Abstract:
Briefly, in accordance with one or more embodiments, a femto access point scans an area of a network to find a serving base station in the area, requests one or more physical link profiles from a network server on the network, receives one or more physical link profiles from the network server in response to the requesting, determines which one of the physical link profiles exhibit a lower amount of interference with the serving base station, and then operates with the physical link profile determined to exhibit a lower amount of interference with the serving base station.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims the benefit of U.S. Provisional Application No. 61/110,544 filed Oct. 31, 2008. Said Application No. 61/110,544 is hereby incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    A femto access point (FAP) is a lower power micro base station (BS) operating in a licensed spectrum to be deployed at a local area to enhance wireless service coverage and/or performance in a wireless wide area network (WWAN). Typically, such femto access points are deployed be end users in a home or office location wherein the end user is not involved in extensive configuration of the femto access point. A femto access point may be deployed at the edge of service coverage and/or inside a building where service quality may be lower such. Femto access points may be backhauled to the network via a broadband connection to the network, for example via a cable, fiber, and/or digital subscriber line, such that a client device connects to the network via the locally disposed femto access point rather than via a remotely disposed base station (BS) or a base transceiver station (BTS) of the network. 
         [0003]    In wireless networks such as cellular or other wireless broadband networks, frequency spectrum is a valuable resource that should be controlled to optimize network performance. In general, such frequency spectrum control involves frequency reuse while minimizing interference among two or more devices operating in the same vicinity. 
     
    
     
       DESCRIPTION OF THE DRAWING FIGURES 
         [0004]    Claimed subject matter is particularly pointed out and distinctly claimed in the concluding portion of the specification. However, such subject matter may be understood by reference to the following detailed description when read with the accompanying drawings in which: 
           [0005]      FIG. 1  is block diagram of a wireless wide area network in accordance with one or more embodiments; 
           [0006]      FIG. 2  is a block diagram of a femto access point in accordance with one or more embodiments; 
           [0007]      FIG. 3  is a diagram of a cellular type network illustrating one particular frequency reuse pattern in accordance with one or more embodiments; 
           [0008]      FIG. 4  is a diagram of a cellular type network illustrating another frequency reuse pattern in accordance with one or more embodiments; 
           [0009]      FIG. 5  is a flow diagram of a frequency selection control flow in accordance with one or more embodiments; and 
           [0010]      FIG. 6  is a flow diagram of a method for automatic frequency selection in accordance with one or more embodiments. 
       
    
    
