Abstract:
A technique for transmission of wireless signals across CDMA radio links. Bandwidth is allocated dynamically within a session to specific CDMA subscriber unit based upon data rate determinations. Specifically, a dynamic bandwidth allocation algorithm operates from limits calculated based upon available ports per subscriber, expected user bandwidth, and parallel user bandwidth versus throughput. Provisions for priority service, unbalanced forward and reverse spectrum utilization, voice prioritization, and band switching are also made.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/498,099 filed on Jul. 6, 2009, which is a continuation of U.S. patent application Ser. No. 10/776,558 filed Feb. 11, 2004, which issued as U.S. Pat. No. 7,580,715 on Aug. 25, 2009, which is a continuation of U.S. patent application Ser. No. 10/345,791 filed Jan. 16, 2003, now abandoned, which is a continuation of U.S. patent application Ser. No. 09/596,425 filed Jun. 19, 2000 which issued as U.S. Pat. No. 6,526,281 on Feb. 25, 2003, which is a continuation of U.S. patent application Ser. No. 08/992,760 filed Dec. 17, 1997 which issued as U.S. Pat. No. 6,081,536 on Jun. 27, 2000; which claims the benefit of U.S. Provisional Application Ser. No. 60/050,338 filed Jun. 20, 1997 and U.S. Provisional Application Ser. No. 60/050,277 filed Jun. 20, 1997, which are incorporated by reference as if fully set forth. 
     
    
     BACKGROUND 
       [0002]    The increasing use of wireless telephones and personal computers by the general population has led to a corresponding demand for advanced telecommunication services that were once thought to only be meant for use in specialized applications. 
         [0003]    For example, in the late 1980&#39;s, wireless voice communication such as available with cellular telephony had been the exclusive province of the businessman because of expected high subscriber costs. The same was also true for access to remotely distributed computer networks, whereby until very recently, only business people and large institutions could afford the necessary computers and wireline access equipment. 
         [0004]    However, the general population now increasingly wishes to not only have access to networks such as the Internet and private intranets, but also to access such networks in a wireless fashion as well. This is particularly of concern for the users of portable computers, laptop computers, hand-held personal digital assistants and the like who would prefer to access such networks without being tethered to a telephone line. 
         [0005]    There still is no widely available satisfactory solution for providing low cost, high speed access to the Internet and other networks using existing wireless networks. This situation is most likely an artifact of several unfortunate circumstances. For example, the typical manner of providing high speed data service in the business environment over the wireline network is not readily adaptable to the voice grade service available in most homes or offices. In addition, such standard high speed data services do not lend themselves well to efficient transmission over standard cellular wireless handsets. 
         [0006]    Furthermore, the existing cellular network was originally designed only to deliver voice services. At present, the wireless modulation schemes in use continue their focus on delivering voice information with maximum data rates only in the range of 9.6 kbps being readily available. This is because the cellular switching network in most countries, including the United States, uses analog voice channels having a bandwidth from about 300 to 3600 Hertz. Such a low frequency channel does not lend itself directly to transmitting data at rates of 28.8 kilobits per second (kbps) or even the 56.6 kbps that is now commonly available using inexpensive wire line modems, and which rates are now thought to be the minimum acceptable data rates for Internet access. 
         [0007]    Switching networks with higher speed building blocks are just now coming into use in the United States. Although certain wireline networks, called Integrated Services Digital Networks (ISDN), capable of higher speed data access have been known for a number of years, their costs have only been recently reduced to the point where they are attractive to the residential customer, even for wireline service. Although such networks were known at the time that cellular systems were originally deployed, for the most part, there is no provision for providing ISDN-grade data services over cellular network topologies. 
         [0008]    ISDN is an inherently circuit switched protocol, and was, therefore, designed to continuously send bits in order to maintain synchronization from end node to end node to maintain a connection. Unfortunately, in wireless environments, access to channels is expensive and there is competition for them; the nature of the medium is such that they are expected to be shared. This is dissimilar to the usual wireline ISDN environment in which channels are not intended to be shared by definition. 
