U.S. patent application number 11/037526 was filed with the patent office on 2005-06-16 for ultra-wideband communication system and method.
Invention is credited to Moore, Steven A., Santhoff, John.
Application Number | 20050129092 11/037526 |
Document ID | / |
Family ID | 33451866 |
Filed Date | 2005-06-16 |
United States Patent
Application |
20050129092 |
Kind Code |
A1 |
Santhoff, John ; et
al. |
June 16, 2005 |
Ultra-wideband communication system and method
Abstract
The present invention provides systems and methods for
communication between ultra-wideband (UWB) devices. In general, the
UWB device may characterize the attenuation, and other
characteristics of the communication environment. Using these
characteristics the UWB device can adapt various communication
parameters to improve the communication quality. The UWB device may
use these characteristics to establish zones and sectors for
communication with other UWB devices. Based on this zone and sector
assignment the UWB device may select communication parameters for
communication with other UWB devices. This Abstract is provided for
the sole purpose of complying with the Abstract requirement rules
that allow a reader to quickly ascertain the subject matter of the
disclosure contained herein. This Abstract is submitted with the
explicit understanding that it will not be used to interpret or to
limit the scope or the meaning of the claims.
Inventors: |
Santhoff, John; (San Diego,
CA) ; Moore, Steven A.; (Escondido, CA) |
Correspondence
Address: |
PULSE-LINK, INC.
1969 KELLOGG AVENUE
CARLSBAD
CA
92008
US
|
Family ID: |
33451866 |
Appl. No.: |
11/037526 |
Filed: |
January 18, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11037526 |
Jan 18, 2005 |
|
|
|
10449789 |
May 30, 2003 |
|
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Current U.S.
Class: |
375/130 |
Current CPC
Class: |
H04W 28/18 20130101;
H04L 1/0026 20130101; H04L 1/203 20130101; H04J 3/0638 20130101;
H04L 25/4902 20130101; H04B 1/7183 20130101; H04L 1/0002 20130101;
H04B 1/719 20130101; H04B 1/71632 20130101; G01S 13/765 20130101;
H04W 24/00 20130101; H04L 1/18 20130101; H04L 12/189 20130101 |
Class at
Publication: |
375/130 |
International
Class: |
H04B 001/69 |
Claims
What is claimed is:
1. A method of selecting at least one communication parameter in an
ultra-wideband communication system based on a bit-error-rate, the
method comprising the steps of: providing a first ultra-wideband
device; transmitting a bit-error-rate message from the first
ultra-wideband device to a second ultra-wideband device; receiving
a bit-error-rate response message from the second ultra-wideband
device; and selecting at least one communication parameter based on
the bit-error-rate.
2. The method of claim 1, wherein the transmitted bit-error-rate
message comprises a known number of bits.
3. The method of claim 1, wherein the received bit-error-rate
message sent from the second ultra-wideband device includes
information relating to the number of bits received.
4. The method of claim 1, wherein the communication parameter is
selected from at least one of a group consisting of an
ultra-wideband pulse modulation technique, a method of error
detection, a method of error correction, a method of error control,
a ultra-wideband pulse recurrence frequency, a data rate, a power
of transmission, an ultra-wideband pulse shape, a configuration of
a receiver, an ultra-wideband pulse width, a frame length, and a
rate of time synchronization.
5. A computer program product for selecting at least one
communication parameter in an ultra-wideband communication system
based on a bit-error-rate, comprising: computer logic for
transmitting a bit-error-rate message from a first ultra-wideband
device to a second ultra-wideband device; computer logic for
receiving a bit-error-rate response message from the second
ultra-wideband device; and computer logic for selecting at least
one communication parameter based on the bit-error-rate.
6. The computer program product of claim 5, wherein the transmitted
bit-error-rate message comprises a known number of bits.
7. The computer program product of claim 5, wherein the received
bit-error-rate message sent from the second ultra-wideband device
includes information relating to the number of bits received.
8. The computer program product of claim 5, wherein the
communication parameter is selected from at least one of a group
consisting of: an ultra-wideband pulse modulation technique, a
method of error detection, a method of error correction, a method
of error control, a ultra-wideband pulse recurrence frequency, a
data rate, a power of transmission, an ultra-wideband pulse shape,
a configuration of a receiver, an ultra-wideband pulse width, a
frame length, and a rate of time synchronization.
9. The computer program product or claim 5, wherein the computer
program product is translated into a physical implementation.
10. A method of selecting at least one communication parameter in
an ultra-wideband communication system based on a bit-error-rate,
the method comprising the steps of: means for providing a first
ultra-wideband device; means for transmitting a bit-error-rate
message from the first ultra-wideband device to a second
ultra-wideband device; means for receiving a bit-error-rate
response message from the second ultra-wideband device; and means
for selecting at least one communication parameter based on the
bit-error-rate.
11. The method of claim 10, wherein the transmitted bit-error-rate
message comprises a known number of bits.
12. The method of claim 10, wherein the received bit-error-rate
message sent from the second ultra-wideband device includes
information relating to the number of bits received.
13. The method of claim 10, wherein the communication parameter is
selected from at least one of a group consisting of: an
ultra-wideband pulse modulation technique, a method of error
detection, a method of error correction, a method of error control,
a ultra-wideband pulse recurrence frequency, a data rate, a power
of transmission, an ultra-wideband pulse shape, a configuration of
a receiver, an ultra-wideband pulse width, a frame length, and a
rate of time synchronization.
Description
[0001] This application is a divisional application of, and claims
priority to, co-pending United States non-provisional application
Ser. No. 10/449,789, filed May 30, 2003, entitled "ULTRA-WIDEBAND
COMMUNICATION SYSTEM AND METHOD."
FIELD OF THE INVENTION
[0002] The present invention relates generally to the field of
wireless communications, and more specifically to ultra-wideband
wireless communication that employs several communication
parameters.
BACKGROUND OF THE INVENTION
[0003] The wireless device industry has recently seen unprecedented
growth. With the growth of this industry, communication between
wireless devices has become increasingly important. There are a
number of different technologies for inter-device communications.
Radio Frequency (RF) technology has been the predominant technology
for wireless device communications. Alternatively, electro-optical
devices have been used in wireless communications. Electro-optical
technology suffers from low ranges and a strict need for line of
sight. RF devices therefore provide significant advantages over
electro-optical devices.
