Abstract:
An array antenna is utilized to enhance the adaptive acquisition capability of a communication connection with one or more wireless subscribers. Subscribers who are located outside the omnidirectional range of the array antenna are acquired by using adaptive beamforming techniques to create an acquisition beam dedicated to acquiring new connections with wireless subscribers. The acquisition beam may sweep through the coverage of the array antenna seeking subscribers who lie beyond the omni range of the array antenna, but fall within the acquisition range using adaptive beamforming.

Description:
TECHNICAL FIELD 
     This application relates generally to wireless communication. More particularly, this application relates to enhancing connection acquisition using an array antenna. 
     BACKGROUND 
     Radio frequency (RF) signals are commonly used for transmitting and receiving communications wirelessly. Antenna design has played an integral part in technological advancements made with respect to radio communications. Conventionally, a single antenna element such as a dipole antenna has provided an omnidirectional gain, at least within a particular dimensional plane (e.g., the earth&#39;s surface). Omnidirectional gain may be characterized by an antenna transmitting somewhat equal amounts of electromagnetic radiation in all directions within the plane, or likewise being equally sensitive to receiving radio frequencies from sources at equal distances around the antenna. 
     Clusters of antenna elements transmitting related signals, called array antennas, have been known to strengthen and/or weaken the collective gain of RF signals in particular directions and/or at particular times. For example, four antenna elements transmitting the same signal placed at strategic locations near each other (e.g., one half wavelength apart), may produce a beam, or strengthened gain, within a particular direction extending out from the antenna. Likewise, other directions achieve diminished gain. This is due at least in part to constructive and destructive interference caused by electromagnetic waves emitted from or transmitted to nearby elements. The effect can extend the reach of an array antenna over greater distances or into and through obstacles such as buildings. The effect can also be used to position areas of diminished gain so as to avoid disruptive radio sources or reflections in particular directions. 
     Advanced array antennas controlled by digital signal processors can adaptively modify the direction and strength of beams by, for example, making slight modifications to the phase of signals transmitted or received by the various elements of an array antenna. This process is referred to as beamforming, and beams formed in this fashion can extend the range of the array antenna beyond the normal omnidirectional range under equal transmitted power that the antenna might otherwise be limited to. Beamforming techniques have been used to extend the reach of an antenna and also to reduce the interference to the environment in order to maintain ongoing communications with a remote wireless subscriber. However, acquiring connections to wireless subscribers has been limited to the smaller omnidirectional range of the array antenna. This prevents the array antenna from acquiring connections to subscribers outside the omnidirectional range, but within the reach of beams. 
     SUMMARY 
     It should be appreciated that this Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
     According to one or more embodiments described herein, methods, systems, and computer-readable media provide for enhancing acquisition of connections to wireless subscribers. A beam of an array antenna is allocated for use as an acquisition beam and a coverage area is defined for the beam. The acquisition beam is directed to move around within the coverage area and determine whether a service request signal is received from a wireless subscriber. In this fashion, the wireless subscriber can be located in an area lying beyond the omnidirectional range of the array antenna, but within the beam reach of the array antenna. 
     Other embodiments provide methods and systems of enhancing acquisition of connections to wireless subscribers using multiple acquisition beams simultaneously. As the array antenna nears capacity, acquisition beams can be reallocated for the purpose of maintaining ongoing communications with connected subscribers. 
     Other systems, methods, and/or computer program products according to embodiments will be or become apparent to one with skill in the art upon review of the following drawings and Detailed Description. It is intended that all such additional systems, methods, and/or computer program products be included within this description, be within the scope of the present invention, and be protected by the accompanying claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a network diagram depicting an example of a base station and system in which one or more embodiments may be implemented; 
         FIGS. 2 and 3  are radiation pattern diagrams depicting array antenna gain according to one or more embodiments; and 
         FIG. 4  is a flow diagram depicting a process for enhancing the acquisition of connections to wireless subscribers using an array antenna according to one or more embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is directed to methods, systems, and computer-readable media for enhancing connection acquisition using an array antenna. In the following detailed description, references are made to the accompanying drawings that form a part hereof, and which are shown, by way of illustration, using specific embodiments or examples. Referring now to the drawings, in which like numerals represent like elements through the several figures, aspects of the methods, systems, and computer-readable media provided herein will be described. 
