred to the memory 158 and then from the memory 158
to the OFDM block 154. Similarly, when OFDM-based communication may
be more efficiently performed via the cellular block 152, the
processor 156 may coordinate the transfer of information from the
OFDM block 154 to the cellular block 152. In this regard,
information from the OFDM block 154 may be transferred to the
memory 158 and then from the memory 158 to the cellular block
152.
[0040] FIG. 1B is a flow chart illustrating exemplary steps for
cellular and OFDM collaboration, in accordance with an embodiment
of the invention. Referring to FIG. 1B, there is shown a flow
diagram 170 for collaborative operation of cellular and OFDM
communication in the mobile terminal 150 in FIG. 1A. After start
step 172, in step 174, the processor 156 may configure the OFDM
block 154 to operate in one of a plurality of OFDM configuration
modes. The parameters that support each OFDM configuration mode may
be transferred to the plurality of registers 157 in the OFDM block
from the memory 156.
[0041] In step 176, the processor 156 may arbitrate and/or schedule
collaborative communication between the cellular block 152 and the
OFDM block 154. In this regard, the processor 156 may determine,
based on information provided by the cellular block 152 and/or the
OFDM block 154, whether cellular data may be communicated by
utilizing the OFDM block 154 or whether OFDM-based information may
be communicated by utilizing the cellular block 152. For example,
when the quality of WCDMA communication link supported by the
cellular block 152 becomes low and the transmission rate via that
WCDMA communication link degrades, the cellular block 152 may
generate a signal to the processor 156 to provide access to the
cellular data to its recipient via the OFDM block 154. Similarly,
when the quality of WLAN communication link supported by the OFDM
block 154 becomes low and the transmission rate via that WLAN
communication link degrades, the OFDM block 154 may generate a
signal to the processor 156 to provide access to the WLAN
information to its recipient via the cellular block 152. In either
case, the processor 156 may request information from the other
block to determine whether the necessary resources for
collaboration are available. When the resources are available,
collaboration between the OFDM block 154 and the cellular block 152
may be implemented.
[0042] In step 178, when the processor 156 determines that cellular
data may be sent via the OFDM block 154, that is, collaboration may
be implemented, the process may proceed to step 180. In step 180,
the cellular data may be transferred to the OFDM block 154 from the
cellular block 152 via the common bus 160. In this regard, the
cellular data may be first stored in the memory 158 before final
transfer to the OFDM block 154. After step 180 the process may
proceed to end step 188.
[0043] Returning to step 178, when the processor 156 determines
that cellular data may not be sent via the OFDM block 154, that is,
collaboration may not be implemented, the process may proceed to
step 182. In step 182, when the processor 156 determines that OFDM
data may be sent via the cellular block 152, that is, collaboration
may be implemented, the process may proceed to step 184. In step
184, the OFDM data may be transferred to the cellular block 152
from the OFDM block 154 via the common bus 160. In this regard, the
OFDM data may be first stored in the memory 158 before final
transfer to the cellular block 152. After step 184 the process may
proceed to end step 188.
[0044] Returning to step 182, when the processor 156 determines
that OFDM data may not be sent via the cellular block 152, that is,
collaboration may not be implemented, the process may proceed to
step 186. In step 186, the cellular data may be sent via the
cellular block 152 and/or the OFDM data may be sent via the OFDM
block 154 in accordance with the communication rates that may be
supported by each of those blocks. In this regard, when
collaboration may not be implemented, the cellular communication
and the OFDM-based communication of the mobile terminal 150 may
each be limited by their corresponding communication links.
[0045] FIG. 1C is a block diagram illustrating an exemplary
reconfigurable OFDM chip with single channel weight diversity, in
accordance with an embodiment of the invention. Referring to FIG.
1C, there is shown a reconfigurable OFDM block 190 that may
comprise a transmit path 191a and a receive path 191b. The
reconfigurable OFDM block 190 may be adapted to support single
weight diversity in the transmit path 191a and/or in the receive
path 191b, for example. The transmit path 191a may comprise an
outer coder 192a, an inner coder 193a, a mapper 194a, a pilot and
transmission parameter signaling (TPS) insertion block 195a, an
inverse FFT (IFFT) 196a, a guard interval insertion block 197a, and
a radio frequency (RF) modulation block 198a. The receive path 191b
may comprise an RF modulation block 198b, a guard interval removal
block 197b, an FFT 196b, a pilot and TPS removal block 195b, a
demapper 194b, an inner decoder 193b, and an outer decoder
192b.
[0046] The outer coder 192a may comprise suitable logic, circuitry,
and/or code that may be adapted to provide a first encoding of the
data to be transmitted. For example, the outer coder 192a may be
adapted to perform a Reed-Solomon error correction encoding
operation. In this regard, the outer coder 192a may be utilized to
implement forward error correction (FEC) operations, for example,
where such FEC operations of the outer coder 192a may be
configurable. The inner coder 193a may comprise suitable logic,
circuitry, and/or code that may be adapted to provide a second
encoding of the data to be transmitted. For example, the inner
coder 193a may be adapted to perform a convolutional code on the
output of the outer coder 192a. When the inner coder 193a is
implemented utilizing a convolutional encoder, the convolutional
encoder may be configured to an encoding rate of R=1/2, and an
encoder's length constraint ranging between K=7 and K=9, for
example. When the outer coder 192a is implemented utilizing a
puncturer, the rates of the puncturer may be configured to 2/3,
3/4, or , for example. A puncturer may be utilized to periodically
delete selected bits to reduce coding overhead. In some instances,
the outer coder 192a may be implemented using an interleaver, for
example. When appropriate, the encoding rate, the encoder's length
constraint, the interleaver, and/or the puncturer rate of the inner
coder 193a may be configurable.
[0047] The mapper 194a may comprise suitable logic, circuitry,
and/or code that may be adapted to map the output of the inner
coder 193a to a specified modulation constellation. For example,
the mapper 194a may be adapted to perform X-QAM, where X indicates
the size of the constellation to be used for quadrature amplitude
modulation. The mapper 194a may be configured to map the output of
the inner coder 193a to quadrature phase shift keying (QPSK),
binary phase shift keying (BPSK), 16-QAM, or 64-QAM, for example.
Moreover, the mapping performed by the mapper 194a may result in an
in-phase (I) data stream and a phase quadrature (Q) data
stream.
[0048] The pilot and TPS insertion block 195a may comprise suitable
logic, circuitry, and/or code that may be adapted to insert OFDM
pilot signals and/or transmission parameters signals into the I and
Q data streams. The IFFT 196a may comprise suitable logic,
circuitry, and/or code that may be adapted to perform an inverse
FFT operation of the output of the pilot and TPS insertion block
195a. In this regard, the number of points to be used by the IFFT
196a may be configurable and may be modified in accordance with the
OFDM configuration mode selected. The IFFT 196a may have a range
from 64 points to 8K points, for example. The IFFT 196a may be
implemented as a one-dimensional IFFT for data, text, and/or audio
applications, and may be implemented as a two-dimensional IFFT for
images and/or video applications, for example. The guard interval
insertion block 197a may comprise suitable logic, circuitry, and/or
code that may be adapted to insert a guard interval into the
contents of the I and Q data streams. The time interval inserted by
the guard interval insertion block 197a may be configurable. For
example, the time interval inserted may range between 400 ns and
800 ns.
