Title of Invention

METHOD AND APPARATUS FOR PROVIDING IN-BAND WIRELESS BACKHAUL

Abstract Various embodiments are described to address the need for providing wireless backhaul that may reduce operator startup costs while avoiding some of the drawbacks present in the prior art approaches. Generally expressed, the wireless network equipment (WNE) (121) of a collector cell provides access to a backhaul network (151) to one or more neighboring cells (122) via in-band wireless signaling. Given the frequency bands used by the collector cell WNE for communication with remote units, one portion of each band used for user traffic while another portion of each band is used for backhaul traffic. Having backhaul and user traffic share the assigned frequency bands can eliminate the need to license additional bands for wireless backhaul. Moreover, utilizing a portion of the existing, in-band orthogonal channels may be more spectrally efficient than using a separate radio in the same band.
Full Text METHOD AND APPARATUS FOR PROVIDING IN-BAND WIRELESS
BACKHAUL
Field of the Invention
The present invention relates generally to wireless communications
and, in particular, to providing in-band wireless backhaul for wireless
10 communication systems.
Background of the Invention
IEEE (Institute of Electrical and Electronics Engineers) 802.16-based
systems, such as 802.16e WiMAX (Wireless Maximize) systems, have
relatively small cell radii. When such systems are designed for continuous
coverage, cellular-type applications, there is a need to connect a relatively
large number of radio sites in each given area to the greater serving network.
Connection to the greater serving network is via so-called "backhaul"
connections, each of which can require substantial expense. Such "backhaul"
expenses raise the startup cost that a prospective operator often must be
willing to bear before building and establishing a large customer base.
To reduce startup costs associated with backhaul, the industry has
turned to a couple of wireless approaches. The first approach is to multiplex
the traffic from several radio sectors at a site and then use a much higher
speed radio at the site to backhaul the traffic to yet another site. This typically
requires additional multiplexing hardware, high bandwidth radios and a
separate frequency band. A second approach under consideration is to further
multiplex the traffic from several sites to one master site using a second
frequency band wide enough to multiplex several sites worth of traffic.
However, this type of approach is believed to require a very fast Media

Access Control (MAC) protocol, which is believed to have not yet been
developed.
Accordingly, it would be desirable to have a method and apparatus for
providing wireless backhaul that may reduce operator startup costs while
avoiding some of the drawbacks present in the prior art approaches.
Brief Description of the Drawings
FIG. 1 is a block diagram depiction of a wireless communication
system in accordance with multiple embodiments of the present invention.
FIG. 2 is a block diagram depiction of a dual-antenna system in
accordance with multiple embodiments of the present invention.
FIG. 3 is a block diagram depiction of frame processing in accordance
with multiple embodiments of the present invention.
FIG. 4 is another depiction of a dual-antenna system in accordance
with multiple embodiments of the present invention.
FIG. 5 is a block diagram depiction of an idealized 1:3:3 frequency plan
in accordance with multiple embodiments of the present invention.
FIG. 6 is a block diagram depiction of an idealized 1:4:2 frequency plan
in accordance with multiple embodiments of the present invention.
FIG. 7 is a block diagram depiction of an idealized 1:6:6 frequency plan
with collector cells aligned across the centers of sectors in accordance with
multiple embodiments of the present invention.

FIG. 8 is a block diagram depiction of an idealized 1:6:6 frequency plan
with collector cells aligned along the edges of sectors in accordance with
multiple embodiments of the present invention.
Specific embodiments of the present invention are disclosed below with
reference to FIGs. 1-8. Both the description and the illustrations have been
drafted with the intent to enhance understanding. For example, the
dimensions of some of the figure elements may be exaggerated relative to
other elements, and well-known elements that are beneficial or even
necessary to a commercially successful implementation may not be depicted
so that a less obstructed and a more clear presentation of embodiments may
be achieved.
Simplicity and clarity in both illustration and description are sought to
effectively enable a person of skill in the art to make, use, and best practice
the present invention in view of what is already known in the art. One of skill in
the art will appreciate that various modifications and changes may be made to
the specific embodiments described below without departing from the spirit
and scope of the present invention. Thus, the specification and drawings are
to be regarded as illustrative and exemplary rather than restrictive or all-
encompassing, and all such modifications to the specific embodiments
described below are intended to be included within the scope of the present
invention.
Detailed Description of Embodiments
Various embodiments are described to address the need for providing
wireless backhaul that may reduce operator startup costs while avoiding some
of the drawbacks present in the prior art approaches. Generally expressed,
the wireless network equipment (WNE) of a collector cell provides access to a
backhaul network to one or more neighboring cells via in-band wireless
signaling. Given the frequency bands used by the collector cell WNE for

communication with remote units, one portion of each band used for user
traffic while another portion of each band is used for backhaul traffic. Having
backhaul and user traffic share the assigned frequency bands can eliminate
the need to license additional bands for wireless backhaul. Moreover, utilizing
a portion of the existing, in-band orthogonal channels may be more spectrally
efficient than using a separate radio in the same band.
The present invention can be more fully understood with reference to
FIGs. 1-8. FIG. 1 is a block diagram depiction of a wireless communication
system 100 in accordance with multiple embodiments of the present
invention. At present, standards bodies such as OMA (Open Mobile Alliance),
3GPP (3rd Generation Partnership Project), 3GPP2 (3rd Generation
Partnership Project 2) and IEEE 802 are developing standards specifications
for wireless telecommunications systems. (These groups may be contacted
via http://www.openmobilealliance.com, http://www.3qpp.org/,
http://www.3qpp2.com/ and http://www.ieee802.org/. respectively.)
Communication system 100 represents a system having an architecture in
accordance with IEEE 802.16 technologies, suitably modified to implement
the present invention. Alternative embodiments of the present invention may
be implemented in communication systems that employ other or additional
technologies such as, but not limited to, those described in the other IEEE
802 specifications, the 3GPP specifications and/or those described in the
3GPP2 specifications.
Communication system 100 is depicted in a very generalized manner,
shown to comprise packet network 151, wireless network equipment (WNE)
121 and 122, and remote units 101-104. Those skilled in the art will recognize
that FIG. 1 does not depict all of the network equipment necessary for system
100 to operate commercially but only those system components and logical
entities particularly relevant to the description of embodiments herein. For
example, depending on the embodiment, WNE 121 and 122 may each
represent a base transceiver station (BTS), an access point (AP), and/or a
higher order device such as a wideband base station (WBS) or WLAN
(wireless local area network) station or even a radio access network (RAN) or