       SUMMARY 
       [0009]    The present invention provides high speed data and voice service over standard wireless connections via an unique integration of ISDN protocols and existing cellular signaling such as is available with Code Division Multiple Access (CDMA) type modulated systems. The present invention achieves high data rates through more efficient allocation of access to the CDMA wireless channels. In particular, a number of subchannels are defined within a standard CDMA channel bandwidth, which is normally necessary to support the ISDN protocol, such as by assigning different codes to each subchannel. The instantaneous bandwidth needs of each on-line subscriber unit are met by dynamically allocating multiple subchannels of the RF carrier on an as needed basis for each session. For example, multiple subchannels are granted during times when the subscriber bandwidth requirements are relatively high, such as when downloading Web pages and released during times when the line content is relatively light, such as when the subscriber is reading a Web page which has been previously downloaded or is performing other tasks. 
         [0010]    Subchannel assignment algorithms may be implemented to offer various levels of priority service to particular subscribers. These may be assigned based upon available ports per subscriber, expected user bandwidth, service premium payments, and so on. 
         [0011]    In accordance with another aspect of the invention, some portion of the available bandwidth is initially allocated to establish a communication session. Once the session has been established, if a subscriber unit has no data to present for transmission, namely, if the data path remains quiescent for some period of time, the previously assigned bandwidth is deallocated. In addition, it is preferable that not all of the previously assigned bandwidth be deallocated, but rather at least some portion be kept available for use by an in-session subscriber. If the inactivity continues for a further period of time, then even the remaining portion of the bandwidth can be deallocated from the session. A logical session connection at a network layer protocol is still maintained even if no subchannels are assigned. 
         [0012]    In a preferred arrangement, a single subchannel is maintained for a predetermined minimum idle time for each network layer connection. This assists with more efficient management of channel setup and tear down. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    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. 
           [0014]      FIG. 1  is a block diagram of a wireless communication system making use of a bandwidth management scheme according to the invention. 
           [0015]      FIG. 2  is an Open System Interconnect (OSI) type layered protocol diagram showing where the bandwidth management scheme is implemented in terms of communication protocols. 
           [0016]      FIG. 3  is a diagram showing how subchannels are assigned within a given radio frequency (RF) channel. 
           [0017]      FIG. 4  is a more detailed block diagram of the elements of a subscriber unit. 
           [0018]      FIG. 5  is a state diagram of the operations performed by a subscriber unit to request and release subchannels dynamically. 
           [0019]      FIG. 6  is a block diagram of a portion of a base station unit necessary to service each subscriber unit. 
           [0020]      FIG. 7  is a high level structured English description of a process performed by the base station to manage bandwidth dynamically according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Turning attention now to the drawings more particularly,  FIG. 1  is a block diagram of a system  100  for providing high speed data and voice service over a wireless connection by seamlessly integrating a digital data protocol such as, for example, Integrated Services Digital Network (ISDN) with a digitally modulated wireless service such as Code Division Multiple Access (CDMA). 
         [0022]    The system  100  consists of two different types of components, including subscriber units  101 ,  102  and base stations  170 . Both types of these components  101  and  170  cooperate to provide the functions necessary in order to achieve the desired implementation of the invention. The subscriber unit  101  provides wireless data services to a portable computing device  110  such as a laptop computer, portable computer, personal digital assistant (PDA) or the like. The base station  170  cooperates with the subscriber unit  101  to permit the transmission of data between the portable computing device  110  and other devices such as those connected to the Public Switched Telephone Network (PSTN)  180 . 
         [0023]    More particularly, data and/or voice services are also provided by the subscriber unit  101  to the portable computer  110  as well as one or more other devices such as telephones  112 - 1 ,  112 - 2  (collectively referred to herein as telephones  112 . (The telephones  112  themselves may in turn be connected to other modems and computers which are not shown in  FIG. 1 ). In the usual parlance of ISDN, the portable computer  110  and telephones  112  are referred to as terminal equipment ((TE). The subscriber unit  101  provides the functions referred to as a network termination type 1 (NT-1). The illustrated subscriber unit  101  is in particular meant to operate with a so-called basic rate interface (BRI) type ISDN connection that provides two bearer or “B” channels and a single data or “D” channel with the usual-designation-being 2B+D. 