[0004] Conventional RF technology employs continuous sine waves
that are transmitted with data embedded in the modulation of the
sine waves' amplitude or frequency. For example, a conventional
cellular phone must operate at a particular frequency band of a
example, a conventional cellular phone must operate at a particular
frequency band of a particular width in the total frequency
spectrum. Specifically, in the United States, the Federal
Communications Commission has allocated cellular phone
communications in the 800 to 900 MHz band. Generally, cellular
phone operators divide the allocated band into 25 MHz portions,
with selected portions transmitting cellular phone signals, and
other portions receiving cellular phone signals.
[0005] Another type of inter-device communication technology is
ultra-wideband (UWB). UWB wireless technology is fundamentally
different from conventional forms of RF technology. UWB employs a
"carrier free" architecture, which does not require the use of high
frequency carrier generation hardware; carrier modulation hardware;
frequency and phase discrimination hardware or other devices
employed in conventional frequency domain communication systems.
UWB communications systems and devices additionally benefit from
the capability to measure distance and geo-position. Generally,
these UWB devices measure the time it takes for a UWB pulse, or
signal to travel from one UWB device to another UWB device, and use
the speed of light to determine the distance between UWB
devices.
[0006] However, the broad concept of using time and the speed of
light to determine distance has been employed for centuries. The
first recorded attempts to establish the speed of light by the use
of distance date back to the experiments of Galileo in the 1600s.
His only conclusion based on his terrestrial experiments was that
light moves very fast. In 1676, Olaf Roemer was able to measure the
speed of light to be approximately 2.14.times.10 8 based on his
assumptions of the distance between Jupiter and the Earth. The
current accepted measurement of 2.9997924588.times.108 was obtained
using laser interferometery.
[0007] In theory, a wireless ultra-wideband (UWB) communications
pulse, or signal transmitted from a source and received by a target
arrives without any delays or distortions caused by the surrounding
environment. Such an ideal environment is difficult to realize
outside the vacuum of outer space. In more practical environments
and especially in urban settings, the environment may have a
substantial impact on the reception of a UWB pulse, or signal.
[0008] Generally, the distance between communicating devices
affects the quality of the communications channel. Electromagnetic
radiation dissipates proportionally to distance squared.
Additionally, the terrain affects radio waves. Thus, the
opportunity for multi-path, or "fading" effects generally increases
with distance. There are essentially two types of fading in
electromagnetic communications. Local multi-path fluctuation is
known as fast-fading or Raleigh fading. More distance fading
effects may be caused by long term variation in average power
levels, slow fading or log-normal fading, which is caused by
movement over distances long enough to produce significant
variations in the signal path length. Multi-path reflections can
also cause a signal to arrive at the receiver in multiple
reflections, each at a different time. This is commonly referred to
as delay spread. As signal strength attenuates or decreases, the
signal-to-noise ratio (SNR) degrades as well, generally leading to
increased bit-error-rates (BER).
[0009] Therefore, there exists a need for an ultra-wideband
communication system that provides reliable communication at a
variety of distances, and in a variety of environments.
SUMMARY OF THE INVENTION
[0010] The present invention provides reliable systems and methods
for communication between ultra-wideband (UWB) devices located a
variety of distances from each other. One method of the present
invention selects at least one communication parameter that enables
reliable communication between UWB devices. This method comprises
transmitting a time request signal from a first UWB device to a
time synchronized UWB device. The time synchronized UWB device
sends a response message to the first UWB device, which determines
a time difference between the time of receipt of the time response
message and the time of transmission contained within the time
response message. A communication parameter is the selected, based
at least on the time difference.
[0011] Another embodiment of the present invention characterizes
the attenuation characteristics of the wireless medium though which
the UWB devices are transmitting. Using these characteristics the
UWB devices can adapt various communication parameters to improve
the quality of communications.
[0012] These and other features and advantages of the present
invention will be appreciated from review of the following detailed
description of the invention, along with the accompanying figures
in which like reference numerals refer to like parts
throughout.
BRIEF DESCRIPTION OF THE DRAWING
[0013] FIG. 1 is an illustration of different communication
methods;
[0014] FIG. 2 is an illustration of two ultra-wideband pulses;
[0015] FIG. 3 is an illustration of zones and sectors established
by a UWB device in accordance with one embodiment of the present
invention;
[0016] FIG. 4 shows a time request message and an associated time
response message in accordance with one embodiment of the present
invention;
[0017] FIG. 5 shows a distance request message and an associated
distance response message in accordance with one embodiment of the
present invention;
[0018] FIG. 6 shows a BER request message and an associated BER
response message in accordance with one embodiment of the present
invention;
[0019] FIG. 7 shows a fixed energy request message and an
associated fixed energy response message in accordance with one
embodiment of the present invention;
[0020] FIG. 8 shows a sectorized zone system with a fixed access
point in accordance with one embodiment of the present
invention;
[0021] FIG. 9 shows UWB enabled devices communicating in a
sectorized zone system with a fixed access point in accordance with
one embodiment of the present invention;
[0022] FIG. 10 shows a UWB enabled device communicating with other
UWB enabled devices in the absence of a fixed access point in
accordance with one embodiment of the present invention; and
[0023] FIG. 11 shows spatial diversity assignment of time bins in
accordance with one embodiment of the present invention.
[0024] It will be recognized that some or all of the Figures are
schematic representations for purposes of illustration and do not
necessarily depict the actual relative sizes or locations of the
elements shown.
DETAILED DESCRIPTION OF THE INVENTION
[0025] In the following paragraphs, the present invention will be
described in detail by way of example with reference to the
attached drawings. Throughout this description, the preferred
embodiment and examples shown should be considered as exemplars,
rather than as limitations on the present invention. As used
herein, the "present invention" refers to any one of the
embodiments of the invention described herein, and any equivalents.
Furthermore, reference to various feature(s) of the "present
invention" throughout this document does not mean that all claimed
embodiments or methods must include the referenced feature(s).
[0026] The present invention provides reliable systems and methods
for communication between ultra-wideband (UWB) devices located a
variety of distances from each other. Generally, each UWB device
employing the methods of the present invention may use various
communication parameters in response to different distance, power,
environmental, and other conditions when communicating with each
other.
[0027] One method of the present invention selects at least one
communication parameter that enables reliable communication between
UWB devices. This method comprises transmitting a time request
signal from a UWB device to a time synchronized UWB device. The
time synchronized UWB device sends a response message to the first
UWB device, which determines a time difference between the time of
receipt of the time response message and the time of transmission
contained within the time response message. A communication
parameter is the selected, based at least on the time
difference.
