Abstract:
A system for wireless communication comprises an architecture of routers connected to a network and having connected transceivers for wireless transmission and reception of data, and a plurality of hand-held commuoicators adapted for users to communicate with the network through the routers. The system is adapted to provide wireless Data Network Telephony (DNT), and the hand-held communicators execute Quality of Service (QoS) code adapted to prioritize DNT packet code over all non-DNT traffic, thereby preserving the real-time nature of the DNT code.

Description:
CROSS-REFERENCE TO RELATED DOCUMENTS 
     The present invention application is a reissue application of U.S. Pat. No. 6,795,406 which issued on Sep. 21, 2004 based on application Ser. No. 09/955,323 filed on Sep. 17, 2001, which is a divisional application of prior co-pending application Ser. No. 09/351,998 filed on Jul. 12, 1999, now U.S. Pat. No. 6,625,126, entitled: “Methods and Apparatus for Enhancing Wireless Data Network Telephony, Including Quality of Service”, which is a divisional application of Ser. No. 09/069,221 filed on Apr. 28, 1998, now U.S. Pat. No. 6,078,566. The specification for Ser. No. 09/351,998 filed on Jul. 12, 1999 is incorporated herein in its entirety by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention is in the field of network communications, including Data Network Telephony (DNT), such as lnternet Protocol Network Telephony (lPNT) and pertains more particularly to methods and apparatus for enhancing DNT in narrow bandwidth wireless links. 
     BACKGROUND OF THE INVENTION 
     The art of telephony communication has grown in proportion with improved telephony infrastructure, equipment, and methods of practice. Conventionally and historically telephone communication has been practiced by use of networks that provide dedicated connections and guaranteed bandwidth, such as in Publicly Switched Telephony Networks (PSTN). ln such networks a call placed from a telephone connected to a local service is switched over dedicated channels to a destination, and as long as the connection is maintained, the dedicated path, having a dedicated bandwidth, is also maintained. Such networks may he termed Connection Oriented/Switched Telephony (COST) networks, and this term is used in this specification. 
     More recently, with the development of extensive data networks, of which the well-known Internet is a prime example, a newer type of telephony communication has been introduced. This form of telephony is termed herein Data Network Telephony (DNT), and, in the context of the Internet data network lnternet Protocol Network Telephony (IPNT). Data networks typically link computers over one or more sub-nets, which may include local area networks (LAN), wide area networks (WAN) such as the lnternet, company lntranets, and combinations of these and other data networks. 
     In DNT, such as lPNT, dedicated connectinns are not provided except in rare and special instances. Instead, digital audio data is prepared in standardized audio packets complete with header information and the like. The packets are prepared in near real-time and broadcast over the data network(s) connecting involved computers adapted for DNT applications. The header for each packet includes a destination for the packet. 
     Data Network Telephony, such as IPNT is well-known in the art, and wireless data transmission is also quite well-known in many applications. Internet service providers, for example, are recently providing high data-rate wireless Internet access by satellite systems, and, where bandwidth is not substantially restricted at the receiver&#39;s end, such systems have proven successful for WEB page delivery and the like. Such systems have not proved to be friendly for DNT applications, and there are a number of reasons, which apply to these kinds of systems and to other kinds of wireless systems of more limited bandwidth even more so. 
     The problems for Data Network Telephony in wireless systems are related tn the real-time nature of telephony data and the typically limited bandwidth available in such systems. In relatively high-bandwidth systems having a relatively large number of users the distribution probabilities provide a situation where it is uncommon for several or many users to demand unusual bandwidth at the same time. The phenomenon is known in the art as averaging. Even with known high-use times, it can be expected that distribution will be such that bandwidth will be adequate. In most wireless systems however, bandwidth is more precious, and averaging is hence not as helpful. 
