Abstract:
An architecture is provided for coupling wireless local area network (WLAN) signals between an internetworking device and a remotely located access point using a transport network. The access point is coupled to the transport network for communicating with the internetworking device. The access point includes a wireless local area network (WLAN) access point and an access point remote converter. The WLAN access point receives wireless local area network signals from wireless computing equipment and converts such signals to local area network compatible signals. The access point remote converter receives the local area network compatible signals from the WLAN access point and converts the signals to transport modulated format signals suitable for transmission over the transport network. The transport network also provides a power signal to power at least some components of the access point.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 10/806,032, filed Mar. 22, 2004, and U.S. application Ser. No. 10/869,468, filed Jun. 16, 2004, both of which are continuation-in-parts of U.S. application Ser. No. 10/606,655, filed Jun. 26, 2003, now U.S. Pat. No. 7,359,392, which is a continuation-in-part of U.S. application Ser. No. 09/332,518, filed Jun. 14, 1999, now U.S. Pat. No. 6,587,479, which claims the benefit of U.S. Provisional Application Ser. No. 60/130,445, filed Apr. 21, 1999. The entire teachings of the above applications are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present invention relates generally to wireless local area network systems and more particularly to a distribution network for coupling wireless local area network signals between centrally located internetworking devices and remotely located access points. 
         [0003]    The most common user applications for personal computers now require a connection to a computer network of some type. Such applications include the viewing of e-mail, sharing of data files, and accessing the Internet and the World Wide Web. Various techniques are used for connecting computers together so that they may send data to and receive data from each other, more or less in real time. Most often this so-called physical layer is implemented using wires and the bits of data to be exchanged are converted into electrical signals that move through the wires. Traditionally, local area networks (LANs) were implemented using privately installed wiring, such as coaxial cable or twisted pair type cable and network adapter circuits. Later, it became possible to construct LANs through the use of the public switched telephone network and modem equipment. 
         [0004]    However, networks that use infrared light or radio frequency energy at the physical layer are growing in popularity. These so-called wireless local area networks (“wireless LANs”) convert the bits of data into radio waves to enable their transmission over the air, which in turn minimizes the need for hard wired connections. 
         [0005]    Wireless LANs have tended to find application where user mobility and portability is important, such as in the healthcare, retail, manufacturing, and warehousing industries. This limited use has no doubt been the result of the added cost of the required wireless network adapters. However, they are also becoming more widely recognized as a general purpose alternative for a broad range of business applications as the cost of mobile computing equipment such as laptop computers and personal digital assistants (PDAs) continues to decrease. With a wireless LAN, users can access shared information without first stopping to find a place to plug-in their equipment. In addition, network managers can set up or augment such networks without installing or moving wires around from place to place. 
         [0006]    The simplest wireless LAN configuration is an independent type network that connects a set of computers with wireless adapters. Anytime any two or more of the wireless adapters are within radio range of one another, they can set up a network. More common is a type of multi-user LAN wherein multiple devices referred to as access points collect signals at a central location. The access points collect signals transmitted from personal computers equipped with wireless network adapters, and distribute them over wire physical media to other internetworking devices such as repeaters (hubs), bridges, routers, and gateways, to provide interconnectivity to larger networks. 
         [0007]    The range of a wireless LAN is limited by how far the signals can travel over the air between the access points and the network adapters connected to the PCs. Currently, the Institute of Electrical and Electronic Engineers (IEEE) 802.11 wireless LAN standard, which is the most widely used, specifies power output levels which carry signals over a few hundred feet. 
         [0008]    To extend coverage beyond this limited range, a network of access points with overlapping radio ranges must be located throughout the desired coverage area. These so-called infrastructure wireless LANs are implemented in a manner which is similar to a cellular telephone system. At any given time, a mobile personal computer equipped with a wireless LAN adapter communicates with a single access point within the current microcell within which it is located. On the landline side, the access points are interconnected using network-compatible twisted pair wiring such as that which is compliant with the Ethernet/802.3 10 baseT or 100 baseT standard. The network signals can then be further forwarded to a local- or wide-area network using standard internetworking protocols and devices. 
