Abstract:
A method and apparatus for implementing wireless internet connections for a plurality of portable computing devices located within a given area or hotspot. The invention employs a combination of wired and wireless links to manage propagation effects of the transmitted signal and to reduce interference with signals transmitted in adjacent spaces. In accordance with one aspect of the invention, the existing wiring infrastructure at the hotspot, which may be coaxial cable for CATV, is used as the wired segment. A broadband signal, containing internet data obtained from a central computer, is transmitted from a plurality of access points. The signals transmitted from the access points are injected onto the existing wiring, with the broadband signal isolated from the data or power signals carried by the wiring infrastructure. At the outlet ends of the coaxial cable, the broadband signals are separated from the existing data or power signals and coupled to high efficiency antennas which radiate a signal throughout the corresponding living or activity space. In the case of a hotel room, for example, the signal is broadcast for reception anywhere within the hotel room. In accordance with one aspect of the method of the invention, the broadband signals are broadcast from the various access points using several carrier frequencies or channels, and distribution of the channels is arranged to avoid adjacent room same channel interference.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to internet technology. More particularly, the invention is directed to a method and apparatus for facilitating wireless bi-directional communication between a central computer and a plurality of relatively closely spaced personal computers located within a single venue.  
         [0003]     2. Description of the Prior Art  
         [0004]     Internet use has been on the increase ever since the early 1990s, with many new products and services being offered to facilitate all types of personal and commercial endeavors. As a result, laptop computers, PDAs, and other portable computing devices have been promoted and refined in recent years to allow for wireless internet access at virtually any place the portable device can be taken.  
         [0005]     One way of facilitating communication with the internet using a portable computing device involves the use of a wireless LAN technology known as “Wi-Fi”, which is short for “wireless fidelity”. This technology facilitates internet access for a plurality of computing devices located at a designated venue, which is known as a “hotspot”, such as an airport or hotel.  
         [0006]     With the introduction of Wi-Fi technology and hotspots in public areas, the demand for accessing high speed data, also known as broadband, by the general population has increased significantly in the last few years, with projections indicating that in the next few years there will be tens of thousands of these hotspots. One of the primary reasons for the increase is the ease with which internet users can obtain high speed internet access. The most popular hotspots are cafés, bookstores, hotels, restaurants, airports, conference centers, and marinas where people can access the internet easily via their Wi-Fi enabled laptops or PDAs. Typically, these hotspots are connected to the internet as a backhaul connection via T1/E1, cable modems, wireless, or DSL. Typical backhaul connection speed is less than 1.5 Mbps.  
         [0007]     Wi-Fi equipment is based on the IEEE 802.11 standard, it is sometimes referred to as wireless Ethernet to emphasize the linkage with the traditional wired Ethernet 802.3. In other words, Wi-Fi equipment is designed and certified to work with wired Ethernet products. There are currently several 802.11/b/a/g standard products available. The most popular 802.11b product is based on the 2.4 GHz ISM band and operates at a data rate of up to 11 Mbps, which is more than 9 times faster than the typical backhaul connection speed. Recently certified products based on IEEE 802.11g standard, are also based on 2.4 GHz ISM band and operate at data rates of up to 54 Mbps.  
         [0008]     A typical hotspot based on current Wi-Fi products has the following characteristics:  
         [0009]     1. Typical data speed of the backhaul connection is 1.5 Mbps or less.  
         [0010]     2. Maximum data speed of Wi-Fi products is 54 Mbps with an effective range of about 150 feet in open space.  
         [0011]     3. Multiple access point devices are needed to cover client-dense venues such as hotels and apartments. Poor placement of the access points, limited transmitted power, poor channel planning, and coverage problems that are unique to the building structure are the main reasons for the high cost of deploying the Wi-Fi solution in highly dense environments.  
