WO2014106539A1

WO2014106539A1 - Method of adaptive antenna beam forming for wireless base station in-channel self-backhauling

Info

Publication number: WO2014106539A1
Application number: PCT/EP2013/050068
Authority: WO
Inventors: Mats Hogberg
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2013-01-03
Filing date: 2013-01-03
Publication date: 2014-07-10

Abstract

A self-backhauling wireless base station and method provide wireless subscriber access to a network and wirelessly backhaul wireless subscriber traffic. The base station or backhaul node establish the wireless backhaul link by searching for a backhaul connections or BTS connections and adapting radiation patterns associated with the one or several base stations or one or several backhaul nodes antenna to establish the backhaul connections. Beam forming includes defining a radiation pattern having a lobe oriented toward the source of the detected backhaul connection by searching for a vector amongst a vector range including a vector oriented toward a backhaul node.

Description

METHOD OF ADAPTIVE ANTENNA BEAM FORMING FOR WIRELESS BASE STATION

IN-CHANNEL SELF-BACKHAULING

FIELD

[0001] Aspects of the present disclosure generally relate to wireless subscriber backhaul. More specifically, aspects of the present disclosure relate to wireless base stations having an antenna configured for wireless subscriber and wireless backhaul communication and related methods for establishing and configuring such backhaul links.

BACKGROUND [0002] Data communication networks include a network core and a network edge. The network core typically includes a number of network nodes connected links extending between pairs of network nodes. The links may be physical connections such as wire conductors and fiber optic cables or microwave radio links. The network edge includes base transceiver stations (base stations) that communicate with network subscribers. Base stations function to tie network subscribers into the core network by aggregating network subscriber traffic into a backhaul link to a core network node, and vice versa. Network subscribers in turn connect to base stations either directly through a physical, wired connection, or wireless, using a radio-based connection.

[0003] Backhaul links may be either wired or wireless. Wired backhaul links are relatively stable and are less susceptible to interference from other wireless devices. Wireless backhaul links do not require a physical connection to a network node, and are therefore less costly to install and setup, but are susceptible to electromagnetic interference. Base stations equipped for wireless backhaul typically include an antenna for wireless subscriber traffic and a separate antenna for wireless backhaul communication.

[0004] One problem with conventional base stations is the need for a second backhaul antenna. Typically, the backhaul link antenna is a unidirectional antenna configured to direct RF energy in a single direction. This adds cost to the base station and makes base station installation more complex as the backhaul antenna must be oriented so as to have line of sight with the node on the other end of the radio link. This need in turn limits the locations in which the base station can be employed. [0005] There is therefore a need for a base station having an antenna configured for wireless subscriber traffic and wireless backhaul communication. There is a further need for a base station having a common subscriber and backhaul antenna capable of detecting a network node connection and configuring the antenna beam such that the wireless backhaul connection is established and maintained without interfering with wireless subscribers served by the antenna.

BRIEF DESCRIPTION OF EMBODIMENTS

[0006] A method of self-backhauling is described. The method includes searching for an available backhaul connection, detecting at least one available backhaul connection, electronically conforming a radiation pattern associated with an antenna to the detected backhaul connection, and establishing a backhaul using the conformed radiation pattern.

[0007] A base transceiver station (base stations) is described. The station has an antenna operatively connected to a digital central unit. The digital central unit is configured to wirelessly couple a plurality of wireless subscribers to the system using a first frequency and to backhaul the wireless subscriber communication using a second frequency. The digital central unit also integrates communication from the wireless subscribers on the first frequency with wireless backhaul communication on the second frequency using a common antenna.

[0008] A base transceiver system is described. The base transceiver unit has a digital control unit with a processor and a memory operatively coupled to an antenna array unit. The memory includes a non-transitory machine readable memory having instructions recorded thereon that, when read by the processor, cause the digital control unit to search for an available backhaul connection be electronically sweeping the antenna array across a first set of pre-coded vectors, detect at least one available backhaul connection by measuring an uplink pilot power, select an available backhaul connection, and send a connection request (such as a paging message) using the available backhaul connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The foregoing and other advantages and features of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: [0010] Fig. 1 is a schematic diagram of a network;

[0011] Fig. 2 is a schematic diagram of an exemplary wireless backhaul connection;

[0012] Fig. 3 shows an embodiment of a self-backhauling base station configured for adaptive beam forming and having a common wireless subscriber and wireless backhaul antenna;