     A contributing problem is in the nature of real-time audio data as opposed to data transmitting stored documents and the like, which may be called data-data as opposed to voice-data. Data-data is prepared in packets for transmission from stored data of known capacity. The number of data packets needed to transmit a stored document, whether text, graphic, audio, or other, is a known quantity. Moreover, there is no fundamental loss if such data becomes delayed in transit. Once it arrives at a destination, the document may be reproduced. 
     Voice-data packets for real-time conversations are different. The packets for voice-data have to be prepared and transmitted in essentially real time in both directions or a meaningful conversation cannot be held. Moreover, the magnitude of packaged voice-data for a conversation will be inflated by acoustical background noise, which under some conditions can double or triple or even further multiply the amount of data having to be sent, imposing severe demand on available bandwidth. 
     The inventor has carefully considered the possibilities of a number of types of potential DNT applications, and has determined that it is desirable to provide DNT in wireless systems of many sorts to take advantage of some of the inherent advantages of DNT over dedicated connection-type telephony systems, and to provide DNT capability in systems that also are capable of data transfer of the data-data type described above, such as of stored digital documents and entities. A novel system in this patent application is proposed, for example, using relatively small, battery-powered, hand-held computer communicators with DNT capability to be carried by users within range of multiple Network lnterface Adapters (satellite transceivers). In a preferred embodiment wireless communication is provided by RF signaling. The invention, however, is not limited to RF, and could be implemented in an Infra system or any other system providing wireless communication. 
     In such a system the Network lnterface Adapters may he coupled, for example, to a Local Area Network. Such a system would be quite useful on a company premises for workers to keep in touch, hold phone conversations, share documents locally (Campus lntranet), and communicate with the lnternet and other connected computers as well (Inter Campus lntranets or Extranets). Many variations of such systems are possible, but present technology does not render such systems really practical. Methods and apparatus according to various embodiments and aspects of the present invention, taught in enabling detail below, provide substantial improvements rendering such voice/data systems on narrow bandwidth links quite feasible and useful. 
     SUMMARY OF THE INVENTION 
     In a preferred embodiment of the present invention a data network telephony (DNT) system is provided, comprising a base station connected to a DNT-capable data network and to a wireless transceiver and adapted to operate the transceiver by a two-way, narrow-baod, multiple-chaonel, real-time duplex radio protocol, and to process DNT calls on the DNT-capable data network and to broadcast and receive the DNT calls to and from the plurality of communicator units via the transceiver as DNT data packets; aod a plurality of portable computer-enhanced communicator units, including microphooe and speaker apparatus, each adapted to communicate with the base station by the two-way real-time radio protocol and to process DNT calls. The portable, computer-enhaoced communicator units are adapted to prioritize DNT data over other data when transmitting on the wireless network, such that DNT data always is processed before non-DNT data. 
     In one embodiment the DNT-capable data network is a local area network (LAN). 
     Io some embodiments one or more of the communicator units is equipped with Digital Sigoal Processors (DSPs) adapted for recognizing human speech, and wherein audio data for DNT calls is processed hy the DSPs, allowiog substantially only human speech to be prepared as DNT packets for transmission. In other embodiments ooe or more of the communicator units is equipped with noise cancellation microphone and speaker apparatus adapted for creating a noise reduction zone in tbe region of a principle speech input microphone. 
     In aootber aspect, in a system providing wireless communication between a portable communication unit and a base station over a dedicated channel, wherein the portable device is adapted for Data Network Telephony (DNT), a method is provided for enhancing quality of DNT calls, comprising steps of (a) monitoring all outgoing wireless traffic at the portable communication unit; (h) recognizing DNT data as opposed to non-DNT data; and (c) transmitting DNT data always with preference over non-DNT data. In this method, in some embodiments the portable communication unit comprises a CPU and a memory, and the method is provided by the CPU executing a Quality of Service (QoS) algorithm stored in the memory. In other embodiments the method is provided by the CPU executing Quality of Service (QoS) code prnvided as a portion of an operating system (OS) or a BIOS. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         FIG. 1  is an architectural overview of a wireless DNT system according to ao embodiment of the present invention. 