         [0024]    The subscriber unit  101  itself consists of an ISDN modem  120 , a device referred to herein as the protocol converter  130  that performs the various functions according to the invention including spoofing  132  and bandwidth management  134 , a CDMA transceiver  140 , and subscriber unit antenna  150 . The various components of the subscriber unit  101  may be realized in discrete devices or as an integrated unit. For example, an existing conventional ISDN modem  120  such as is readily available from any number of manufacturers may be used together with existing CDMA transceivers  140 . In this case, the unique functions are provided entirely by the protocol converter  130  which may be sold as a separate device. Alternatively, the ISDN modem  120 , protocol converter  130 , and CDMA transceiver  140  may be integrated as a complete unit and sold as a single subscriber unit device  101 . 
         [0025]    The ISDN modem  120  converts data and voice signals between the terminal equipment  110  and  112  to format required by the standard ISDN “U” interface. The U interface is a reference point in ISDN systems that designates a point of the connection between the network termination (NT) and the telephone company. 
         [0026]    The protocol converter  130  performs spoofing  132  and basic bandwidth management  134  functions, which will be described in greater detail below. In general, spoofing  132  consists of insuring that the subscriber unit  101  appears to the terminal equipment  110 ,  112  that is connected to the public switched telephone network  180  on the other side of the base station  170  at all times. 
         [0027]    The bandwidth management function  134  is responsible for allocating and deallocating CDMA radio channels  160  as required. Bandwidth management also includes the dynamic management of the bandwidth allocated to a given session by dynamically assigning sub-portions of the CDMA channels  160  in a manner which is more fully described below. 
         [0028]    The CDMA transceiver  140  accepts the data from the protocol converter  130  and reformats this data in appropriate form for transmission through a subscriber unit antenna  150  over CDMA radio link  160 - 1 . The CDMA transceiver  140  may operate over only a single 1.25 MHz radio frequency channel or, alternatively, in a preferred embodiment, may be tunable over multiple allocatable radio frequency channels. 
         [0029]    CDMA signal transmissions are then received at the base station and processed by the base station equipment  170 . The base station equipment  170  typically consists of multichannel antennas  171 , multiple CDMA transceivers  172 , and a bandwidth management functionality  174 . Bandwidth management controls the allocation of CDMA radio channels  160  and subchannels. The base station  170  then couples the demodulated radio signals to the Public Switch Telephone Network (PSTN)  180  in a manner which is well known in the art. For example, the base station  170  may communicate with the PSTN  180  over any number of different efficient communication protocols such as primary rate ISDN, or other LAPD based protocols such as IS-634 or V5.2. 
         [0030]    It should also be understood that data signals travel bidirectionally across the CDMA radio channels  160 , i.e., data signals originate at the portable computer  110  are coupled to the PSTN  180 , and data signals received from the PSTN  180  are coupled to the portable computer  110 . 
         [0031]    Other types of subscriber units-such-as unit  102  may be used to provide higher speed data services. Such subscriber units  102  typically provide a service referred to as nB+D type service that may use a so-called Primary Rate Interface (PRI) type protocol to communicate with the terminal equipment  110 ,  112 . These units provide a higher speed service such as 512 kbps across the U interface. Operation of the protocol converter  130  and CDMA transceiver  140  are similar for the nB+D type subscriber unit  102  as previously described for subscriber unit  101 , with the understanding that the number of radio links  160  to support subscriber unit  102  are greater in number or each have a greater bandwidth. 
         [0032]    Turning attention now to  FIG. 2 , the invention may be described in the context of an Open Systems Interconnect multilayer protocol diagram. The three protocol stacks  220 ,  230 , and  240  are for the ISDN modem  120 , protocol converter  130 , and base station  170 , respectively. 
         [0033]    The protocol stack  220  used by the ISDN modem  120  is conventional for ISDN communications and includes, on the terminal equipment side, the analog to digital conversion (and digital to analog conversion)  221  and digital data formatting  222  at layer one, and an applications layer  223  at layer two. On the U interface side, the protocol functions include Basic Rate Interface (BRI) such as according to standard 1.430 at layer one, a LAPD protocol stack at layer two, such as specified by standard Q.921, and higher level network layer protocols such as Q.931 or X.227 and high level end to end signaling  228  required to establish network level sessions between modes. 
