Abstract:
The present invention is to provide an effective means of wirelessly distributing electronic contents such as Internet data and multiple streams of real-time multimedia programming over a wireless local area network (WLAN). It provides a facility to effectively utilize all radio channels of wireless medium allowed in a given WLAN implementation and enables wireless clients to participate in the wireless contents distribution with a single radio.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    U.S. Pat. No. 5,960,344, Sep. 28, 1999 by Ronald L. Mahany U.S. Pat. No. 6,259,898 B1, Jul. 10, 2001 by Daniel E. Lewis 
     
    
     
       BACKGROUND OF INVENTION  
         [0002]    The present invention generally relates to wireless distribution of electronic contents such as Internet data or multimedia programming streams over Wireless Local Area Network (WLAN).  
           [0003]    WLAN divides wireless medium into multiple radio channels based on frequency or other criteria adopted in a specific implementation of a given WLAN system. In one case, access point establishes a wireless local area network, commonly known as Basic Service Set (BSS) over a single radio channel. In another case, an access point may have multiple radios to establish multiple BSSs with each BSS over a different radio channel. Wireless clients register with BSS to exchange data over BSS. Access points provide registered wireless clients with access to external network. IEEE 802.11 family of WLAN standards adopted Carrier Sense Multiple Access (CSMA) as a means for accessing wireless medium in which each transmitter listens to its radio channel in wireless medium to see if it is available for transmission.  
           [0004]    Wireless Local Area Network (WLAN) such as the one defined by IEEE 802.11 family of specifications including 802.11, 802.11a, 802.11b, 802.11g has gained wide-spread market acceptance. Its usage for non-time critical data transfer over WLAN is a common practice nowadays. However its usage for bandwidth-intensive applications such as real-time multimedia streaming application has been limited due to the lack of art in effectively utilizing all radio channels that are allowed in a given WLAN standard.  
           [0005]    Some prior WLANs deal with data transmission over a single BSS based on Quality of Service requirement but they do not address data transmission beyond the data capacity of a single radio channel.  
           [0006]    U.S. Pat. No. 5,960,344 to Mahany describes an access point with two radios. In one mode of operation both radios operate on the same channel to provide radio channel redundancy. In another mode of operation two radios are provided to have one radio monitor transmission from the other radio. In the third mode of operation dual radios offer path continuity when Distribution System path is disconnected. The use of multiple radios in this art was not for increasing bandwidth capacity of the network.  
           [0007]    U.S. Pat. No. 6,259,898 to Lewis describes an art for an access point, which provides for simultaneous communications with two or more mobile terminals on different channels. In this art, each mobile terminal is registered with all communication channels that access point operates, and goes into a sleep mode with respect to all communications channels except for one. This art places a burden on access point to keep all mobile terminals registered on all communications channels and provide sleep mode services to mobile terminals. The burden increases as the number of communication channels increases. In addition, the usage of beacon in this art is not consistent with the usage as defined by such standard specifications such as IEEE 802.11 family of specifications; thereby, causing interoperability issues with standard-based wireless terminals.  
           [0008]    The present invention describes an efficient means of distributing electronic contents such as Internet data and multiple streams of real-time multimedia programming over wireless local area networks. It provides a facility to efficiently utilize multiple radio channels of wireless medium allowed in a given WLAN implementation and allows wireless clients to participate in the wireless contents distribution with a single radio.  
           [0009]    As new generations of WLAN specifications and implementations are developed, the present invention should be readily adaptable to them by people familiar with the art in WLAN and multimedia communications.  
         SUMMARY OF INVENTION  
         [0010]    The present invention is to provide an effective means of wirelessly distributing electronic contents such as Internet data and multiple streams of real-time multimedia programming over a wireless communication network based on Wireless Local Area Network (WLAN). It provides a facility to effectively utilize all radio channels of wireless medium in a given WLAN implementation and allows wireless clients to participate in the contents distribution cost-effectively with a single radio.  
           [0011]    The present invention describes Wireless Contents Distribution System (WCDS) comprising a base system and one or more wireless clients. The base system comprises one or more access points with each access point equipped with one or more radios, contents source, external network path, distribution processor, and backbone link. Access points, contents source, distribution processor, external network path, and distribution processor are connected over backbone link. The distribution processor coordinates activities within WCDS. An example of backbone link is Ethernet. The examples of contents source are multimedia server and multimedia storage. External network path may be Ethernet connected to Internet or wireless local area network. External contents source is accessible through this path. Although the contents source is provided here to show that a contents source can be tightly built into base system, some embodiment of the present invention may not include contents source as part of base system. In some embodiment of the present invention the base system may be viewed as a single large access point that has more elements than conventional access points.  
           [0012]    In one aspect of the present invention the base system establishes wireless local area network, commonly known as Basic Service Set (BSS), as needed as it receives request for content delivery or bandwidth reservation. This request may originate from wireless clients, contents server, or external network. In other embodiment of the present invention base system establishes more BSSs in advance than needed in anticipation of needing them in the future.  
           [0013]    In another aspect of the present invention, base system, when receiving request from wireless clients for content delivery or bandwidth reservation with Quality of Service requirement, selects a BSS to use and informs the requesting wireless client of the selected BSS so that the requesting wireless client may participate in the BSS through the re-registration policy adopted in a given embodiment of the present invention. The base system may select an existing BSS to accommodate request for content delivery or bandwidth reservation. The base system may dynamically establish BSS upon receiving the request and select it for use. The base system may dynamically adjust the number of BSSs it maintains in accordance with the expected communication needs. In some embodiment of the present invention it is expected that the placement of access points and wireless clients is such that all BSSs established by base system are reachable by all wireless clients. When it is anticipated that this expectation is not met, the re-registration process may employ a scheme to verify that the requesting wireless client can be served on the selected Basic Service Set so that base system can assign a new Basic Service Set to serve the requesting wireless client if needed.  
           [0014]    WCDS may designate one or more Basic Service Sets for the purpose of registration and require wireless clients to initially register only with these Basic Service Sets according to the authorization process adopted by a given embodiment of the present invention. Under this scheme the effect of registration is limited to the designated Basic Service Sets.  
           [0015]    When a wireless client makes request for content delivery or bandwidth reservation that cannot be met with a data capacity of a single BSS, base system selects multiple Basic Service Sets for serving the request. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0016]    [0016]FIG. 1 describes Wireless Contents Distribution System.  
         [0017]    [0017]FIG. 2 describes base system.  
         [0018]    [0018]FIG. 3 describes the usage of BSS as Management BSS.  
         [0019]    [0019]FIG. 4 describes the usage of BSS as Content BSS.  
         [0020]    [0020]FIG. 5 describes how base system manages Management BSS.  
         [0021]    [0021]FIG. 6 describes how base system manages Content BSS.  
         [0022]    [0022]FIG. 7 describes activities of wireless client.  
         [0023]    [0023]FIG. 8 describes how two Content BSSs are combined to accommodate a delivery of a single content whose bandwidth requirement exceeds that of a single BSS. 
     
    
     DETAILED DESCRIPTION  
       [0024]    The present invention is described with references to the included figures.  
         [0025]    In FIG. 1, an exemplary embodiment of the present invention is provided. It is a wireless contents distribution system (WCDS) that distributes electronic contents such as Internet data and multiple streams of real-time multimedia programming over wireless local area networks referred to as Basic Service Sets (BSS) in the present invention.  
         [0026]    WCDS comprises base system  690 _ 1 , wireless clients  101  and  105 . Each wireless client  101  is equipped with one radio. Each wireless client  105  is equipped with two or more radios.  
         [0027]    The base system  690 _ 1  comprises one access point  201 _ 1 , multimedia storage  501 _ 1 , external network path  602 , distribution processor  401 _ 1 , and backbone link  601 .  
         [0028]    The access point  201 _ 1  has multiple radios  112 , access point processor  113 _ 1 .  
         [0029]    The access point processor  113 _ 1  controls radios  112 , communicates with distribution processor  401 _ 1  to coordinate activities for contents distribution.  
         [0030]    The multimedia storage  501 _ 1  is the contents sources built into base system  690 _ 1 .  
         [0031]    Access point  201 _ 1 , contents source  501 _ 1 , external network path  602 , distribution processor  401 _ 1  are connected over backbone link  601 . An example of a backbone link is Ethernet.  
         [0032]    The external network path  602  is a connection to external network  801  such as wired local area network or Internet. WCDS may receive multimedia contents from external network  801  through external network path  602  for distribution to wireless clients 101  and  105 .  
         [0033]    The distribution processor  401 _ 1  coordinates activities within WCDS. The distribution processor  401 _ 1  handles contents delivery from service providers that are available through external network  801 .  
         [0034]    The number of BSSs that access point  201 _ 1  can establish is limited by the number of radios it is equipped with.  
         [0035]    Although multimedia storage  501 _ 1  as a contents source is provided here to show that a contents source can be tightly built into base system  690 _ 1 , some embodiment of the present invention may not include contents source as part of WCDS; instead, base system  690 _ 1  may access external contents source  851  for distribution to wireless clients  101  and  105 .  
         [0036]    In FIG. 2, another exemplary embodiment of the present invention for a base system is provided to show how different combinations of components of base system are built into separate physical units. This base system  691 _ 1  comprises access point  201 _ 1  as a stand-alone unit, access point  201 _ 2  as a stand-alone unit, multimedia storage with a built-in distribution processor  511 _ 1  as a stand-alone unit, and a backbone link  601  through which access points  201  and multimedia storage with a built-in distribution processor  511 _ 1  and external network path  602  are connected. An example of the backbone link  601  is Ethernet. In some embodiment of the present invention, AP processor may incorporate the role of distribution processor instead of having a separate distribution processor.  
         [0037]    In FIG. 3, the usage of BSS as Management BSS in an exemplary embodiment of the present invention is described. BSS  161 _ 1  is established by base system  690 _ 1 . Wireless clients  101 _ 1 ,  101 _ 2 , and  101 _ 3  are registered with BSS  161 _ 1  according to the registration process adopted in a given embodiment of the present invention. Base system  690 _ 1  provides services to registered wireless clients  101 _ 1 ,  101 _ 2 ,  101 _ 3  over BSS  161 _ 1  according to the Quality of Service scheme adopted for use on BSS  161 _ 1  according to a given embodiment of the present invention.  
         [0038]    The wireless client  101 _ 4  requires no service from base system  690 _ 1  and has not registered with BSS  161 _ 1 .  
         [0039]    The base system may designate certain BSSs and allow initial registration of wireless clients only through these particular BS s, which are referred to as Management BSSs in the present invention. BSS  161 _ 1  is designated as Management BSS in this example. The base system  690 _ 1  provides access to the external network over external network path  602  for the registered wireless clients over Management BSS  161 _ 1 . The external network service accommodated over Management BSS  161 _ 1  is limited by the data capacity of BSS  161 _ 1 . The base system  690 _ 1  provides service to the registered wireless clients according to the Quality of Service policy adopted in a given embodiment of the present invention but the service provided over BSS  161 _ 1  is limited by the data capacity of BSS  161 _ 1 . When base system  690 _ 1  determines that additional Management BSS is required to serve additional wireless clients, it may establish more Management BSSs. When base system  690 _ 1  determines that a certain Management BSS is no longer needed, it de-establishes Management BSS.  
         [0040]    In FIG. 4, the usage of BSS as Content BSS in an exemplary embodiment of the present invention is described. Wireless client  101 _ 2  initially registers with Management BSS  161 _ 1  according to the registration procedure adopted in a given embodiment of the present invention. The wireless client  101 _ 2  requests the base system  690 _ 1  to deliver a certain program referred to as content_ 1   621 _ 1 . The base system  690 _ 1  verifies the eligibility of the requesting wireless client for participating in Content BSS. The base system  690 _ 1  establishes BSS  171 _ 1  to deliver the requested content and notifies wireless client  101 _ 2  of Content BSS  171 _ 1 . The BSS selected, which is BSS  171 _ 1  in this case, to serve wireless client for content delivery or bandwidth reservation is referred to as Content BSS. The wireless client  101 _ 2  de-registers from Management BSS  161 _ 1  and re-registers with Content BSS  171 _ 1  and receives the content. All communication between wireless client  101 _ 2  and base system  690 _ 1  now takes place over BSS  171 _ 1 .  
         [0041]    In certain embodiment of the present invention, the re-registration alone automatically implies de-registration from the BSS that wireless client is registered with at the time of re-registration and base system updates its database accordingly.  
         [0042]    Wireless client  101 _ 4  initially registers with Management BSS  161 _ 1  according to the registration procedure adopted in a given embodiment of the present invention. The wireless client  101 _ 4  requests the base system  690 _ 1  to deliver Content_ 2   621 _ 2 . The base system  690 _ 1  verifies the eligibility of the requesting wireless client for participating in Content BSS, base system  690 _ 1  establishes a BSS  171 _ 2  to deliver the requested content and notifies wireless client  101 _ 2  of Content BSS  171 _ 2 . The wireless client  101 _ 4  de-registers from Management BSS  161 _ 1  and re-registers with Content BSS  171 _ 2  and receives the content.  
         [0043]    Wireless client  101 _ 3  initially registers with Management BSS  161 _ 1  according to the registration procedure adopted in a given embodiment of the present invention. The wireless client  101 _ 3  requests the base system  690 _ 1  to deliver Content_ 1   621 _ 1 . The base system  690 _ 1  verifies the eligibility of the requesting wireless client for participating in Content BSS. The base system  690 _ 1  is aware that Content_ 1   621 _ 1  is already being delivered over Content BSS  171 _ 1  and notifies the requesting wireless client of Content BSS  171 _ 1 . The wireless client  101 _ 3  re-registers with Content BSS  171 and receives the content.  
         [0044]    The wireless client  101 _ 1  is registered with Management BSS  161 _ 1 . The base system  690 _ 1  delivers data between wireless client  101 _ 1  and external network.  
         [0045]    When a wireless client requests delivery of content that resides in external contents source  851  reachable over external network  801 , distribution processor  401 _ 1  selects a BSS and informs the requesting wireless clients of the selected BSS in the same way as in the case of content delivery of Content_ 1  and Content_ 2 . The external contents source  851  may be a fee-based subscription service and distribution processor  401 _ 1  may handle information exchange with the subscription service provider for such things as fee payment and encryption key exchange on behalf of the requesting wireless client.  
         [0046]    A given embodiment of the present invention may adopt a proper procedure for Content BSS re-registration. Encryption key distribution may be implemented as part of the procedure.  
         [0047]    A wireless client may request bandwidth reservation with a specified Quality of Service to base system for its use with external network or another wireless client. This request from an authorized wireless client causes base system to allocate a Content BSS just as in the case of content delivery request.  
         [0048]    The base system  690 _ 1  may receive initial registration request over Content BSS  171  from wireless client  101 _ 5 . In this case base system  690 _ 1  may grant the registration request if it determines that the registration will not affect the service being provided to the wireless clients registered with Content BSS  171 . In case base system  690 _ 1  denies the initial registration request over Content BSS  171 , base system  690 _ 1  informs the requesting wireless client  101 _ 5  of Management BSS  161 _ 1  so that wireless client  101 _ 5  may try registration with Management  161 _ 1 .  
         [0049]    In some embodiment of the present invention it is expected that placement of base system and wireless clients are such that all BSSs established by base system are reachable by all wireless clients. When this expectation is not met, the re-registration process may employ a scheme to verify that the requesting wireless client can be served on the selected BSS so that base system can assign a new BSS to serve the requesting wireless client if needed.  
         [0050]    A given embodiment of the present invention implements a procedure to follow in case any of the registration and re-registration procedure fails.  
         [0051]    In FIG. 5, the description of how base system manages Management BSS is provided in flowchart in accordance with an exemplary embodiment of the present invention. The base system monitors radio channels and selects a good radio channel and establishes Management BSS with a radio it selects and broadcasts the presence of Management BSS over all existing BSSs that may exist. Each embodiment of the present invention may apply its own criteria as to what a good radio channel is. The base system constantly monitors the status of Management BSS. If the condition of Management BSS deteriorates, base system notifies its intention to remove Management BSS over Management BSS and over any existing Content BSS, after which it removes Management BSS. This process continues. The distribution processor allows wireless clients to register with Management BSS according to a procedure adopted in a given embodiment of the present invention. The base system may disallow any new registration of wireless clients if the new registration is likely to disturb on-going traffic in Management BSS. When base system rejects registration request from a wireless client, it may inform requesting wireless client of an alternative BSS to try registration. When base system directs wireless client to available BSSs, the registration can take shorter time than the case in which wireless client tries different BSSs until wireless client obtains registration. The wireless clients registered with Management BSS issues over Management BSS content delivery request. The base system rejects content delivery requests from wireless client without proper authorization. For the content that is already being delivered, base system notifies requesting client of the existing Content BSS. The base system may select a new BSS for the content delivery, in which case base system establishes a new Content BSS and notifies the requesting wireless client of the new Content BSS. The base system may choose to select an existing Content BSS to deliver content if the data capacity of the existing Content BSS is sufficient to accommodate the new content. If no proper radio channel is available, the content delivery request is denied. Where applicable, base system handles security key distribution between contents source and recipient of the content. The base system may use Management BSS as Content BSS if it determines that the dual use will not keep it from providing service at the required level of Quality of Service. In some embodiment of the present invention base system provides a facility for wireless clients to combine the process of initial registration and content request. In some embodiment of the present invention base system provides a facility for wireless clients to combine the process of de-registration from current BSS and registration with a new BSS. In some embodiment of the present invention, as base system plans to establish/remove BSS, it broadcasts the plan with time indication of future events over all BSSs. In this embodiment wireless clients are aware of all existing BSS and planned establishment/removal of BSSs and wireless clients may use this information in reducing radio channel interferences caused by each other. In another embodiment of the present invention, base system may dynamically establish additional Management BSSs as they are needed and remove each Management BSS as it is no longer needed. In this case if base system decides that existing Management BSSs cannot accommodate any new wireless client, it establishes a new Management BSS to provide services to new wireless clients. As registration request arrives, base system accepts the registration request if it can accommodate the requesting wireless client in the Management BSS over which the request is received. In another embodiment of the present invention, base system may keep multiple Management BSSs whether they are needed currently or not.  
         [0052]    In FIG. 6, the description of how base system manages Content BSSs is provided in flowchart in accordance with an exemplary embodiment of the present invention. The base system constantly monitors the status of each Content BSS. This monitoring process involves examining the reporting of reception quality from wireless clients registered on Content BSS. If base system determines that the radio channel for a given Content BSS is no longer good, it establishes a new Content BSS and delivers contents over the new Content BSS and notifies all wireless clients on bad Content BSS of its removal and the establishment of the new Content BSS. With advance notification of Content BSS removal/establishment, wireless clients should be able to schedule for Content BSS switchover accordingly. In one embodiment, as base system plans to establish/remove BSS, it broadcasts the plan with time indication of events over all BSS. In this embodiment wireless clients are aware of all existing BSSs and planned establishment/removal of BSSs and wireless clients may use this information in reducing radio channel interferences caused by each other. In case there is no good radio channel available to replace the bad Content BSS, the base system may try to deliver as many contents as possible. A wireless client may request termination of content delivery. The base system removes Content BSS for the content if there is no wireless client remaining registered with the BSS. Wireless client registered in Content BSS may request the delivery of a new content. If the requested content is already being delivered, the requesting wireless client is notified of the existing Content BSS. If the requested content is not currently being delivered, base system establishes a new Content BSS. As base system receives request for termination of content delivery over a Content BSS, base system terminates the delivery of the content if there is no other wireless client receiving the content. Base system removes the existing Content BSS if there is no wireless client registered with it. Where applicable, base system handles security key distribution between content source and content consumer.  
         [0053]    In FIG. 7, activities of wireless client are described in flowchart in accordance with an exemplary embodiment of the present invention. The wireless client scans radio channels and identifies Management BSS and registers with Management BSS when it needs service from base system. If the registration request is denied by base system, wireless client continues by scanning other radio channels for a BSS to register with. The wireless client monitors the condition of Management BSS. If the wireless client determines that Management BSS is bad, the wireless client reports its observation over Management BSS to base system and de-registers with the Management BSS and start looking for a different Management BSS. When wireless client wants to receive content, it issues the request for content delivery over Management BSS. When wireless client wants to reserve bandwidth with Quality of Service requirement, it issues the request for bandwidth reservation with a specified Quality of Service requirement. When Content BSS is notified, the requesting wireless client de-registers with Management BSS and re-registers with Content BSS. The requesting wireless client receives content over Content BSS. If it is a bandwidth reservation request, the wireless client exchanges content with external network over Content BSS.  
         [0054]    If the bandwidth requirement changes or wireless client wants to receive new content, the wireless client issues the request over the current Content BSS. It may de-register from the current Content BSS and register with Management BSS to issue a new request. When notified of the new Content BSS, the requesting wireless client de-registers from current Content BSS and re-registers with new Content BSS. In case new content is delivered over the present Content BSS, requesting wireless client stays registered with the present Content BSS. When wireless client no longer desires the content delivery, it reports its intention not to receive the content and de-registers from Content BSS.  
         [0055]    In FIG. 8, description of how two Content BSSs are combined to accommodate a delivery of a single content whose bandwidth requirement exceeds that of a single BSS. Wireless client  105 _ 1  is equipped with two radios. Wireless client  105 _ 1  initially registers with Management BSS  161 _ 1  to request the delivery of content_ 3   621 _ 3 . If the bandwidth required for the delivery exceeds that of a single BSS, base system  690 _ 1  allocates two BSSs for the delivery and informs requesting wireless client of the allocated BSSs.  
         [0056]    If a request for bandwidth reservation from a wireless client requires two BSSs and the requesting wireless client is equipped with two radios, base system allocates two BSSs for bandwidth reservation and informs the requesting wireless client of the allocated BSSs.