         FIG. 2  is a system diagram of the components and connectivity of components within a hand-held DNT device and associated network elements according to an embodiment of the present invention. 
         FIG. 3A  is a block diagram illustratiog DSP function according to an embodiment of the present invention. 
         FIG. 3B  is a perspective view of unit  100  of  FIG. 1  showing speaker and microphone placement. 
         FIG. 4  is a conceptual diagram illustrating QoS components and negotiation according to an embodiment of the preseot ioveotion. 
         FIG. 5  is a block diagram illustrating dynamic address translation according to an embodiment of the present iovention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is an architectural overview of a wireless DNT voice-data system  99  according to ooe embodiment of the preseot inveotion. Wireless voice/data system  99  comprises a plurality of receiving/sending hand-held units  100 - 600  that may be carried and used by individuals mohile throughout a local area such as a corporate campus baviog several buildings, aod so oo. System  99  in various embodiments is a radio-frequency (RF) based communication system, aod may be a time-division-duplex multiple access (TDMA) system, a code-divisioo multiple access (CDMA) system, or any other type two-way wireless protocol system, all of which are well-known in the art or may be inveoted io the future, but that are essentially wireless systems. 
     ln other embodiments, voice/data system  99  may operate via infrared or other known or future form of wireless communication. Radio frequency systems are used in this embodiment for illustratioo because of their flexibility aod abundance in the art. In some situations a combination of wireless technology may be used such as RF in combination with infrared capability with the infrared capability attributed to peripheral devices that may be used with a system. 
     Each hand-held uoit  100 - 600  (there may be more or fewer) is of the form of a portable computer and communication device such as a palm-top computer. Such devices are knowo io the art and may be suitable for practice of the preseot iovention with addition of certain elements which will he clear from following descriptions. Each receiving/sending unit communicates via RF, as previously described, and has an RF interface module such as ioterface module  109  that is capable of receiviog and sending radio signals and has a oetwork ioterface capability. 
     Each unit  100 - 600  has appropriate computer functionality attributed to palm-top and other portable style computers, and is powered, in most embodiments, via rechargeable battery. ln some embodiments where portability is not an issue, they may be powered electrically via wall socket adapters as well, with recharge capability for battery packs. However, in a preferred embodiment unit  100  is portable. It will be apparent to the skilled artisan that many more units as allowed by available bandwidth may be used within a voice/data system  99 . 
     Each unit  100 - 600  is capable of communicating in RF mode with a satellite transceiver  400  that may be located io a convenient proximity (communication range) to the sum of portable units within a sub-net of system  99 . Satellite traosceiver  400  is dedicated to broadcasting and receiving data in RF mode to and from each unit such as unit  100 - 600  and has appropriate interface capability for computer communication as well as radio frequency sending and receiving capability. Satellite transceiver  400  is linked via dedicated digital connection  401  to a router  410  in the embodiment shown. This link may be any one of many sorts, such as serial pair, optical liok, and so on. 
     Router  410  is, more specifically, a digital routing oode, adapted for routing data packets as in a digital network like the Internet. However, io some specialized embodimeots wherein calls are received from a telephone network such as the Public Switch Telephone Network (PSTN) as well as from a digital network, a router encompassiog both types of telephony capabilities may be used. A router with dual capability (i.e. routing both PSTN calls that are converted to DNT calls and originally sourced DNT calls) is known to the inventor. 
     Router  410  is linked via digital network connection to a network  500 . Network  500  may be of the form of a local area network (LAN), a wide area network (WAN), the Internet, an lntranet, or another type of public or private digital network koowo in the art. Router  410  may be further linked as illustrated via dedicated coonections  411 , and  412  to other routers or transceivers (not shown) as would be the case with a multi-distributed system wherein voice/data systems such as system  99  are duplicated and distributed over a larger geographical area (i.e. a campus) and lioked to a network such as network  500 . Dedicated connections  411  and  412  are identical in scope to connection  401  as previously described. 
     lo an exemplary system according to the inveotion, each transceiver, such as transceiver  400 , communicates with users over 16 dedicated narrow-bandwidth channels. There may be, in some instances, more than 16 uoits  100 - 600  in a transceiver area and assigned to users and a transceiver channel. In some cases, a channel may be shared by two or more infrequent users while a frequeot user may have a dedicated channel. In embodiments of system  99  having multiple transceivers, users with communication devices roam from system to system as will be described further below. 