[0013] Fig. 4 shows an embodiment of a self-backhauling base station configured for adaptive beam forming and having a dedicated wireless subscriber and wireless backhaul antennas;

[0014] Fig. 5 is a process flow diagram of a method of establishing a wireless backhaul connection;

[0015] Fig. 6 is a process flow diagram for detecting an available backhaul connection;

[0016] Fig. 7 is a process flow diagram for electronically conforming a radiation pattern a detected backhaul connection;

[0017] Fig. 8 is a process flow diagram for establishing a backhaul connection using a portion of a conformed radiation pattern of an antenna array to a detected backhaul connection;

[0018] Fig. 9 is exemplary method for establishing a wireless backhaul connection where a network node selects a wireless base station for wireless backhaul; and [0019] Fig. 10 is exemplary method for establishing a wireless backhaul connection where a base station selects a network node for wireless backhaul.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0020] Detailed illustrative embodiments are disclosed herein. While specific configurations and arrangements of communications network systems, wireless backhaul systems, and methods of establishing self-backhauling wireless connections, it should be understood that these are for illustrative purposes and non-limiting. A person skilled in the pertinent art will appreciate that other configurations and arrangements of the can be used without departing from the spirit and scope of the present description.

[0021] It will further be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. It will also be understood that, although the terms communicatively couple, connect, access, and link may be used herein to relate various elements, these elements should not be limited by these terms. As further used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

[0022] As used herein, the term 'uplink' refers to communication originating from a base station and destined for a network node. As also used herein, the term 'downlink' refers to communication originating from a network node and destined for a base station.

[0023] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved. [0024] Fig. 1 is a schematic diagram of an exemplary communications network 10. Network 10 comprises a core network 12 connecting network subscribers to public data networks such as the network and/or public switched telephone networks. The core network 12 couples to a voice communication network 14 through a connection 16. Core network 12 also couples to a data network 18 such as the internet through a connection 20. Although the illustrated network shows separate connections for voice and data communications, core networks having individual connections for both voice and data traffic are within scope the invention described herein.

[0025] Network 10 comprises a first backhaul node 22 and a second backhaul node 26. As used herein, the term "backhaul" means getting data to a point from which it can be distributed over a network. First backhaul node 22 communicatively couples to the core network 12 through a wired connection 24. Second backhaul node 26 communicatively couples to the core network 12 through a wired connection 28. As used herein, the term "wired" refers to a physical connection between network components such as an electrical conductor or fiber optic cable configured to pass data and/or voice communication traffic. Network 10 further comprises a base station 30 configured for passing wireless data and/or voice communications traffic. Base station 30 wirelessly couples to the second backhaul node 26 (and core network 12) through a wireless backhaul connection 32. As used herein, the term "wireless" refers" to a non-physical connection between network components to pass data and/voice communication traffic. A non- limiting list of examples includes radio frequency, microwave, and infrared. [0026] Network 10 passes voice and data traffic associated with at least one wireless network subscriber (34, 36, 42, 46). First subscriber 34 and a second subscriber 36 access network 10 through base station 30 and backhaul node 26. Third subscriber 42 and a fourth subscriber 46 access network 10 through backhaul node 22. Wireless subscribers 34 and 36 access network 10 by wirelessly coupling to base station 30 through wireless connections 38 and 40. Wireless subscribers 42 and 46 access network 10 by wirelessly coupling to backhaul node 22. As would be appreciated by one of skill in the art, network 10 may provide network access to varying numbers of network subscribers, some or all the subscribers accessing the network through wired connections, and some or all the subscribers accessing the network through wireless connections. In an embodiment, the base station is a micro-base station operative to extend the geographic reach and/or wireless subscriber capacity of the network without the need for a emplacing a wired connection. Alternatively, the base station is operative to extend the geographic reach and/or wireless subscriber capacity the network using a physical connection.