access network (AN); however, none of these devices are specifically shown
in FIG. 1.
Remote units 101-104 and WNE 121 and 122 are shown
communicating via technology-dependent, wireless interfaces such as the
802.16e air interface. Remote units, subscriber stations (SSs) or user
equipment (LJEs), may be thought of as mobile stations (MSs); however,
remote units are not necessarily mobile nor able to move. In addition, remote
unit platforms are known to refer to a wide variety of consumer electronic
platforms such as, but not limited to, mobile stations (MSs), access terminals
(ATs), terminal equipment, mobile devices, gaming devices, personal
computers, and personal digital assistants (PDAs). In particular, remote units
101-104 comprise a processing unit (not shown) and transceiver (not shown).
Depending on the embodiment, remote units 101-104 may additionally
comprise a keypad (not shown), a speaker (not shown), a microphone (not
shown), and a display (not shown). Processing units, transceivers, keypads,
speakers, microphones, and displays as used in remote units are all well-
known in the art.
In general, components such as processing units and transceivers are
well-known. For example, processing units are known to comprise basic
components such as, but neither limited to nor necessarily requiring,
microprocessors, microcontrollers, memory devices, application-specific
integrated circuits (ASICs), and/or logic circuitry. Such components are
typically adapted to implement algorithms and/or protocols that have been
expressed using high-level design languages or descriptions, expressed using
computer instructions, expressed using signaling flow diagrams, and/or
expressed using logic flow diagrams.
Thus, given a high-level description, an algorithm, a logic flow, a
messaging / signaling flow, and/or a protocol specification, those skilled in the
art are aware of the many design and development techniques available to
implement a processing unit that performs the given logic. Therefore, WNE
121 and 122 represent known devices that have been adapted, in accordance

with the description herein, to implement multiple embodiments of the present
invention.
Furthermore, those skilled in the art will recognize that aspects of the
present invention may be implemented in and/or across various physical
components and none are necessarily limited to single platform
implementations. For example, the WNE may be implemented in or across
one or more networked or otherwise communicatively coupled devices, such
as communication infrastructure devices and/or wireless devices. Also, WNE
and remote unit transceivers are referred to throughout the present
application as "transceiver"; however, "transceiver," as used herein, should
more generally be understood to refer to transceiver equipment which may be
embodied to include more than one physical transceiver device.
First, to provide specific examples of some of the different aspects of
particular embodiments of the present invention, one implementation (referred
to as "BackLite") will be described in detail below with reference to FIGs. 2-8.
FIGs. 2 and 4 depict a dual-antenna system and FIG. 3 depicts frame
processing, all in accordance with the BackLite implementation and multiple
embodiments of the present invention. With BackLite, as with various other
embodiments of the present invention, the startup costs associated with
installing an 802.16e system can be reduced. Also, having backhaul and user
traffic share the assigned frequency band can eliminate, the need to license
another band for wireless backhaul.
In this approach, some of the orthogonal channels, which are not
needed for the initial system deployment, are used for backhaul traffic.
Utilizing some of the existing orthogonal channels is much more spectrally
efficient than placing a separate radio in the same band. Thus, in BackLite,
some of the receive channels pick up regular traffic from users and utilize
predefined transmit channels to relay the information to a "collection site"
using the same base equipment. In a similar manner, some predefined
receive channels catch traffic from the collection site meant for users and
transmit it on normal traffic channels down to the users, again using the same
base equipment. The collection site uses slightly modified Customer Premises

Equipment (CPE) 410, referred to as "CPE+", to move the backhaul traffic in
an out of the larger communications network.
In general, a transmitter and a receiver at a BackLite base station
(a.k.a., wideband base station or cellular access point) are used
simultaneously for subscriber traffic and wireless backhaul. In each TDD (time
division duplex) burst, part of the uplink and downlink sub-bursts is reserved
for backhaul traffic. For backhauling uplink traffic, the uplink traffic 210 (see
FIGs. 2 and 3) from the subscriber units is captured and decoded by the
receiver, stored in a buffer 305, then packed into part 310 of the downlink
burst. When the downlink burst is sent, it goes out both antenna systems
simultaneously, one (access antenna system 202) pointed at the traffic
coverage area and one (narrowbeam antenna system 201) along a path to a
backhaul collection point (which is co-located with another base station). A
receiver at the collection site, built like a Customer Premises Equipment
(CPE), knows that part of the sub-burst dedicated to backhaul traffic and
decodes it, and then sends it along another higher rate backhaul system to
the larger network. In similar manner, downlink traffic 211 is transmitted back
along this same path by the modified CPE, where the base station receiver,
which has some of its capacity allocated to backhaul, captures it and, through
a buffer 306, packs the information into the part 311 of the downlink sub-burst
dedicated to subscriber traffic.
Stated differently, the essence of what happens is that the base
receiver collects information from both the user uplink traffic 210 and
information from the backhaul collection point which contains the user
downlink traffic 211. Information collected from user traffic needs to move to a
backhaul collecting point (backhaul uplink traffic 250) and is thus inserted in
the transmit burst part 220 of the timeslot, using the "channels" reserved for
backhaul traffic. Subscribers are not assigned these channels. Information for
users that needs to be sent on the downlink will come from the CPE+
(backhaul downlink traffic 211), again received by the base receiver, and
inserted into downlink channels reserved for user traffic 251. This to/from
arrangement is the backhaul. When the transmit part of the timeslot is sent, it