       FIG. 1  and the following discussion are intended to provide a brief, general description of a suitable operating environment in which embodiments of the invention may be implemented. While embodiments of the invention will be described in the general context of program modules that execute in a computer system, those skilled in the art will recognize that other embodiments of the invention may also be implemented in combination with other systems and program modules. Generally, program modules include routines, programs, components, data structures, and other types of structures that perform particular tasks or implement particular abstract data types. Moreover, those skilled in the art will appreciate that embodiments of the invention may be practiced with other computer system configurations, including hand-held devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers, set top boxes, and other system configurations capable of executing the methods described. Embodiments of the invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices. 
     With reference to  FIG. 1 , embodiments of the invention may include a system  100  for enhancing wireless connection acquisition using an array antenna  102 . The system  100  may include a base station  103  working in conjunction with the array antenna  102  to enhance the range within which a wireless subscriber  111  may connect his or her wireless equipment  101  to the base station  103  in order to engage in ongoing wireless communication. As used herein, the term wireless subscriber  111  is intended to encompass all users and devices capable of utilizing wireless services and that may be authorized to do so. 
     The wireless communication may include data communications between a subscriber&#39;s computer  110  with other computers via a network  104 , which may include the Internet. Likewise, the wireless communication may include voice communications (e.g., cellular phone service, Voice over Internet Protocol (VOIP)), broadcast communications (e.g., cable television, Internet Protocol Television (IPTV)), and other services usable over a wireless communication link. 
     In acquiring a new connection to the wireless equipment  101  of the wireless subscriber  111 , the base station  103  may communicate with a server  105  via the network  104  in order to authenticate the wireless subscriber  111  and ensure that the subscriber should receive wireless communication access. The wireless equipment  101  may include, for example, a wireless modem, or any other device capable of making a wireless communications connection. The wireless equipment  101  may be handheld in size, or larger, and may utilize one or more wireless communication standards including, but not limited to, Worldwide Interoperability for Microwave Access (WiMAX), third-generation mobile phone (3G), Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access (CDMA), CDMA2000, High-Speed Downlink Packet Access (HSDPA), Global System for Mobile Communication (GSM), Enhanced Data Rates for GSM Evolution (EDGE), General Packet Radio Services (GPRS), Enhanced GPRS (EGPRS), Advanced Mobile Phone System (AMPS), and Digital AMPS (D-AMPS). 
     In the configuration of  FIG. 1 , the base station  103  includes at least one processing unit  133 , a memory  134 , radio frequency (RF) components  131 , and one or more digital signal processors (DSPs)  132 . The various functional components of the base station  103  may communicate with each other via one or more buses  130 . Other techniques for passing information among components of the base station  103  may be available. 
     Components within base station  103  may communicate with other devices, such as the server  105 , via a network such as via a network connection  135  over the network  104 , further discussed below. The network connection  135  may communicate with the network  104  over a wired or wireless communications link. For example, the network connection  135  may facilitate communication over a high-speed optical fiber connected to the network  104 . Alternatively, the network connection  135  may facilitate communication between the base station  103  and the network  104  using a wireless medium, such as a microwave link, for example. 
     Within the base station  103 , the processing unit  133  may include one or more microprocessors, microcontrollers, co-processors, field programmable gate arrays (FPGAs), complex programmable logic devices (CPLDs), application specific integrated circuits (ASICs), and other devices capable of executing the methods and operations set forth below. Depending on the configuration of the base station  103 , the memory  134  may be volatile (e.g., Random Access Memory (RAM)), non-volatile (e.g., Read-Only Memory (ROM), flash memory, hard drives), or some combination thereof. 