[0027] For illustrative purposes, a method or wireless self-backhauling associated with BTS 30 using Long-Term Evolution (LTE) system architecture is described. This is for illustrative purposes only and non-limiting. As would be appreciated by one of skill in the art, the technical solution provided by aspects of the invention are applicable to other system architectures, such as the global system for mobile communications systems (GSM), time division-synchronous code division multiple access (TD-SCDMA) systems, code division multiple access (CDMA) systems, worldwide interoperability for microwave access (WIMAX) systems, and wideband code division multiple access (W-CDMA) systems. [0028] Fig. 2 is a schematic diagram of base station 30, backhaul node 26, and the wireless connection 32 extending between the base station 30 and node 26. Base station 30 comprises an antenna array unit 50, a radio-transceiver unit 52, and a digital central unit 54, the digital central unit having a processor 56 and a memory 58. Processor 56 is communicatively connected to memory 58. Processor 56 is also operatively coupled to the digital central unit 54. The digital central unit 54 is operatively connected to the radio-transceiver unit 52 and antenna array unit 50 and configured to control the beam form of a signal received and transmitted by the antenna array unit 50. The memory 58 is a non-transitory computer readable media such as a hard disk, CD-ROM, or flash memory, and has encoded thereon a set of instructions that, when read by the processor, cause the base station to perform certain actions. For example, the base station 30 may detect the presence of a node configured for wireless backhaul communication, thereby passing traffic destined for and/or originating from network subscribers connected to the base station. The base station may also detect the presence of backhaul nodes by searching for wireless-capable backhaul node(s) within a wireless footprint of the antenna unit or by scanning across a wide antenna beam to connect to the node(s). In an embodiment, the base station configures the backhaul connection by optimizing a signal to interference plus noise ratio (SINR) associated with one of the down link and uplink backhaul connection32. It does so by using a training sequence and pre-coded vectors stored within the base station memory and usable by the antenna array unit 50 to create antenna beams (70, 72, 74, 76, 78) with feedback information from one of or both backhaul node and base station.. The backhaul node may also use pre-coded antenna vectors stored on the backhaul node memory for antenna 60 to optimize the SINR of backhaul connection 38 associated with antenna beams patterns (82, 84, 86, 88, 90) for one or both of the uplink and downlink connections. The base station may also be configured to control BB, power, sync, etc. of the wireless signal emanating from the antenna array unit 50. In an embodiment, the antenna unit 50 comprises a multiband antenna array. The antenna may be a single band antenna or a multiband antenna. The antenna may further be configured to use a first portion of the frequencies utilized by the base station is allocated to backhaul communication and a second portion of the frequencies utilized by the base station is allocated to wireless subscriber traffic. The frequencies will be within same RF band for a single band antenna and for a multi band antenna the RF frequencies can be allocated in different RF frequency bands. [0029] Node 26 comprises an antenna unit 60, a radio transceiver unit 62, and a digital central unit 64 having a processor 66 and a memory 68. In an embodiment, node 26 is a TDD node having a single radio and is configured to support both wireless subscriber traffic and wireless backhaul communication. In another embodiment, node 26 is an FDD node more than one radio and is configured to support both wireless subscriber traffic and wireless backhaul communication. The processor 66 operatively couples to the digital central unit 64 and the memory 68. The digital central unit 64 operatively couples to the radio filter unit 62 and the antenna unit 60. The memory 68 is a non-transitory machine readable media, and in an embodiment, may further comprise set of instructions that when read by the processor 68 cause the backhaul node 26 to perform certain actions. For example, node 26 may to detect the presence of BTS 30 within wireless range, scan across or use a wide antenna beam to connect to BTS 30. Node 26 may also use a training sequence to optimize antenna beam on the backhaul node side of wireless connection 32, and determine at least one of base power, SINR, and modulation settings associated with a received and/transmitted antenna beam. In an embodiment, the backhaul user equipment listens only. In the embodiment, upon receipt of a base station paging request, the backhaul user equipment responds to the base station paging request. Node 26 may also be configured to control BB, power, sync, etc. of the wireless signal emanating from the antenna unit 60. The antenna might be a single band antenna or a multiband antenna. The antenna may be configured to use a first portion of the frequencies utilized by the base station is allocated to backhaul communication and a second portion of the frequencies utilized by the base station is allocated to wireless subscriber traffic. The frequencies will be within same RF band for a single band antenna and for a multi band antenna the RF frequencies can be allocated in different RF frequency bands.

[0030] Base station 30 is configured to self-backhaul. As used herein, "self-backhauling" means that the base station is configured to locate a network node within wireless range and/or establish a backhaul wireless connection with the node. In one embodiment, the base station self-backhauls using a first radio transceiver module for network subscribers and a second radio transceiver module for backhaul communication. Base station 30 may provide network access to wireless subscribers (34, 38) using a radio configured to operate using a first frequency band, and wirelessly backhaul to the node 26 using second frequency band. A radio combining unit (not shown) operatively connected the radios and the antenna unit combines and divides traffic based on traffic direction. In another embodiment, BTS 30 self-backhauls using the same radio access module for its serviced network subscriber traffic as the BTS 30 uses for backhaul traffic.