[0028] Another embodiment of the present invention characterizes
the attenuation characteristics of the wireless medium though which
the UWB devices are transmitting. Using these characteristics the
UWB devices can adapt various communication parameters to improve
the quality of communications.
[0029] In another embodiment of the present invention, a UWB
enabled wireless device obtains distance information to at least
one other UWB enabled wireless device. The distance information is
then used to determine a zone location for each UWB device.
Specific communication parameters are then employed for each zone.
When communicating with other UWB enabled devices the first UWB
device adapts its communication parameters in accordance with the
zone parameters.
[0030] In another embodiment of the present invention, a UWB
enabled device obtains Received Signal Strength Indicator (RSSI)
information from at least one UWB enabled device. The first UWB
device uses the RSSI information to derive RSSI-based zones for
communication with the UWB enabled devices. Alternatively, the
first UWB device may use the RSSI and distance information to
characterize the communications environment within the zone.
[0031] In a still further embodiment of the present invention, an
access point assigns communication frame parameters to each zone to
reduce the probability of multi-user interference.
[0032] Conventional radio frequency technology employs continuous
sine waves that are transmitted with data embedded in the
modulation of the sine waves' amplitude or frequency. For example,
a conventional cellular phone must operate at a particular
frequency band of a particular width in the total frequency
spectrum. Specifically, in the United States, the Federal
Communications Commission has allocated cellular phone
communications in the 800 to 900 MHz band. Cellular phone operators
use 25 MHz of the allocated band to transmit cellular phone
signals, and another 25 MHz of the allocated band to receive
cellular phone signals.
[0033] Another example of a conventional radio frequency technology
is illustrated in FIG. 1. 802.11a, a wireless local area network
(LAN) protocol, transmits radio frequency signals at a 5 GHz center
frequency, with a radio frequency spread of about 5 MHz.
[0034] In contrast, a UWB pulse may have a 1.8 GHz center
frequency, with a frequency spread of approximately 3.2 GHz, as
shown in FIG. 2, which illustrates two typical UWB pulses. FIG. 2
illustrates that the narrower the UWB pulse in time, the broader
the spread of its frequency spectrum. This is because frequency is
inversely proportional to the time duration of the pulse. A 600
picosecond UWB pulse may have about a 1.8 GHz center frequency,
with a frequency spread of approximately 1.6 GHz. And a 300
picosecond UWB pulse may have about a 3 GHz center frequency, with
a frequency spread of approximately 3.2 GHz. Thus, UWB pulses
generally do not operate within a specific frequency, as shown in
FIG. 1. And because UWB pulses are spread across an extremely wide
frequency range, UWB communication systems allow communications at
very high data rates, such as 100 megabits per second or
greater.
[0035] Further details of UWB technology are disclosed in U.S. Pat.
No. 3,728,632 (in the name of Gerald F. Ross, and titled:
Transmission and Reception System for Generating and Receiving
Base-Band Duration Pulse Signals without Distortion for Short
Base-Band Pulse Communication System), which is referred to and
incorporated herein in its entirety by this reference.
[0036] Also, because the UWB pulse is spread across an extremely
wide frequency range, the power sampled at a single, or specific
frequency is very low. For example, a UWB one-watt signal of one
nano-second duration spreads the one-watt over the entire frequency
occupied by the pulse. At any single frequency, such as a cellular
phone carrier frequency, the UWB pulse power present is one
nano-watt (for a frequency band of 1 GHz). This is well within the
noise floor of any cellular phone system and therefore does not
interfere with the demodulation and recovery of the original
cellular phone signals. Generally, the multiplicity of UWB pulses
are transmitted at relatively low power (when sampled at a single,
or specific frequency), for example, at less than -30 power
decibels to -60 power decibels, which minimizes interference with
conventional radio frequencies.
[0037] As described above, wireless devices communicate with Radio
Frequency (RF) energy. Conventional technologies for RF
communications employ RF carrier waves. Data is modulated onto the
carrier wave, amplified and transmitted from the first RF device. A
second RF wireless device receives the carrier wave, amplifies the
wave, and demodulates the data. RF communications suffer from
fading, multi-path interference, and channel attenuation. Since RF
energy strength is proportional to the inverse of the transmitted
distance squared, the quality of RF wireless device communication
is dependent on the relative location of the RF devices that are
communicating. Atmospheric conditions, terrain, natural and
man-made objects can additionally degrade the received signal
strength of RF communications.
[0038] As is well known in the art, propagation of RF energy is
strongly influenced by the environment, both man-made and natural.
For example, urban areas are generally dominated by large man-made
structures. Suburban areas typically contain residential
structures, and rural areas may be more open, with wooded areas and
the occasional man-made structure.
[0039] One feature of the present invention is that it adapts
communication parameters to maximize the communication quality
between UWB enabled devices. Thus, one assortment of communication
parameters may be used for urban areas, another assortment for
residential areas, with yet another assortment used for rural
areas. The assortment is not fixed for each environment, rather the
communication parameters used in each environment may be altered,
or other communication parameters may be employed to obtain the
best possible communication quality.
[0040] The distance between communicating devices is one important
characteristic in communications quality. There are numerous
methods of establishing distance between communicating devices. One
feature of ultra-wideband (UWB) systems is that they can determine
the time of arrival of a UWB pulse, or signal very precisely. For
example, UWB systems can determine pulse or signal time of arrival
(TOA) to within 200 pico-seconds. With an approximate propagation
speed of 10 centimeters per nano-second, this UWB system may be
capable of accurately measuring distance to approximately 2
centimeters. As time resolutions decrease in UWB devices, their
ability to resolve distance is further enhanced. Thus, because UWB
technology can determine TOA to very precise resolutions, accurate
distances can be determined.
[0041] Co-pending U.S. patent application Ser. No. 09/805,735,
filed Mar. 13, 2001, titled: MAINTAINING A GLOBAL TIME REFERENCE
AMONG A GROUP OF NETWORKED DEVICES, teaches synchronization of UWB
enabled devices to a single master time reference. This application
is incorporated herein in its entirety by this reference. Once the
communicating UWB devices are synchronized to the master time
reference, distance measurements may be made by any of the
communicating devices. To determine distance, a receiving UWB
device only needs to know the time of transmission and the time of
arrival of the UWB pulse, or signal. Since the communicating UWB
devices are synchronized to the same master time reference, the
reference for the time of transmission is consistent between the
UWB devices. The time of arrival of the UWB signal is determined by
the receiving device, and contained within the UWB signal is the
signal's time of transmission. The distance between UWB devices is
obtained by determining the difference between the transmission
time and the arrival time, and multiplying it by the UWB signal
speed. Because the transmission time and the arrival time are both
referenced to the same master time reference, the distance
calculation will be accurate.