       [0011]    It will be appreciated that for simplicity and/or clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, if considered appropriate, reference numerals have been repeated among the figures to indicate corresponding and/or analogous elements. 
       DETAILED DESCRIPTION 
       [0012]    In the following detailed description, numerous specific details are set forth to provide a thorough understanding of claimed subject matter. However, it will be understood by those skilled in the art that claimed subject matter may be practiced without these specific details. In other instances, well-known methods, procedures, components and/or circuits have not been described in detail. 
         [0013]    In the following description and/or claims, the terms coupled and/or connected, along with their derivatives, may be used. In particular embodiments, connected may be used to indicate that two or more elements are in direct physical and/or electrical contact with each other. Coupled may mean that two or more elements are in direct physical and/or electrical contact. However, coupled may also mean that two or more elements may not be in direct contact with each other, but yet may still cooperate and/or interact with each other. For example, “coupled” may mean that two or more elements do not contact each other but are indirectly joined together via another element or intermediate elements. Finally, the terms “on,” “overlying,” and “over” may be used in the following description and claims. “On,” “overlying,” and “over” may be used to indicate that two or more elements are in direct physical contact with each other. However, “over” may also mean that two or more elements are not in direct contact with each other. For example, “over” may mean that one element is above another element but not contact each other and may have another element or elements in between the two elements. Furthermore, the term “and/or” may mean “and”, it may mean “or”, it may mean “exclusive-or”, it may mean “one”, it may mean “some, but not all”, it may mean “neither”, and/or it may mean “both”, although the scope of claimed subject matter is not limited in this respect. In the following description and/or claims, the terms “comprise” and “include,” along with their derivatives, may be used and are intended as synonyms for each other. 
         [0014]    Referring now to  FIG. 1 , a block diagram of a wireless wide area network in accordance with one or more embodiments will be discussed. As shown in  FIG. 1 , network  100  may be an internet protocol (IP) type network comprising an Internet  110  type network or the like that is capable of supporting mobile wireless access and/or fixed wireless access to internet  110 . In one or more embodiments, network  100  may be in compliance with a Worldwide Interoperability for Microwave Access (WiMAX) standard or future generations of WiMAX, and in one particular embodiment may be in compliance with an Institute for Electrical and Electronics Engineers 802.16 standard (IEEE 802.16-2009). In one or more alternative embodiments network  100  may be in compliance with a Third Generation Partnership Project Long Term Evolution (3GPP LTE) or a 3GPP2 Air Interface Evolution (3GPP2 AIE) standard, and/or a future generation cellular broadband network standard. In general, network  100  may comprise any type of orthogonal frequency division multiple access (OFDMA) based wireless network, and the scope of the claimed subject matter is not limited in these respects. As an example of mobile wireless access, access service network gateway (ASN-GW)  112  is capable of coupling with base station (BS)  114  to provide wireless communication between subscriber station (SS)  116  and Internet  110 . Subscriber station  116  may comprise a mobile type device or information handling system capable of wirelessly communicating via network  100 , for example a notebook type computer, a cellular telephone, a personal digital assistant, or the like. ASN-GW  112  may implement profiles that are capable of defining the mapping of network functions to one or more physical entities on network  100 . Base station  114  may comprise radio equipment to provide radio-frequency (RF) communication with subscriber station  116 , and may comprise, for example, the physical layer (PHY) and media access control (MAC) layer equipment in compliance with an IEEE 802.16-2009 type standard. Alternatively, base station  112  may also be referred to as a base transceiver station (BTS) in one or more embodiments. Base station  114  may further comprise an IP backplane to couple to Internet  110  via ASN-GW  112 , although the scope of the claimed subject matter is not limited in these respects. 
         [0015]    Network  100  may further comprise a visited connectivity service network/authentication, authorization, and accounting (CSN/AAA) server  124  capable of providing one or more network functions including but not limited to proxy and/or relay type functions, for example authentication, authorization and accounting (AAA) functions, dynamic host configuration protocol (DHCP) functions, or domain name service controls or the like, domain gateways such as public switched telephone network (PSTN) gateways or voice over internet protocol (VOIP) gateways, and/or internet protocol (IP) type server functions, or the like. However, these are merely example of the types of functions that are capable of being provided by visited CSN/AAA or home CSN/AAA  126 , and the scope of the claimed subject matter is not limited in these respects. Visited CSN/AAA  124  may be referred to as a visited CSN/AAA in the case for example where visited CSN/AAA  124  is not part of the regular service provider of subscriber station  116 , for example where subscriber station  116  is roaming away from its home CSN/AAA such as home CSN/AAA  126 , or for example where network  100  is part of the regular service provider of subscriber station but where network  100  may be in another location or state that is not the main or home location of subscriber station  116 . In a fixed wireless arrangement, WiMAX type customer premises equipment (CPE)  122  may be located in a home or business to provide home or business customer broadband access to internet  110  via base station  120 , ASN-GW  118 , and home CSN/AAA  126  in a manner similar to access by subscriber station  116  via base station  114 , ASN-GW  112 , and visited CSN/AAA  124 , a difference being that WiMAX CPE  122  is generally disposed in a stationary location, although it may be moved to different locations as needed, whereas subscriber station may be utilized at one or more locations if subscriber station  116  is within range of base station  114  for example. In accordance with one or more embodiments, operation support system, self organizing networks (OSS (SON)) sever  128  may be part of network  100  to provide management functions for network  100  and to provide interfaces between functional entities of network  100 . Network  100  of  FIG. 1  is merely one type of wireless network showing a certain number of the components of network  100 , however the scope of the claimed subject matter is not limited in these respects. 