         [0034]    The lower layers of the protocol stack  220  aggregate two bearer (B)-channels to achieve a single 128 kilobits per second (kbps) data rate in a manner which is well known in the art. Similar functionality can be provided in a primary rate interface, such as used by subscriber unit  102 , to aggregate multiple B channels to achieve up to 512 kbps data rate over the U interface. 
         [0035]    The protocol stack  230  associated with the protocol converter  130  consists of a layer one basic rate interface  231  and a layer two LAPD interface  232  on the U interface side, to match the corresponding layers of the ISDN modem stack  220 . 
         [0036]    At the next higher layer, usually referred to as the network layer, a bandwidth management functionality  235  spans both the U interface side and the CDMA radio link side of the protocol converter stack  230 . On the CDMA radio link side  160 , the protocol depends upon the type of CDMA radio communication in use. An efficient wireless protocol referred to herein as EW[x]  234 , encapsulates the layer one  231  and layer two  232  ISDN protocol stacks in such a manner that the terminal equipment  110  may be disconnected from one or more CDMA radio channels without interrupting a higher network layer session. 
         [0037]    The base station  170  contains the matching CDMA  241  and EW[x]  242  protocols as well as bandwidth management  243 . On the PSTN side, the protocols may convert back to basic rate interface  244  and LAPD  245  or may also include higher level network layer protocols as Q.931 or V5.2  246 . 
         [0038]    Call processing functionality  247  allows the network layer to set up and tear down channels and provide other processing required to support end to end session connections between nodes as is known in the art. 
         [0039]    The spoofing function  132  performed by the EW[x] protocol  234  includes the necessary functions to keep the U interface for the ISDN connection properly maintained, even in the absence of a CDMA radio link  160  being available. This is necessary because ISDN, being a protocol originally developed for wire line connections, expects to send a continuous stream of synchronous data bits regardless of whether the terminal equipment at either end actually has any data to transmit. Without the spoofing function  132 , radio links  160  of sufficient bandwidth to support at least a 192 kbps data rate would be required throughout the duration of an end to end network layer session, whether or not data is actually presented. 
         [0040]    EW[x]  234  therefore involves having the CDMA transceiver  140  loop back these synchronous data bits over the ISDN communication path to spoof the terminal equipment  110 ,  112  into believing that a sufficiently wide wireless communication link  160  is continuously available. However, only when there is actually data present from the terminal equipment to the wireless transceiver  140  is wireless bandwidth allocated. Therefore, unlike the prior art, the network layer need not allocate the assigned wireless bandwidth for the entirety of the communications session. That is, when data is not being presented upon the terminal equipment to the network equipment, the bandwidth management function  235  deallocates initially assigned radio channel bandwidth  160  and makes it available for another transceiver and another subscriber unit  101 . 
         [0041]    In order to better understand how bandwidth management  235  and  243  accomplish the dynamic allocation of radio bandwidth, turn attention now to  FIG. 3 . This figure illustrates one possible frequency plan for the wireless links  160  according to the invention. In particular, a typical transceiver  170  can be tuned on command to any 1.25 MHz channel within a much larger bandwidth, such as up to 30 MHz. In the case of location in an existing cellular radio frequency bands, these bandwidths are typically made available in the range of from 800 to 900 MHz. For personal communication systems (PCS) type wireless systems, the bandwidth is typically allocated in the range from about 1.8 to 2.0 GigaHertz (GHz). In addition, there are typically two matching bands active simultaneously, separated by a guard band, such as 80 MHz; the two matching bands form a forward and reverse full duplex link. 
         [0042]    Each of the CDMA transceivers, such as transceiver  140  in the subscriber unit  101  and transceivers  172  in the base station  170 , are capable of being tuned at any given point in time to a given 1.25 MHz radio frequency channel. It is generally understood that such 1.25 MHz radio frequency carrier provides, at best, a total equivalent of about 500 to 600 kbps maximum data rate transmission within acceptable bit error rate limitations. 