is listened to by both the subscribers and the CPE+. Their transmissions will
come from different antenna systems, a directional one for backhaul, and the
typical access antenna system for subscriber coverage. The subscribers will
find and decode their traffic channels, and the CPE+ will find and decode its
backhaul channels.
Backhaul via BackLite is accomplished by utilizing part of the transmit
and receive TDD half-frames for traffic moving to and away from each base
site, and therefore all access traffic and backhaul traffic are in the same
frequency band. Traffic intended for subscriber devices within the range of the
WBS co-located with the collection point is sent from the network directly to
the unmodified WBS 411 where it is inserted in the downlink channel to the
subscriber units. Information targeted for subscriber units located in the
remote sites whose backhaul is served by the collection point is routed from
the network to the CPE+ 410 where it is transmitted in the uplink channel to
the modified WBS at the remote site. From there, the data are routed
internally from the receive part of the burst in the modified WBS and inserted
in the downlink channel to the target subscriber devices in channels dedicated
to access.
In the reverse direction, subscriber data intended to be sent into the
network is sent in the uplink channel from the subscriber to the modified WBS
where it is captured in the receive part of the burst and inserted into the
downlink channel toward the CPE+ 410 at the collection point, then delivered
to the router 412 that sends the information to the "system backhaul." Access
data from subscriber devices served by the unmodified WBS 411 that is co-
located with the collection point CPE+ devices 410 is sent on an access
channel uplink to the WBS and delivered to the router 412 into the "system
backhaul" network.
Note that at the modified WBSs, the access and backhaul traffic are
both received on the receive half of the TDD burst, while the access and
backhaul traffic are both transmitted on the Tx part of the burst. Physically,
both access and backhaul traffic go in and out simultaneously on both the
access and narrowbeam (high gain) backhaul antenna systems. But because

subscribers do not look for the backhaul channels and the CPE+ does not
look for the access channels, and because the antenna systems are
effectively isolated from each other, access traffic and backhaul can share the
same carrier.
Note also that the collection points are made up entirely of CPE+s that
exclusively carry backhaul traffic. At the collection point locations, the
unmodified WBSs handle the local traffic. Also, other than combining different
traffic and backhaul channels together in the TDD burst, which should not
require any special processing of the channels, access and backhaul traffic
need not be combined elsewhere in the system.
A CPE+ has the same Tx and Rx characteristics as a typical CPE,
except that a CPE+ is capable of extracting several channels, not just one.
This is because it is transmitting and receiving the entire backhaul traffic for a
sector at the collection point. Collection points are co-located with some of the
WBSs. In a 1:3:3 plan, for example, one in four WBSs has a collection point
associated with it. Each collection point, in a 1:3:3 plan, consists of 9 CPE+s
and lines connecting them to some router to the next level of backhaul (e.g.,
T1, OC-3, another wireless backhaul, etc.) The CPE+s use high gain,
narrowbeam antennas and do not need to share the WBS antenna systems.
Physically the collection points could be anywhere, but for convenience (and
due to the frequency reuse plan) they are co-located with a WBS. Only on
non-collection point WBSs are a narrowbeam and access antenna system
connected together for use by the WBS transceiver. At the collection points,
the backhaul part of the system, embodied by the CPE+s, and the WBS need
not be connected at all.
Changes to a WBS recommended to implement a BackLite system
include the following. A buffering mechanism should be attached on a data
bus from the uplink channel decoder to capture all up link access traffic
coming from system subscribers. All of this traffic will be backhauled via the
downlink part of the TDD burst. This downlink is simultaneously going
physically "down" and "across" to the collection point. Since the backhaul
"downlink" channels are not assigned to users, they are invisible to users,

even though they are emitted from the access antenna system. Since this
backhaul traffic probably cannot be transmitted immediately due to hardware
and software constraints, it must be held and placed in the channels assigned
to backhaul on the downlink TDD half burst at the first available downlink TDD
burst.
Similarly, a buffering mechanism should be attached on a data bus
from the uplink channel decoder, to capture all backhaul data traffic from the
CPE+ coming from the collection point on the narrowbeam antenna. These
two buffer mechanisms should know how channels are allocated between
access and backhaul.
The Tx/Rx antenna system needs to have added to it a narrowbeam,
high gain antenna system for backhaul. The transceiver is attached to both
the access antenna system and the narrowbeam antenna system. It is
preferred that most of the power go to/from the access antenna system by
using a connector and a tap for the backhaul narrowbeam antenna. It should
be determined how low the power to the backhaul antenna can be by using a
combination of antenna gain, point-to-point propagation and low-order
modulation. Two sectors may possibly be combined onto one narrowbeam
antenna in some implementations.
Changes to a CPE recommended to implement a BackLite CPE+
include the following. It is the CPE+ that is connected to the ingress/egress for
the system. The collection point is independent of the co-located WBS as far
as radio processing is concerned. However, they may of course share
electrical, tower and the like. Each CPE+ needs to have processing power
enough to move the traffic for its sector in and out after FFT (Fast Fourier
transform) and other processing, whereas a CPE is currently designed to
handle the traffic of a single user.
The CPE+'s narrowbeam antenna will sometimes be faced in the same
direction as the adjacent channel, and therefore some isolation may be
required at the collection point for these two antennas. Also, CPE+s may
share a narrowbeam antenna. Either way, more stringent filtering than that for