         [0016]    In one or more embodiments, subscriber station  116  may couple to Internet  110  via a wireless communication link with femto access point (FAP)  128  rather than a wireless communication link with base station  114 . As shown in  FIG. 1 , femto access point  128  comprises a lower power base station device designed enhance the coverage area for subscriber stations  116  located at or near the edge, or outside of the coverage are of one or more base stations  114  and/or base stations  120  of network  100 . Alternatively, femto access point  128  may increase performance of subscriber stations located within buildings that may attenuate or otherwise interfere with wireless communications with base station  114 . In such an arrangement, subscriber station  116  may communicate with femto access point  128  which is coupled to a modem  130  such as a cable modem, digital subscriber line (DSL) modem, or the like. Femto access point  128  may couple to network  100  via an Internet service provider (ISP) network  132  which may allow femto access point  128  to access the WiMAX network  100  and services via WiMAX gateway  134 . As a result, subscriber station  128  is capable of coupling to Internet  110  and/or to the services provided by WiMAX network such as, for example, software services, voice over internet protocol (VoIP) services, database access, and so on. Thus, a locally deployed femto access point  128  can enhance access of subscriber station  116  to network  100  in situations where subscriber station  116  may have difficulty communicating with base station  114  and/or base station  120 , although the scope of the claimed subject matter is not limited in this respect. An example block diagram of femto access point  128  is discussed with respect to  FIG. 2 , below. 
         [0017]    Referring now to  FIG. 2 , a block diagram of a femto access point in accordance with one or more embodiments will be discussed.  FIG. 2  illustrates an example block diagram of femto access point  128  as shown in and described with respect to  FIG. 1 , above.  FIG. 2  depicts the major elements of an example femto access point  128 , however fewer or additional elements may be included in alternative embodiments in addition to various other elements that are not shown herein, and the scope of the claimed subject matter is not limited in these respects. Femto access point  128  may comprise a baseband processor  210  coupled to memory  212  for performing the control functions of femto access point  128 . Input/output (I/O) block  214  may comprise various circuits for coupling femto access point  128  to one or more other devices. For example, I/O block  214  may include one or more Ethernet ports and/or one or more universal serial bus (USB) ports for coupling femto access point  128  to modem  130  or other devices. For wireless communication, femto access point  128  may further include a radio-frequency (RF) modulator/demodulator for modulating signals to be transmitted and/or for demodulating signals received via a wireless communication link. A digital-to-analog (D/A) converter  216  may convert digital signals from baseband processor  210  to analog signals for modulation and broadcasting by RF modulator/demodulator via analog and/or digital RF transmission techniques. Likewise, analog-to-digital (A/D) converter  218  may convert analog signals received and demodulated by RF modulator/demodulator  220  digital signals in a format capable of being handled by baseband processor  210 . Power amplifier (PA)  222  transmits outgoing signals via one or more antennas  228  and/or  230 , and low noise amplifier (LNA)  224  receives one or more incoming signals via antennas  228  and/or  230 , which may be coupled via duplexer  226  to control such bidirectional communication. In one or more embodiments, femto access point  128  may implement single input, single output (SISO) type communication, and in one or more alternative embodiments femto access point  128  may implement multiple input, multiple output (MIMO) communications, although the scope of the claimed subject matter is not limited in these respects. Example deployments of one or more femto access points  128  such as shown in  FIG. 2  are shown in and described with respect to  FIG. 3  and  FIG. 4  below. 
         [0018]    Referring now to  FIG. 3 , a diagram of a cellular type network illustrating one particular frequency reuse pattern in accordance with one or more embodiments will be discussed.  FIG. 3  illustrates an arrangement of the cells  310  of a wireless wide area network such as a WiMAX or cellular type network in one or more embodiments. In a typical deployment, one base station  114  may handle three cells and implement a (3, 3, ⅓) frequency reuse pattern. In such an arrangement, there are three cells  310  in a cluster of cells that utilize three frequencies, frequency F 1 , frequency F 2 , and frequency F 3 . Each cell  310  comprises three sectors  312  as delineated by dashed lines in  FIG. 3  within a given cell. A given cell  310  uses one of the three available frequencies, and each sector  312  of the cell  310  uses one-third of the bandwidth of the frequency assigned to that cell  310 , delineated as F 1   a  for the first sector, F 1   b  for the second sector, and F 1   c  for the third sector for a cell utilizing frequency F 1 . 
         [0019]    As shown in  FIG. 3  as an example of frequency allocation and reuse, one sector of cell  314  may include five femto access points labeled as femto access point A (A), femto access point B (B), femto access point C (C), femto access point D (D), and femto access point E (E). In order to assign a frequency and bandwidth portion of the frequency to the access points under the such that interference may be reduced or minimized, the allowable operating frequencies of respective femto access points (FAP)  128  in cell  314  may be assigned as follows in one particular arrangement: 
         [0000]                                                FAP A:   F2b, F3a           FAP B:   F2a, F2b, F2c, F3a, F3b, F3c           FAP C:   F2c, F3b           FAP D:   F2a, F2b, F3b, F3c           FAP E:   F1b, F1c, F2a, F2b, F2c, F3a, F3b, F3c                        
In the above frequency assignment table, OSS (SON) server  136  may assign the respective femto access points  128  one of the frequencies available to the femto access point  128  according to the table, and by doing so interference among the femto access points may be relatively reduced or minimized, or nearly minimized to an acceptable level. However, this is merely one example of frequency reuse and allocation, and other arrangements may be likewise implemented, and the scope of the claimed subject matter is not limited in this respect. Another type of frequency allocation and reuse pattern is shown in and described with respect to  FIG. 4 , below.
 