       SUMMARY 
       [0009]    The present invention provides a simple and low cost architecture for coupling wireless local area network (“wireless LAN”) signals between geographically distributed access points and centrally located internetworking devices. The invention eliminates complexities involved with the deployment of such systems in the past, which have typically required the computer network-compatible wiring to be extended to each access point directly from an internetworking device such as a repeater, bridge, router, or gateway. 
         [0010]    The present invention makes it economically efficient to deploy wireless local area networking equipment in locations where wired network infrastructure is not readily available. In particular, any convenient existing physical wiring, such as may be provided by the existing coaxial cable used to distribute cable television signals, or the existing twisted pair cabling used to distribute standard telephone signals, is used as a physical layer transport medium to carry the wireless local area network signals between the access points and centrally located network hub equipment. 
         [0011]    According to the invention, an architecture is provided that couples wireless local area network (WLAN) signals between an internetworking device and a remotely located access point using a transport network. The access point is coupled to the transport network for communicating with the internetworking device. The access point includes a wireless local area network (WLAN) access point and an access point remote converter. The WLAN access point receives wireless local area network signals from wireless computing equipment and converts such signals to local area network compatible signals. The access point remote converter receives the local area network compatible signals from the WLAN access point and converts the signals to transport modulated format signals suitable for transmission over the transport network. The transport network also provides a power signal to power at least some components of the access point. 
         [0012]    The transport network can be implemented as an analog signal transport medium. In one particular embodiment, the transport network is a twisted pair telephone cabling and the access point remote converter converts the local area network signals to a Digital Subscriber Line (xDSL) format. The access point further includes a power supply connected to be energized by the power signal from the transport network to supply power to at least some components of the access point. 
         [0013]    In another particular embodiment, the transport network is an optical fiber network and the access point remote converter converts the local area network signals to an optical wavelength compatible with the fiber network. The access point further includes a power supply connected to be energized by the power signal from the optical fiber network to supply power to at least some components of the access point. 
         [0014]    A power inserter can be used for inserting the power signal onto the transport network and a signal coupler can also be used to couple the power signal from the transport network to the access point. 
         [0015]    A head end access point that includes a head end remote bridge can be connected to receive the transport modulated format signals from the transport network and to convert such signals to data network compatible signals. A local area network hub can then be used to receive the data network compatible signals from the head end remote bridge and to forward such signals to the internetworking device. 
         [0016]    In further particular embodiments, an access point is associated with each wireless local area network microcell. The access point includes access point equipment for communicating with portable computing equipment located within the microcell, such as may be provided in accordance with standard wireless network specifications such as the Institute of Electrical and Electronic Engineers (IEEE) 802.11 wireless LAN standard. 
         [0017]    Rather than couple the wire line side of the access point directly through local area network format cabling such as 10 baseT or 100 baseT, an access point remote converter first converts such signals to a convenient transport format. The transport format implemented by the remote converter depends upon the available cabling. 
         [0018]    The available transport cabling can also provide a power signal to power at least some portions of the access point. 
         [0019]    The transport signals are collected at a central distribution or headend access point (HAP). At this location, a remote bridge then converts the signals from the convenient transport format back to the wired local area network format such as Ethernet/802.3 10 baseT or 100 baseT. These Ethernet signals are then suitable for coupling to a local area network hub, or other internetworking equipment such as repeaters, bridges, routers, gateways and the like. 
         [0020]    As a result, it is not necessary to deploy Ethernet-compatible or other data network cabling directly to the physical location of each access point within the desired coverage area. Rather, the access points may be deployed in configurations wherever there is available transport cabling, without consideration for the cost and/or logistics of deploying local area network compatible cabling. 
     
    
     
       DRAWINGS 
         [0021]    The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
           [0022]      FIG. 1  is a diagram of a system for providing wireless local area network access using transport cabling according to the invention. 
           [0023]      FIG. 2  is a more detailed block diagram of a cable access point and head end access point making use of a cable television transport media. 
           [0024]      FIG. 3  is a block diagram of a cable access point and head end access point making use of a cable transport with IEEE 802.14 cable modem compatible interconnects. 
           [0025]      FIG. 4  is a block diagram of a cable access point and head end access point using a twisted pair transport media. 