         [0012]     Because of limited backhaul connection speed, e-mail, web surfing, and accessing corporate networks via VPN are the most popular applications that are used in hotspots. Data speed of 300 Kbps is sufficient to run these applications. However, running multimedia applications such as video on demand, distance learning, training, and stream video advertisements requires much higher bandwidth at the hotspots. To solve this problem, each hotspot requires a local cache gateway that interfaces with a backhaul connection as well as wireless access points. Essentially, the local cache gateway stores the information such as advertisements, training materials, or movies, downloaded in non real time from the central server and then plays back the information in real time when client devices request the information. This implementation is relatively straightforward for a hotspot location where only one access point is required. However, when several access points are required, the aforementioned problems relating to transmission of the broadband signal arise. Accordingly, it would be desirable to provide an efficient and cost effective way of providing wireless broadband internet connection for a plurality of portable computing devices located within a predetermined venue, especially when that venue covers a large area and is partitioned into separate rooms or living spaces.  
       SUMMARY OF THE INVENTION  
       [0013]     Briefly, the invention comprises a method and apparatus for implementing wireless internet connections for a plurality of portable computing devices located within a given large area venue. The invention employs a combination of wired and wireless links to manage propagation effects of the transmitted signal and to reduce interference with signals transmitted in adjacent spaces within the venue. In accordance with one aspect of the invention, the existing wiring infrastructure at the venue, which may be coaxial cable for CATV or satellite TV, is used as the wired segment. A broadband signal, containing internet data obtained from a central computer at a relatively low data rate, is transmitted from a local cache gateway to a plurality of access points at a relatively high data rate. The signals transmitted from the access points are injected onto the existing wiring also at a relatively high data rate, with means provided to isolate the broadband data signal from the data or power signals carried by the wiring infrastructure. At the outlet ends of the coaxial cable, the broadband signals are separated from the existing data or power signals and coupled to high efficiency antennas which radiate a signal throughout the corresponding living or activity space. In the case of a hotel room, for example, the signal from the high efficiency antenna is broadcast for reception anywhere within the hotel room. In accordance with another aspect of the method of the invention, the broadband signals are broadcast from the various access points using several carrier frequencies or channels, and distribution of the channels is arranged to avoid adjacent room same channel interference. In accordance with another aspect of the invention, the broadband signal may be any broadband signal such as a cell phone signal.  
         [0014]     Accordingly, it is a principal object of the invention to provide a network architecture for the distribution of a wireless broadband internet signal throughout a given venue at a high data rate.  
         [0015]     It is a major object of this invention to provide a network architecture for the bi-directional communication of digital data between a local cache gateway and a plurality of client devices within a given area at a relatively high data rate, while said local cache gateway bi-directionally communicates digital data with a central computer at a relatively low data rate.  
         [0016]     It is another object of the invention to provide a network architecture for the distribution of a wireless broadband internet signal throughout a given area having both wired and wireless segments.  
         [0017]     It is another object of the invention to provide a network architecture for the distribution of any wireless broadband signal throughout a given area having both wired and wireless segments.  
         [0018]     It is another object of the invention to provide a method for distributing a broadband signal throughout a partitioned building using the existing wiring infrastructure.  
         [0019]     It is another object of the invention to provide a method for delivering multimedia content in real time throughout a local area network having at least one wireless segment.  
         [0020]     Finally, it is a general goal of the invention to provide improved elements and arrangements thereof in an apparatus fully effective in accomplishing its intended purposes.  
         [0021]     These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.  
         [0022]     The present invention meets or exceeds all the above objects and goals. Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     Various other objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:  
         [0024]      FIG. 1  shows an overview of the system of the invention.  
         [0025]      FIG. 2  shows a block diagram of the hybrid network of the invention.  
         [0026]      FIG. 3  shows a block diagram of a wall unit used with the hybrid network of the invention.  
         [0027]      FIG. 4  shows an actual layout implementation of a diplexer and splitter network.  
         [0028]      FIG. 5  shows a circuit layout of a wall unit diplexer.  