         [0020]    Referring now to  FIG. 4 , a diagram of a cellular type network illustrating another frequency reuse pattern in accordance with one or more embodiments will be discussed.  FIG. 4  illustrates an alternative arrangement of the cells  310  of a wireless wide area network such as a WiMAX or cellular type network in one or more embodiments. In another typical deployment, three base stations  114  may be collocated at a single site and implement a (3, 3, 1) frequency reuse pattern. In such an arrangement, there are three cells  310  in a cluster of cells that utilize three frequencies, frequency F 1 , frequency F 2 , and frequency F 3 . Each cell  310  comprises three sectors  312  as delineated by dashed lines in  FIG. 4  within a given cell. A given cell  310  uses one of the three available frequencies, and each sector  312  of the cell  310  uses all or nearly all of the bandwidth of the frequency assigned to that cell  310 . 
         [0021]    As shown in  FIG. 4  as an example of frequency allocation and reuse, one sector of cell  314  may include five femto access points labeled as femto access point A (A), femto access point B (B), femto access point C (C), femto access point D (D), and femto access point E (E). In order to assign a frequency and bandwidth portion of the frequency to the access points under the such that interference may be reduced or minimized, the allowable operating frequencies of respective femto access points (FAP)  128  in cell  314  may be assigned as follows in one particular arrangement: 
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 FAP A: 
                 F3, F1 
               