[0031] In an embodiment, base station30 comprises a radio access module (not shown) operatively coupled to the digital central unit 54. The module is configured to provide wireless subscriber access and wireless backhaul using LTE system architecture and frequency-division duplexing (FDD), the BTS radio module operative to transmit and receive using different carrier frequencies. Advantageously, because wireless subscribers and the wireless backhaul connection use LTE FDD, the wireless subscribers and the wireless backhaul connection share equipment for subscriber traffic and backhaul traffic. Shared equipment may include the base station antenna array unit, the base station radio -transceiver, the base station BB, and the base station traffic hardware/software. Advantageously, the embodiment has a relatively simple configuration, low cost, and a smaller number of modules (i.e. boxes) for emplacement at the base station emplacement location.

[0032] In an embodiment, base station 30 comprises a radio access module configured to provide both wireless subscriber access and wireless backhaul using LTE system architecture and time-division duplexing (TDD), the base station radio module operative to transmit and receive at different times. Advantageously, because wireless subscribers and the wireless backhaul connection use LTE TDD, the wireless subscribers and the wireless backhaul connection share equipment for subscriber traffic and backhaul traffic. Shared equipment may include the base station antenna array, the base station radio, the base station BB, and base station traffic hardware/software. Advantageously, the embodiment has a relatively simple configuration, low cost, and a smaller number of modules (i.e. boxes) for emplacement at the base station emplacement location.

[0033] In an embodiment, base station 30 comprises a radio access module configured to provide wireless subscriber access using LTE system architecture applying FDD subscriber communication, and wireless backhaul using LTE system architecture applying TDD to backhaul communication. Advantageously, a common BTS antenna can be used for wireless backhaul and for the wireless subscribers.

[0034] In an embodiment, base station 30 comprises a radio access module configured to provide wireless subscriber access using the universal mobile telecommunications system (UMTS) and wireless backhaul using LTE system architecture and TDD. Advantageously, a common base station antenna can be used for wireless backhaul and for the wireless subscribers.

[0035] In an embodiment, base station 30 comprises a radio access module configured to provide both wireless subscriber access using LTE system architecture and FDD or LTD system architecture and TDD, and wireless backhaul using WiFi. Advantageously, a common BTS antenna can be used for wireless backhaul and for the wireless subscribers.

[0036] In an embodiment, base station 30 comprises a radio access module configured to provide both wireless subscriber access using WiFi and wireless backhaul also using WiFi. Advantageously, a common base station antenna can be used for wireless backhaul and for the wireless subscribers.

[0037] As shown in Fig. 2, base station 30 is configured to generate a radiation pattern defining a plurality of lobes (70, 72, 74, 76, 78) across a coverage angle 80. At least one of the generated lobes 70 wirelessly connects base station 30 to node 26 for wireless backhaul. In an embodiment, the lobes define a set of pre-coding vectors 1 - N selectable by the digital control unit of the BTS 30. For example, the wireless subscribers traffic can have 1 -N lobes using a first frequency channel, and the wireless backhaul communication can have 1 -N lobes using a second frequency channel. The second frequency will be substantially orthogonal to the first frequency.

[0038] Node 26 is similarly configured to generate a radiation pattern defining a plurality of lobes (82, 84, 86, 88, 90) across a coverage angle 92. In an embodiment, the lobes define a set of pre-coding vectors 1-M selectable by the digital control unit of the node 26. At least one lobe of the generated lobes 84 wirelessly connects base station 30 to node 26 for wireless backhaul. In the illustrated embodiment, base station 30 selects the antenna lobe 70 oriented toward the node 26, and establishes the wireless backhaul connection 32 using the at least one antenna lobe 70 and corresponding at least one antenna lobe 84 for wireless backhaul connectivity. Advantageously, in embodiments of the base station in environments having objects/structures (A, B, C, D) obstructing wireless communications such as buildings, the selected antenna lobes (70, 82) provide a less-obstructed wireless backhaul path having greater quality and/or providing greater bandwidth by self-optimizing at least one backhaul link using multipurpose equipment to support wireless subscriber traffic and wireless backhaul traffic. Moreover, in the event that more than one antenna lobe is suitable for wireless backhaul, the base station can establish and/or configure more than one wireless backhaul link.