a consumer CPE may be required. Additionally, the signals from the CPE+s to
the WBS receivers need to be time aligned with the received access signals.
IEEE 802.16e allows considerable flexibility in the setting of operating
parameters. The BackLite implementation can take advantage of some of this
flexibility. Depending upon the exact TDD burst time settings, and the cell
sizes used in a particular system design, a number of parameters can be
advantageously manipulated. As has been mentioned, backhaul is done to
and from a collection point co-located with a base station. Propagation to and
from that collection point will, by design, be further than a cell radius, and
hence will experience delay and attenuation different than that in the user
coverage area.
It is expected that the backhaul antenna system will be mounted higher
than the coverage area antennas or at least aimed horizontally toward the
collection point. The propagation time will be longer (at least twice as long),
but the attenuation constant will be lower. It is likely that the popular 70%
downlink 30% uplink split of the TDD frame will need to be closer to 50-50%.
It could be that higher order modulation will be used in the backhaul channels
to take up less time in each sub-burst. There will be a power loss at any
splitter used to connect the two antenna systems to the transceiver. However,
the much lower propagation constant, and the directional gain of the backhaul
antenna system can make up for the losses. If the extra propagation time from
the backhaul collection point interferes with the burst length/guard time of the
individual cells, the backhaul transmit burst may have to be shortened.
Although the same frequency bands are used for both access and
backhaul traffic, the transmit and receive paths for backhaul use physically
separate narrow beam antennas pointed to create a different frequency reuse
pattern than the traffic frequency reuse pattern. FIGs. 5-8 provide some, but
not all examples, of the possible frequency plans that may be used. FIG. 5 is
a block diagram depiction of an idealized 1:3:3 frequency plan (each cell
having 3 sectors and using 3 unique frequency bands) in accordance with
multiple embodiments of the present invention. Frequency plan 500
represents a basic 802.16e frequency plan (although it is not limited to

802.16e by any means) with the addition of a backhaul collector cell (shown
by the small circle at the cell center). The collector cell includes wireless
coverage areas 501-503, which correspond to a first, a second and a third
sector of the collector cell, respectively.
Since frequency plan 500 is a 1:3:3 frequency plan, each cell uses
three unique frequency bands, a first, a second and a third frequency band.
Sectors of each cell that are labeled with a reference number ending in a "1"
use the first frequency band, sectors labeled with a reference number ending
in a "2" use the second frequency band, and sectors labeled with a reference
number ending in a "3" use the third frequency band. The dashed-line arrows
depict the direction of the narrowbeam antennas used for transmitting
backhaul traffic from each neighbor cell to the collector cell (and to other
collector cells not shown). In frequency plan 500, all of the neighbor cells
transmitting backhaul traffic to the collector cell are also adjacent to the
collector cell, but this need not necessarily be the case with other frequency
plans.
As depicted in FIG. 5, the six neighbor cells each transmit and receive
backhaul traffic for one or two of their respective sectors to and from the
collector cell. Furthermore, the backhaul traffic from each sector is transmitted
and received using the frequency band (more specifically, the backhaul
portion of the frequency band) associated with that individual sector. For
example, backhaul traffic for sector 513 is transmitted and received, to and
from the collector cell using the third frequency band. Thus, as depicted in
FIG. 5, backhaul traffic for sectors 513, 521, 523, 531, 541, 542, 552, 562 and
563 is transmitted and received, to and from the collector cell using a
backhaul portion of the frequency band indicated by the sector's ending
reference number digit.
It can be seen from FIG. 5 that the backhaul distance in each case is 2r
and the interference distance is therefore 6r, where r is the nominal cell
radius. The collector cell handles traffic from 12 sectors, its own three and
nine others. While this traffic may come from seven physical base stations
(depending on the embodiment), it represents the traffic of four cells. Also,

while there are nine carriers impinging on a single collection point, the nine
may be isolated from each other by the directionality of the narrowbeam
antennas used. In frequency plan 500, the angular separation between them
is 60 degrees, which is wider than required. However, in some cases, for
geographical or propagation reasons, it may be necessary to change the
polarization of some of the narrowbeam antennas to increase the isolation
between paths on the same frequency, for example among 542, 552 and 562.
FIG. 6 is a block diagram depiction of an idealized 1:4:2 frequency plan
in accordance with multiple embodiments of the present invention. Frequency
plan 600 represents an alternative frequency plan with the addition of
backhaul collector cells (shown by the small circles at various cell centers).
The collector cell in the center includes wireless coverage areas 601, 651,
602 and 652, which correspond to a first, a second, a third and a fourth sector
of the collector cell, respectively.
Since frequency plan 600 is a 1:4:2 frequency plan, each cell has four
sectors but uses two unique frequency bands, a first and a second frequency
band. Sectors of each cell that are labeled with a reference number below 650
use the first frequency band, while sectors labeled with a reference number
greater than 650 use the second frequency band. The dashed-line arrows
depict the direction of the narrowbeam antennas used for transmitting
backhaul traffic from each neighbor cell to the collector cells (and to other
collector cells not shown). In frequency plan 600, all of the neighbor cells
transmitting backhaul traffic to the collector cells are also adjacent to the
target collector cells, but this need not necessarily be the case with other
frequency plans.
As depicted in FIG. 6, the four neighbor cells (left, right, top and
bottom) of the central collector cell each transmit and receive backhaul traffic
for one of their respective sectors to and from the collector cell. Furthermore,
the backhaul traffic from each sector is transmitted and received using the
frequency band (more specifically, the backhaul portion of the frequency
band) associated with that individual sector. For example, backhaul traffic for
sector 656 is transmitted and received, to and from the collector cell using the