[0049] The RF modulation block 198a may comprise suitable logic,
circuitry, and/or code that may be adapted to modulate the output
of the guard interval insertion block 197a in accordance with the
OFDM configuration mode. In this regard, the operating bandwidth of
the RF modulation block 198a may be configurable. The operating
bandwidth may range between 20 MHz and 80 Mhz, for example. When
the RF modulation block 198a supports single weight diversity,
channel weights to be applied to at least one of the R transmit
antennas 155a (Tx.sub.--0), . . . , 155b (Tx_R-1) may be generated
by the RF modulation block 198a. The RF modulation block 198a may
then transmit weighted signals via the R transmit antennas 155a
(Tx.sub.--0), . . . , 155b (Tx_R-1).
[0050] The RF demodulation block 198b may comprise suitable logic,
circuitry, and/or code that may be adapted to demodulate the input
signals received via the P receive antennas 155c (Rx.sub.--0), . .
. , 155d (Rx_P-1). For example, the operating bandwidth of the RF
demodulation block 198b may be configurable. In this regard, the
operating bandwidth may range between 20 MHz and 80 Mhz, for
example. When the RF demodulation block 198b supports single weight
diversity, channel weights to be applied to at least one of the P
receive antennas 155c (Rx.sub.--0), . . . , 155d (Rx_P-1) may be
generated by the RF demodulation block 198b. The RF modulation
block 198b may then transfer the I and Q data streams generated
from a combination of the weighted received signals to the guard
interval removal block 187b. The weight generation in the RF
demodulation block 198b may be configurable. For example, channel
estimation operations for weight generation may be configured in a
per-tone estimation basis.
[0051] The guard interval removal block 197b may comprise suitable
logic, circuitry, and/or code that may be adapted to remove a guard
interval introduced into the contents of the I and Q data streams.
The time interval removal by the guard interval removal block 197a
may be configurable. For example, the time interval removal may
range between 400 ns and 800 ns and may be selected in accordance
with the OFDM configuration mode.
[0052] The FFT 196b may comprise suitable logic, circuitry, and/or
code that may be adapted to perform an FFT operation of the output
of the guard interval removal block 197b. In this regard, the
number of points to be used by the FFT 196b may be configurable and
may be modified in accordance with the OFDM configuration mode
selected. The FFT 196b may have a range from 64 points to 8K
points, for example. The FFT 196b may be implemented as a
one-dimensional FFT for data, text, and/or audio applications, and
may be implemented as a two-dimensional FFT for images and/or video
applications, for example. The pilot and TPS removal block 195b may
comprise suitable logic, circuitry, and/or code that may be adapted
to remove OFDM pilot signals and/or transmission parameters signals
inserted into the I and Q data streams.
[0053] The demapper 194b may comprise suitable logic, circuitry,
and/or code that may be adapted to reverse the mapping of the I and
Q data streams from the pilot and TPS removal block 195b. The
demapper 194b may be configured to reverse map QPSK, BPSK, 16-QAM,
or 64-QAM, for example. Moreover, the reverse mapping performed by
the demapper 194b may result in a combined data stream from the I
and Q data streams from the pilot and TPS removal block 195b.
[0054] The inner decoder 193b may comprise suitable logic,
circuitry, and/or code that may be adapted to provide a first
decoding of the data received. For example, the inner decoder 193b
may be adapted to perform a Viterbi decoding on the output of the
demapper 194b. When appropriate, the decoding rate, the decoder's
length constraint, and/or the puncturer rate of the inner decoder
193ba may be configurable.
[0055] The outer decoder 192b may comprise suitable logic,
circuitry, and/or code that may be adapted to provide a second
decoding of the data to be received. For example, the outer decoder
192b may be adapted to perform a Reed-Solomon error correction
decoding operation. In this regard, the outer decoder 192a FEC
operations may be configurable. The output of the outer decoder
192b is the signal or data received.
[0056] The configurable portions of the reconfigurable OFDM block
190 in FIG. 1C may be programmed via the plurality of registers 157
in FIG. 1A. In this regard, the processor 156 may generate at least
one signal to transfer the appropriate values to be utilized by the
configurable portions of the reconfigurable OFDM block 190 from the
memory 158 to the plurality of registers 157.
[0057] During transmission operation, the processor 156 may
generate at least one signal to program portions of the transmit
path 191a and portions of the receive path 191b in accordance with
a selected OFDM configuration mode. Data to be transmitted may be
first encoded by the outer coder 192a and then by the inner coder
193a. The output of the inner coder 193a may be mapped in the
mapper 194a to the configured constellation to generate I and Q
data streams. The pilot and TPS insertion block 195a may insert
signals into the I and Q data streams generated by the mapper 194a.
The IFFT 196a may operate on the output of the pilot and TPS
insertion block 195a in accordance with the configured number of
points and may transfer the results to the guard interval insertion
block 197a. The guard interval insertion block 197a may insert a
configured time interval into the contents of the I and Q data
streams and may transfer the results to the RF modulation block
198a. The RF modulation block 198a may modulate the signals
received from the guard interval insertion block 197a. The RF
modulation block 198a, when supporting single weight diversity, may
generate channel weights that may be utilized to generate a
plurality of signals to be transmitted via the R transmit antennas
155a (Tx.sub.--0), . . . , 155b (Tx_R-1).
[0058] During reception operation, signals may be received by the P
receive antennas 155d (Rx.sub.--0), . . . , 155d (Rx_P-1). When
supporting single weight diversity, the RF demodulation block 198b
may generate channel weights to modify the received signals. A
single received signal for RF demodulation may be generated by
combining the weighted received signals. The RF demodulation block
198b may generate I and Q data streams by demodulating the single
received signal generated. The guard interval removal block 197b
may remove a configured time interval from the contents of the I
and Q data streams and may transfer the results to the FFT 196b.
The FFT 196b may operate on the output of the guard interval
removal block 197b in accordance with the configured number of
points and may transfer the results to the pilot and TPS removal
block 195b. The pilot and TPS removal block 195b may remove signals
inserted into the I and Q data streams and may transfer the results
to the demapper 194b. The demapper 194b may reverse map the I and Q
data streams outputs from the pilot and TPS removal block 195b into
a single data stream in accordance with the configuration provided.
The inner decoder 193b may decode the data stream from the demapper
1954b and the outer decoder 192b may decode the data stream from
the inner decoder 193b. In this regard, the inner decoder 193b and
the outer decoder 192b may perform decoding operations that
correspond to the encoding operations performed by the inner coder
193a and the outer coder 192a respectively. The output of the outer
decoder 192b may correspond to the received data.
[0059] U.S. application Ser. No. ______ (Attorney Docket No.
16847US02) and U.S. application Ser. No. ______ (Attorney Docket
No. 16848US02) provide a detailed description of a configurable
OFDM block and are hereby incorporated herein by reference in their
entirety.
[0060] FIG. 2A is a block diagram of an exemplary two-transmit
(2-Tx) and two-receive (2-Rx) antennas wireless communication
system with receiver channel estimation, in accordance with an
embodiment of the invention. Referring to FIG. 2A, the wireless
communication system 200 may comprise a transmitter 226, a first
transmit antenna (Tx.sub.--1) 238, an additional transmit antenna
(Tx.sub.--2) 240, a first receive antenna (Rx.sub.--1) 206, and an
additional receive antenna (Rx.sub.--2) 208. The wireless
communication system 200 may further comprise a mixer 210, an adder
212, an RF block 214, a filter 216, a baseband (BB) processor 220,
a single weight baseband generator (SWBBG) 221, a single weight
generator (SWG) channel estimator 222, and a SWG algorithm block
224.