[0039] Fig. 3 shows an embodiment of a self-backhauling base station 130 operative to cover wireless subscribers and wirelessly backhaul using adaptive beam forming, an integrated antenna and frequency division duplexing. Base station 130 comprises a single antenna unit 150, the antenna unit further comprising an antenna array 152. Antenna unit 150 is an integrated antenna unit, meaning that the single antenna is configured to define a first radiation pattern 154 using at least a first frequency and covering an area having wireless subscribers (132, 134). First radiation pattern 154 is shown in the figure in broken lines. Antenna unit 150 is configured to define a second radiation pattern 156 using at least a second frequency and forming at least a backhaul lobe 156 (shown in solid lines). Base station 130 is configured to selectively orient the lobe 156 such that radiation emanating to and from antenna unit aligns itself to a selected vector. Operatively, base station 130 detects the presence of a wireless-capable backhaul node 126, conforms a radiation pattern emanating from the antenna unit 150 such that an antenna lobe of radiation is oriented in a direction (along a selected vector) toward the detected backhaul node. Lobe 156 thereby defines a portion of the wireless backhaul connection over which subscribers 132 and 134 pass data and/or voice communication traffic. In an embodiment, backhaul node 126 correspondingly conforms a lobe 162 of a radiation pattern emanating from an antenna unit 160 such that the lobe of radiation is oriented in a direction (also along a selected vector) toward base station 130. As would be appreciated by one of skill in the art, adaptive beam forming may also be used to define wireless subscriber lobes appropriate for a distribution of wireless subscribers within the covered area of base station 130.

[0040] Operatively, base station 130 is configured to adapt (beam form) a first portion of electromagnetic radiation emitted from antenna array 152 to 'cover' wireless subscribers (132, 134) using a first frequency. The first radiation portion is shown using broken lines extending from antenna array 152. Base station 130 is further configured to adapt (beam form) a second portion of electromagnetic radiation emitted by antenna array 152 toward backhaul node 126 using a second frequency. The second radiation portion is shown using solid lines extending from antenna array 152 toward backhaul node 126. In an embodiment of Applicant's invention, the backhaul node is further configured to adapt (beam form) electromagnetic radiation emitted from antenna array unit 160. Advantageously, embodiments of base station 130 communicate with wireless subscribers and wireless backhaul subscriber traffic using a common antenna, thereby reducing hardware and software associated with the base station. In the illustrated embodiment the base station uses frequency division duplexing to communicate with wireless subscribers and the backhaul node using a common antenna array unit.

Fig. 4 is a schematic diagram of another exemplary wireless backhaul connection between a backhaul node 226 and a base station 230. Structurally, backhaul node 226 and base station 230 differ from the above -described embodiment in that their respective antennas, digital control units, and radio -transceiver units are configured for communication using time division duplexing. This means that, once a synchronization operation has been done between the base station and backhaul node, the base station and backhaul nodes take turns transmitting and receiving using at least one shared frequency. Operatively, this is illustrated in the figure through illustration of an antenna lobe emanating from the base station extending toward (and nearly touching) the backhaul node while a corresponding antenna lobe emanating from the backhaul node is terminates some distance from the base station - the figure thereby illustrating the base station in the midst of its 'transmitting' turn and the backhaul node in the midst of its 'receiving' turn. As would be appreciated by one of skill in the art in view of the above discussion, the electromagnetic radiation transmitted by the base station and/or backhaul node is adapted (beam formed) using an antenna training method in view of at least one signal parameter.

[0041] Fig. 5 shows a method of self-backhauling 100. The method comprises searching 110 for a backhaul connection; detecting 120 an available backhaul connection; electronically adapting a radiation pattern associated with an antenna to the detected backhaul connection; and establishing a backhaul connection using at least a portion of the conformed radiation pattern. In an embodiment, base station is configured to electromagnetically manipulate a radiation pattern associated the base station antenna using adaptive antenna beam forming for in-channel backhauling.

[0042] Fig. 6 shows an embodiment of method 100 wherein searching 110 further comprises electronically sweeping 112 the antenna across a plurality of pre-coded vectors, such as a set of pre- coding vectors 1-N defined in the base station memory. Searching 110 may further comprise searching 116 for an uplink associated with a backhaul node directed along at least one of the swept vectors. Searching 110 may also comprise measuring and/or determining a power associated with the uplink. Searching 110 may also comprise selecting 118 at least one available backhaul connection. In an exemplary embodiment, base station 30 searches for an available backhaul connection by sweeping a pattern of radiation defined by the base station antenna unit along a plurality of pre-coding vectors 1 - N. Base station 30 may then select a backhaul connection based on measured uplink pilot power. In an embodiment, both the base station and the backhaul node use the above-described adaptive antenna processing to establish and/or configure the backhaul connection (link).