           [0026]      FIG. 5  is a more detailed block diagram of the typical equipment deployed at the head end. 
           [0027]      FIG. 6  is a more detailed diagram of the head end access point making use of a wireless local area network bridge and translation stage. 
           [0028]      FIG. 7  is a more detailed block diagram of an alternative implementation of the cable access point. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    Turning attention now to the drawings,  FIG. 1  is a generalized diagram of a wireless data network  10  configured according to the invention. The wireless data network  10  makes use of multiple remotely located wireless local area network (LAN) access point locations to provide wireless LAN interconnectivity over a broad coverage area. The wireless data network  10  uses widely available, already installed cabling such as a coaxial cable, optical fiber, or twisted pair as a transport medium. This architecture provides an inexpensive way to deploy wireless LAN coverage from a centralized internetworking device without the need to distribute LAN compatible cabling to each access point location in a geographic region  11 . 
         [0030]    More specifically, the wireless data network  10  consists of a number of microcells  12 - 1 ,  12 - 2 , . . . ,  12 - 4  distributed throughout a geographic region. Some of the microcells  12  may be located adjacent to other microcells and located in areas of particularly high population density, such as in an office park. Other microcells  12  may be located in residential and/or rural areas, such as microcell  12 - 4 , and may have no adjacent microcells  12 . 
         [0031]    The present invention allows the implementation of wireless data network  10  in areas where data network wired backbone infrastructure is not readily available. For example, in the residential or rural area  12 - 4 , such data network infrastructure is not available. Likewise, the invention can be advantageously deployed even in areas such as the office park in microcell  12 - 3  where such backbone connections may already be available. In this case, the invention provides a way to distribute access points throughout a wide geographic region  11  without the need to provide network connectivity to each access point, such as through leased data lines or other transport media requiring expensive monthly rental payments. 
         [0032]    Each microcell  12  has associated with it a corresponding cable access point (CAP)  14 - 1 ,  14 - 2 , . . . ,  14 - 4 . The cable access points  14  are connected to one another either serially or in parallel via an intercell transport medium  15 . It will be understood shortly the transport medium  15  is advantageously selected to be an existing wiring located in the region  11 . For example, the transport medium  15  is selected to be a cable television (CATV) cable plant, or twisted pair cabling used to provide plain old telephone service (POTS). 
         [0033]    Heretofore, it has been required to provide a high speed, wired connection such as an Ethernet/802.3 10 baseT or 100 baseT compatible connection to each of the microcells  12 - 1  in order to carry wireless local area network signals from the access points  14  back to an internetworking device such as a LAN repeater or hub  18 . However, the invention uses especially adapted cable access points  14  and head end access points (HAPs)  16  in order to transport the wireless local area network signals over the available transport media  15 . 
         [0034]    The head end access point (HAP)  16  couples the LAN signals between the available transport medium  15  and internetworking equipment such as a LAN repeater or hub  18 . From the LAN hub  18 , the signals may then be fed through LAN switches  20  to wired LANs  22 , through routers  22  to corporate networks  26  or public backbone Internet connections  28 , or to other internetworking equipment. 
         [0035]      FIG. 2  is a more detailed diagram of a CAP  14 - 1  and HAP  16 - 1  that make use of existing CATV plant transport medium  15 - 1 . The CAP  14 - 1  includes an access point  34 - 1 , a remote bridge  36 - 1 , a radio frequency (RF) translator  38 - 1 , power extractor  40 - 1  and power supply  42 - 1 . Although only a single CAP  14 - 1  is shown connected to the CATV plant  15 - 1 , it should be understood that other CAPs  14  are similarly connected to the HAP  16 - 1 . 
         [0036]    The CAP  14 - 1  receives wireless LAN signals from computing equipment  17 - 1  and  17 - 2  located within its respective microcell  12 - 1 . For example, mobile computing equipment  17 - 1  such as a laptop computer or personal digital assistant (PDA) may be fitted with a wireless LAN adapter  30 - 1  which transmits and receives wireless LAN signals  32 - 1  to and from a wireless LAN access point  34 - 1 . It should be understood that in addition to the portable type computing equipment  17 - 1 , there may also be desktop computers  17 - 2  located within the microcell  12 , equipped with wireless LAN adapters  30 - 2 . 