     According to a preferred embodiment of the present invention, DNT such as IPNT may be practiced by a user operating a portable communication device such as unit  100  while connected in wireless mode to a voice/data system such as system  99 , enabling the user to actively send and receive real-time data associated with DNT as well as to perform other data tasks such as file downloading, uploading and the like without losing the quality of the real-time DNT communication. Such a user may also roam away from and out of range of system  99 , in a multi-distributed embodiment, wherein any real-time data that was sent but not received by the user as he or she moves between transceiver regioos is immediately rerouted as the user is associated with a new satellite traosceiver. This feature allows a user to be completely mobile during real-time data transfer. 
     As previously described with refereoce to the background section, DNT is not curreotly practical wheo practiced on networks having narrow dedicated bandwidth such as TDMA or CDMA systems as compared to high bandwidth systems (i.e. satellite wireless aod coooection-oriented systems) whereio sufficient bandwidth for DNT and other data transfer can be assured by packet averaging techniques and so on. Therefore, it is an object of the invention to provide method and apparatus for enabling successful and ecooomical practice of DNT including IPNT over wireless networks of the prevalently existing narrow-bandwidth type described above. Such method and apparatus of the present invention is detailed in various embodiments below. 
       FIG. 2  is a system diagram of the components and connectivity of compooents within voice/data unit  100  of  FIG. 1 , and associated network elements external to unit  100  according to an embodiment of tbe present inveotion. Voice/data haod-held unit  100  is shown in  FIG. 2  as a block diagram to reveal various components aod features, some of which are enabling to unique features of the preseot invention, aod some of which are standard features available in current art and geoeric to such devices. 
     Unit  100  has a central processing unit (CPU)  101  in this embodiment including a digital signal processor (DSP)  101 a. ln some embodiments, DSP  101 a may be separate from CPU  101 , such as a separate chip communicating on bus  113 . DSP  101 a is adapted for voice recognition and may discern human voice from background ooise. DSP functionality as provided in tbis embodimeot is unique and is described in further detail below. 
     Because unit  100  is a portable computer as well as a DNT communication device, suitable memory for storing programs and data is provided as memory (MEM)  102  and non-volatile memory (NV MEM)  103 . 
     A speech system  104  contains the necessary components for enabling DNT and lPNT telephony communication, aod for doing necessary A/D and D/A conversion between digital voice-data and analog voice signals from a microphone (mic) or to operate a speaker. In this embodiment, a microphone  106  and a speaker  105  are provided for audible send and receive fuoction. ln some cases ao additional ooise cancellation microphone  106 b and a ooise caoccllatioo speaker  105 b are included for tbe purpose of minimizing background noise. More detail regarding this unique noise elimination technique as applied to an embodiment of the present invention is provided below. 
     An infrared transceiver  107  is provided for the purpose of interfacing with peripherals that communicate via infrared sigoal. Iofrared transceiver  107  accepts input from such peripherals and converts the data to digital form for bus  113 . Of course aoy other type of wired (such as USB) or wireless desktop network could he employed, including but oot limited to induction, RF and so forth. Data-data, as referenced in the background section, such as file documents and the like, may be converted to infrared data aod stored, executed, or printed on infrared-capable peripherals that may be used with system  99 . 