[0042] Another method of determining the distance between
ultra-wideband (UWB) devices is disclosed in the following
co-pending United States patent application that is herein
incorporated in its entirety by this reference: USE OF THIRD PARTY
ULTRA-WIDEBAND DEVICES TO ESTABLISH GEO-POSITIONAL DATA, Ser. No.
10/263,213, filed Aug. 28, 2002, which is a continuation-in-part of
U.S. Pat. No. 6,519,464, titled: USE OF THIRD PARTY ULTRA-WIDEBAND
DEVICES TO ESTABLISH GEO-POSITIONAL DATA, Ser. No. 09/745,498,
filed Dec. 22, 2000, which claims priority to U.S. provisional
patent application Ser. No. 60/255,469, filed Dec. 14, 2000,
titled: ULTRA-WIDEBAND COMMUNICATION SYSTEM AND METHOD.
[0043] In the above-incorporated reference, an UWB device may
determine it geographical position based on the position of other
UWB devices. In this embodiment, a first UWB device may send a
position request message to two, or more UWB devices that know
their geographical location. The other UWB devices would respond
with a message that includes their geographical location. The first
UWB device may then determine its own geographical position based
on the geographical location of the responding UWB devices.
Communication parameters may then be selected based on the distance
between the UWB devices.
[0044] One embodiment of the present invention uses distance as one
factor to select various communications parameters. Other
embodiments of the present invention may use a data bit-error-rate
(BER) and/or a received signal strength indicator (RSSI) as factors
in selecting communication parameters. In addition, one embodiment
of the present invention may use the derived distance information
to designate "zones" that extend outward from the UWB device. Sets
of communication parameters may then be assigned for each zone.
[0045] However, UWB pulse, or signal propagation characteristics
may vary within each zone. As shown in FIG. 3, zones Z1, Z2, Z3 and
Z4 emanate outward from a UWB device (not shown) located at the
center of zone Z1. For convenience of illustration, only four zones
are illustrated, however embodiments of the present invention may
have less than or more than four zones.
[0046] One feature of the present invention enables more accurate
selection of communication parameters by partitioning each zone
into discrete sectors. Sectorization may be accomplished in a
number of ways. In one embodiment, sectors are assigned as portions
of a circle measured in degrees. Shown in FIG. 3, a four-sector
system, including sector 1, sector 2, sector 3 and sector 4 would
comprise 90-degree portions of each zone Z1, Z2, Z3 and Z4.
Depending upon the communications environment, and other factors,
the number of sectors may be greater than, or less than the four
illustrated sectors. Once zones and sectors are established the UWB
device selects various parameters to be used for inter-device
communications based on the zone and sector of the destination UWB
device.
[0047] There are various communication parameters that may be
employed to enable communication between UWB devices. These
communication parameters may include the UWB pulse modulation
technique, the method of error detection and correction, the error
control algorithm, the UWB pulse recurrence frequency, the data
rate, the power of transmission, the UWB pulse shape, the
configuration of the receiver, the UWB pulse width, the frame
length, the frequency of master time reference synchronization, and
other suitable communication parameters.
[0048] Ultra-wideband pulse modulation techniques enable a single
representative data symbol to represent a plurality of binary
digits, or bits. This has the obvious advantage of increasing the
data rate in a communications system. A few examples of modulation
include Pulse Width Modulation (PWM), Pulse Amplitude Modulation
(PAM), and Pulse Position Modulation (PPM). In PWM, a series of
predefined UWB pulse widths are used to represent different sets of
bits. For example, in a system employing 8 different UWB pulse
widths, each symbol could represent one of 8 combinations. This
symbol would carry 3 bits of information. In PAM, predefined UWB
pulse amplitudes are used to represent different sets of bits. A
system employing PAM16 would have 16 predefined UWB pulse
amplitudes. This system would be able to carry 4 bits of
information per symbol. In a PPM system, predefined positions
within an UWB pulse timeslot are used to carry a set of bits. A
system employing PPM16 would be capable of carrying 4 bits of
information per symbol. Additional UWB pulse modulation techniques
may include: Coded Recurrence Modulation (CRM) as described in
co-pending U.S. patent application Ser. No. 10/294,021, titled
"ULTRA-WIDEBAND PULSE MODULATION SYSTEM AND METHOD"; Sloped
Amplitude Modulation (SLAM) as described in co-pending U.S. patent
application Ser. No. 10/188,987, titled "ULTRA-WIDEBAND PULSE
GENERATION SYSTEM AND METHOD"; ternary modulation, as described in
co-pending U.S. patent application Ser. No. ______ to be assigned,
filed Apr. 28, 2003, titled "ULTRA-WIDEBAND PULSE MODULATION SYSTEM
AND METHOD", which claims priority to provisional patent
application Ser. No. 60/452,020, of the same title; 1-pulse
modulation, as described in co-pending U.S. patent application,
Ser. No. ______ to be assigned, filed Apr. 29, 2003, titled
"ULTRA-WIDEBAND PULSE MODULATION SYSTEM AND METHOD"; and other UWB
pulse modulation methods as described in co-pending U.S. patent
application Ser. No. 09/710,065, titled "ULTRA-WIDEBAND
COMMUNICATION SYSTEM WITH AMPLITUDE MODULATION AND TIME MODULATION.
All of the above-listed non-provisional and provisional United
States patent applications are incorporated herein by reference in
their entirety.
[0049] There are various methods of error detection and correction
used in communication systems. The simplest form of error detection
involves the use of a parity bit per block of data. The additional
bit is set to ensure that the block has either an even number of
ones, if even parity is used, or an odd number of ones if odd
parity is employed. Use of parity will only detect an odd number of
errors in a given block of data.
[0050] Another type of error detection is the Longitudinal
Redundancy Check (LRC)/Vertical Redundancy Check (VRC) scheme. This
method uses not only one parity bit per word, or row of the frame,
considered now as a matrix, but also a "parity check character",
comprising the entire last row of the matrix, with each bit in the
row checking the parity of the corresponding column. The row parity
bits form the last column and are called the VRC, while the column
parity bits form the last row and are called the LRC or the parity
check character. LRC/VRC will fail to detect conditions that have
even number of errors in each column and each row.