[0061] The transmitter 226 may comprise suitable logic, circuitry,
and/or code that may be adapted to process single channel (SC)
communication signals for transmission utilizing OFDM modulation
techniques. The transmitter 226 may also be adapted to receive
feedback from a wireless receiver via a feedback link 202. The
transmitter 226 may be adapted to transmit signals via the first
transmit antenna (Tx.sub.--1) 238 and the additional transmit
antenna (Tx.sub.--2) 240. The first transmit antenna, Tx.sub.--1
238, and the additional or second transmit antenna, Tx.sub.--2 240,
may comprise suitable hardware that may be adapted to transmit a
plurality of SC communication signals, s.sub.T, from the
transmitter 226. The first receive antenna, Rx.sub.--1 206, and the
additional or second receive antenna, Rx.sub.--2 208, may comprise
suitable hardware that may be adapted to receive at least a portion
of the transmitted SC communication signals in a wireless receiver
device. For example, the receive antenna Rx.sub.--1 206 may receive
signal s.sub.R1 while the receive antenna Rx.sub.--2 208 may
receive signal s.sub.R2. The propagation channels that corresponds
to the paths taken by the SC communication signals transmitted from
the transmit antennas Tx.sub.--1 238 and Tx.sub.--2 240 and
received by the receive antenna Rx.sub.--1 206 may be represented
by h.sub.11 and h.sub.12 respectively. In this regard, h.sub.11 and
h.sub.12 may represent the actual time varying impulse responses of
the radio frequency (RF) paths taken by the SC communication
signals transmitted from the transmit antennas Tx.sub.--1 238 and
Tx.sub.--2 240 and received by the receive antenna Rx.sub.--1
206.
[0062] Similarly, the propagation channels that corresponds to the
paths taken by the SC communication signals transmitted from the
transmit antennas Tx.sub.--1 238 and Tx.sub.--2 240 and received by
the receive antenna Rx.sub.--2 208 may be represented by h.sub.21
and h.sub.22 respectively. In this regard, h.sub.21 and h.sub.22
may represent the actual time varying impulse responses of the RF
paths taken by the SC communication signals transmitted from the
transmit antennas Tx.sub.--1 238 and Tx.sub.--2 240 and received by
the receive antenna Rx.sub.--2 208. In some instances, a wireless
transmitter device comprising a single transmit antenna may be
adapted to periodically transmit calibration and/or pilot signal
that may be utilized by a 2-Rx antennas wireless receiver device to
determine estimates of h.sub.11, h.sub.12, h.sub.21, and h.sub.22.
The 2-Tx and 2-Rx antennas wireless communication system 200 in
FIG. 2A may represent a MIMO communication system whereby the
diversity gain may be increased for the transmitted data.
[0063] The mixer 210 may comprise suitable logic and/or circuitry
that may be adapted to operate as a complex multiplier that may
modify the amplitude and/or phase of the portion of the SC
communication signals received by the receive antenna Rx.sub.--2
208 via a rotation waveform e.sup.jw.sup.r.sup.t provided by the
SWBBG 121, where w.sub.r=2.pi.f.sub.r and f.sub.r is the rotation
frequency. In this regard, a channel weight comprising an amplitude
component and phase component may be provided by the SWBBG 221 for
modifying the signal received by the receive antenna Rx.sub.--2 208
to achieve channel orthogonality between the receive antenna
Rx.sub.--1 206 and the receive antenna Rx.sub.--2 208. In some
implementations, the mixer 210 may comprise an amplifier and a
phase shifter, for example.
[0064] Through the achieved channel orthogonality, estimates of
h.sub.11, h.sub.12, h.sub.21, and h.sub.22 may be determined by the
SWG channel estimator 222 in the SWBBG 221. The h.sub.11, h.sub.12,
h.sub.21, and h.sub.22 estimates may be utilized by the SWG
algorithm block 224 to determine an optimum amplitude A and phase
.phi. that modify signals received by the receive antenna
Rx.sub.--2 208 via mixer 210 so that the receiver
signal-to-interference-and-noise ratio (SINR) is maximized. In some
instances, instead of utilizing the rotation waveform
e.sup.jw.sup.r.sup.t to achieve the channel orthogonality between
the receive antenna Rx.sub.--1 106 and the receive antenna
Rx.sub.--2 108, square or triangular waveforms may be also
utilized. Moreover, waveforms representing different orthogonal
codes may also be utilized.
[0065] In some instances, the output of the mixer 210 may be
transferred to a bandpass filter, a low noise amplifier (LNA),
and/or a phase shifter for further processing of the received
signals. The adder 212 may comprise suitable hardware, logic,
and/or circuitry that may be adapted to add the output of the
receive antenna Rx.sub.--1 206 and the output of the mixer 210 to
generate a combined received SC communication signal, s.sub.RC. In
some instances, bringing the output signals of the receive antenna
Rx.sub.--1 206 and the mixer 210 together into a single electrical
connection may provide the functionality of the adder 212.
Notwithstanding, an output of the adder 212 may be transferred to
the RF block 214 for further processing of the combined received SC
communication signal, s.sub.RC.
[0066] The RF block 214 may comprise suitable logic and/or
circuitry that may be adapted to process the combined received SC
communication signal, s.sub.RC. The RF block 214 may perform, for
example, filtering, amplification, and/or analog-to-digital (A/D)
conversion operations. The BB processor 220 may comprise suitable
logic, circuitry, and/or code that may be adapted to determine a
first baseband combined channel estimate, h.sub.1, which may
comprise information regarding propagation channels h.sub.11 and
h.sub.21. The BB processor 220 may also be adapted to process the
output of the RF block 214 to determine a second baseband combined
channel estimate, h.sub.2, which may comprise information regarding
propagation channels h.sub.12 and h.sub.22. The BB processor 220
may also be adapted to determine an estimate of the transmitted SC
communication signals, s.sub.T. The filter 216 may comprise
suitable logic, circuitry, and/or code that may be adapted to limit
the bandwidth of the digital output from the RF block 214. The
output of the filter 216 may be transferred, for example, to the BB
processor 220 for further processing.
[0067] The SWBBG 221 may comprise suitable logic, circuitry, and/or
code that may be adapted to receive the first and second baseband
combined channel estimates, h.sub.1 and h.sub.2, from the BB
processor 220 and generate phase and amplitude components of the
rotation waveform to be applied by the mixer 210 to modify the
portion of the SC communication signals received by the receive
antenna Rx.sub.--2 208, s.sub.R2. The SWG channel estimator 222 may
comprise suitable logic, circuitry, and/or code that may be adapted
to process the first and second baseband combined channel
estimates, h.sub.1 and h.sub.2, generated by the BB processor 220
and may determine a matrix H.sub.2.times.2 of propagation channel
estimates h.sub.11, h.sub.12, h.sub.21, and h.sub.22, which
correspond to estimates of a matrix H.sub.2.times.2 of time varying
impulse responses h.sub.11, h.sub.12, h.sub.21, and h.sub.22
respectively. The SWG algorithm block 224 may comprise suitable
logic, circuitry, and/or code that may be adapted to determine a
channel weight to be transferred to the mixer 210 to modify the
signal s.sub.R2 so that the receiver SINR is maximized. The channel
weight to be transferred to the mixer 210 may refer to a phase,
.phi., and amplitude, A, that results in a maximum SINR. Moreover,
the SWG algorithm block 224 may be adapted to generate feedback
factors to the transmitter 226 jointly and/or concurrently with the
channel weight for the mixer 210.