     A standard keyboard  112  and screen  110  are provided to unit  100  as with most portable computers. The screen may be any of a broad variety of such devices as known in the art. The keyboard may be a QWERTY keyhoard or another sort. A mini-keyboard  111  may also adapt to unit  100  io some embodiments instead of keyboard  112  for the purpose of input for operation of unit  100 , for example mimicking a simple telephone interface. Similarly, peripheral devices such as a full size keyboard  151  a PC  152  may communicate with unit  100  via infrared or other wired or wireless link as previously described. RF interface  109  provides digital wireless interface witb transceiver  400 . 
     It will be apparent to one with skill in the art that there may be generic or new features inherent or koowo to the inventor to a palm-top or lap-top computer that are not described in detail in this embodiment. The inventor intends only to detail those aspects incorporated into unit  100  that are relevant to operation of the present invention. Commonly found components such as screen  110  aod keyboard  112  will not be described with great detail because to do so may obscure the innovative aspects of the present invention. More detail regarding the iooovative aspects according to embodiments of the preseot ioventioo are provided below. 
     Improved Noise Reduction for DNT Applicatioo 
     In embodiments of tbe inveotion each satellite transceiver  400  in the system of  FIG. 2  (there may be additional such transceivers coooected to router  410 , or to equivalent routers) typically broadcasts on a fixed number of channels within an assigned frequency range over an area surrounding tbe transceiver. Typically, each hand-held unit tunes to a particular channel, which may be negotiated with router  410  or other intelligence in the system. As a result there are typically a relatively small number of users in such a system in the raoge of one satellite, and each user is dealiog with router  410  through transceiver  400  over a very “thio pipe”. By thin pipe in this specification is meant a connection to a user via a channel with very limited bandwidth. 
     It appears to the present inventor tbat a major coocern when practicing DNT over such a narrow-band thin pipe is noise reduction capability. As previously descrihed in the background section, background nuise severely limits the bandwidth available, because as packets are prepared io substantially real time, packets must be prepared for background noise, even during long pauses in conversation. Bandwidth may therefore be wasted that could profitably be used for other purposes, such as exchange of data-data or, depending on the wireless network, for sharing with other users. The inventor proposes two approaches which may be used separately or may be combined to considerably reduce the waste of bandwidth by background noise for DNT over a narrow-band pipe. 
     The first implementation involves the use of DSP (see DSP  101 a of  FIG. 2 ) technology with speech recognition capability, and is described and illustrated below. 
       FIG. 3A  is a block diagram illustrating DSP function according to an embodiment of the present inventioo wherein only voice data packets aod real data packets are sent during a transaction with a calling or called party. 
     DSP technology, while known in the art and applicable to many different types of products, is an innovative approach as it is applied to an embodiment of the present invention. The ioventor knows of no current narrow-band wireless application wherein DSP with speech recognition is used for the purpose of managing bandwidth whereby only necessary data packets for voice-data are created during a real time transaction such as a DNT voice call. Data-data associated with file transfers and the like are created oormally and sent along with voice data. ln some instances, CPUs can be used to perform DSP tasks, and hence no extra physical implementation of the DSP has to exist. Also, some newer DSP design lend themselves to handle general purpose CPU/MPU functions, and hence can haodle all aspects by themselves. 
     Referring now to  FIG. 3A , as a user speaks into a microphone during a call. DSP  101 a with speech recognition capability monitors ioput, sorts out speech from non-speech, and creates data packets for voice only and will not create packets during pauses when the user is not speaking. ln this way, bandwidth is made available for other functions because data packets containing background noise aod the like are never created. Data-data packets containing non-voice data such as file-transfer data and the like are created in normal fashion and sent along with DNT packets if the user is, of course, transferring a file and talking on the unit at the same time. This technique in this embodiment assumes that there is sufficient bandwidth for muti-task functions while actively engaged in a DNT call. 