[0051] A common and powerful technique of error detection is
Cyclical Redundancy Check (CRC). In CRC the transmitter generates a
Frame Check Sequence (FCS) of a length necessary to ensure that
when the FCS is appended to the block of bits the augmented block
is divisible by a predetermined number. On receipt, the number of
bits is divided by the predetermined number, and if there is no
remainder, the receiver assumes that the message is error free. Any
of the above-described error detection methods, and other error
detection methods not described, may be employed by the present
invention.
[0052] There are essentially two groups of error correction
algorithms: Backward Error Correction (BEC) and Forward Error
Correction (FEC). In BEC, also known as Reverse Error Correction
(REC), the first device sends a message, packet, or frame to a
receiver. The second device checks the received data for error. If
an error is detected, a request to retransmit the message, packet,
or frame is sent to the first device. In contrast, when using
Forward Error Correction (FEC) the second device corrects the error
without retransmission of data from the first device. BEC has the
advantage of simplicity, but generally requires duplex
communications channels. Additionally, since the first device is
required to retransmit frames, the overall information throughput
is reduced. FEC allows for one-sided communications, but can be
significantly more complex than BEC and can impose additional
overhead in the data.
[0053] FEC algorithms are usually based on redundancy. The simplest
form of FEC is to repeat each data bit a number of times. The
receiving device could simply vote on what the data bit should be
based on the bits received. In general, "n" errors can be detected
and corrected using this method by repeating every bit 2n+1 times.
There are numerous more complex FEC algorithms including, for
example only, and not for limitation, Reed-Solomon coding, Viterbi
coding, Turbo coding, and BCH coding. In the present invention, the
methods of error detection and error correction are communication
parameters that an UWB enabled device can select to optimize
communication with other UWB devices.
[0054] There are various common error control algorithms that are
used in communication systems. Most of these algorithms are
classified as automatic repeat request (ARQ) algorithms. In some
error control schemes such as stop-and-wait ARQ, the receiving
device responds to every message with either an acknowledgement
(ACK) or with a negative acknowledgement (NACK). The first device
will not continue transmission until either a NACK or an ACK is
received from the second device. In Go-Back-N ARQ, the first device
sends a number of frames and maintains a sliding window of size N.
If an error is detected in a frame, the second device sends a NACK
to the first device, and it discards all incoming frames until the
erroneous frame is properly received. The first device must
retransmit all frames from the one containing the error. Another
variation on error control is Selective-Reject ARQ. In this
algorithm the second device processes the correct frames and sends
a NACK to the first device. The first device is then required to
resend only frames received in error. In the present invention,
these and other error control methods may be communication
parameters that an UWB enabled device can employ to optimize
communication with other UWB devices.
[0055] The ultra-wideband pulse recurrence frequency (PRF), or
pulse transmission rate, is an additional communication parameter
that a UWB enabled device employing the methods of the present
invention may select. The PRF may be selected to be fixed, or
variable based on the type or amount of data, or pseudo-random.
Generally, a fixed PRF creates spectral lines at the PRF and its
integer harmonics. This may be advantageous when concentration of
spectral energy is desired. A pseudo-random PRF spreads or
"whitens" the spectrum occupied by the UWB communications. Using a
pseudo-random PRF spreads the UWB energy relatively evenly across
the entire spectrum occupied. A variable PRF may be additionally
employed where the PRF is "hopped" periodically based on some other
parameter, which may include but is not limited to the data to be
sent.
[0056] For example, in one embodiment of the present invention, an
UWB device may select the data rate of a communication link based
on distance information, RSSI information, or other types of
information. The data rate in a UWB pulsed communication system is
usually calculated as the product of the PRF and the number of
bits-per-symbol that the selected modulation technique encodes on
the UWB pulse stream. When using a variable or pseudo-random PRF
the data rate is generally dependent on the effective PRF.
[0057] Another factor affecting communication quality and
reliability is the bit-error-rate (BER), which is usually
calculated as the ratio of bad bits to good bits. Thus, the BER is
a way to measure data transmission integrity. Generally, the BER is
usually dependent on the signal-to-noise ratio (SNR) at the
receiver. One method to reduce BER and thereby improve the quality
of service (QOS) is to improve the SNR by increasing the power of
transmission of the UWB pulses, or signal. In one embodiment of the
present invention, an UWB enabled device may select the UWB signal
transmission power level as a communication parameter.
[0058] Another communication parameter that may be employed by the
present invention is UWB pulse transmission power. Since Power
Spectral Density (PSD) is the Fourier Transform of the
autocorrelation function, and the shape of a UWB pulse affects the
shape of the autocorrelation function, the specific shape of the
transmitted UWB pulses impacts the distribution of the UWB signal
power in the spectrum occupied. In environments where the
transmitted power in certain frequencies is limited, UWB pulse
shape is one method of controlling transmitted power levels. In one
embodiment of the present invention, UWB pulse shape may be a
parameter that an UWB enabled device may select when communicating
with other UWB enabled devices. For example, the UWB pulse shape
may comprise a Gaussian mono-cycle, a filtered substantially square
pulse, a pre-distorted pulse, a pulse with a predetermined phase, a
pulse with a predetermined amplitude, and other suitable pulse
shapes.
[0059] Multi-path effects is another factor that affects
communication quality and reliability. UWB pulses may be propagated
over different paths, arriving at the intended receiver at
different times, causing multi-path interference, or fading. One
method of minimizing multi-path effects in wireless communication
systems uses RAKE receivers. With a RAKE receiver, a number of
delayed copies of the signal are correlated and added to the
original signal to improve the SNR. The number of "fingers" in the
receiver designates the number of delayed copies to be correlated
and summed. In one embodiment of the present invention, the number
of "fingers" in the receiver may be a parameter that may be
selected to improve the quality and reliability of a communication
system employing the methods of the present invention.
[0060] Another communication parameter that may be employed by the
present invention is UWB variable pulse widths, or durations.
According to the scaling property of the Fourier Transform, as the
UWB pulse time duration or width increases, frequency content
becomes more compact. The transmitted power for wide, or long
duration UWB pulses in some cases may rise above the noise floor,
possibly interfering with conventional RF signals. In one
embodiment of the present invention, the power spectral density of
wider, or longer duration UWB pulses may be controlled to ensure
coexistence with conventional RF signals and to reduce distortion
from the natural bandwidth of the channel. Additionally, wider, or
longer duration UWB pulses contain more energy. For example, one
embodiment of the present invention may employ UWB pulse widths, or
durations that range from about 0.01 nanoseconds to about 1
millisecond. In one embodiment of the present invention, UWB pulse
width, or duration is a parameter that may be selected by an UWB
enabled device to improve the quality and reliability of an UWB
communication system.