               
                   
                 FAP B: 
                 F3, F2 
               
               
                   
                 FAP C: 
                 F2, F1 
               
               
                   
                 FAP D: 
                 F2, F3 
               
               
                   
                 FAP E: 
                 F1, F2, F3 
               
               
                   
                   
               
             
          
         
       
     
         [0022]    In the above frequency assignment table, OSS (SON) server  136  may assign the respective femto access points  128  one of the frequencies available to the femto access point  128  according to the table, and by doing so interference among the femto access points may be relatively reduced or minimized, or nearly minimized to an acceptable level. However, this is merely one example of frequency reuse and allocation, and other arrangements may be likewise implemented, and the scope of the claimed subject matter is not limited in this respect. Selection of a frequency assigned to one or more femto access points  128  by OSS (SON) server  136  is shown and described with respect to  FIG. 5 , below. 
         [0023]    Referring now to  FIG. 5 , a flow diagram of a frequency selection control flow in accordance with one or more embodiments will be discussed.  FIG. 5  shows one particular arrangement of a flow for frequency selection for one or femto access points  128 , and other arrangements may likewise be implemented, including fewer or mores procedures, and the scope of the claimed subject matter is not limited in this respect. Likewise, a  FIG. 5  illustrates a WiMAX implementation of a frequency selection control flow  500 , however frequency selection control flow  500  may also be adapted to other types of networks such as cellular networks or the like, and the scope of the claimed subject matter is not limited in this respect. In operation of frequency selection control flow  500  on network  100  of  FIG. 1 , which in this example comprises a WiMAX network, WiMAX femto access point  128  and CSN/AAA server  124  perform authentication and authorization procedures at block  510 . If WiMAX femto access point  128  is authenticated and authorized by CSN/AAA server  124  to provide femto access point services, a backhaul connection is created between femto access point  128  and ASN-GW at the service provider network. In one or more embodiments, since the connection for authentication and authorization to take place goes through public Internet  110  and/or ISP network  132 , the connection may comprise a secure connection, although the scope of the claimed subject matter is not limited in this respect. 
         [0024]    At block  512 , femto access point  132  performs scanning of base stations  114  in the area without association with a base station  114  to find a serving base station  114  in that area based at least in part on the best, or nearly the best, received signal strength indication (RSSI) measurement between the base station  114  and the femto access point  128 . The serving base station  114  may be identified by a 48-bit base station identification (BSID) that contains a 24-bit Operator identification (ID) and a 24-bit base Station ID. At block  514 , femto access point  128  sends a scan physical link profile request (SCAN_PHY_PROFILE_REQ) message along with the serving base station ID and measured RSSI parameters to OSS (SON) server  136 . Based at least in part on the serving base station ID and RSSI parameters, OSS (SON) server  136  will look up in a preconfigured database the list of available physical link (PHY) Profiles that femto access point  128  may utilize without causing unacceptable interference to the base stations  114  in the area. The PHY Profile contains attributes such as center frequency, frame duration, cyclic prefix, fast Fourier transform (FFT) size, and so on, of the physical (PHY) layer that femto access point  128  may utilize to transmit signals over the air interface. Example correlations between a location of one of more femto access points  128  and a list of PHY profiles are shown in and described with respect to  FIG. 3  and/or  FIG. 4 , above. For example, as shown in  FIG. 3 , if a measured RSSI is low, then that particular femto access point  128 , such as FAP A, FAP C, and/or FAP D, is likely located far away from the serving base station  114 . As a result, the list of available frequencies to be selected for these femto access points  128  may include the sectors F 2   a , F 2   b , F 2   c , F 3   a , F 3   b,  and/or F 3   c , and so on. 
         [0025]    At block  516  OSS (SON) server  136  returns a SCAN_PHY_PROFILE_REQ message with the list of available PHY Profiles to femto access point  128 . At block  518 , in response to receiving the list of available PHY Profiles from OSS (SON) server  136 , femto access point  128  selects an operating frequency by selecting a PHY Profile having a minimum, or nearly minimum, RSSI. At block  520 , after selecting an operating frequency, femto access point  128  sends a reply physical profile request (REP_PHY_PROFILE_REQ) message to OSS (SON) server for the PHY Profile that is expected to result in an acceptable level interference with base station  114  to OSS (SON) server  136 . Upon receiving the PHY profile request message from femto access point  128 , OSS (SON) server  136  returns a reply PHY profile acknowledgement (REP_PHY_PROFILE_ACK) message to femto access point  128  at block  522  to indicate to femto access point  128  that it is okay for femto access point  128  to use the requested PHY Profile. It should be noted that  FIG. 5  shows one example frequency selection control flow, and the scope of the claimed subject matter is not limited in this respect. Details of an example frequency selection algorithm implemented by femto access point  128  are shown in and described with respect to  FIG. 6 , below. 