     The memory  134  may serve as a storage location for an operating system, one or more program modules, and/or program data, as well as other modules and data. In various embodiments, the program modules stored in the memory  134  may include an enhanced acquisition module  136 , an application including similar logic, or any other set of instructions comprising such logic. It should be noted that the logic of the enhanced acquisition module  136  may be distributed and/or shared across multiple devices, including the base station  103 , the server  105 , the wireless equipment  101 , and other devices in communication with the base station  103 . More information regarding the function of the enhanced acquisition module  136  is provided below. 
     The base station  103  may include general and/or specialized digital signal processors  132  for use in conjunction with the analog radio signals transmitted and received via the RF components  131 . The digital signal processors  132  may convert analog radio frequency signals to digital values, process the digital values, and convert the processed digital values back to analog signals for transmission over the RF components  131 . Processing the digital values may include encoding data into and decoding data from the analog signals. Processing the digital values may further include introducing variations (e.g., phase variations) between analog signals sent for transmission on different elements  120   a - 120   n  of the array antenna  102 . These variations may result in differences in the directionality of, or sensitivity to, a radiation pattern for the collection of elements  120   a - 120   n  that make up the array antenna  102 . The practice of introducing variations between elements  120   a - 120   n  of the array antenna  102  in order to modify the radiation pattern may be referred to as beamforming. The functionality of the DSPs  132  may be replaced or assisted by digital signal processing program modules executing on the processing unit  133 . 
     The RF components  131  may include components typically associated with radio transmitters and receivers, including RF amplifiers, modulators, and demodulators. Other components utilized to transmit or receive radio signals via the array antenna  102  may also be part of the RF components  131 . It should be noted that although the array antenna  102  and the base station  103  are depicted as separate components joined by a transmission line  137 , the functionality of the array antenna  102  and the base station  103  may be combined or divided in other ways. For example, the RF components  131  and the DSPs  132  may be packaged with the array antenna  102 , and the remaining components of the base station  103  may communicate with such an antenna package via a digital bus or serial communication line, for example. 
     The array antenna  102  is depicted in  FIG. 1  as having 16 antenna elements  120   a - 120   n , but other quantities of elements may be used, from two on up. Additional elements may add to the processing complexity required for beamforming, but additional elements may also incrementally increase the range of the antenna, as well as allow for additional simultaneous beams to be formed. The array antenna  102  may be a variety of smart antenna which, in concert with the digital signal processors  132  and RF components  131 , is capable of determining a direction of arrival of an incoming signal and then use beamforming techniques to track the source of the incoming signal and maintain communication. The array antenna  102  may further be a multiple input multiple output (MIMO) type antenna, which is capable of increasing the speed, range, reliability and spectral efficiency of wireless communications. 
     The base station  103  may include additional features and functionality other than those shown. For example, the base station  103  may include additional computer storage media, including media implemented in any method or technology for storage of information, including computer readable instructions, data structures, program modules, or other data. Examples of computer storage media can include RAM, ROM, electrically-erasable programmable ROM (EEPROM), flash memory, CD-ROM, DVD, cassettes, magnetic tape, and magnetic disks. Any such computer storage media may be accessed by components within the base station  103 , or which are external to the base station  103  and connected via a communications link (e.g., Bluetooth®, USB, parallel, serial, infrared). 
     The base station  103  may also include one or more input devices (not shown) for accepting user input. Examples of the input devices include a keyboard, mouse, digitizing pen, microphone, touchpad, touch-display, and combinations thereof. Similarly, the base station  103  may incorporate or communicate with output devices such as video displays, speakers, printers, and combinations thereof. It should be understood that the base station  103  may also include additional forms of storage, input, and output devices, including communication ports and associated hardware for communicating with external input and output devices rather than including only components within the base station  103 . 