         [0043]    In the prior art, it was thus generally understood that in order to support an ISDN type like connection which may contain information at a rate of 128 kbps that, at best, only about (500 kbps/128 kbps) or only 3 ISDN subscriber units could be supported at best. 
         [0044]    In contrast to this, the present invention subdivides the available approximately 500 to 600 kbps bandwidth into a relatively large number of subchannels. In the illustrated example, the bandwidth is divided into 64 subchannels  300 , each providing an 8 kbps data rate. A given subchannel  300  is physically implemented by encoding a transmission with one of a number of different assignable pseudorandom codes. For example, the 64 subchannels  300  may be defined within a single CDMA RF carrier by using a different orthogonal Walsh codes for each defined subchannel  300 . 
         [0045]    The basic idea behind the invention is to allocate the subchannels  300  only as needed. For example, multiple subchannels  300  are granted during times when a particular ISDN subscriber unit  101  is requesting that large amounts of data be transferred. These subchannels  300  are released during times when the subscriber unit  101  is relatively lightly loaded. 
         [0046]    Before discussing how the subchannels are preferably allocated and deallocated, it will help to understand a typical subscriber unit  101  in greater detail. Turning attention now to  FIG. 4 , it can be seen that an exemplary protocol converter  130  consists of a microcontroller  410 , reverse link processing  420 , and forward link processing  430 . The reverse link processing  420  further includes ISDN reverse spoofer  422 , voice data detector  423 , voice decoder  424 , data handler  426 , and channel multiplexer  428 . The forward link processing  430  contains analogous functions operating in the reverse direction, including a channel multiplexer  438 , voice data detector  433 , voice decoder  434 , data handler  436 , and ISDN forward spoofer  432 . 
         [0047]    In operation, the reverse link  420  first accepts channel data from the ISDN modem  120  over the U interface and forwards it to the ISDN reverse spoofer  432 . Any repeating, redundant “echo” bits are removed from data received and once extracted, sent to the forward spoofer  432 . The remaining layer three and higher level bits are thus information that needs to be sent over a wireless link. 
         [0048]    This extracted data is sent to the voice decoder  424  or data handler  426 , depending upon the type of data being processed. 
         [0049]    Any D channel data from the ISDN modem  120  is sent directly to voice data detection  423  for insertion on the D channel inputs to the channel multiplexer  428 . The voice data detection circuit  423  determines the content of the D channels by analyzing commands received on the D channel. 
         [0050]    D channel commands may also be interpreted to control a class of wireless services provided. For example, the controller  410  may store a customer parameter table that contains information about the customer&#39;s desired class of service which may include parameters such as maximum data rate and the like. Appropriate commands are thus sent to the channel multiplexer  428  to request one or more required subchannels  300  over the radio links  160  for communication. Then, depending upon whether the information is voice or data, either the voice decoder  424  or data handler  426  begins feeding data inputs to the channel multiplexer  428 . 
         [0051]    The channel multiplexer  428  may make further use of control signals provided by the voice data detection circuits  423 , depending upon whether the information is voice or data. 
         [0052]    In addition, the CPU controller  410 , operating in connection with the channel multiplexer  428 , assists in providing the necessary implementation of the EW[x] protocol  234  between the subscriber unit  101  and the base station  170 . For example, subchannel requests; channel setup, and channel tear down commands are sent via commands placed on the wireless control channel  440 . These commands are intercepted by the equivalent functionality in the base station  170  to cause the proper allocation of subchannels  300  to particular network layer sessions. 
         [0053]    The data handler  426  provides an estimate of the data rate required to the CPU controller  410  so that appropriate commands can be sent over the control channel  440  to allocate an appropriate number of subchannels. The data handler  426  may also perform packet assembly and buffering of the layer three data into the appropriate format for transmission. 
         [0054]    The forward link  430  operates in analogous fashion. In particular, signals are first received from the channels  160  by the channel multiplexer  438 . In response to receiving information on the control channels  440 , control information is routed to the voice data detection circuit  433 . Upon a determination that the received information contains data, the received bits are routed to the data handler  436 . Alternatively, the information is voice information, and routed to the voice decoder  434 . 