[0043] Fig. 7 shows an embodiment of method 100 wherein electronically conforming 130 the radiation pattern associated with the antenna unit further comprises defining 132 an antenna lobe oriented along the detected backhaul connection; sending 134 a connection request along the backhaul connection; sending 136 an uplink along the detected backhaul connection; and iteratively adjusting 138 the antenna lobe orientation along a vector based on at least one measured parameter associated with the backhaul connection. Examples of parameters include signal power, SINR, interference, etc. In an embodiment, the parameters include a change in the backhaul connection signal initiated by the backhaul node.

[0044] Selecting 118 a backhaul connection 120 may further comprise selecting a single detected backhaul connection by forming an uplink using one of an integrated antenna array or a dedicated antenna array of the base station 30. The formed beam is configured to direct radiation in the direction of the detected connection node. In an embodiment, selecting 118 the available backhaul may further comprise selecting a plurality of available backhaul connections. In an embodiment, selecting 1 18 the available backhaul may comprise selecting at least one from amongst a plurality of backhaul connections based on a parameter associated with the backhaul connection - such as signal strength, noise, interference, proximity to signal(s) associated with wireless subscribers served by the base station. Selecting 118 the available backhaul connection may further comprise sending 122 a connection request along the backhaul connection to the originating backhaul node. In an embodiment, selecting base station 30 selects the best from a plurality of available backhaul connections by sending a connection request and downlink pilot along a detected backhaul connection to a backhaul node comprising backhaul user equipment. [0045] Method 100 may further comprise dividing a radio-frequency spectrum allocated to the base station into a first portion used for communicating with wireless subscribers and a second portion used for wireless backhaul communication with a backhaul node. Dividing the radio frequency ordinarily allocated for wireless subscribers into a first portion dedicated to wireless subscribers and a second portion dedicated to wireless backhaul has the technical effect of providing backhaul connectivity without and leaving spectrum for other spectrum users. Interference to (and from) the backhaul link is reduced by configuring the radiation pattern into backhaul lobes, and spectrum allocated to wireless traffic can be efficiently used.

[0046] Fig. 8 shows an embodiment of method 100 wherein establishing 140 the backhaul connection further comprises electronically sweeping 142 an antenna array unit of the backhaul node across a plurality of vectors, detecting 144 a downlink pilot associated with at least one swept vector, measuring 146 power associated with the detected downlink power, defining 148 an antenna lobe defined by the antenna array radiation pattern along the vector associated with the downlink pilot, and iterative ly adjusting 149 the antenna lobe orientation based on a parameter associated with backhaul connection. The beam is configured to direct at least a portion of the radiation emanating from the backhaul antenna unit toward the base station, and in an embodiment, a majority of the radiation associated with the backhaul connection. Establishing 140 the backhaul connection may further comprise responding to a connection issued by the base station over the backhaul connection. In an embodiment, conditioning comprises sweeping the beam across a set of pre- coding vectors 1 - M. Establishing the connection may also comprise measuring and/or determining a downlink power associated with base station 30 along at least one of the swept vectors. In an exemplary embodiment, backhaul node sweeps antenna pre -coding vectors 1 - M and selects a pre- coding vector to maximize the received downlink pilot power.

[0047] In an embodiment of method 100, the backhaul node establishes the connection by measuring backhaul uplink pilot power associated with at least one vector. Establishing the link may also comprise sweeping the formed lobe over a second set of pre-coded vectors having a narrower range than vectors 1-M.

[0048] Method 100 has the technical effect of providing wireless backhaul as an alternative to fixed backhaul (e.g. copper wire with xDSL, Ethernet, optical, GPON or P2P fiber) for base transceiver stations. Embodiments of method 100 include but are not limited to wireless self- backhauling using WiFi, microwave links, TDD, and FDD with external equipment or integrated equipment. Embodiments of method 100 implemented with external equipment may further comprise a modem, R/F microwave, and antenna operatively coupled to the digital control unit of the base station. [0049] Embodiments of method 100 have the technical effect of providing self-optimized radio links defining a wireless backhaul connection between a base transceiver unit and a backhaul node. Embodiments of method 100 define antenna lobes on at least one of the base station antenna side and the backhaul node antenna sides that direct radiation carrying backhaul communication traffic into (and from) a network and wireless subscribers services by the base station. Exemplary embodiments of method 100 may use other techniques to improve backhaul connection quality and/or bandwidth (capacity) including higher order modulation and/or multiple input multiple output (MEVIO). As such, embodiments of the systems and methods of adaptive beam forming disclosed herein have the technical effect providing flexible site solutions and 'plug and play' backhaul configuration components. Such wireless backhaul links can be readily dialed-in or optimized without manual configuration or careful site selection.