         [0029]      FIG. 6  illustrates channel distribution within a structure having a wiring infrastructure adapted for use with the hybrid network of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0030]     Referring now to  FIG. 1 , an overview of the system  10  of the present invention is shown. It can be seen that the system comprises four main elements; the central server  12 , the local cache gateways  14 , the access points  16 , and the computing devices or client devices  17  which allow the individual users or clients to communicate with the central server  12  and access the internet  18 . The central server  12  communicates to a plurality of local cache gateways  14 , which may be located in geographically disparate locations, via the internet  18 . Each venue or hotspot  20  has at least one local cache gateway  14 , one or more access points  16 , and one or more client devices  17 .  
         [0031]     The central server  12  performs the usual functions of network resource management and ensures a uniform connection experience for users operating client devices  17  connected to the various gateways  14 . The local cache gateways  14  and access points  16  are managed and monitored by the central server  12 . Authentication, authorization, and accounting functions are all handled by the central server  12 . In one aspect of the invention, the central server  12  distributes commercial software products or any content to the various local cache gateways  14 . The software products or other content may then be downloaded from the gateways  14  via the various access points, obviating the need for individual client devices  17  to directly access the internet  18 , as is the case with all WLAN arrangements. Storing the software or content at the gateway  14  streamlines the software purchasing process greatly, and the cost to the consumers as well as the download times are correspondingly reduced. As an additional benefit, security is greatly enhanced, as the authorizing and accounting functions are handled between the gateway  14  and the central server  12 , allowing for much more sophisticated firewall and security protocols than a client device connected directly to, e.g. a phone line. Also, as the gateway  14  can store large amounts of data from the central computer  12  for later broadcast to client devices at high speed in real time, the apparent download speed to the user of the client device  17  is greatly enhanced.  
         [0032]     In order to provide uniform internet access for all client devices  17  on a wireless LAN (WLAN), and to allow for real time access to multimedia content for all client devices  17  at the hotspot, a local cache gateway  14  is required. It should be noted here that the WLAN  19  of the present invention is defined by the network extending from the local cache gateway  14  to the various client devices  17  or end terminals as will be explained in more detail later. The local cache gateway  14  may be a server such as a Dell® Power Edge 4600 server, and is connected to the central computer  12  via a relatively slow backhaul link which may be, for example, the existing telephone lines etc., the backhaul link being understood to encompass that portion of the physical infrastructure of the internet  18  between the local cache gateway  14  and the central computer  12 . Typically a local cache gateway  14  has two logical interfaces, one to the backhaul internet connection allowing for connection to the internet  18  for two-way communication between the central server  12  and the gateway  14 , the second interface allowing for two way communication between the gateway  14  and the access points  16 . Each hotspot  20  has at least one gateway  14  which has stored therein, in addition to the operating system software and data transfer protocols, multimedia and application software. Each gateway  14  distributes, in response to client device  17  requests, multimedia and applications software such as music, movies, mpeg video images, training materials, proprietary software products, all in real time if necessary. It can be appreciated that client devices  17  would not be able to access certain multimedia applications in real time by directly accessing the internet  18  due to bandwidth constraints. To that end the gateway  14  preferably has a very large memory capacity, on the order of 20 to 1000 gigabytes. This large memory capacity, combined with the high bandwidth capability of the gateway  14  and the WLAN  19  of the present invention allows for each hotspot  20  to be a retail point of sale for various multimedia and software products, with the capability to transmit these products, which are stored at the gateway  14  to several client devices  17  in a client dense environment at a relatively high data rate. A key aspect of the invention is that the communication of data along the WLAN  19  is at a much higher speed or rate than the speed at which the gateway  14  communicates with the central computer  12 .  