         [0037]    The following discussion considers the path of a reverse link direction signal that is traveling from the computer  17  towards the LAN hub  18 . However, it should be understood that communication paths in a network are full duplex and therefore must travel in both directions; the analogous inverse operations are therefore carried out in the forward link direction. 
         [0038]    The radio signals transmitted by the wireless LAN adapter  30 - 1  and the wireless access point  34 - 1  are preferably in accordance with the known standardized signaling format such as the Institute of Electrical and Electronic Engineers (IEEE) 802.11 wireless LAN standard. The access point  34 - 1  and wireless LAN adapter  30 - 1  are therefore available as inexpensive, off-the-shelf items. 
         [0039]    The network side port of the access point  34 - 1  is, in the preferred embodiment, most commonly provided as a standardized Ethernet type signal compatible with 10 baseT or 100 baseT standard signaling. The remote bridge  36 - 1  thus converts the Ethernet signals provided by the access point  34 - 1  to a format suitable for connecting such signals over long distances, depending upon the available transport medium  15 . 
         [0040]    In the case of the illustrated CATV plant  15 - 1 , the bridge  36 - 1  modulates such signals to a standard line signaling formats such as T1 carrier format. However, rather than bring the T1 compatible telecommunication line signaling directly to the location of the CAP  14 - 1  in the microcell  12 , the T1 formatted signal is instead provided to a translator  38 - 1 . The translator  38 - 1  up-converts the T1 signal to an appropriate intermediate frequency (IF) carrier for coupling over the CATV plant  15 - 1 . For example, the 1.5 MHz bandwidth T1 signal may, in the reverse link direction, be upbanded to a carrier in the range of from 5-40 MHz. In the forward link direction, that is, signals being carried from the central LAN hub  18  towards the computers  17 , the translator  38 - 1  receives signals on the intermediate frequency carrier in a range from 50-750 MHz and translates them down to a baseband T1 signaling format. 
         [0041]    The power inserter  45  may be located at any point in the CATV plant  15 - 1 , and inserts a suitable low frequency alternating current (AC) power signal. This signal energizes the power extractor  40 - 1  and power supply  42 - 1  to generate a direct current supply signal for the CAPs  14 . A signal coupler  43  couples this AC power signal and the intermediate frequency signal energy from the translator  38 - 1  to the CATV plant  15 - 1 , and vice versa. 
         [0042]    The head end access point (HAP)  16 - 1  contains a power supply  48 - 1 , translator  44 - 1 , and remote bridge  46 - 1 . The translator  44 - 1  provides the inverse function of the translator  38 - 1 . That is, in the reverse link direction, it converts the T1 formatted signals from the intermediate frequency carrier in a range of from 5-40 MHz back down to the baseband T1 format. 
         [0043]    In the forward link direction, the translator  44 - 1  accepts signals converted from the LAN hub  18  through the bridge  46 - 1 , upbanding them onto a convenient carrier such as in the range of from 50-750 MHz for coupling over the CATV plant  15 - 1 . 
         [0044]    For more information concerning the details of a suitable translator  38 - 1  and  44 - 1 , reference can be had to a co-pending U.S. patent application Ser. No. 08/998,874 filed Dec. 24, 1997 entitled “Remotely Controlled Gain Control of Transceiver Used to Interconnect Wireless Telephones to a Broadband Network.” 
         [0045]    The remote bridge  46 - 1  then reconverts the translated reverse link signals back to Ethernet compatible signals, such as 10 baseT or 100 baseT signals which may then be processed by the LAN hub  18  or other compatible internetworking devices. 
         [0046]    It should be understood that the CATV plant  15 - 1  may be replaced by other types of broadband distribution networks which may be conveniently available within the area  11 . The one consideration which cannot be altered is that the end-to-end propagation delays of the remoting medium must be considered to comply with the end-to-end delay criteria specified by the Ethernet/802.3 standard. For example, optical transport media may also be used in the place of the coaxial cable used for the CATV plant  15 - 1 , such as described in a co-pending U.S. patent application Ser. No. 09/256,244 filed Feb. 23, 1999 entitled “Optical Simulcast Network with Centralized Call Processing.” 