[0061] Another communication parameter that may be employed by the
present invention is UWB variable frame sizes, or lengths. A frame
is a group of time periods, or time bins into which UWB pulses may
be placed. The frame may include UWB pulses that provide
information for synchronization, carry data, aid in error
correction, or contain other types of information, or provide other
functions. Frame length and the frequency of synchronization can
additionally impact the BER and therefore the QOS. Frames of long
duration in a communication system that uses minimal
synchronization frequency can suffer from increased BER due to
relative clock drift between UWB enabled devices. In one embodiment
of the present invention, frame length and the frequency of
synchronization are parameters that may be selected, and varied by
a UWB enabled device to improve the quality and reliability of an
UWB communication system.
[0062] With reference to FIG. 3, one embodiment of an
ultra-wideband communication system employing the methods described
above may function in the following way: a UWB device located at
the center of zone Z1 may communicate with a UWB device located in
zone Z2, sector 1, by employing Reed-Solomon forward error
correction, 16 level pulse amplitude modulation, a Gaussian
monocycle pulse shape, a fixed pulse recurrence frequency of 100
MHz with an average power of 0.5 watts. The UWB device may select
to process received communications from the remote UWB device in
zone Z2 using 3 fingers in a RAKE receiver.
[0063] The same UWB device located at the center of zone Z1, when
communicating with another UWB device in zone Z4, sector 2, may
select Viterbi forward error correction, 4 level pulse amplitude
modulation with 4 level pulse position modulation, a fixed pulse
recurrence frequency of 75 MHz, an essentially rectangular pulse
shape of 300 pico-second duration, and an average transmission
power of one watt. The UWB device may select to process received
communications from the UWB device in zone Z4 using 5 fingers in a
RAKE receiver.
[0064] Another feature of the present invention is that it provides
a method of sharing bandwidth between UWB enabled devices. In this
embodiment, a UWB enabled device may route communications through
other UWB enabled devices in order to achieve a reliable, and
higher QOS communications link to the destination UWB enabled
device. In one implementation of this embodiment, an UWB enabled
device can obtain an estimation of the available bandwidth in the
zones and sectors it has access to, and forward this information to
other UWB enabled devices that it is communicating with. Thus, a
first UWB device wishing to communicate with a second UWB device
may establish either a direct communications link with the second
UWB device, or alternatively route communications to the second UWB
device through other UWB enabled devices, based on the provided
available bandwidth information.
[0065] In one embodiment of the present invention, one of the UWB
enabled devices is a fixed network access point (FNAP). In this
embodiment, the FNAP knows its own geo-position in
three-dimensional space. On function of the FNAP is to characterize
the UWB communications environment within its geo-position to all
UWB enabled devices in its range. Thus, the FNAP establishes
preferred communications parameters with in its local
communications environment and stores a channel model, a zone
designation, and the communications parameters associated with is
three-dimensional coordinates. As a new UWB enabled device powers
up, or moves within range of the FNAP, the appropriate zone,
three-dimensional geo-coordinates, and associated communications
parameters are assigned to the new UWB enabled device by the
FNAP.
[0066] A FNAP may be part of a larger UWB network, or may it may
establish its own network. As defined herein, a network is a group
of points or nodes connected by communication paths. The
communication paths may be connected by wires, or they may be
wirelessly connected. A network as defined herein can interconnect
with other networks and contain subnetworks. A network as defined
herein can be characterized in terms of a spatial distance, for
example, such as a local area network (LAN), a personal area
network (PAN), a metropolitan area network (MAN), a wide area
network (WAN), and a wireless personal area network (WPAN), among
others. A network as defined herein can also be characterized by
the type of data transmission technology in use on it, for example,
a TCP/IP network, and a Systems Network Architecture network, among
others. A network as defined herein can also be characterized by
whether it carries voice, data, or both kinds of signals. A network
as defined herein can also be characterized by who can use the
network, for example, a public switched telephone network (PSTN),
other types of public networks, and a private network (such as
within a single room or home), among others. A network as defined
herein can also be characterized by the usual nature of its
connections, for example, a dial-up network, a switched network, a
dedicated network, and a nonswitched network, among others. A
network as defined herein can also be characterized by the types of
physical links that it employs, for example, optical fiber, coaxial
cable, a mix of both, unshielded twisted pair, shielded twisted
pair, or a wireless medium, such as air.
[0067] One drawback of a network is the possibility of multi-user
interference (MUI), which generally results from multiple UWB
enabled devices communicating in a close geographical region. In
one embodiment of the present invention, a fixed access point
assigns time periods to each zone for communication. In this
embodiment, consecutive time periods are assigned to zones that may
not be geographically contiguous. This assignment may be
accomplished on a functional logic block (FLB) basis that may be
similar to a Time Division Multiple Access (TDMA) scheme. For
example, in one embodiment of the present invention, a fixed access
point may divide its surrounding area into 4 concentric zones Z1,
Z2, Z3 and Z4, as shown in FIG. 3. A first FLB, FLB 1 may be
assigned to UWB enabled devices within zone Z2, and a second FLB,
FLB 2 may be assigned to devices within zone Z4, a third FLB, FLB 3
may be assigned to UWB enabled devices within zone Z1, and a fourth
FLB, FLB 4 may be assigned to zone Z3. Alternatively, time slots
within a FLB may be assigned to zones in a similar manner. Devices
within each zone can access the assigned time period on either a
contention basis, such as employed by ALOHA, CSMA, or CSMA-CD
schemes, or on a pre-assigned basis.
[0068] Referring to TABLE 1, one embodiment of the present
invention comprises a method for assignment of time periods
available for transmitting UWB pulses within a UWB communications
network. The time periods are made available by first determining
the number of zones within a geographical area. Once the number of
zones is established, the number of FLBs, or alternatively, time
slots within the FLBs are selected. Diversity, or non-repetition in
time period assignment is then created by first counting
incrementally by the appropriate zone number, then eliminating
repetition between the time bins assigned. For example, in one type
of system there may be eight zones (Z1-Z8), and the assignment
repetition rate may be 30. That is, 30 time bins are included
within a frame (as defined above, a frame is a group of time
periods, or time bins into which UWB pulses may be placed), and
each zone is allocated specific time bins within the frame. Thus,
each UWB device must only analyze the time bins that are allocated
to it, depending upon which zone the UWB device is located.