second frequency band. Thus, as depicted in FIG. 6, backhaul traffic for
sectors 656, 610, 665 and 611 is transmitted and received, to and from the
collector cell using a backhaul portion of the frequency band indicated by the
sector's reference number.
FIG. 7 is a block diagram depiction of an idealized 1:6:6 frequency plan
with collector cells aligned across the centers of sectors in accordance with
multiple embodiments of the present invention. Frequency plan 700
represents another alternative frequency plan with the addition of a backhaul
collector cell (shown by the small circle at the cell center). The collector cell
includes wireless coverage areas 701-706, which correspond to a first, a
second, a third, a fourth, a fifth and a sixth sector of the collector cell,
respectively.
Since frequency plan 700 is a 1:6:6 frequency plan, each cell has six
sectors and uses six unique frequency bands, a first, a second, a third, a
fourth, a fifth and a sixth frequency band. Sectors of each cell that are labeled
with a reference number ending in a "1" use the first frequency band, sectors
labeled with a reference number ending in a "2" use the second frequency
band, sectors labeled with a reference number ending in a "3" use the third
frequency band, sectors labeled with a reference number ending in a "4" use
the fourth frequency band, sectors labeled with a reference number ending in
a "5" use the fifth frequency band, and sectors labeled with a reference
number ending in a "6" use the sixth frequency band. The dashed-line arrows
depict the direction of the narrowbeam antennas used for transmitting
backhaul traffic from each neighbor cell to the collector cell (and to other
collector cells not shown). In frequency plan 700, all of the neighbor cells
transmitting backhaul traffic to the collector cell are also adjacent to the
collector cell, but this need not necessarily be the case with other frequency
plans.
As depicted in FIG. 7, the six neighbor cells each transmit and receive
backhaul traffic for three of their respective sectors to and from the collector
cell. Furthermore, the backhaul traffic from each sector is transmitted and
received using the frequency band (more specifically, the backhaul portion of

the frequency band) associated with that individual sector. For example,
backhaul traffic for sector 714 is transmitted and received, to and from the
collector cell using the fourth frequency band. Thus, as depicted in FIG. 7,
backhaul traffic for sectors 713-715, 724-726, 731, 735, 736, 741, 742, 746,
751-753 and 762-764 is transmitted and received, to and from the collector
cell using a backhaul portion of the frequency band indicated by the sector's
ending reference number digit.
FIG. 8 is a block diagram depiction of an idealized 1:6:6 frequency plan
with collector cells aligned along the edges of sectors in accordance with
multiple embodiments of the present invention. Frequency plan 800
represents another alternative frequency plan with the addition of a backhaul
collector cell (shown by the small circle at the cell center). The collector cell
includes wireless coverage areas 801-806, which correspond to a first, a
second, a third, a fourth, a fifth and a sixth sector of the collector cell,
respectively.
Since frequency plan 800 is a 1:6:6 frequency plan, each cell has six
sectors and uses six unique frequency bands, a first, a second, a third, a
fourth, a fifth and a sixth frequency band. Sectors of each cell that are labeled
with a reference number ending in a "1" use the first frequency band, sectors
labeled with a reference number ending in a "2" use the second frequency
band, sectors labeled with a reference number ending in a "3" use the third
frequency band, sectors labeled with a reference number ending in a "4" use
the fourth frequency band, sectors labeled with a reference number ending in
a "5" use the fifth frequency band, and sectors labeled with a reference
number ending in a "6" use the sixth frequency band. The dashed-line arrows
depict the direction of the narrowbeam antennas used for transmitting
backhaul traffic from each neighbor cell to the collector cell (and to other
collector cells not shown). In frequency plan 800, all of the neighbor cells
transmitting backhaul traffic to the collector cell are also adjacent to the
collector cell, but this need not necessarily be the case with other frequency
plans.

As depicted in FIG. 8, the six neighbor cells each transmit and receive
backhaul traffic for two of their respective sectors (the sectors with asterisks,
e.g.) to and from the collector cell. Furthermore, the backhaul traffic from each
sector is transmitted and received using the frequency band (more
specifically, the backhaul portion of the frequency band) associated with that
individual sector. For example, backhaul traffic for sector 814 is transmitted
and received, to and from the collector cell using the fourth frequency band.
Thus, as depicted in FIG. 8, backhaul traffic for sectors 813, 814, 825, 826,
835, 836, 841, 846, 851, 852, 862 and 863 is transmitted and received, to and
from the collector cell using a backhaul portion of the frequency band
indicated by the sector's ending reference number digit.
A detailed description of the BackLite implementation and some
potential frequency plans has been provided above. Operation of some more
generalized embodiments of the present invention occurs substantially as
follows, with reference to FIG. 1. Wireless network equipment (WNE) 121 and
122 respectively represent collector cell equipment and neighbor cell
equipment. As collector cell equipment, WNE 121 includes network interface
127 which provides connectivity to a backhaul network such as packet
network 151. As neighbor cell equipment, WNE 122 utilizes wireless backhaul
signaling with WNE 121 to obtain connectivity to the backhaul network.
Processing unit 126 of WNE 122 receives uplink traffic from remote
units 103 and/or 104 within the wireless coverage area of WNE 122 using
transceiver 124 and a user portion of at least one frequency band. Remote
units 103 and 104 may be in the same coverage area or sector of WNE 122
or in different coverage areas of WNE 122, and depending on the frequency
plan being used, they may in either case be using the same or different
frequency bands for communication with WNE 122.
Also, depending on the particular embodiment, the uplink traffic may be
transmitted in uplink frames, perhaps OFDM (orthogonal frequency division
multiplexing) uplink frames. In the case in which OFDM signaling is used, the
frequency bands include OFDM subchannels (i.e., frequency subchannels).
Thus, the user portion of a frequency band may comprise a set of the OFDM