[0050] In an exemplary embodiment of a self-backhauling method shown in Fig. 9, a base station broadcasts an uplink pilot to an audience of available backhaul nodes and establishes a backhaul connection based on backhaul responses. The method comprises (i) transmitting, from a base station, at least one of a synchronization cannel (SCH), a broadcast channel (BCH), and a reference signal (RS) on pre-defined antenna vectors 1 - N; (ii) (a) detecting, at a backhaul node, at least one of transmitted the SCH, BCH, and RS; (b) obtaining system information associated with the base station; and (c) measuring a signal strength associated with the RS; (iii) (a) selecting, using the backhaul node, a base station with which to establish a backhaul connection, and (b) sending, using the backhaul node, a random access channel (PRACH) to the base station; (iv) storing, using the base station, the available base station and a pre-coded antenna vector associated with the backhaul node; and (v) establishing, using the base station, a backhaul connection with the backhaul node.

[0051] As also shown in the embodiment of Fig. 9, the transmitting (i) operation further comprises transmitting the at least one of an SCH, a BCH, and an RS from each of a plurality of base stations, and the selecting a base station further comprises selecting from amongst the plurality of base stations a base station having a better connection. In an embodiment, the storing (iv) operation further comprises (a) storing a plurality of available base station and pre-coded antenna combinations at the base station, and (b) selecting the best backhaul node or plurality of backhaul nodes with which to establish a backhaul connection. In an embodiment, establishing (v) a backhaul connection may further comprise optimizing an uplink radio link associated with the backhaul connection. Advantageously, such methods have the technical effect of optimizing the uplink between the base station and the backhaul node.

[0052] In an embodiment, establishing (v) a backhaul connection further comprises (a) transmitting, from the base station, feedback to the backhaul node including a desired pre-coded antenna vector for the downlink between the backhaul node and base station; and (b) altering (setting), using the backhaul node, the antenna vector associated with the downlink to the base station to the desired antenna vector. These operations may be iteratively repeated until such time that the base station deems the downlink sufficient and no longer sends feedback to the backhaul node for an antenna vector change. Advantageously, methods incorporating these operations have the technical effect of optimizing the downlink between the backhaul node and the base station.

[0053] In another embodiment of a self-backhauling method shown in Fig. 10, a backhaul node broadcasts a downlink pilot to an audience of base stations and establishes a backhaul connection based on a base station response. The method comprises (i) receiving, at a base station, a backhaul node downlink pilot on at least one of a plurality of pre-coded antenna vectors 1 - N; (ii) transmitting, from the base station, a connection request from the base station to the backhaul node; (iii) connecting the backhaul node to the base station; and (iv) establishing a backhaul node to base station uplink radio link. In an embodiment of the method, the receiving (i) further comprises (a) receiving, at the base station, a plurality of backhaul downlink pilots associated with different backhaul nodes; and (b) selecting from amongst the plurality of backhaul nodes a backhaul node to connect with base on a power measurement associated with the downlink pilot.

[0054] In the embodiment illustrated in Fig. 10, establishing (iv) a backhaul connection further comprises (a) transmitting, from the backhaul node, feedback to the base station including a desired pre-coded antenna vector for the uplink between the base station and backhaul node; and (b) altering (setting), using the base station, an antenna vector associated with the uplink from the base station to the backhaul node to the desired antenna vector. These operations may be iteratively repeated until such time that the backhaul node deems the uplink of sufficient quality or having adequate stability to pass data and no longer sends feedback to the base station for an antenna vector change. Advantageously, methods incorporating these operations have the technical effect of optimizing the uplink between the base station and the backhaul node.

[0055] In an embodiment, a single base station may establish wireless backhaul connections with more than one backhaul node using the above-described self-backhauling method. In another embodiment, a single backhaul node may wirelessly backhaul more than one wireless base station. Advantageously, multiple connections provide redundancy to the backhauled wireless base stations and increased data traffic capacity. Networks incorporating such redundant or additional connections are more robust and reliable than would otherwise be the case.