     The base station  103  may include one or more network connections  135  that include hardware and/or software which enable the base station  103  and the wireless subscriber  111  to communicate with other devices over the network  104 . The network  104  may include a wireless network such as, but not limited to, a Wireless Local Area Network (WLAN) such as a WiFi network, a Wireless Wide Area Network (WWAN), a Wireless Personal Area Network (WPAN) such as one enabled by Bluetooth® technology, a Wireless Metropolitan Area Network (WMAN) such as a WiMAX network, a cellular network, and/or a satellite network. Alternatively, the network  104  may include a wired network such as, but not limited to, a cable television network, a telecommunications network, a wired Wide Area Network (WAN), a wired (Local Area Network) LAN such as the Ethernet, a wired Personal Area Network (PAN), and/or a wired Metropolitan Area Network (MAN). The network  104  may also include any combination of the networks described above. Communication media, in the form of computer readable instructions, data structures, program modules, or other data in a modulated data signal, may be shared with and by the base station  104  via the communication connection  135 . A modulated data signal may mean a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal, and may include a modulated carrier wave or other transport mechanism. 
       FIG. 2  depicts the array antenna  102  with multiple nearby subscribers  204   a ,  204   b ,  204   c ,  204   d ,  204   e ,  204   f  (collectively, the subscribers  204 ), in addition to the omnidirectional coverage  202 , and multiple beams  203   a ,  203   b , and  203   c  (collectively, the beams  203 ). The depiction of  FIG. 2  can be interpreted as a top-down view of the array antenna  102  and subscribers  204 . The top-down view can be interpreted as showing no obstacles between the subscribers  204  and the array antenna  102 . The omnidirectional coverage  202  area may be defined by the overlapping gains of each antenna element  120   a - 120   n  considered without constructive and/or destructive interference. 
     The array antenna  102  may be a sectored antenna, in that it does not service fully 360 degrees of coverage. Such a sectored antenna may be in use with other sectored antennas, each taking a portion of the compass. Such a configuration may be suited for use on multiple faces of a cell tower, for example. The array antenna  102  may use one or more communication techniques to enable communications with multiple subscribers  204  simultaneously. Communication techniques may include frequency division duplexing (FDD), where different frequencies may be utilized for transmitting and receiving with particular subscribers  204 , and time division duplexing (TDD), where particular subscribers  204  are assigned particular slots of time to transmit or receive information. 
     In  FIG. 2 , the subscribers  204   a ,  204   c ,  204   f  have successfully initiated their connections with the array antenna  102 , or been acquired. The array antenna  102 , under the command of the base station  103 , has adaptively extended the beams  203  to each of the acquired subscribers  204   a ,  204   c ,  204   f  upon acquisition, possibly to strengthen or extend ongoing communications and/or to increase throughput. Other reasons that the beams  203  may be adaptively extended to the acquired subscribers  204   a ,  204   c ,  204   f  include avoiding or accounting for reflections or other obstacles preventing higher throughput, or to avoid interference or noise from other sources. Although subscriber  204   a  is presently outside the omnidirectional range  202 , the subscriber  204   a  started inside the omnidirectional range  202  and moved beyond the range. The connection of the subscriber  204   a  is maintained because the subscriber  204   a  is still within the beam reach of the array antenna  102 . The array antenna  102 , at the behest of the digital signal processors  132  or instructions processed by the processing unit  133 , may adaptively move and modify beam  203   a  to account for movements by the subscriber  204   a.    
     In some embodiments, when the array antenna  102  acquires a new connection to a subscriber, such as the wireless subscriber  111 , successful acquisition may rely on the wireless subscriber  111  being within the omnidirectional range  202  at some point in time. In  FIG. 2 , subscribers  204   b ,  204   d ,  204   e  have not been acquired by the array antenna  102  under this approach because they are outside the omnidirectional range  202 . Although these unacquired subscribers  204   b ,  204   d ,  204   e  could be serviced by additional beams  203 , they are not presently in communication with the array antenna  102 . 