         [0047]      FIG. 3  is a block diagram of an embodiment of the CAP  14  and HAP  16  using cable modem equipment. In this embodiment, a cable modem  37 - 1  replaces the bridge  36 - 1  and translator  38 - 1 . The cable modem  37 - 1  may be IEEE 802.14, Multimedia Cable Network System (MCNS), or Data Over Cable Service Interface Specification (DOCSIS) compatible. The net result is the same in that the Ethernet signals used for communication with the access point  34 - 1  are converted to cable signals in the 5-750 MHz bandwidth. 
         [0048]      FIG. 4  illustrates an alternative embodiment of the CAP  14 - 2  and HAP  16 - 2  which use twisted pair type transport medium  15 - 2 . As before, a wireless LAN compatible access point  34 - 2  provides Ethernet/802.3 compatible signals to a remote bridge  36 - 2 . In this instance, the remote bridge  36 - 2  provides a high speed digital output signal compatible with digital subscriber line (xDSL) signaling technology. Such xDSL technology uses sophisticated modulation schemes to pack data onto standard copper twisted pair wires. 
         [0049]    Likewise, the bridge  46 - 2  disposed within the HAP  16 - 2  is compatible for converting xDSL signaling to Ethernet/802.3 signaling. The embodiment of  FIG. 4  may typically be more advisable to use in areas  11  having readily available twisted pair copper wires such as used for carrying standard telephone signaling, and wherein such signaling requires only a short run to a local central telephone office of 20,000 feet shorter distance compatible with xDSL specifications. 
         [0050]    The understanding therefore is that the bridge  36 - 1  or  36 - 2  and  46 - 1  or  46 - 2  may be any suitable type of layer two (L2) bridging to the appropriate available transport media  15 - 1  or  15 - 2 , be it up-converted T1 over cable or fiber, or xDSL. 
         [0051]    A complete implementation for a local area network  10  may thus be as shown in  FIG. 5 . In particular, the subscriber site  52  contains the remotely located computers  17 . They exchange wireless local area network signaling with devices located with the CAPs  14  located at the stranded plant microcell sites  54 . In turn, the CAPs  14  use an analog distribution network implemented using whatever transport medium  15  that is readily available. The HAP  16  may itself use other analog distribution networks converts such analog signals back to appropriate Ethernet/802.3 signal formatting and forwards them to the hub  18 . The hub  18  thus provides local area network signals such as compatible with the 10 baseT standard, to network router  58  which may provide such signals to other networks over whatever long distance digital signaling is appropriate, such as to other local sub-networks over Ethernet/802.3 10 baseT type signaling, or to other remote locations such as over frame relay trunks. 
         [0052]      FIG. 6  is a detailed view of an alternate embodiment of the HAP  16 . Here, the 802.11 air interface signal is translated in frequency to CATV transport frequencies between the HAP  16  and CAP  14 . The HAP  16  consists generally of a translating stage  60  and bridging stage  62 . A translating stage  60  provides an radio frequency translation function, accepting signals from the transport medium  15  and converting their radio band of operation. In this particular embodiment of the HAP  16 , the bridging stage  62  is provided by an 802.11 compatible wireless bridge. This device accepts signals from a wireless local area network at baseband and converts them to the 802.11 protocol for frequency conversion by the translating stage  60 . In this instance then, the translating stage  60  disposed between the bridging stage and the transport medium  15  converts the IF signaling used on the CATV transport medium  15  in the range of 5-750 MHz to the signaling in the ISM band compatible with the 802.11 wireless bridging stage  62 . 
         [0053]    Finally,  FIG. 7  shows an alternate embodiment of the CAP  14  that uses a direct RF translator  38 - 3  to interface between the CATV transport medium  15  and the 802.11 format signals in the unlicensed ISM bands (e.g., 2.4 GHz or 5.8 GHz). In particular, the analog distribution network signals in the 5-750 MHz band are translated in frequency up to an ISM band carrier by the RF translator  38 - 3 . 
         [0054]    While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.