[0056] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

What is claimed is:

1. A method of self-backhauling, the method comprising:

at base transceiver station having an antenna configured for wireless subscriber communication and wireless backhaul,

searching for a backhaul connection;

detecting at least one available backhaul connection;

electronically conforming a radiation pattern emitted by the antenna to the detected backhaul connection; and

establishing a backhaul connection using the conformed radiation pattern.

2. The method of claim 1, wherein the searching for a backhaul connection further comprises:

electronically sweeping an antenna across a plurality of vectors;

detecting a downlink pilot associated with at least one of the swept vectors; and measuring a power associated with the detected downlink pilot.

3. The method of claim 1 , further comprising dividing an allocated portion of wireless frequency spectrum into at least a first frequency for wireless subscribers and at least a second frequency for wireless backhaul.

4. The method of claim 3, further comprising integrating wireless subscriber communication using the first frequency with wireless backhaul communication using the second frequency for use with the common antenna.

5. The method of claim 1, wherein electronically conforming the radiation pattern associated with the antenna further comprises sending a connection request along the backhaul connection.

6. The method of claim 1, wherein electronically conforming the radiation pattern associated with the antenna further comprises sending an uplink pilot along the backhaul connection.

7. The method of claim 1, wherein the electronically conforming a radiation pattern associated with an antenna to the detected backhaul connection comprises:

defining, using radiation emanating from the antenna, an antenna lobe oriented along a vector associated with the detected backhaul connection;

sending a connection request along the backhaul connection;

sending an uplink request along the detected backhaul connection; and

iteratively adjusting the antenna lobe orientation in response to at least one parameter associated with the backhaul connection,

wherein an antenna lobe associated with both the uplink and the downlink is adjusted to establish the backhaul connection.

8. The method of claim 7, wherein the at least one parameter comprises at least one of signal strength, signal noise, signal interference, and backhaul connection proximity to wireless subscribers.

9. The method of claim 1, wherein establishing a backhaul connection using the conformed radiation pattern further comprises:

electronically sweeping the antenna across a plurality of vectors;

10. The method of claim 9, wherein establishing the backhaul connection using the conformed radiation pattern further comprises:

defining, in radiation emanating from the antenna, an antenna lobe oriented along the vector associated with the detected downlink pilot; and

iteratively adjusting the antenna lobe orientation in response to at least one parameter associated with the backhaul connection.

11. The method of claim 10, wherein the at least one parameter comprises at least one of signal strength, signal noise, and signal interference.

12. A base transceiver station, comprising:

an antenna configured for wireless subscriber communication and wireless backhaul, the antenna being operatively coupled to a digital central unit,

wherein the antenna is configured to wirelessly couple a plurality of wireless subscribers using a first frequency,

wherein the digital central unit is configured to wirelessly backhaul subscriber data and/or voice communication using a second frequency,

wherein the digital central unit is configured to optimize connection antenna lobes for both the backhaul connection downlink and uplink.

13. The system of claim 12, wherein the digital control unit is configured to define a lobe in a radiation pattern emitted by the antenna along a vector.

14. The system of claim 12, wherein the digital control unit is configured to sweep a beam formed by the antenna across a plurality of directions.

15. A base transceiver system, comprising:

a digital control unit having a processor and a memory; and

an antenna configured for wireless subscriber communication and wireless backhaul, the antenna being operatively coupled to the digital control unit,

wherein the memory further comprises a non-transitory machine readable media having instructions recorded thereon that cause the processor to:

search for an available backhaul connection by electronically sweeping the antenna across a first set of pre-coded vectors,

detect an available backhaul connection by measuring an uplink pilot power, select an available backhaul connection, and

send a connection request along the available backhaul connection.

16. The system of claim 15, wherein the non-transitory machine readable media instructions further cause the processor to: receive a response to the sent connection request,

measure the uplink pilot power again, and

sweeping the antenna across a second set of pre-coded vectors.

17. The system of claim 16, wherein the second set of pre-coded vectors define a vector range smaller than a vector range associated with the first set of pre-coded vectors.

18. The method of claim 1 , wherein the searching for a backhaul connection further comprises using an LTE cell selection algorithm.

19. The method of claim 1 , wherein the searching for a backhaul connection further comprises searching for a downlink request broadcast by an available backhaul node across a plurality of pre-coded antenna vectors.

20. The method of claim 1 , where the searching for a backhaul connection further comprises broadcasting an uplink request from a wireless base station across a plurality of pre- coded antenna vectors.