[0068] FIG. 2B is a block diagram of an exemplary two-transmit
(2-Tx) and multiple-receive (M-Rx) antennas wireless communication
system with receiver channel estimation, in accordance with an
embodiment of the invention. Referring to FIG. 2B, the wireless
communication system 250 may differ from the wireless communication
system 200 in FIG. 2A in that (M-1) additional receive antennas
Rx.sub.--2 208 to Rx_M 209, and (M-1) mixers 210 to 211 may be
utilized, where M is the total number of receive antennas in the
wireless receiver.
[0069] The propagation channels that correspond to the paths taken
by the SC communication signals transmitted from the transmit
antennas Tx.sub.--1 238 and Tx.sub.--2 240 and received by the
receive antennas Rx.sub.--1 206 to Rx_M 209 may be represented by
an M.times.2 matrix, H.sub.M.times.2. The matrix H.sub.M.times.2
may comprise propagation channels h.sub.11 to h.sub.M1, and
h.sub.12 to h.sub.M2. In this regard, h.sub.11 to h.sub.M1 may
represent the time varying impulse responses of the RF paths taken
by the portion of the transmitted SC communication signals
transmitted by transmit antenna Tx.sub.--1 238 and received by the
receive antennas Rx.sub.--1 206 to Rx_M 209 respectively.
Similarly, h.sub.12 to h.sub.M2 may represent the time varying
impulse responses of the RF paths taken by the portion of the
transmitted SC communication signals transmitted by transmit
antenna Tx.sub.--2 240 and received by the receive antennas
Rx.sub.--1 206 to Rx_M 209 respectively. In some instances, a
wireless transmitter device comprising a first and a second
transmit antenna may be adapted to periodically transmit
calibration and/or pilot signals that may be utilized by an M-Rx
antenna wireless receiver device to determine estimates of h.sub.11
to h.sub.M1 and h.sub.12 to h.sub.M2. The 2-Tx and M-Rx antennas
wireless communication system 250 in FIG. 2B may represent a MIMO
communication system whereby the diversity gain may be increased
for the transmitted data.
[0070] The mixers 210 to 211 may comprise suitable logic and/or
circuitry that may be adapted to operate as a complex multiplier
that may modify the phase of the portion of the SC communication
signals received by the receive antennas Rx.sub.--2 208 to Rx_M 209
via a rotation waveforms e.sup.jw.sup.r1.sup.t to
e.sup.jw.sup.r(M-1).sup.t, where w.sub.rk=2.pi.f.sub.rk and
f.sub.rk is the rotation frequency that preserves the orthogonality
of the received signals at the multiple receiving antennas
Rx.sub.--1 206 to Rx_M 209. The rotation frequency that preserves
the signal orthogonality at the receiving antennas may be selected
as f.sub.rk=kf.sub.r where k=1, 2, 3, . . . , M-1. Other rotation
waveforms such as triangular or square waveforms may be utilized
with the same frequency relationships. In addition, waveforms
representing different orthogonal codes of the same frequency may
be utilized. In this regard, the following exemplary sequences may
be utilized: the first receive antenna Rx.sub.--1 206 may utilize
the sequence [1 1 1 1], the second receive antenna Rx.sub.--2 208
may utilize the sequence [-1 -1 1 1], a third receive antenna
(Rx.sub.--3) may utilize the sequence [-1 1 -1 1], and so on. In
this embodiment, e.sup.jw.sup.rk.sup.t is used as an exemplary
waveform.
[0071] The channel weights comprising phase components for the
rotation waveforms may be provided by the SWBBG 221 for modifying
the signals received by the receive antennas Rx.sub.--2 208 to Rx_M
209 to achieve channel orthogonality between the receive antenna
Rx.sub.--1 206 and the receive antennas Rx.sub.--2 208 to Rx_M 209.
In some instances, the output of the mixers 210 to 211 may be
transferred to a bandpass filter and/or a low noise amplifier (LNA)
for further processing of the received signals. The adder 212 may
comprise suitable hardware, logic, and/or circuitry that may be
adapted to add the output of the receive antenna Rx.sub.--1 206
with the output of the mixers 210 to 211 to generate a combined
received SC communication signal, s.sub.RC, or gain balanced point.
In some instances, bringing the output signals of the receive
antenna Rx.sub.--1 206 and the mixers 210 to 211 together into a
single electrical connection may provide the functionality of the
adder 212. Notwithstanding, an output of the adder 212 may be
transferred to the RF block 214 for further processing of the
combined received SC communication signal, s.sub.RC.
[0072] The BB processor 220 in FIG. 2B may be adapted to determine
a first baseband combined channel estimate, h.sub.1, which may
comprise information regarding propagation channels h.sub.11 to
h.sub.M1. For example, a portion of h.sub.1 may comprise
information regarding the propagation channels between the transmit
antenna Tx.sub.--1 238 and the receive antennas Rx.sub.--1 206 and
Rx.sub.--2 208, that is, h.sub.11 and h.sub.21, while another
portion of h.sub.1 may comprise information regarding the
propagation channels between the transmit antenna Tx.sub.--1 238
and the receive antennas Rx.sub.--1 206 and Rx_M 209, that is,
h.sub.11 and h.sub.M1. The actual time varying impulse responses
h.sub.11 to h.sub.M1, may comprise multiple propagation paths
arriving at different time delays.
[0073] The BB processor 220 in FIG. 2B may also be adapted to
determine a second baseband combined channel estimate, h.sub.2,
which may comprise information regarding propagation channels
h.sub.12 to h.sub.M2. For example, a portion of h.sub.2 may
comprise information regarding the propagation channels between the
transmit antenna Tx.sub.--2 240 and the receive antennas Rx.sub.--1
206 and Rx.sub.--2 208, that is, h.sub.12 and h.sub.22, while
another portion of h.sub.2 may comprise information regarding the
propagation channels between the transmit antenna Tx.sub.--2 240
and the receive antennas Rx.sub.--1 206 and Rx_M 209, that is,
h.sub.12 and h.sub.M2. The actual time varying impulse responses
h.sub.12 to h.sub.M2 may comprise multiple propagation paths
arriving at different time delays. The combined channel estimates
may be determined, that is, may be separated, in the BB processor
220 utilizing the orthogonality of the received signals, for
example.
[0074] The SWG channel estimator 222 in FIG. 2B may be adapted to
process the first and second baseband combined channel estimates,
h.sub.1 and h.sub.2, determined by the BB processor 220 and may
determine a matrix H.sub.M.times.2 of propagation channel estimates
h.sub.11 to hM1, and h.sub.12 to h.sub.M2, which correspond to
estimates of the matrix H.sub.M.times.2 of time varying impulse
responses h.sub.11 to h.sub.M1 and h.sub.12 to h.sub.M2,
respectively. The SWG algorithm block 224 may utilize the contents
of the matrix H.sub.M.times.2 to determine (M-1) channel weights to
be applied to the mixers 210 to 211 to modify the portions of the
transmitted SC communication signals received by the additional
receive antennas Rx.sub.--2 208 to Rx_M 209 so that the receiver
SINR is maximized, for example. The (M-1) channel weights may
comprise amplitude and phase components, A.sub.1 to A.sub.M-1 and
.phi..sub.1 to .phi..sub.M-1, for example. Moreover, the SWG
algorithm block 224 may be adapted to generate feedback information
jointly and/or concurrently with the (M-1) channel weights.