subchannels. For a receive frame, then, the user portion would be the user
subchannels of the receive frame.
Processing unit 126 of WNE 122 then transmits the uplink traffic from
the remote units to WNE 121 using transceiver 124 and a backhaul portion of
the one or more frequency bands used to receive the uplink traffic from the
remote units. In the OFDM embodiments, the backhaul portion of the one or
more frequency bands may also comprise a set of the OFDM subchannels in
these frequency bands. For a transmit frame, then, the backhaul portion
would be the backhaul subchannels of the transmit frame.
Processing unit 126 of WNE 122 also receives downlink traffic from
WNE 121 using transceiver 124 and a backhaul portion of the one or more
frequency bands used for the targeted remote units. In the OFDM
embodiments, the backhaul portion of the one or more frequency bands may
also comprise a set of the OFDM subchannels in these frequency bands.
Also, for a given receive frame, the user set of subchannels and the backhaul
set of subchannels would be non-overlapping.
Processing unit 126 of WNE 122 then transmits the downlink traffic
from WNE 121 to the targeted remote units using transceiver 124 and a user
portion of the one or more frequency bands used for the targeted remote
units. Again, in the OFDM embodiments and for a given transmit frame the
user set of subchannels (the user portion of a frequency band) and the
backhaul set of subchannels would be non-overlapping.
Thus, processing unit 125 of WNE 121 transmits and receives traffic to
and from WNE 122 using transceiver 123 and a backhaul portion of one or
more frequency bands. The received backhaul traffic destined for the
backhaul network is then forwarded by processing unit 125 on to network 151
via network interface 127. Processing unit 125 of WNE 121 also, of course,
transmits and receives traffic to and from remote units 101 and 102, e.g.,
within the wireless coverage area of WNE 121 using transceiver 123 and a
user portion of one or more frequency bands.
As described above with respect to embodiments such as the BackLite
embodiments, transceivers 123 and 124 may comprise both access antenna

systems and narrowbeam antenna systems. In these embodiments,
communication between transceivers 123 and 124 and their respective
remote units would utilize the access antenna systems, while communication
between transceivers 123 and 124 (i.e., between collector and neighbor cell
equipment) would utilize the narrowbeam antenna systems.
Benefits, other advantages, and solutions to problems have been
described above with regard to specific embodiments of the present invention.
However, the benefits, advantages, solutions to problems, and any element(s)
that may cause or result in such benefits, advantages, or solutions, or cause
such benefits, advantages, or solutions to become more pronounced are not
to be construed as a critical, required, or essential feature or element of any
or all the claims.
As used herein and in the appended claims, the term "comprises,"
"comprising," or any other variation thereof is intended to refer to a non-
exclusive inclusion, such that a process, method, article of manufacture, or
apparatus that comprises a list of elements does not include only those
elements in the list, but may include other elements not expressly listed or
inherent to such process, method, article of manufacture, or apparatus. The
terms a or an, as used herein, are defined as one or more than one. The term
plurality, as used herein, is defined as two or more than two. The term
another, as used herein, is defined as at least a second or more. The terms
including and/or having, as used herein, are defined as comprising (i.e., open
language). The term coupled, as used herein, is defined as connected,
although not necessarily directly, and not necessarily mechanically.
Terminology derived from the word "indicating" (e.g., "indicates" and
"indication") are intended to encompass all the various techniques available
for communicating or referencing the object being indicated. Some, but not all
examples of techniques available for communicating or referencing the object
being indicated include the conveyance of the object being indicated, the
conveyance of an identifier of the object being indicated, the conveyance of
information used to generate the object being indicated, the conveyance of
some part or portion of the object being indicated, the conveyance of some

derivation of the object being indicated, and the conveyance of some symbol
representing the object being indicated. The terms program, computer
program, and computer instructions, as used herein, are defined as a
sequence of instructions designed for execution on a computer system. This
sequence of instructions may include, but is not limited to, a subroutine, a
function, a procedure, an object method, an object implementation, an
executable application, an applet, a servlet, a shared library/dynamic load
library, a source code, an object code and/or an assembly code.
What is claimed is:

Claims
1. A method for providing in-band wireless backhaul comprising:
transmitting and receiving traffic, by wireless network equipment
(WNE) of a collector cell, to and from remote units within a wireless coverage
area of the collector cell using a user portion of at least one frequency band;
transmitting and receiving traffic, by the WNE of the collector cell, to
and from WNE of a neighbor cell using a backhaul portion of the at least one
frequency band.
2. The method of claim 1,
wherein transmitting and receiving traffic to and from the remote units
and to and from the WNE of the neighbor cell comprises transmitting and
receiving traffic using uplink and downlink frames and
wherein each uplink frame and each downlink frame utilizes a
frequency band of the at least one frequency band and wherein the frequency
band utilized by each uplink frame and each downlink frame comprises a user
portion and a backhaul portion.
3. The method of claim 2,
wherein the uplink and downlink frames comprise OFDM (orthogonal
frequency division multiplexing) uplink and downlink frames,
wherein the frequency band of the at least one frequency band
comprises OFDM subchannels,
wherein the user portion of each uplink frame comprises a first set of
OFDM subchannels and the backhaul portion of each uplink frame comprises
a second set of OFDM subchannels, and
wherein the user portion of each downlink frame comprises a third set
of OFDM subchannels and the backhaul portion of each downlink frame
comprises a fourth set of OFDM subchannels.
4. The method of claim 1,