         [0033]     As has been previously mentioned, each gateway  14  is capable of transmitting data at very high speeds, up to 9 times the speed available with the typical backhaul connection, between the gateway  14 , the internet  18 , and the central server  12 . The Wi-Fi equipment utilized to transfer data along the WLAN  19  is based on the IEEE 802.11 standard, sometimes referred to as the wireless internet. A standard 802.11b product is based on the 2.4 GHz ISM band, operating at a data rate of up to 11 Mbps, with recently certified products based on the 802.11g standard capable of operating at data rates of up to 54 Mbps. Thus, a hybrid WLAN with a locally high bandwidth can be facilitated using 802.11 products, with the local cache gateway  14  allowing for video games, etc. to be downloaded to the client devices  17  at a relatively high speed in a manner transparent to the user.  
         [0034]     In addition to controlling the high speed transmission of data between the gateway  14  and the client devices  17 , the gateway  14  can monitor and control all of the access points  16  on the WLAN  19 , with access point  16  activity transmitted to the central server  12 . The gateway  14  also controls the bandwidth and maintains the integrity of data transfer along the WLAN  19 .  
         [0035]     Distribution of high speed data within the infrastructure of the hotspot  20  is accomplished in part by using the existing wiring at the hotspot  20 . The hotspot  20  may be a single structure  30  ( FIG. 6 ), several adjoining structures  30 , or other predetermined area hardwired for the distribution of cable television signals, electrical power, telephones signals, etc., such as a marina or train station, the system of the present invention only requires that the wiring be physically continuous throughout the various structures  30  or area to facilitate distribution by a single gateway  14 . If there are several structures  30  not electrically connected by a single wiring network, additional gateways  14  may be required.  
         [0036]     The existing wiring at the hotspot  20  may be either CAT 3 twisted pair wiring, CAT 5 twisted pair wiring, AC power line, or TV coaxial cabling. Most hotels and apartments already have coaxial line and CAT 3 wiring infrastructure for video (TV) and voice (telephone) applications, and of course all buildings have AC wiring.  
         [0037]     Several technologies are readily available for delivery of broadband service to each room  42  or common area of venues  20  such as hotels, apartments, or office buildings. For wireless technologies, many products are available based on standard IEEE 802.11/a/b/g. This technology offers flexibility in the placement of client devices  17  and minimizes the need to modify the existing wiring within the structure  30 . As previously mentioned, 802.11b products are designed to transmit data at a maximum data rate of 11 Mbps, with an effective range of about 150 feet in open space. However, in practice, a lower data rate is expected, and the effective range is dependent on the obstructions placed between the access point  16  and receiver, i.e., laptop or other client device. For 802.11g products, a maximum data rate of 54 Mbps is supported, which is significantly faster than the backhaul internet  18  connection between the central computer  12  and the gateway  14  which may be limited to only 600 or 700 kbps or less. The radio spectrum for these products operates in the unlicensed bands around 2.4 GHz and 5.8 GHz, and consequently, the link is limited by constraints on power spectral density and by propagation effects to about 90 feet per access point  16  and it requires large outlays in network hardware to cover client-dense environments. In particular, there are serious multi-path, fading, and mutual interference effects that severely limit the delivery of high bandwidth service by purely wireless means in a high-density environment. As a result, wireless deployments for individual rooms can be material and labor intensive.  
         [0038]     For wired technologies, many products are available through IEEE 802.3 standard using a CAT 5 wire, through DSL technology using a CAT 3 wire, or through DOCSIS compliant technology using coaxial cable. The wired technologies generally give reliable and secure communication channels. Many hotels and apartments have the coaxial cable and telephone lines, but may not have CAT 5 wire installed. As a result, these rooms require extensive re-wiring or installation of new CAT 5 wiring to support IEEE 802.3 technology. For DSL and DOCSIS technologies, it may require expensive installation of network products and supporting non standard client interfaces.  