[0075] FIG. 3A is a flow diagram illustrating exemplary steps for
channel estimation in a 2-Tx and M-Rx antennas wireless
communication system, in accordance with an embodiment of the
invention. Referring to FIG. 3A, after start step 302, in step 304,
the SC communication signals, s.sub.T, may be transmitted from the
transmit antennas Tx.sub.--1 238 and Tx.sub.--2 240 in FIG. 2B. In
step 306, the first and additional receive antennas, Rx.sub.--1 206
to Rx_M 209, may receive a portion of the transmitted SC
communication signals. In step 308, the signals received by the
additional receive antennas Rx.sub.--1 206 to Rx_M 209 may be
multiplied by, for example, rotation waveforms, such as sine,
square, or triangular waveforms for example, in the mixers 210 to
211 in FIG. 2B. In this regard, the rotation waveforms may have a
given set of amplitude and phase component values. In step 310, the
output of the receive antenna Rx.sub.--1 206 and the output of the
mixers 210 to 211 associated with the additional receive antennas
Rx.sub.--2 208 to Rx_M 209 may be added or combined into the
received SC communication signal, s.sub.RC. The combination may
occur in the adder 212, for example.
[0076] In step 312, the BB processor 220 may determine the first
and second baseband combined channel estimates, h.sub.1 and
h.sub.2, which comprise information regarding propagation channels
h.sub.11 to h.sub.M1, and h.sub.12 to h.sub.M2. In step 314, the
SWG channel estimator 222 in the SWBBG 221 may determine the matrix
H.sub.M.times.2 of propagation channel estimates h.sub.11 to
h.sub.M1 and h.sub.12 to h.sub.M2. In this regard, the propagation
channel estimates h.sub.11 to h.sub.M1 and h.sub.12 to h.sub.M2 may
be determined concurrently.
[0077] In step 316, the (M-1) maximum SNIR channel weights that
comprise amplitude and phase components, A.sub.1 to A.sub.M-1 and
.phi..sub.1 to .phi..sub.M-1, may be generated concurrently. The
feedback information provided to the transmitter 226 may be
generated concurrently with the (M-1) maximum SNIR channel weights.
In step 318, additional SC communication signals received may be
phase and amplitude adjusted based on the maximum SNIR channel
weights applied to the mixers 210 to 211. The channel estimation
phase rotation and the maximum SINR phase/amplitude adjustment
described in flow chart 300 may be performed continuously or may be
performed periodically. In this regard, FIG. 3B illustrates an
exemplary periodic phase rotation for an in-phase (I) signal 330
received in one of the additional receive antennas, in accordance
with an embodiment of the invention. Aspects of single weight
diversity operations and/or implementations as described in FIGS.
2A-3B may also be utilized in the reconfigurable OFDM block 190 in
FIG. 1C.
[0078] FIG. 4A is a block diagram of an exemplary single weight
baseband generator (SWBBG) that may be utilized in a 2-Tx and 2-Rx
antennas system, in accordance with an embodiment of the invention.
Referring to FIG. 4A, a receiver system 400 may comprise a first
receive antenna (Rx.sub.--1) 402, an additional receive antenna
(Rx.sub.--2) 404, an adder 406, a mixer 408, and a single weight
baseband generator (SWBBG) 410. The SWBBG 410 may comprise a phase
rotator start controller 414, a delay block 416, a single weight
generator (SWG) channel estimator 418, an SWG algorithm block 420,
and an RF phase and amplitude controller 412. The SWBBG 410 may
represent an exemplary implementation of the SWBBG 221 in FIG. 2B.
At least some of the various portions of the receiver system 400 in
FIG. 4A may be implemented in the reconfigurable OFDM block 190 in
FIG. 1C to support single weight diversity, for example.
[0079] The first receive antenna, Rx.sub.--1 402, and the
additional or second receive antenna, Rx.sub.--2 404, may comprise
suitable hardware that may be adapted to receive at least a portion
of transmitted SC communication signals in the receiver system 400.
For example, the receive antenna Rx.sub.--1 402 may receive a
signal s.sub.R1 while the receive antenna Rx.sub.--2 404 may
receive a signal s.sub.R2. The mixer 408 may correspond to, for
example, the mixer 210 in FIG. 2B. In some instances, the output of
the mixer 308 may be communicated to a bandpass filter and/or a low
noise amplifier (LNA) for further processing of the received
signals.
[0080] The adder 406 may comprise suitable hardware, logic, and/or
circuitry that may be adapted to add the output of the receive
antenna Rx.sub.--1 402 and the output of the mixer 408 to generate
a combined received SC communication signal, s.sub.RC. In some
instances, bringing the output signals of the receive antenna
Rx.sub.--1 402 and the mixer 408 together into a single electrical
connection may provide the functionality of the adder 406. The
output of the adder 406 may be transferred to additional processing
blocks for RF and baseband processing of the combined received SC
communication signal, s.sub.RC.
[0081] The phase rotator and start controller 414 may comprise
suitable logic, circuitry, and/or code that may be adapted to
control portions of the operation of the RF phase and amplitude
controller 412 and to control the delay block 416. The phase
rotator and start controller 414 may receive a signal, such as a
reset signal, from, for example, the BB processor 220 in FIG. 2B,
or from firmware operating in a processor, to indicate the start of
operations that determine the propagation channel estimates and/or
the channel weight to apply to the mixer 408. The delay block 416
may comprise suitable logic, circuitry, and/or code that may be
adapted to provide a time delay to compensate for the RF/modem
delay. The delay may be applied in order to compensate for the
interval of time that may occur between receiving the combined
channel estimates, h.sub.1 and h.sub.2, modified by the rotation
waveform and the actual rotating waveform at the mixer 408.
[0082] The SWG channel estimator 418 may comprise suitable logic,
circuitry, and/or code that may be adapted to process the first and
second baseband combined channel estimates, h.sub.1 and h.sub.2,
and determine the matrix H.sub.2.times.2 of propagation channel
estimates h.sub.11, h.sub.12, h.sub.21, and h.sub.22. The SWG
channel estimator 418 may also be adapted to generate an algorithm
start signal to the SWG algorithm block 420 to indicate that the
propagation channel estimates h.sub.11, h.sub.12, h.sub.21, and
h.sub.22 are available for processing. In this regard, the
algorithm start signal may be asserted when integration operations
performed by the SWG channel estimator 418 have completed.
[0083] The SWG algorithm block 420 may comprise suitable logic,
circuitry, and/or code that may be adapted to determine a channel
weight to be transferred to the mixer 408 via the RF phase and
amplitude controller 412 to modify the signal s.sub.R2. The channel
weight to be transferred to the mixer 408 may refer to the phase,
.phi., and amplitude, A. The channel weight may be based on the
propagation channel estimates h.sub.11, h.sub.12, h.sub.21, and
h.sub.22 and on additional information such as noise power
estimates and interference propagation channel estimates, for
example. The SWG algorithm block 420 may also be adapted to
generate an algorithm end signal to indicate to the RF phase and
amplitude controller 412 that the channel weight has been
determined and that it may be applied to the mixer 408. The SWG
algorithm block 420 in FIG. 4A may also be adapted to determine the
feedback information that may be transferred to the transmitter 226
in FIG. 2A. The feedback information may be calculated jointly to
maximize the receiver SINR, for example.