wherein the wireless coverage area of the collector cell comprises a
first, a second and a third sector of the collector cell,
wherein traffic is transmitted and received to and from remote units
within the first sector of the collector cell using a user portion of a first
frequency band of the at least one frequency band,
wherein traffic is transmitted and received to and from remote units
within the second sector of the collector cell using a user portion of a second
frequency band of the at least one frequency band, and
wherein traffic is transmitted and received to and from remote units
within the third sector of the collector cell using a user portion of a third
frequency band of the at least one frequency band.
5. The method of claim 4,
wherein a wireless coverage area of the neighbor cell comprises a first
sector of the neighbor cell,
wherein the first sector of the neighbor cell is adjacent to both the first
sector and the second sector of the collector cell, and
wherein transmitting and receiving the traffic to and from the WNE of
the neighbor cell comprises transmitting and receiving traffic for the first sector
of the neighbor cell using a backhaul portion of the third frequency band of the
at least one frequency band.
6. The method of claim 4,
wherein a wireless coverage area of the neighbor cell comprises a first
sector and a second sector of the neighbor cell,
wherein the first sector of the neighbor cell is adjacent to the first sector
of the collector cell but is not adjacent to the second sector of the collector cell
nor the third sector of the collector cell,
wherein the second sector of the neighbor cell is adjacent to the first
sector of the collector cell but is not adjacent to the second sector of the
collector cell nor the third sector of the collector cell,

wherein transmitting and receiving the traffic to and from the WNE of
the neighbor cell comprises transmitting and receiving traffic for the first sector
of the neighbor cell using a backhaul portion of the second frequency band of
the at least one frequency band, and
wherein transmitting and receiving the traffic to and from the WNE of
the neighbor cell comprises transmitting and receiving traffic for the second
sector of the neighbor cell using a backhaul portion of the third frequency
band of the at least one frequency band.
7. The method of claim 1,
wherein the wireless coverage area of the collector cell comprises a
first, a second, a third, and a fourth sector of the collector cell,
wherein traffic is transmitted and received to and from remote units
within the first sector of the collector cell and within the third sector of the
collector cell using a user portion of a first frequency band of the at least one
frequency band, and
wherein traffic is transmitted and received to and from remote units
within the second sector of the collector cell and within the fourth sector of the
collector cell using a user portion of a second frequency band of the at least
one frequency band.
8. The method of claim 7,
wherein a wireless coverage area of the neighbor cell comprises a first
sector of the neighbor cell,
wherein the first sector of the neighbor cell is adjacent to the first sector
of the collector cell, is not adjacent to the third sector of the collector cell, and
is not substantially adjacent to either the second or the fourth sector of the
collector cell,
wherein transmitting and receiving the traffic to and from the WNE of
the neighbor cell comprises transmitting and receiving traffic for the first sector
of the neighbor cell using a backhaul portion of the second frequency band of
the at least one frequency band.

9. The method of claim 1,
wherein the wireless coverage area of the collector cell comprises a
first, a second, a third, a fourth, a fifth, and a sixth sector of the collector cell,
wherein the first sector of the collector cell is adjacent to the second
and the sixth sector of the collector cell but is not substantially adjacent to
either the third, the fourth, or the fifth sector of the collector cell,
wherein the second and the sixth sector of the collector cell are not
substantially adjacent to each other,
wherein the fourth sector of the collector cell is adjacent to the third and
the fifth sector of the collector cell but is not substantially adjacent to either the
first, the second, or the sixth sector of the collector cell,
wherein the third and the fifth sector of the collector cell are not
substantially adjacent to each other,
wherein traffic is transmitted and received to and from remote units
within the first sector of the collector cell using a user portion of a first
frequency band of the at least one frequency band,
wherein traffic is transmitted and received to and from remote units
within the second sector of the collector cell using a user portion of a second
frequency band of the at least one frequency band,
wherein traffic is transmitted and received to and from remote units
within the third sector of the collector cell using a user portion of a third
frequency band of the at least one frequency band,
wherein traffic is transmitted and received to and from remote units
within the fourth sector of the collector cell using a user portion of a fourth
frequency band of the at least one frequency band,
wherein traffic is transmitted and received to and from remote units
within the fifth sector of the collector cell using a user portion of a fifth
frequency band of the at least one frequency band,
wherein traffic is transmitted and received to and from remote units
within the sixth sector of the collector cell using a user portion of a sixth
frequency band of the at least one frequency band,

10. The method of claim 9,
wherein a wireless coverage area of the neighbor cell comprises a first,
a second and a third sector of the neighbor cell,
wherein the second sector of the neighbor cell is adjacent to the first
and the third sector of the neighbor cell,
wherein the first and the third sector of the neighbor cell are not
substantially adjacent to each other,
wherein the second sector of the neighbor cell is adjacent to the first
sector of the collector cell but is not substantially adjacent to either the second
or the sixth sector of the collector cell,
wherein transmitting and receiving the traffic to and from the WNE of
the neighbor cell comprises transmitting and receiving traffic for the first, the
second, and the third sector of the neighbor cell using a backhaul portion of
the third frequency band, a backhaul portion of the fourth frequency band, and
a backhaul portion of the fifth frequency band.

11. The method of claim 9,
wherein a wireless coverage area of the neighbor cell comprises a first,
a second and a third sector of the neighbor cell,
wherein the second sector of the neighbor cell is adjacent to the first
and the third sector of the neighbor cell,
wherein the first and the third sector of the neighbor cell are not
substantially adjacent to each other,
wherein the second sector of the neighbor cell is adjacent to the first
sector of the collector cell but is not substantially adjacent to either the second
or the sixth sector of the collector cell,
wherein transmitting and receiving the traffic to and from the WNE of
the neighbor cell comprises transmitting and receiving traffic for the first and
the second sector of the neighbor cell using a backhaul portion of the third
frequency band and a backhaul portion of the fourth frequency band.