       FIG. 3  depicts an alternative method for acquiring connections to nearby subscribers  204 . Here, a beam  301  of the antenna array  102  has been allocated specifically for acquiring connections to subscribers  204 . The acquisition beam  301  extends the acquisition range from beyond the omnidirectional range  202 , at least for the slice of the compass to which it is directed at time t 0 . In order to increase the acquisition range for other slices of the compass, the acquisition beam  301  is moved to a second position t 1  after a period of time. After another period of time, a third position t 2  is selected for the acquisition beam  301 . 
     The acquisition beam  301  may continue to sweep across the range of the array antenna  102  until it reaches the end of the beam&#39;s coverage area  303 , here a sector. At that point, the acquisition beam  301  may be repositioned to a different coverage area or restart in the current coverage area. As the subscribers  204  are detected by the acquisition beam  301 , they may be handed off for processing in order to provision service for ongoing wireless communication with each subscriber. Utilizing the acquisition beam  301  to acquire the subscribers  204  effectively extends the acquisition range of the array antenna  102  from the omnidirectional range  202  to a beam range  302 . 
     Although depicted in  FIG. 3  as a single sweep through a single coverage area, other embodiments may utilize the acquisition beam  301  differently. Embodiments may, for example, allocate multiple beams as acquisition beams  301 . Each acquisition beam  301  may be responsible for a portion of the available range in a multiple acquisition beam embodiment. For example, two acquisition beams may divide up the coverage area  303  of the array antenna  201  in  FIG. 3 . In this example, the coverage area  303  could be divided up into two sections, and a second acquisition beam could start at a position t 10 , for example, moving through the remainder of the sector at the same time that the acquisition beam  301  is moving through the first half of the sector. In a time division duplexing (TDD) communication environment, different numbers of acquisition beams  301  may be allocated during each of multiple time slots. 
     In some embodiments, the acquisition beams  301  may additionally be allocated or deallocated depending on the current capacity of the antenna array  102  and the base station  103 . If additional connections are available, and subsequently fewer beams are in use for ongoing communications, additional acquisition beams  301  may be allocated to speed the acquisition process. As the additional subscribers  204  are acquired, and the need for beams for ongoing communications increases, some or all of the acquisition beams  301  may be deallocated or reallocated. Other embodiments need not utilize a sweep of the acquisition beam  301 . It should be noted that the acquisition beam  301  need not move in only a stepped fashion, as depicted in  FIG. 3 . The acquisition beam  301  may move in a smooth sweep. Likewise, the acquisition beam  301  or beams may jump from location to location and still accomplish a search for subscribers  204 . Jumping rather than sweeping may be useful when the subscribers  204  are found within particular predictable portions of the acquisition range, for example. Acquisition beams  301  may further be modified in an effort to acquire the subscribers  204 . For example, the strength and breadth of the acquisition beams  301  may be extended or diminished depending on the actual or likely locations of the subscribers  204 , obstacles, radio sources, and other environmental particulars which may affect subscriber acquisition. 
     Turning now to  FIG. 4 , a flowchart depicting a process  400  for enhancing subscriber acquisition using an antenna array is described. The process  400  may be implemented on one or more computing devices, such as the base station  100 , and may be utilized by embodiments of the enhanced acquisition module  136 . The logical operations of the various implementations presented, may be (1) a sequence of computer implemented acts or program modules running on one or more computing devices, such as the base station  100 , and/or (2) interconnected machine logic circuits or circuit modules within the base station  100 . The implementation is a matter of choice dependent on the performance requirements of the base station  100  on which the embodiments are implemented. Accordingly, the functional operations making up the implementations are referred to variously as operations, structural devices, acts, or modules. It will be recognized by one skilled in the art that these operations, structure devices, acts, and modules may be implemented in software, in firmware, in special purpose digital logic, and/or any combination thereof without deviating from the spirit and scope of the attached claims. Moreover, it will be apparent to those skilled in the art that the operations described may be combined, divided, reordered, skipped, and otherwise modified, also without deviating from the spirit and scope of the attached claims. 