         [0055]    Voice and data information are then sent to the ISDN forward spoofer  432  for construction into proper ISDN protocol format. This assembly of information is coordinated with the receipt of echo bits from the ISDN reverse spoofer  422  to maintain the proper expected synchronization on the U interface with the ISDN modem  120 . 
         [0056]    It can now be seen how a network layer communication session may be maintained even though wireless bandwidth initially allocated for transmission is reassigned to other uses when there is no information to transmit. In particular, the reverse  422  and forward  432  spoofers cooperate to loop back non-information bearing signals, such as flag patterns, sync bits, and other necessary information, so as to spoof the data terminal equipment connected to the ISDN modem  120  into continuing to operate as though the allocated wireless path over the CDMA transceiver  150  is continuously available. 
         [0057]    Therefore, unless there is an actual need to transmit information from the terminal equipment being presented to the channel multiplexers  428 , or actual information being received from the channel multiplexers  438 , the invention may deallocate initially assigned subchannel  300 , thus making them available for another subscriber unit  101  of the wireless system  100 . 
         [0058]    The CPU controller  410  may also perform additional functions to implement the EW[x] protocol  234 , including error correction, packet buffering, and bit error rate measurement. 
         [0059]    The functions necessary to implement bandwidth management  235  in the subscriber unit  101  are carried out in connection with the EW[x] protocol typically by the CPU controller  410  operating in cooperation with the channel multiplexers  428 ,  438 , and data handlers  420 ,  436 . In general, bandwidth assignments are made for each network layer session base&amp; upon measured short term data rate needs. One or more subchannels  300  are then assigned based upon these measurements and other parameters such as amount of data in queue or priority of service as assigned by the service provider. In addition, when a given session is idle, a connection is preferably still maintained end to end, although with a minimum number of, such as a single subchannel being assigned. For example, this single subchannel may eventually be dropped after a predetermined minimum idle time is observed. 
         [0060]      FIG. 5  is a detailed view of the process by which a subscriber unit  101  may request subchannel  300  allocations from the base station  170  according to the invention. In a first state  502 , the process is in an idle state. At some point, data becomes ready to transmit and state  504  is entered, where the fact that data is ready to be transmitted may be detected by an input data buffer in the data handler  426  indicated that there is data ready. 
         [0061]    In state  504 , a request is made, such as via a control channel  440  for the allocation of a subchannel to subscriber unit  101 . If a subchannel is not immediately available, a pacing state  506  may be entered in which the subscriber unit simply waits and queues its request for a subchannel to be assigned. 
         [0062]    Eventually, a subchannel  300  is granted by the base station and the process continues to state  508 . In this state, data transfer may then begin using the single assigned subchannel. The process will continue in this state as long as the single subchannel  300  is sufficient for maintaining the required data transfer and/or is being utilized. However, if the input buffer should become empty, such as notified by the data handler  426 , then the process will proceed to a state  510 . In this state  510 , the subchannel will remain assigned in the event that data traffic again resumes. In this case, such as when the input buffer begins to once again become full and data is again ready to transmit, then the process returns to state  508 . However, from state  510  should a low traffic timer expire, then the process proceeds to state  512  in which the single subchannel  300  is released. The process then returns to the idle state  502 . In state  512 , if a queue request is pending from states  506  or  516 , the subchannel is used to satisfy such request instead of releasing it. 
         [0063]    Returning to state  508 , if instead the contents of the input buffer are beginning to fill at a rate which exceeds a predetermined threshold indicating that the single subchannel  300  is insufficient to maintain the necessary data flow, then a state  514  is entered in which more subchannels  300  are requested. A subchannel request message is again sent over the control channel  440  or through a subchannel  300  already allocated. If additional subchannels  300  are not immediately available, then a pacing state  516  may be entered and the request may be retried by returning to state  514  and  516  as required. Eventually, an additional subchannel will be granted and processing can return to state  508 . 
         [0064]    With the additional subchannels being now available, the processing continues to state  518  where data transfer may be made on a multiple N of the subchannels. This may be done at the same time through a channel bonding function or other mechanism for allocating the incoming data among the N subchannels. As the input buffer contents is reduced below an empty threshold, then a waiting state  520  may be entered. 