         [0039]     Accordingly, a key aspect of the invention is to utilize a hybrid wired/wireless LAN, the wired portion using the existing wiring infrastructure available at the hotspot  20  as has been previously mentioned. Preferably, the CATV wiring, if available, is used. The chief advantage in using a hybrid network is a substantial reduction in signal attenuation as compared to a typical all wireless network. Given a 100 foot propagation scenario, a hybrid network can yield approximately a 10 dB signal strength advantage versus an all wireless network, even accounting for the relatively indirect routing of CATV wiring through a building. An additional advantage obtained through the use of the hybrid network of the invention is improved signal immunity, given that the longer of the propagation paths, the wired or CATV portion of the network, is through shielded coaxial cable giving inherently superior interference immunity. This advantage can of course be improved upon by increasing the relative proportion of wired portion propagation distance to wireless portion propagation distance. Maximum interference immunity is obtained by an all wired network, which is within the purview of the inventive concept. Further interference immunity is obtained by a frequency distribution scheme as will be explained below. It should be noted that in most cases the existing CATV wiring can be used for the majority of the wired portion of the network.  
         [0040]     Referring now to  FIG. 6 , a structure  30  having pre-existing CATV wiring  38  is shown. The CATV wiring  38  may be fed CATV signals received and processed by a dish  40  and associated receiver circuitry. The wiring  38  is routed through the structure  30  so as to be available in every living space or common area  42 ,  142 ,  242 , etc. It should be noted that a living space  42  may not be a single room but may be a suite with, e.g., 2 bedrooms, a bathroom, and a living room. Such a living space  42  would require at least two CATV receptacles, but only a single transmitting antenna as will be explained in more detail later.  
         [0041]     An overall schematic of the hybrid system is shown in  FIG. 2 . Signals from both the CATV receiver and the access point  16  are applied to a diplexer  50 . The access point  16 , which is a transceiver built to one of the 802.11 standards, may be one of several commercially available units from such vendors as Orinoco®, Linksys®, or Cisco®. The diplexer  50  combines TV and Wi-Fi signals onto a common port while providing good isolation between the TV and Wi-Fi input ports. The frequency bands of interest afford a wide variety of options for diplexer  50  implementation. In the preferred embodiment, the diplexer  50  utilizes printed circuit elements to implement the desired filtering function. Additional circuit elements shown in dashed lines may be needed where there is increased cable loss between the access point  16  and diplexer  50  as would be the case when there is considerable distance between the access point  16  and diplexer  50 . An amplifier  49  and circulators  51  are optionally included to boost signal strength to make up for the increased cable loss. Circulators  51  are employed to preserve bi-directionality of the link.  
         [0042]     The combined TV and Wi-Fi signals enter a splitter  52  and are divided into several signals of lesser amplitude. The diplexer  50  and splitter  52  may alternatively be combined on to a single printed circuit board as shown in  FIG. 4 . It can be seen that the PC board  53  shown has input terminals J 1  and J 2  which serve as inputs for the TV and Wi-Fi signals, with the appropriate DC isolation and filtering circuits comprised of capacitor C 1 -C 4 , and indiuctor L 1 . The card  53  has eight outputs  55 , two each connected to resistors R 1 -R 4 , and thus functions as an eight way diplexer/splitter.  
         [0043]     It should be noted that cable wiring in most buildings is of two types: home run and tapped line. In the home run configuration, cables are run from a central location individually to each room, and all large buildings that have been constructed recently are wired this way. The tapped line configuration is found in older installations where a main line runs down a corridor and is tapped at intervals with splices into individual rooms. The tapped line requires a greater assortment of components to implement and is therefore not the preferred configuration. The more modern home run provides the ideal configuration from the viewpoint of equipment cost, operation, and maintenance. The present invention is readily adapted to both configurations. Accordingly, each splitter output  55  connects to a coaxial cable  54  that runs directly to an individual room or to the main line of a tapped configuration. In the latter case, alternately, the access point  16  may be connected through a diplexer directly into each tapped line, bypassing the main line.  