12. A method for providing in-band wireless backhaul comprising:
receiving, by wireless network equipment (WNE) of a cell, uplink traffic
from remote units within a wireless coverage area of the cell using a user
portion of at least one frequency band;
receiving, by the WNE of the cell, downlink traffic from WNE of a
collector cell using a backhaul portion of the at least one frequency band;
transmitting, by the WNE of the cell, the uplink traffic from the remote
units to the WNE of the collector cell using a backhaul portion of the at least
one frequency band;
transmitting, by the WNE of the cell, the downlink traffic from the WNE
of the collector cell to the remote units using a user portion of the at least one
frequency band.
13. The method of claim 12,
wherein the receiving of the uplink traffic from the remote units and the
receiving of the downlink traffic from the WNE of the collector cell is
accomplished by receiving uplink frames;
wherein the transmitting of the uplink traffic to the WNE of the collector
cell and the transmitting of the downlink traffic to the remote units is
accomplished by transmitting downlink frames;
wherein each uplink frame and each downlink frame utilizes a
frequency band of the at least one frequency band and wherein the frequency
band utilized by each uplink frame and each downlink frame comprises a user
portion and a backhaul portion.

14. The method of claim 13,
wherein the uplink and downlink frames comprise OFDM (orthogonal
frequency division multiplexing) uplink and downlink frames,
wherein the frequency band of the at least one frequency band
comprises OFDM subchannels,
wherein the user portion of each uplink frame comprises a first set of
OFDM subchannels and the backhaul portion of each uplink frame comprises
a second set of OFDM subchannels, and
wherein the user portion of each downlink frame comprises a third set
of OFDM subchannels and the backhaul portion of each downlink frame
comprises a fourth set of OFDM subchannels.

15. Wireless network equipment (WNE) comprising:
a transceiver;
a network interface adapted to provide connectivity to a backhaul
network;
a processing unit, communicatively coupled to the transceiver and the
network interface,
adapted to transmit and receive traffic to and from remote units
within a wireless coverage area of a collector cell using
the transceiver and a user portion of at least one
frequency band, and
adapted to transmit and receive traffic to and from WNE of a
neighbor cell using the transceiver and a backhaul portion
of the at least one frequency band.
16. The WNE of claim 15,
wherein the transceiver comprises at least one access antenna and at
least one narrowbeam antenna,
wherein the processing unit is further adapted to transmit and receive
traffic to and from the remote units using the at least one access antenna, and
wherein the processing unit is further adapted to transmit and receive
traffic to and from the WNE of the neighbor cell using the at least one
narrowbeam antenna.
17. The WNE of claim 16, wherein the processing unit is further adapted to
transmit both the user portion and the backhaul portion of the at least one
frequency band using each of the at least one access antenna and each of
the at least one narrowbeam antenna.

18. Wireless network equipment (WNE) comprising:
a transceiver;
a processing unit, communicatively coupled to the transceiver,
adapted to receive uplink traffic from remote units within a
wireless coverage area of a cell using the transceiver and
a user portion of at least one frequency band,
adapted to receive downlink traffic from WNE of a collector cell
using the transceiver and a backhaul portion of the at
least one frequency band,
adapted to transmit the uplink traffic from the remote units to the
WNE of the collector cell using the transceiver and a
backhaul portion of the at least one frequency band, and
adapted to transmit the downlink traffic from the WNE of the
collector cell to the remote units using the transceiver and
a user portion of the at least one frequency band.
19. The WNE of claim 18,
wherein the transceiver comprises at least one access antenna and at
least one narrowbeam antenna,
wherein the processing unit is further adapted to receive uplink traffic
from the remote units using the at least one access antenna,
wherein the processing unit is further adapted to receive downlink
traffic from the WNE of the collector cell using the at least one narrowbeam
antenna,
wherein the processing unit is further adapted to transmit the uplink
traffic from the remote units to the WNE of the collector cell using the at least
one narrowbeam antenna, and
wherein the processing unit is further adapted to transmit the downlink
traffic from the WNE of the collector cell to the remote units using the at least
one access antenna.

20. The WNE of claim 19, wherein the processing unit is further adapted to
transmit both the user portion and the backhaul portion of the at least one
frequency band using each of the at least one access antenna and each of
the at least one narrowbeam antenna.

Various embodiments are described to address the need for providing wireless backhaul that may reduce operator
startup costs while avoiding some of the drawbacks present in the prior art approaches. Generally expressed, the wireless network
equipment (WNE) (121) of a collector cell provides access to a backhaul network (151) to one or more neighboring cells (122) via
in-band wireless signaling. Given the frequency bands used by the collector cell WNE for communication with remote units, one
portion of each band used for user traffic while another portion of each band is used for backhaul traffic. Having backhaul and
user traffic share the assigned frequency bands can eliminate the need to license additional bands for wireless backhaul. Moreover,
utilizing a portion of the existing, in-band orthogonal channels may be more spectrally efficient than using a separate radio in the
same band.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=qOAjmSoSNbvBs5gtl1gMQw==&loc=wDBSZCsAt7zoiVrqcFJsRw==


Patent Number 279224
Indian Patent Application Number 4116/KOLNP/2008
PG Journal Number 03/2017
Publication Date 20-Jan-2017
Grant Date 16-Jan-2017
Date of Filing 10-Oct-2008
Name of Patentee MOTOROLA, INC.
Applicant Address 1303 EAST ALGONQUIN ROAD, SCHAUMBURG, ILLINOIS
Inventors:
# Inventor's Name Inventor's Address
1 LABEDZ, GERALD, P. 740 N. TALMAN AVENUE, CHICAGO, ILLINOIS 60645
PCT International Classification Number A01M 3/02
PCT International Application Number PCT/US2007/067453
PCT International Filing date 2007-04-26
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 11/434312 2006-05-15 U.S.A.