[0069] The first step of the assignment method of the present
invention is to count sequentially by zone number as shown in TABLE
1.
1TABLE 1 Zone Time Periods Z1 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
29, 30 Z2 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29 Z3
1, 4, 7, 10, 13, 17, 20, 23, 26, 29 Z4 1, 5, 9, 13, 17, 21, 25, 29
Z5 1, 6, 11, 16, 21, 26 Z6 1, 7, 13, 19, 25 Z7 1, 8, 15, 23, 30 Z8
1, 9, 17, 25
[0070] Following the initial assignment, duplicate time periods, or
bins are eliminated. This can be accomplished in a number of ways.
In this example, the elimination of duplicate time bins is
accomplished from the highest numerical zone (Z8) to the lowest
numerical zone (Z1). In zone Z8 there is an assignment of the 1, 9,
17, and 25 time bins. These time bins are eliminated in the frames
used by UWB devices located in zones Z1 through Z7, as shown below
in TABLE 2. The remaining time bin assignments for zone Z7 are then
eliminated from zones Z1 through Z6 in the same manner. This
process is continued until all duplicity, or repetition is removed
from the time bin assignments. TABLE 2 shows the result of this
method of time bin assignments.
2 TABLE 2 Zone Time Periods Z1 2, 12, 14, 18, 22, 24, 28 Z2 3, 27
Z3 4, 10, 20 Z4 5, 29 Z5 6, 11, 16, 21, 26 Z6 7, 13, 19 Z7 8, 15,
23, 30 Z8 1, 9, 17, 25
[0071] In TABLE 2 it is seen that the distribution of FLBs or
alternatively time bins is not evenly distributed. The zones
containing more time bins, or FLBs will have a higher bandwidth
capacity than zones with fewer time bins, or FLBs. One feature of
the present invention is that zone allocation may be based on
bandwidth demand. That is, zones may not be geographically
allocated (with a local UWB device at the center of zone Z1), but
instead they may be allocated so that higher bandwidth zones are
allocated to areas that contain a dense population of UWB devices,
or to areas that have a high bandwidth demand. Thus, in one
embodiment of the present invention, a local UWB device may be
located at the center of zone Z8.
[0072] Thus, one feature of the present invention is that it
provides a method, system, computer software or logic and/or
computer hardware for providing a high QOS in an UWB communication
system by providing dynamic bandwidth allocation. In one embodiment
of the present invention, a local UWB enabled device may assign
zones based on a population density of UWB devices within each
zone, assigning zones that contain more time bins to areas that
have a higher density of UWB devices. These zone assignments may
change, based on changes in bandwidth demand. Alternatively, the
geographic configuration of the zones may change, so that areas
that have less UWB devices can be incorporated, or merged into
other zones to create a zone with more users. Thus, this method of
bandwidth allocation may result in zones that are not circular, or
spherical, but instead may have irregular shapes.
[0073] Referring to FIG. 3, one method of practicing the present
invention is illustrated. A first UWB enabled device (not shown) is
located at the center of zone Z1. Other UWB devices may be located
in any of the other zones Z1, Z2, Z3, and Z4. The first UWB device
may obtain distance, RSSI, BER and other types of information
relating to each of the other UWB devices that are in communication
with the first UWB device. Based on the data received from the
communicating UWB devices, zones Z1 through Z4 and sectors 1
through 4 are established. The determination of the number of, and
the size of, zones and sectors may be based on distance data, on
the density of RF signals, on other types of information discussed
above, or on a combination of types of information.
[0074] When communicating with UWB devices, the first UWB device
determines the zone and sector of the other UWB device. Based on
the zone and sector, the first UWB device selects appropriate
communications parameters for communication with the other UWB
device. A UWB device may be a phone, a personal digital assistant,
a portable computer, a laptop computer, any network as described
above (LAN, WAN, PAN etc.), video monitors, computer monitors, or
any other device employing UWB technology.
[0075] Referring to FIG. 4, one type of messaging used to establish
distance between UWB enabled devices is displayed. A first UWB
enabled device broadcasts a "time request message" to at least one
other UWB enabled device, that is time synchronized with the first
UWB device by a master time reference. The "time request message"
includes the time of broadcast, or transmission from the first UWB
device. Other UWB enabled device(s) can then determine the distance
to the first UWB device by subtracting the time that the "time
request message" was received from the embedded transmission time
contained in the "time request message." The time difference is the
propagation time, and because RF energy generally propagates at
approximately the speed of light, the distance between the
communicating UWB devices may be determined.
[0076] In addition, the first UWB device can determine the distance
to other UWB device(s) by receiving a "time response message" that
includes the calculated propagation time from which the distance to
the responding UWB device can be determined. In an alternative
embodiment, the UWB device may also independently verify the
distance to the responding UWB device by subtracting the time that
the "time response message" was received from an embedded
transmission time contained in the "time response message." In this
embodiment, each UWB device includes the transmission time in each
message that is sent. Because all the communicating UWB devices are
time synchronized to each other by a master time reference,
distance calculations based on time differences are accurate.
[0077] Referring to FIG. 5 another method of practicing the present
invention is illustrated. This embodiment is another method of
messaging used to establish distance between UWB enabled devices. A
first UWB enabled device broadcasts a "distance request message" to
at least one other UWB device, that is time synchronized with the
first UWB device by a master time reference. The "distance request
message" includes the time of broadcast, or transmission from the
first UWB device. Other UWB enabled device(s) receive the message,
and also register the time that the message was received. The
receiving UWB device then determine the distance to the first UWB
device by subtracting the time that the "distance request message"
was received from the embedded transmission time contained in the
"time request message."
[0078] In addition, the first UWB device can determine the distance
to other UWB device(s) by receiving a "distance response message"
that includes the distance calculated by the receiving UWB device.
In this embodiment, the "distance response message" includes the
distance and the time of transmission of the "distance response
message," which is referenced to the master time reference. The
first UWB device can verify the distance from each responding UWB
device by referencing the time of transmission included in the
"distance response message" with the time of arrival of the
"distance response message."
[0079] Referring to FIG. 6 another method of practicing the present
invention is illustrated. This embodiment is a method of messaging
used to determine the type of communication parameters for use
between UWB enabled devices. A first UWB device broadcasts a
"bit-error-rate (BER) request message" to at least one UWB enabled
device. The "BER request message" contains a predetermined sequence
of symbols that all the communicating UWB have in computer memory,
or in another suitable location. The sequence of symbols may be a
representation of an arbitrary group of binary digits, such as
"0101," or "00110011," or any other desired group of symbols.