[0084] The RF phase and amplitude controller 412 may comprise
suitable logic, circuitry, and/or code that may be adapted to apply
the rotation waveform e.sup.jw.sup.r.sup.t to the mixer 408. When
phase and amplitude components, A and .phi., that correspond to the
channel weight determined by the SWG algorithm block 420 are
available, the RF phase and amplitude controller 412 may apply
amplitude A and phase .phi. to the mixer 408. In this regard, the
RF phase and amplitude controller 412 may apply the rotation
waveform or the amplitude and phase components in accordance with
the control signals provided by the phase rotator start controller
414 and/or the algorithm end signal generated by the SWG algorithm
block 420.
[0085] The phase rotation operation performed on the s.sub.R2
signal in the additional receive antenna Rx.sub.--2 404 may be
continuous or periodic. A continuous rotation of the s.sub.R2
signal may be perceived by a wireless modem as a high Doppler, and
for some modem implementations this may decrease the modem's
performance. When a periodic rotation operation is utilized
instead, the period between consecutive phase rotations may depend
on the Doppler frequency perceived by the wireless modem. For
example, in a higher Doppler operation, it may be necessary to
perform more frequent channel estimation while in a lower Doppler
operation, channel estimation may be less frequent. The signal
rotation period may also depend on the desired wireless modem
performance and the accuracy of the propagation channel estimation.
For example, when the Doppler frequency is 5 Hz, the period between
consecutive rotations may be 1/50 sec., that is, 10 rotations or
channel estimations per signal fade.
[0086] FIG. 4B is a block diagram of an exemplary single weight
baseband generator (SWBBG) that may be utilized in a 2-Tx and M-Rx
antennas system, in accordance with an embodiment of the invention.
Referring to FIG. 4B, a receiver system 430 may differ from the
receiver system 400 in FIG. 4A in that (M-1) additional receive
antennas, Rx.sub.--2 404 to Rx_M 405, and (M-1) mixers 408 to 409
may be utilized. In this regard, the SWG channel estimator 418 may
be adapted to process the first and second baseband combined
channel estimates, h.sub.11 and h.sub.2, and determine the matrix
H.sub.M.times.2 of propagation channel estimates h.sub.11 to
h.sub.M1, and h.sub.12 to h.sub.M2. At least some of the various
portions of the receiver system 430 may be implemented in the
reconfigurable OFDM block 190 in FIG. 1C to support single weight
diversity, for example.
[0087] The SWG algorithm block 420 may also be adapted to determine
(M-1) channel weights, that may be utilized to maximize receiver
SINR, for example, to be applied to the mixers 408 to 409 to modify
the portions of the transmitted SC communication signals received
by the additional receive antennas Rx.sub.--2 404 to Rx_M 405. The
(M-1) channel weights may comprise amplitude and phase components,
A.sub.1 to A.sub.M-1 and .phi..sub.1 to .phi..sub.M-1. The SWG
algorithm block 420 in FIG. 4B may also be adapted to determine the
feedback information that may be transferred to the transmitter 226
in FIG. 2A. The channel weights and the feedback information may be
calculated jointly to maximize the receiver SINR, for example.
[0088] The RF phase and amplitude controller 412 may also be
adapted to apply rotation waveforms e.sup.jw.sup.r1.sup.t to
e.sup.jw.sup.r(M-1).sup.t or phase and amplitude components,
A.sub.1 to A.sub.M-1 and .phi..sub.1 to .phi..sub.M-1, to the
mixers 408 to 409. In this regard, the RF phase and amplitude
controller 312 may apply the rotation waveforms or the amplitude
and phase components in accordance with the control signals
provided by the phase rotator start controller 414 and/or the
algorithm end signal generated by the SWG algorithm block 420.
[0089] FIG. 4C is a block diagram of an exemplary RF phase and
amplitude controller, in accordance with an embodiment of the
invention. Referring to FIG. 4C, the RF phase and amplitude
controller 412 may comprise a switch 440, a plurality of rotation
waveform sources 442, and a plurality of SWG algorithm weights 444.
The switch 440 may comprise suitable hardware, logic, and/or
circuitry that may be adapted to select between the rotation
waveforms e.sup.jw.sup.r1.sup.t to e.sup.jw.sup.r(M-1).sup.t and
the SWG algorithm determined weights A.sub.1e.sup.j.phi..sup.1 to
A.sub.M-1e.sup.j.phi..sup.M-1. The rotation waveform sources 442
may comprise suitable hardware, logic and/or circuitry that may be
adapted to generate the signal e.sup.jw.sup.rk.sup.t, where
w.sub.rk=2.pi.f.sub.rk and f.sub.rk is the rotation frequency that
preserves the orthogonality of the received signals at the receive
antennas Rx.sub.--2 402 to Rx_M 405 in FIG. 4B, for example. The
rotation frequency that preserves the signal orthogonality at the
receiving antennas may be selected as w.sub.rk=kw.sub.r where k=1,
2, . . . , M-1. Other rotation waveforms such as triangular or
square waveforms may be utilized with the same frequency
relationships. Moreover, waveforms representing different
orthogonal codes of the same frequency may also be utilized. In
this embodiment, the signal e.sup.jw.sup.rk.sup.t may be utilized
as an exemplary waveform. The plurality of SWG algorithm weights
344 may comprise suitable hardware, logic, and/or circuitry that
may be adapted to generate the signals A.sub.1e.sup.j.phi..sup.1 to
A.sub.M-1e.sup.j.phi..sup.M-1 from the amplitude and phase
components, A.sub.1 to A.sub.M-1 and .phi..sub.1 to .phi..sub.M-1,
respectively.
[0090] In operation, the RF phase and amplitude controller 412 may
apply the signals e.sup.jw.sup.r1.sup.t to
e.sup.jw.sup.r(M-1).sup.t to the mixers 408 to 409 in FIG. 4B based
on control information provided by the phase rotator start
controller 414. The switch 440 may select the rotation waveform
sources 442 based on the control information provided by the phase
rotator start controller 414. Once the channel weights are
determined by the SWG algorithm block 420 and the phase and
amplitude components have been transferred to the RF phase and
amplitude controller 412, the algorithm end signal may be utilized
to change the selection of the switch 440. In this regard, the
switch 440 may be utilized to select and apply the signals
A.sub.1e.sup.j.phi..sup.1 to A.sub.M-1e.sup.j.phi..sup.M-1 to the
mixers 408 to 409 in FIG. 4B.
[0091] FIG. 5 is a flow diagram illustrating exemplary steps in the
operation of the single weight baseband generator (SWBBG) that may
be utilized for channel weight generation in a 2-Tx and M-Rx
antennas system, in accordance with an embodiment of the invention.
Referring to FIG. 5, after start step 502, in step 504, the phase
rotator start controller 414 in FIG. 4B may receive the reset
signal to initiate operations for determining propagation channel
estimates and channel weights in the SWBBG 410. The phase rotator
start controller 414 may generate control signals to the delay
block 416 and to the RF phase and amplitude controller 412. The
control signals to the delay block 416 may be utilized to determine
a delay time to be applied by the delay block 416. The control
signals to the RF phase and amplitude controller 412 may be
utilized to determine when to apply the rotation waveforms that
have been modified by the channel weights to the mixers 408 to
409.