         [0026]    Referring now to  FIG. 6 , a flow diagram of a method for automatic frequency selection in accordance with one or more embodiments will be discussed. Although  FIG. 6  illustrates one particular arrangement of the method  600  for automatic frequency selection, various other arrangements may likewise be implemented with a different order of the blocks of method  600 , and/or with greater or fewer blocks than shown in  FIG. 6 , and the scope of the claimed subject matter is not limited in this respect. In method  600 , K number of physical (PHY) profiles are contained in a list of PHY profiles that stored are provided by OSS (SON) server  136  to femto access point  128  as the PHY profiles that are available candidates for femto access point  128 . The PHY profiles in the list may be referenced with an index value. At block  612 , femto access point  128  starts with an initial PHY profile having an index value of 1. This PHY profile having a minimum amount of interference is assigned an index value of 1, and the minimum RSSI is assigned a predetermined initial minimum RSSI value, for example a value of 0 dBm. At block  614 , the current RSSI for the currently selected PHY profile is measured by femto access point  128  by obtaining an RSSI value between femto access point  128  and the serving base station  114 . A determination is made at block  616  whether the current RSSI for the current PHY profile is less than the predetermined minimum RSSI. If the current RSSI is not less than the minimum RSSI, then block  620  executes at which the PHY profile index is increased by one to the next PHY profile. A determination is then made at block  622  whether the value of the PHY profile index is greater than K. If the PHY profile index is not greater than K, meaning that not all of the candidate PHY profile values have been tested for RSSI by femto access point  128 , method  600  continues at block  614  execute another iteration of current RSSI measurement for the next PHY profile. 
         [0027]    For each such iteration, block  616  executes to determine if the current RSSI value for the current PHY profile value is less than the predetermined minimum RSSI value. If the current RSSI value is less than the minimum RSSI, then the current RSSI value is assigned as the new minimum RSSI value at block  618 , and the PHY profile having the minimum interference is updated as being the present PHY profile using the index of the present PHY profile to identify the minimum interference PHY profile. The PHY profile index is increased by one at block  620 , and method  600  may continue with additional iterations of measuring the current RSSI value of each of the PHY profiles until all of the PHY profiles have been tested for current RSSI values. At this time, the PHY profile index value will have been increased to a value greater than K as determined at block  622  at which time the PHY profile having a minimum interference will have been identified at block  624 . Femto access point  128  may then select this identified PHY profile as the PHY profile for the reply PHY profile request to send to OSS (SON) server  136  as indicated at block  520  of flow  500  shown in and described with respect to  FIG. 5 . As a result of method  500  and method  600 , a PHY profile including a selected frequency of operation for femto access point  128  that is expected to result in a minimum amount of interference with serving base station  114  will be determined and selected for utilization by femto access point  128 . It should be noted that such a method  500  and/or method  600  are merely example implementations to allocate a frequency of operation for femto access point  128  that will result in an acceptable level of interference, and/or at least a minimum or nearly minimum amount of interference with serving base station  114 , and other various methods may likewise be implemented. For example, instead of and/or in addition to using a measured RSSI value, a quality of service (QoS) value may be measured by femto access point  128  wherein a PHY profile resulting in a lowest QoS value may be selected such as the PHY profile having the greatest number of dropped packets. However, this is merely one of various parameters that may be measure to select a PHY profile for femto access point  128 , and the scope of the claimed subject matter is not limited in this respect. 
         [0028]    Although the claimed subject matter has been described with a certain degree of particularity, it should be recognized that elements thereof may be altered by persons skilled in the art without departing from the spirit and/or scope of claimed subject matter. It is believed that the subject matter pertaining to frequency selection for a femto access point and/or many of its attendant utilities will be understood by the forgoing description, and it will be apparent that various changes may be made in the form, construction and/or arrangement of the components thereof without departing from the scope and/or spirit of the claimed subject matter or without sacrificing all of its material advantages, the form herein before described being merely an explanatory embodiment thereof, and/or further without providing substantial change thereto. It is the intention of the claims to encompass and/or include such changes.