     The process  400  begins at operation  401 , when the enhanced acquisition module  136  allocates a beam for use as the acquisition beam  301 . The operation  401  may involve assigning the acquisition beam  301  the task of listening to receive a service request from an unacquired subscriber  204 . Likewise, the acquisition beam  301  may be assigned the task of transmitting a subscriber seeking signal and then awaiting responses. At an operation  402 , the acquisition beam  301  is positioned at the start of its sweep or sequence of locations. This may be an arbitrary location on the compass, or one selected based on the probability of finding a subscriber at that location. 
     From the operation  402 , the process  400  continues with an operation  403 , where the acquisition beam  301  listens for service requests, possibly following the transmission of a subscriber seeking signal. Subscriber equipment  101  may repeatedly send a service request signal at a particular frequency or at a particular time, and the acquisition beam  301  may be used to listen for such subscribers. At a decision  404 , the enhanced acquisition module  136  determines whether a request for service is received, then direction and distance information may be forwarded by the enhanced acquisition module  136  to another module for service provisioning at an operation  405 . Direction and distance information may be derived using triangulation techniques based on differences in the phase and amplitude of the service request signal by the different elements  120   a - 120   n  of the array antenna  102 . Direction and distance information may alternatively be derived by the subscriber equipment  101  providing a location, such as an address or longitude and latitude coordinates, and the enhanced acquisition module  136  calculating the difference between the locations of the subscriber equipment  101  and the array antenna  102 . 
     Service provisioning during processing of the service request at operation  405  may involve authenticating the subscriber equipment  101  and/or the wireless subscriber  111 . If the subscriber equipment  101  achieves sufficiently high throughput utilizing the omnidirectional aspects of the array antenna  102 , then a beam may not be allocated for ongoing communication. However, if throughput is not sufficiently high, then power levels at both the array antenna  102  and the subscriber equipment  101  may be adjusted and/or a beam may be allocated for use by the subscriber equipment  101 . Authentication may involve confirming the identity of the wireless subscriber  111  requesting service. Identity may be confirmed by matching a credential or subscriber identifier with a record in a database of all subscribers  204 . The database of subscribers may be located within the base station  103  locally, or it may be located remotely at the server  105 . When authenticating the identity of the wireless subscriber  111 , a service level associated with the subscriber  111  may be determined, possibly leading to further adjustments of any allocated beams to increase or throttle signal throughput appropriately. 
     If the enhanced acquisition module  136  determines that a service request has not been received at decision  404 , or once the service request has been processed or handed off for processing at the operation  405 , then at a decision  406 , the acquisition enhancement module  136  determines whether the current location of the acquisition beam  301  is the last within the particular coverage area defined for the acquisition beam  301 . This determination may be made based solely on the predetermined sweep or sequence, or it may be made based on the need to reallocate the acquisition beam  301  for use in ongoing communication with a recently acquired subscriber  204 . If the current location is not the last location for the acquisition beam  301 , then at an operation  407 , the acquisition beam  301  is repositioned, and the process continues at the operation  403  where a service request signal is awaited. 
     Although the subject matter presented herein has been described in conjunction with one or more particular embodiments and implementations, it is to be understood that the invention defined in the appended claims is not necessarily limited to the specific structure, configuration, or functionality described herein. Rather, the specific structure, configuration, and functionality are disclosed as example forms of implementing the claims. 
     The subject matter described above is provided by way of illustration only and should not be construed as limiting. Various modifications and changes may be made to the subject matter described herein without following the example embodiments and applications illustrated and described, and without departing from the true spirit and scope of the present invention, which is set forth in the following claims.