         [0065]    If, however, a buffer filling rate is exceeded, then state  514  may be entered in which more subchannels  300  are again requested. 
         [0066]    In state  520 , if a high traffic timer has expired, then one or more of the additional subchannels are released in state  522  and the process returns to state  508 . 
         [0067]      FIG. 6  is a block diagram of the components of the base station equipment  170  of the system  100 . These components perform analogous functions to those as already described in detail in  FIG. 4  for the subscriber unit  101 . It should be understood that a forward link  620  and reverse link  630  are required for each subscriber unit  101  or  102  needing to be supported by the base station  170 . 
         [0068]    The base station forward link  620  functions analogously to the reverse link  420  in the subscriber unit  100 , including a subchannel inverse multiplexer  622 , voice data detection  623 , voice decoder  624 , data handler  626 , and ISDN spoofer  622 , with the understanding that the data is traveling in the opposite direction in the base station  170 . Similarly, the base station reverse link  630  includes components analogous to those in the subscriber forward link  430 , including an ISDN spoofer  632 , voice data detection  633 , voice decoder  634 , data handler  636 , and subchannel multiplexer  638 . The base station  170  also requires a CPU controller  610 . 
         [0069]    One difference between the operation of the base station  170  and the subscriber unit  101  is in the implementation of the bandwidth management functionality  243 . This may be implemented in the CPU controller  610  or in another process in the base station  170 . 
         [0070]    A high level description of a software process performed by dynamic channel allocation portion  650  of the bandwidth management  243  is contained in  FIG. 7 . This process includes a main program  710 , which is continuously executed, and includes processing port requests, processing bandwidth release, and processing bandwidth requests, and then locating and tearing down unused subchannels. 
         [0071]    The processing of port requests is more particularly detailed in a code module  720 . These include upon receiving a port request, and reserving a subchannel for the new connection, preferably chosen from the least utilized section of the radio frequency bandwidth. Once the reservation is made, an RF channel frequency and code assignment are returned to the subscriber unit  101  and a table of subchannel allocations is updated. Otherwise, if subchannels are not available, then the port request is added to a queue of port requests. An expected waiting time may be estimated upon the number of pending port requests and priorities, and an appropriate wait message can be returned to the requesting subscriber unit  101 . 
         [0072]    In a bandwidth release module  730 , the channel bonding function executing in the multiplexer  622  in the forward link is notified of the need to release a subchannel. The frequency and code are then returned to an available pool of subchannels and a radio record is updated. 
         [0073]    The following bandwidth request module  740  may include selecting the request having the highest priority with lowest bandwidth utilization. Next, a list of available is subchannels is analyzed for determining the greatest available number. Finally, subchannels are assigned based upon need, priority, and availability. A channel bandwidth bonding function is notified within the subchannel multiplexer  622  and the radio record which maintains which subchannels are assigned to which connections is updated. 
         [0074]    In the bandwidth on demand algorithm, probability theory may typically be employed to manage the number of connections or available ports, and the spectrum needed to maintain expected throughput size and frequency of subchannel assignments. There may also be provisions for priority service based upon subscribers who have paid a premium for their service. 
         [0075]    It should be understood, for example, that in the case of a supporting 128 kbps ISDN subscriber unit  101  that even more than 16.times.8 kbps subchannels may be allocated at a given time. In particular, one may allow a larger number, such as  20  subchannels, to be allocated to compensate for delay and reaction in assigning subchannels. This also permits dealing with bursts of data in a more efficient fashion such as typically experienced during the downloading of Web pages. 
         [0076]    In addition, voice traffic may be prioritized as against data traffic. For example, if a voice call is detected, at least one subchannel  300  may be active at all times and allocated exclusively to the voice transfer. In that way, voice calls blocking probability will be minimized. 
         [0077]    Equivalents 
         [0078]    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. 
         [0079]    For example, instead of ISDN, other wireline digital protocols may be encapsulated by the EW[x] protocol, such as xDSL, Ethernet, and X.25, and therefore may advantageously use the dynamic wireless subchannel assignment scheme described herein. 
         [0080]    Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described specifically herein. Such equivalents are intended to be encompassed in the scope of the claims.