[0092] In step 506, the RF phase and amplitude controller 412 may
apply rotation waveforms, such as those provided by the rotation
waveform sources 442 in FIG. 4C, to the mixers 408 to 409 in FIG.
4B. In step 508, the delay block 416 may apply a time delay signal
to the SWG channel estimator 418 to reflect the interval of time
that may occur between receiving the SC communication signals and
when the first and second baseband combined channel estimates,
h.sub.1 and h.sub.2, are available to the SWG channel estimator
418. For example, the time delay signal may be utilized as an
enable signal to the SWG channel estimator 418, where the assertion
of the time delay signal initiates operations for determining
propagation channel estimates. In step 510, the SWG channel
estimator 418 may process the first and second baseband combined
channel estimates, h.sub.1 and h.sub.2, and may determine the
matrix H.sub.M.times.2 of propagation channel estimates h.sub.1 to
h.sub.M1, and h.sub.12 to h.sub.M2. The SWG channel estimator 418
may transfer the propagation channel estimates h.sub.11 to h.sub.M1
and h.sub.12 to h.sub.M2 to the SWG algorithm block 420. In step
512, the SWG channel estimator 418 may generate the algorithm start
signal and may assert the signal to indicate to the SWG algorithm
block 420 that it may initiate operations for determining channel
weights.
[0093] In step 514, the SWG algorithm block 420 may determine the
channel weights comprising phase and amplitude components, A.sub.1
to A.sub.M-1 and .phi..sub.1 to .phi..sub.M-1, based on the
propagation channel estimates h.sub.11 to h.sub.M1 and h.sub.12 to
h.sub.M2 and/or noise power estimates, for example. The SWG
algorithm block 420 may transfer the channel weights to the RF
phase and amplitude controller 412. In some instances, the SWG
algorithm block 420 may also generate feedback information. In step
516, the SWG algorithm block 420 may generate the algorithm end
signal to indicate to the RF phase and amplitude controller 412
that the channel weights are available to be applied to the mixers
408 to 409. In step 518, the RF phase and amplitude controller 412
may apply the rotation waveforms with phase and amplitude
components, A.sub.1 to A.sub.M-1 and .phi..sub.1 to .phi..sub.M-1,
to the mixers 408 to 409, in accordance with the control signals
provided by the phase rotator start controller 414.
[0094] In step 520, the receiver system 430 in FIG. 4B may
determine whether the phase rotation operation on the received SC
communication signals is periodic. When the phase rotation
operation is not periodic but continuous, the process may proceed
to step 508 where a delay may be applied to the SWG channel
estimator 418. In instances when the phase rotation operation is
periodic, the process may proceed to step 522 where the receiver
system 430 may wait until the next phase rotation operation is
initiated by the reset signal. In this regard, the process control
may proceed to step 504 upon assertion of the reset signal to the
phase rotator start controller 414.
[0095] FIG. 6 is a block diagram of an exemplary channel estimator
for a 2-Tx and 2-Rx antennas system, in accordance with an
embodiment of the invention. Referring to FIG. 6, the SWG channel
estimator 418 in FIG. 4A utilized in, for example, a 2-Tx and 2-Rx
antenna system may comprise a first channel estimator block 601 and
a second channel estimator block 603. The first channel estimator
block 601 may comprise a phase rotator 602, a mixer 606, a first
integrator 604, and a second integrator 608. The second channel
estimator block 603 may also comprise a phase rotator 602, a mixer
606, a first integrator 604, and a second integrator 608. The phase
rotator 602 may comprise suitable logic, circuitry, and/or code
that may be adapted to generate a complex conjugate of the rotation
waveform e.sup.jw.sup.r.sup.t. The first integrator 604 and the
second integrator 608 may comprise suitable logic, circuitry,
and/or code that may be adapted to integrate an input signal over a
360-degree phase rotation period.
[0096] The accuracy and/or time of the integration may vary and may
be selected by the SWGGB 410 in FIG. 4A. The mixer 606 may comprise
suitable logic and/or circuitry that may be adapted to multiply the
rotation waveform complex conjugate and a baseband combined channel
estimate. For example, the mixer 606 in the first channel estimator
block 601 and the mixer 606 in the second channel estimator block
603 may multiply, respectively, the first and second baseband
combined channel estimates, h.sub.1 and h.sub.2, where
h.sub.1=h.sub.11+e.sup.jw.sup.r.sup.th.sub.21 and
h.sub.2=h.sub.12+e.sup.jw.sup.r.sup.th.sub.22, with the rotation
waveform complex conjugate.
[0097] In operation, the delay signal from the delay block 416 may
indicate to the phase rotator 602, the first integrator 604, and/or
the second integrator 608 when to start operations for determining
the propagation channel estimates. After the delay signal is
asserted, the second integrator 608 may receive the baseband
combined channel estimate and may integrate the baseband combined
channel estimate over a 360-degree phase rotation period. The
integration time may be selected based on channel estimation
accuracy and required modem performance. A longer integration time
may result in more accurate channel estimates. The second
integrator 608 in the first channel estimator block 601 and the
second integrator 608 in the second channel estimator block 603 may
determine, respectively, the propagation channel estimates h.sub.11
and h.sub.12 by determining the expectation values of h.sub.1 and
h.sub.2 as follows:
h.sub.11=E[h.sub.11+e.sup.jw.sup.r.sup.th.sub.21]=h.sub.11+E[e.-
sup.jw.sup.r.sup.th.sub.21], and
h.sub.12=E[h.sub.12+e.sup.jw.sup.r.sup.th.sub.22]=h.sub.12+E[e.sup.jw.sup-
.r.sup.th.sub.22], where E[e.sup.jw.sup.r.sup.th.sub.21] and
E[e.sup.jw.sup.r.sup.th.sub.22] over a full 360-degre rotation
period are equal to zero. In this regard, channel estimates
h.sub.11 and h.sub.12 may referred to as first channel estimates
because they correspond to propagation channels related to a first
transmit antenna.
[0098] After the delay signal is asserted, the first integrator 604
in the first channel estimator block 601 and the first integrator
604 in the second channel estimator block 603 may receive,
respectively, the signals e.sup.-jw.sup.r.sup.th.sub.1 and
e.sup.-jw.sup.r.sup.th.sub.2. The first integrator 604 in the first
channel estimator block 601 and the first integrator 604 in the
second channel estimator block 603 may determine, respectively, the
channel estimates h.sub.21 and h.sub.22 by determining the
expectation values of e.sup.-jw.sup.r.sup.th.sub.1 and
e.sup.-jw.sup.r.sup.th.sub.2 as follows:
h.sub.21=E[e.sup.-jw.sup.r.sup.th.sub.1]=E[e.sup.-jw.sup.r.sup.t(h.sub.11-
+e.sup.jw.sup.r.sup.th.sub.21)]=E[e.sup.-jw.sup.r.sup.th.sub.11+h.sub.21]=-
E[e.sup.jw.sup.r.sup.th.sub.11]+h.sub.21, and
h.sub.22=E[e.sup.-jw.sup.r.sup.th.sub.2]=E[e.sup.-jw.sup.r.sup.t(h.sub.12-
+e.sup.jw.sup.r.sup.th.sub.22)]=E[e.sup.-jw.sup.r.sup.th.sub.12+h.sub.22]=-
E[e.sup.-jw.sup.r.sup.th.sub.12]+h.sub.22 where
E[e.sup.-jw.sup.r.sup.th.sub.11] and
E[e.sup.-jw.sup.r.sup.th.sub.12] over a full 360-degree rotation
period is equal to zero. In this regard, channel estimates h.sub.21
and h.sub.22 may referred to as second channel estimates because
they correspond to propagation channels related to a second
transmit antenna.