         [0044]     Referring now to  FIGS. 3 and 5 , each cable  54  terminates in a wall unit  56  that is housed in each room. The wall unit  56 , which may also be formed on a single printed circuit board  57  as shown in  FIG. 5 , consists of a diplexer  58  that separates the TV and Wi-Fi signals along separate paths. The TV signal path terminates in a coaxial connector  60  that passes through a hole centered in an existing plastic wall plate (not shown) and protrudes from the wall plate (not shown) into the living space  42 , and to which a TV cable is attached. The Wi-Fi signal path terminates either in a miniature antenna  62  that radiates the energy into the room, or in a coaxial connector  64  that provides a wired connection to the client device  17 . Units that have the antenna  62  installed incorporate the wireless segment of the link. A corresponding antenna in the client device  17  receives this signal and channels it to an integral transceiver within the device  17  for further conditioning and processing. Transmitted signals from the client device  17  likewise are received by the antenna  62  in the wall unit  56  and routed through the diplexer  58  and cable  54  back toward the AP  16 . In the preferred embodiment, the wall unit&#39;s diplexer  58  is implemented with printed circuit board  57  with the antenna  62  and connectors being the only components requiring attachment during assembly of the WLAN. The antenna  62  if present is hidden from view by the wall plate. A modified wall plate is required for cable-only installations, to accommodate the extra terminal  64  needed for the broadband signal.  
         [0045]      FIG. 3  includes optional components shown in dashed outline to include cases where longer cable  54  runs may be required than can be supported by only passive components. In such cases, an active amplifier  68  may be included to boost signal strength to make up for the increased cable loss. Circulators  70  are employed to preserve bi-directionality of the link. Clearly, the isolation of these circulators must exceed amplifier  68  gain to ensure stable operation. An RF switch  72  may be included that steers the Wi-Fi signal to the antenna  62  or to the coaxial output  65 . While these enhancements increase the cost and complexity of the wall unit  56  because of the increased component count and the need for supplying dc power to the active components, they are unavoidable especially when the network operates in the 2.4 GHz band where cable losses are higher.  
         [0046]     In the event that multiple access points  16  are used, each access point  16  may be tuned to a different channel, and broadband signals therefrom may be routed so that adjacent living areas  42  are not on the same channel. Preferably, any two living areas on the same channel are separated by two or more living areas to minimize interference. Referring again to  FIG. 6 , adjacent rooms  42 ,  142 ,  242 , and  342  are fed from four different access points (not shown) so that room  42  is on a first channel,  142  is on a second channel,  242 , is on a third channel, and  342  is on a cable outlet. Thus, no adjacent rooms are on the same channel to reduce interference. The sequence begins again with room  442  on the first channel, room  542  on the second channel, and so on. Of course, each individual building  30  will have a unique layout, as well as unforeseeable idiosyncrasies, so that the channel assignments should be varied on a case by case basis to maximize the interference reduction obtained by the channel distribution arrangement discussed above. While in the example given a four channel scenario is demostrated, there may be more or fewer channels depending upon the layout of the hotspot  20 .  
         [0047]     In operation, broadband signals are transmitted between the client device  17  and the local cache gateway  14  along the WLAN  19  at a relatively high speed, the broadband signals containing data and control signals as described above. Accordingly, users of client devices  17  have faster access to their applications because those applications reside at the local gateway  14  and can therefore be downloaded to client devices  17  via the local higher bandwidth link. Furthermore, this benefit is transparent to the particular application; video games, movies, training materials, music, and images can all can be downloaded to client devices via the local high-bandwidth link. A user wishing, for example, to download a software product which has been previously stored on the local cache gateway  14  sends the request via the client device  17  to the central computer  12 , which after handling all accounting and other ancillary matters, authorizes the download. Data transmission between the internet  18  and the client device  17  occuring outside of the WLAN  19  is also under control of the central computer  12 , albeit at the relatively slow speeds as discussed above.  
         [0048]     As has been previously mentioned, the system  10  may be adapted to control and distribute any broadband signal. Thus, for example, the system  10  may be employed to control and distribute cell phone signals in the relevant frequency bands, around 900 Mhz, and 1.9 to 2.1 Ghz.  
         [0049]     From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.  
         [0050]     It is to be understood that the present invention is not limited to the sole embodiment described above, but encompasses any and all embodiments within the scope of the following claims: