Abstract:
The invention provides a method and system for dynamically controlling link parameters during communication between one or more receiver/transmitters. Transmissions are sent as frames from a Base Station Controller to one or more Customer Premises Equipment. Together with a payload, each frame contains a special control message that pre-announces to both the transmitter and receiver the link parameters to be used until changed. The receiving Customer Premises Equipment processes the link parameters and returns a payload of its own within the same frame. With this dynamic approach, link parameters may be changed as often as every frame.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to link parameters in a communication environment involving two or more transmitting and receiving devices. 
     2. Related Art 
     Link parameters are used to establish the operational parameters for a communications session between two or more devices. For example, the Link Control Protocol (LCP) establishes, configures, and tests data-link Internet connections. Before establishing communications over a point-to-point link (PPP), each end of the PPP link must send out LCP packets (handshaking). The LCP packet accepts or rejects the identity of its linked peer, agrees upon packet size limits, and looks for common misconfiguration errors. Essentially, the LCP packet checks the telephone line connection to see whether the connection is good enough to sustain data transmission at the intended rate. Generally, link parameters apply equally to wired and wireless networks. 
     Currently, link parameters at all layers of the protocol stack need to be synchronized between a transmitter and a receiver for communications to take place. When link parameters are static, they can be set at the time that the link is initialized and remain unchanged for the entire communication session. When link parameters are dynamic, then current protocols such as the LCP cited above, require two-way handshaking between the transmitter and the receiver in order to change the link parameters. 
     Two-way handshaking involves a message from the first station to the second station requesting the change in parameters, followed by, a response from the second station back to the first station agreeing to the change. It is only after the second message is reliably received at the first station, that the new link parameters can take effect. 
     While this current state of the art accomplishes the task of allowing link parameters to be changed, it suffers from several drawbacks. First, it consumes additional valuable link bandwidth and slows communication, as additional communication is required to coordinate link parameters between two stations. Second, if the link is highly dynamic the situation may arise that the link parameters have to change faster than the time required to do a handshaking procedure. In this case, the handshaking protocol would not work and data could be lost. 
     Accordingly, it would be advantageous to provide a technique that allows link parameters to be changed quickly and efficiently and avoid the use of two-way handshaking. This is achieved in an embodiment of the invention that is not subject to the drawbacks of the related art. 
     SUMMARY OF THE INVENTION 
     The invention provides a method and system for dynamically controlling link parameters during communication between one or more receiver/transmitters. Transmissions are sent as frames from a Base Station Controller to one or more Customer Premises Equipment. Together with a payload, each frame contains a special control message that pre-announces to both the transmitter and receiver the link parameters to be used until changed. The receiving Customer Premises Equipment processes the link parameters and returns a payload of its own within the same frame. With this dynamic approach, link parameters may be changed as often as each frame. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a block diagram of a system for dynamic link parameter control. 
     FIG. 2 shows a time division duplex frame used in a system for dynamic link parameter control. 
     FIG. 3 shows a process flow of a system for dynamic link parameter control. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the following description, a preferred embodiment of the invention is described with regard to preferred process steps and data structures. Embodiments of the invention can be implemented using general-purpose processors or special purpose processors operating under program control, or other circuits, adapted to particular process steps and data structures described herein. Implementation of the process steps and data structures described herein would not require undue experimentation or further invention. 
     Lexicography 
     The following terms refer or relate to aspects of the invention as described below. The descriptions of general meanings of these terms are not intended to be limiting, only illustrative. 
     base station controller (BSC)—in general, a device for performing coordination and control of a wireless communication cell. There is no particular requirement that the base station controller must be a single device; in alternative embodiments, the base station controller can include a portion of a single device, a combination of multiple devices, or some portion thereof. 
     communication link—in general, an element for sending information from a sender to a recipient. Although in a preferred embodiment the communication links referred to are generally wireless line of sight point to point communication links, there is no particular requirement that they are so restricted. 
     customer premises equipment (CPE)—in general, a device for performing communication processes and tasks at a customer location, and operating in conjunction with the base station controller within a wireless communication cell. There is no particular requirement that the customer premises equipment must be a single device; in alternative embodiments, the customer premises equipment can include a portion of a single device, a combination of multiple devices, or some hybrid thereof. 
     time division duplex (TDD)—in general, a type of multiplexing that combines data streams by assigning each stream a different time slot in a frame. In TDD systems the uplink and downlink channels can be considered reciprocal. Hence, in TDD systems uplink channel information may be used to achieve spatially selective transmission. 
     As noted above, these descriptions of general meanings of these terms are not intended to be limiting, only illustrative. Other and further applications of the invention, including extensions of these terms and concepts, would be clear to those of ordinary skill in the art after perusing this application. These other and further applications are part of the scope and spirit of the invention, and would be clear to those of ordinary skill in the art, without further invention or undue experimentation. 
     System Elements 
     FIG. 1 shows a block diagram of a system for dynamic link parameter control. 
     A system  100  includes a communications network  110 , a base station controller (BSC)  120 , and one or more customer premises equipment (CPE)  130 . 
     The communications network  110  includes an Internet, intranet, extranet, virtual private network, enterprise network, wireless network, or another form of communications network. 
     In embodiments of the invention where the communications network  110  is a wireless network, the network is generally a hexagon-shaped region of local surface area (known as a cell), such as might be found in a metropolitan region. Use of generally hexagon-shaped regions is known in the art of wireless communication because it allows a local region to be tiled with substantially no gaps. There is, however, no requirement in any embodiment of the invention that a hexagon-shaped cell be used. 
     The BSC  120  includes a processor, program and data memory, and mass storage. In embodiments where the BSC  120  is functioning within a wireless network it also includes one or more antennas for sending and/or receiving information using wireless communication techniques. 
     Similar to the BSC  120 , each CPE  130  includes a processor, program and data memory, and mass storage. In embodiments where the CPE  130  is functioning within a wireless network it also includes one or more antennas for sending and/or receiving information using wireless communication techniques. 
     Communication among devices within the communications network  110  is preferably conducted on a one-to-one basis between each CPE  130  and the BSC  120 . Thus, the BSC  120  communicates with each CPE  130 , and each CPE  130  communicates with the BSC  120 . In a preferred embodiment, no CPE  130  communicates directly with any other CPE  130 . In alternate embodiments, however, a CPE  130  may communicate directly with another CPE  130 , with the characteristics of such communication being controlled by the BSC  120 , by one CPE  130  selected by the BSC  120 , or by one CPE  130  mutually agreed upon among the communicating CPE  130 . 
     Communication between the BSC  120  and each CPE  130  is conducted using a TDD technique, in which time durations are divided into repeated individual frames, each one of which includes a “downstream” portion and an “upstream” portion. Unlike existing protocols in which transmissions are controlled by the transmitting side, the BSC  120  controls transmissions for both upstream and downstream directions, without specific requests from the CPE  130 . 
     During the downstream portion of each frame, the BSC  120  transmits, thus sending information to one or more CPE  130 . During the upstream portion of each frame, each CPE  130  is potentially allocated a time slot for transmission for sending information to the BSC  120 . TDD techniques are known in the art of wireless communication. 
     Method of Operation 
     FIG. 2 shows a time division duplex frame used in a system for dynamic link parameter control. 
     A time division duplex (TDD) frame  200  includes a downstream portion  210 , an upstream portion  220 , and one or more guard bands  230 . 
     The downstream portion  210  includes a map  211  and a sequence of downstream payloads  215 , each sent by the BSC  120  to a selected CPE  130 . The map  211  includes one or more link parameters  213  each sent by the BSC  120  to a selected CPE  130 . Link parameters  213  contain control link parameters to be interpreted by each CPE  130 . 
     The guard bands  230  provide synchronization of data flow within each frame ensuring that no single CPE  130  interferes with another CPE  130  when receiving from the BSC  120  or transmitting to the BSC  120 , and that the downstream portion  210  and upstream portion  220  remain discrete. 
     Similar to the downstream portion  210 , the upstream portion  220  includes a sequence of upstream payloads  221 , each sent by a selected CPE  130  to the BSC  120 . 
     The BSC  120  (not the CPE  130 ), through the use of the link parameters  213 , determines the format of the upstream portion  220 . This includes, but is not limited to, the length of the upstream payloads  221  and their type of encoding. 
     Additionally, through the use of the link parameters  213 , the BSC  120  controls all the parameters of the established communications session with each CPE  130  (for example, baud rate and parity). 
     Dynamic control over the upstream portion  220  and the session connection itself is achieved due to the fact that link parameters  213  are embedded within each frame. Thus, for example, a new set of link parameters  213  contained within the downstream portion  210  of frame N can be received by a frame-N-identified CPE  130  along with a request for data element X in a format identified in the new set of link parameters  213 . The frame-N-identified CPE  130  can respond by transmitting to the BSC  120  data element X in the identified format within the upstream portion  220  of frame N. 
     FIG. 3 shows a process flow of a system for dynamic link parameter control. 
     A method  300  includes a set of flow points and a set of steps. The system  100  performs the method  300 . Although the method  300  is described serially, the steps of the method  300  can be performed by separate elements in conjunction or in parallel, whether asynchronously, in a pipelined manner, or otherwise. There is no particular requirement that the method  300  be performed in the same order, in which this description lists the steps, except where so indicated. 
     At a flow point  301 , the system  100  is in a quiescent state, and the BSC  120  and CPE  130  are ready to begin a TDD frame. 
     At a step  303 , the BSC  120  transmits the downstream portion  210  of a TDD frame  200  to the CPE  130 . 
     At a step  305 , the downstream portion  210  of the TDD frame  200  is received at each CPE  130 . 
     At a step  307 , each CPE  130  extracts the link parameters intended for its use from the map  211 . 
     At a step  309 , each CPE  130  extracts its intended portion of the downstream payloads  215 . 
     At a step  311 , each CPE  130  interprets the link parameters and applies them as appropriate. 
     At a step  313 , each CPE  130  encodes its portion of the upstream payloads  221  and transmits it within the same frame to the BSC  120 . Although step  313  would appear to indicate that each CPE  130  transmits its portion of the upstream payloads  221  simultaneously, it should be noted that transmissions from the CPE  130  to the BSC are in fact multiplexed using the guard bands  230  to ensure proper synchronization. 
     At this step , the BSC  120  and CPE  130  have performed one step of sending and receiving information in a single frame and the process may be repeated at step  301  repeatedly for subsequent frames. 
     Generality of the Invention 
     The invention has general applicability to various fields of use, not necessarily related to the services described above. 
     Other and further applications of the invention in its moss general form, would be clear to those skilled in the art after perusal of this application, and are within the scope and spirit of the invention. 
     Alternative Embodiments 
     Although preferred embodiments are disclosed herein, many variations are possible which remain within the concept, scope, and spirit of the invention, and these variations would become clear to those skilled in the art after perusal of this application.