[0099] The channel estimation operations performed by the SWG
channel estimator 418 may be extended to cases where M receive
antennas result in a first and second baseband combined channel
estimates, h.sub.1 and h.sub.2, which comprise information
regarding propagation channels h.sub.11 to h.sub.M1 and h.sub.2 to
h.sub.M2. In that case, a plurality of channel estimator blocks may
be utilized to determine the matrix H.sub.M.times.2 of propagation
channel estimates h.sub.11 to h.sub.M1 and h.sub.12 to hM2.
[0100] FIG. 7 is a flow diagram illustrating exemplary steps for
channel estimation based on complex multiplication and integration
of a first and second baseband combined channel estimates, in
accordance with an embodiment of the invention. Referring to FIG.
7, after start step 702, in step 704, the integration time and/or
integration resolution may be selected for the first and second
integrators in FIG. 6. For example, the SWBBG 221 in FIG. 2A may
select the integration time. In step 706, the delay signal may be
asserted to initiate the operations performed by the phase rotator
602, the first integrator 604, and the second integrator 608. The
phase rotator 602 may generate a complex conjugate of the rotation
waveform e.sup.jw.sup.r.sup.t. In step 708, the first and second
baseband combined channel estimates, h.sub.1 and h.sub.2, may be
transferred to the second integrator 608 and to the mixer 606 for
processing. In step 710, the baseband combined channel estimates,
h.sub.1 and h.sub.2, may be multiplied by the complex conjugate of
the rotation waveform e.sup.jw.sup.r.sup.t.
[0101] In step 712, integration over a 360-degree phase rotation
period may be performed in the first integrator 604 and the second
integrator 608 to determine propagation channel estimates h.sub.21
and h.sub.22 and h.sub.11 and h.sub.2 respectively. In step 714,
after the propagation channel estimates have been determined, the
SWG channel estimator 418 in FIG. 4A may generate the algorithm
start signal to indicate to the SWG algorithm block 420 that the
propagation channel estimates are available. The SWG algorithm
block 420 may start operations for determining channel weights when
the algorithm start signal is asserted. In step 716, the SWG
algorithm block 420 may generate channel weights based on the
propagation channel estimates. The channel weights may be applied
to the additional or second receive antenna.
[0102] In step 718, the receiver system 400 in FIG. 4A may
determine whether the phase rotation operation on the received SC
communication signals is periodic. When the phase rotation is not
periodic but continuous, control may proceed to step 708 where the
next set of first and second baseband combined channel estimates,
h.sub.1 and h.sub.2, from the BB processor 220 in FIG. 2A may be
available for channel estimation. When the phase rotation is
periodic, control may proceed to step 720 where the SWG channel
estimator 418 may wait until the delay signal is asserted to
initiate the operations performed by the phase rotator 602, the
first integrator 604, and the second integrator 608. In this
regard, control may proceed to step 706 upon the assertion of the
reset signal to the phase rotator start controller 414 and the
generation of the control signals to the delay block 416.
[0103] The channel estimation operations described in FIG. 7 may be
extended to cases where M receive antennas result in a first and
second baseband combined channel estimates, h.sub.1 and h.sub.2,
which comprise information regarding propagation channels h.sub.11
to h.sub.M1 and h.sub.12 to h.sub.M2. In that case, a plurality of
channel estimator blocks may be utilized to determine the matrix
H.sub.M.times.2 of propagation channel estimates h.sub.11 to
h.sub.M1, and h.sub.12 to h.sub.M2.
[0104] In an embodiment of the invention, a machine-readable
storage may be provided, having stored thereon, a computer program
having at least one code section executable by a machine, thereby
causing the machine to perform the steps for achieving single
weight diversity in a reconfigurable orthogonal frequency division
multiplexing (OFDM) chip.
[0105] Certain aspects of the invention may correspond to a system
for handling wireless communication, the system comprising
circuitry within a single chip that applies at least one of a
plurality of channel weights generated within the single chip to at
least one of a plurality of signals received via a plurality of
antennas in a single orthogonal frequency division multiplexing
(OFDM) receiver. One of the signals received may be utilized as a
reference signal. Circuitry within the single chip may be adapted
to combine the signals received via the antennas to generate a
single combined received signal. Circuitry within the single chip
may also be adapted to determine a plurality of channel estimates
based on the combined plurality of signals. Circuitry within the
single chip may also be adapted to determine at least one of a
plurality of subsequent channel weights based on the determined
channel estimates.
[0106] The system may also comprise a processor coupled to the
single chip, wherein the processor may be adapted to select an
integration time for determining the channel estimates, for
example. The processor may also be adapted to configure the single
chip in the OFDM receiver to handle at least one of a plurality of
communication protocols based on OFDM. These communication
protocols may comprise an IEEE 802.11 wireless local area network
(WLAN) protocol, an IEEE 802.16 wireless metropolitan area network
(WMAN) protocol, or a digital video broadcasting (DVB) protocol,
for example. Circuitry within the single chip may be adapted to
update at least a portion of the channel weights dynamically.
Moreover, circuitry within the single chip may be adapted to
determine a phase and amplitude component for at least one of the
channel weights.
[0107] The approach described herein for a reconfigurable OFDM chip
supporting single weight diversity may result in higher
transmission rates for various communication standards such as
WLAN, WMAN, and/or DVB-H, for example. Moreover, the collaborative
architecture provided may be utilized in wireless devices to
support efficient cellular and OFDM-based communication.
[0108] Accordingly, the present invention may be realized in
hardware, software, or a combination thereof. The present invention
may be realized in a centralized fashion in at least one computer
system, or in a distributed fashion where different elements may be
spread across several interconnected computer systems. Any kind of
computer system or other apparatus adapted for carrying out the
methods described herein may be suited. A typical combination of
hardware and software may be a general-purpose computer system with
a computer program that, when being loaded and executed, may
control the computer system such that it carries out the methods
described herein.
[0109] The present invention may also be embedded in a computer
program product, which comprises all the features enabling the
implementation of the methods described herein, and which when
loaded in a computer system is able to carry out these methods.
Computer program in the present context means any expression, in
any language, code or notation, of a set of instructions intended
to cause a system having an information processing capability to
perform a particular function either directly or after either or
both of the following: a) conversion to another language, code or
notation; b) reproduction in a different material form.
[0110] While the present invention has been described with
reference to certain embodiments, it will be understood by those
skilled in the art that various changes may be made and equivalents
may be substituted without departing from the scope of the present
invention. In addition, many modifications may be made to adapt a
particular situation or material to the teachings of the present
invention without departing from its scope. Therefore, it is
intended that the present invention not be limited to the
particular embodiment disclosed, but that the present invention
will include all embodiments falling within the scope of the
appended claims.
* * * * *