[0080] The receiving UWB device(s) receive the "BER request
message," and determine the bit-error-rate by comparison of the
received symbols with the predetermined sequence of symbols
contained in computer memory. The UWB device(s) then respond with a
"BER response message" that includes the calculated BER, and if a
distance between the UWB devices is known, the probable BER to
other UWB devices within a similar distance, or zone.
[0081] Referring to FIG. 7 another method of practicing the present
invention is illustrated. This embodiment is another method of
messaging used to determine the type of communication parameters
for use between UWB enabled devices. A first UWB enabled device
broadcasts a "fixed energy request message" at a predetermined
energy level to at least one other UWB enabled device. The other
UWB enabled device(s) know the predetermined energy level, as it
may be contained in computer memory, or in another suitable
location. The UWB device(s) receive the "fixed energy request
message", and determine the received energy of the "fixed energy
request message," comparing it with the predetermined energy level.
The difference is a received signal strength indicator (RSSI). The
receiving UWB device(s) then respond with a "fixed energy response
message" that contains the RSSI. The first UWB device then receives
the "fixed energy response message" containing the RSSI
information, and may then set the types of communication parameters
for the communicating UWB devices, based on the RSSI
information.
[0082] An alternative embodiment of this method may have the first
UWB device calculate its own RSSI by determining the energy level
of the "fixed energy response message"and compare it to the
predetermined energy level. In this way, changing communication
conditions, such as moving UWB devices, or other variables can be
accounted for. In this embodiment, the "fixed energy response
message" is broadcast at a fixed energy level so that the first UWB
device can determine the RSSI for the "fixed energy response
messages" and compare it to the RSSI information in those
responses. By comparing the RSSI information, accurate
communication parameters can be established.
[0083] Shown in FIG. 8 is an example of one embodiment of the
present invention, where at least one of the remote UWB enabled
devices is a fixed UWB access point 100, such as an antenna,
network node, or other suitable device. The fixed access point 100
in this embodiment generates the master time reference for all the
UWB devices that communicate within its range, or network. For
example, each UWB device in range of, or communicating with the
fixed access point 100 synchronizes itself in accordance with the
methods disclosed in co-pending U.S. patent application Ser. No.
09/805,735, filed Mar. 13, 2001, titled: MAINTAINING A GLOBAL TIME
REFERENCE AMONG A GROUP OF NETWORKED DEVICES, which is, and has
been, incorporated herein by reference in its entirety.
Additionally, the fixed access point 100 may or may not assign
zones and sectors to the UWB enabled devices within its range, or
network.
[0084] Referring now to FIG. 9, one embodiment of an ultra-wideband
(UWB) communication network is illustrated. The fixed access point
100 provides a communications link, and a master time reference to
UWB devices D1, D2, D3, and P1. The UWB devices D1, D2, D3, P1 may
communicate directly with the fixed access point 100, as shown by
devices D3 and P1, or within their own network as shown by D1, D2,
and D3. Additionally, the UWB device P1 may communicate directly
with the UWB device D1 that is involved in communications with
devices D2, and D3, which is communicating with the fixed access
point 100. In one embodiment of the present invention, as shown in
FIG. 9, communications between UWB device D1 and the fixed access
point 100 may be routed through UWB device D3 or P1. Alternatively,
based on zone and sector assignment, and/or based on other
communications parameters, device D1 may establish a direct
communications link with fixed access point 100.
[0085] Referring now to FIG. 10, another embodiment of an
ultra-wideband (UWB) communication network is illustrated. In this
embodiment, UWB devices P1, P2, P3, D1, D2, D3 may not be within
range of a fixed access point 100 as shown in FIGS. 8-9 to
establish a communication network through the fixed access point
100. In this embodiment of the present invention, UWB enabled
devices P1, P2, P3, and D1, D2, D3 are shown communicating within
their own respective networks. These networks may be private,
and/or secure, or they may be accessible by other UWB devices. In
this embodiment, a mobile UWB enabled device Q1 can function as a
fixed access point 100, assigning zones and sectors, and
establishing a master time reference to the UWB devices within its
range, or network. Alternatively, each UWB enabled device P1, P2,
P3, D1, D2, D3 may establish its own zones and sectors for enabling
reliable communication to other UWB enabled devices. In addition,
routing of communications between UWB devices may be through any
available path, as shown in FIG. 10, where device P3 and device D1
communicate through UWB device Q1, or UWB devices P3 and D1 may
establish a direct communications link. In this embodiment, time
synchronization between networks of devices may be achieved in
accordance with the methods described in co-pending Unites States
patent application Ser. No. 09/805,735, filed Mar. 13, 2001,
titled: MAINTAINING A GLOBAL TIME REFERENCE AMONG A GROUP OF
NETWORKED DEVICES, which is, and has been, incorporated herein by
reference in its entirety.
[0086] Referring now to FIG. 11, spatial diversity is achieved and
hence multi-user interference (MUI) is reduced by the assignment of
FLBs, or alternatively time bins within FLBs, to different
geographical zones. In this embodiment of the present invention, a
UWB enabled device (not shown) establishes zones 1102 (Z1, Z2, Z3,
and Z4). In communication with other UWB devices within each zone
Z1, Z2, Z3, Z4, the UWB enabled device may use the following FLB or
time bin 1101 assignment: FLB 1101(1) may be used to communicate
with UWB devices within zone Z3; FLB 1101(2) may be used to
communicate with UWB devices within zone Z1; FLB 1101(3) may be
used to communicate with UWB devices within zone Z4; and FLB
1101(4) may be used to communicate with UWB devices within zone Z2.
In this embodiment, the FLB, or time bin assignment pattern is then
repeated for subsequent communications.
[0087] Thus, it is seen that various ultra-wideband wireless
communication methods are provided. One skilled in the art will
appreciate that the present invention can be practiced by other
than the above-described embodiments, which are presented in this
description for purposes of illustration and not of limitation. The
description and examples set forth in this specification and
associated drawings only set forth preferred embodiment(s) of the
present invention. The specification and drawings are not intended
to limit the exclusionary scope of this patent document. Many
designs other than the above described embodiments will fall within
the literal and/or legal scope of the following claims, and the
present invention is limited only by the claims that follow. It is
noted that various equivalents for the particular embodiments
discussed in this description may practice the invention as
well.
* * * * *