     The speech recognition function of the DSP chip may be programmed or traioed to recogoize different languages and so oo. Also long sighs and other verbal non-descriptors may be ignored during the monitoriog and DNT packet generating process. 
     ln another embodiment of the present invention, a DSP chip with speech recognition capability is also provided in routers such as router  410 . By using digital to analog conversion modules known in the art, incoming DNT packets, before encountering may be monitored by a similar DSP at router  410  and non-speech packets in a received DNT data stream can be eliminated, effectively making more efficient use of the narrow bandwidth of each channel to a user. DSP apparatus and techniques as described can effectively minimize bandwidth demand for DNT in narrow wireless channels in either or both directions. 
       FIG. 3B  is a perspective view of unit  100  of  FIG. 1  showing noise-cancellation speaker aod microphooe iocorporation. While DSP with speech recognition capability is effective in reducing unwanted background noise, it may not be 100 percent effective, therefore another noise reduction technique is used wherein possibly a second microphone  106 b aod possibly ooe more speaker  105 b are provided and strategically located on unit  100  for the purpose of canceling background noise that may be present at the users location. Depending on the implementation and the physical design of the device, additional MlC/SPKR may or may not be needed. If a system such as system  99  of  FIG. 1  is implemented in an industrial setting, for example, background noise may be particularly significant. Speaker  105  and microphone  106  are used for normal speech and audio function during a DNT call or may be used in combinatioo for noise cancellation. 
     It will be apparent to one with skill in the art that there may be more than ooe noise-cancellation speaker  105 b as well as more than one noise-cancellation microphone  106 b in unit  100  without departing from the spirit and scope of the present invention. The number and location of such devices will depend in part on intended application. For example, in a quiet environment, they may not be needed at all, whereas, in a noisy environment maximum capability may be desired. ln general, the noise cancellation system works by intercepting background ooise by the auxiliary mic ( 106 b), then playing background noise back through one or more noise cancellation speakers placed to cancel background noise in a region at the principle mic  106 . Such noise cancellation is known in the art for such as traffic noise and the like, but application and implementation to background noise reduction enhancing DNT over narrow wireless links is surely unique aod not obvious 
     It will be appareot to ooe with skill in the art that caocellation speakers and microphones may be held separate from unit  100  without departing from the spirit and scope of the present invention. One example of this would be utilization of a noise cancellation head-set. 
     Pipe-mirroring in a Narrow Band Wireless Multi-access System 
     Attention is directed to  FIG. 2 , to hard wired link  401  between intelligent router  4 I 0  and transceiver  400 . Router  410  is adapted to route data packets for both voice-data in DNT and data-data for such as file transfers to users in an area covered by transceiver  400 . Typically each user is assigned a channel within tbe breadth of the transceiver. Therefore voice-data and data-data for each user nccupies just that chaonel io the wireless link between transceiver  400  and each user&#39;s hand-held unit. The hardwired link  401  is, however, preferably a single line, and carries all of the combioed data for all the users in the area of transceiver  400 . This arrangement, however, can be troublesome, as router  410  sees only the combined baodwidth of all the channels. Therefore, in the event one or more of the users elects to download a large amount of data, router  410  would typically commaod the entire bandwidth of hardwired link  401  to transfer the data to transceiver  400 , and any or all DNT communications may be interrupted. lo a preferred embodiment of the present invention, then, router  410  treats hardwired link  401  as though it were a link of the bandwidth of the wireless channel for each user, dividing the hardwired link into a number nf parallel pipes equal to the number of wireless channels used. Data management between real time voice-data and data-data is tberefore maintained for the system between the router and the users, and DNT may be effectively maintained for the individual users. 
     QoS Functionality on Ultra-thin Pipes 
     lo a preferred embodiment of the present inveotioo, in order to insure that DNT data is prioritized when sending a combination of DNT data and application data via the narrow-band wireless channel for each client, a basic but innovative Quality of Service (QoS) scheme is implemented on the clieot side. 
     Traditional bi-directional QoS application schemes such as resource reservation protocol (RSVP) and similar schemes are known by those skilled in the art to be only used in high bandwidth applications where there are many users sharing available bandwidth. It is also well known that QoS assurance on both ends nf a pipe has to be negotiated along the way from node to node. Also, QoS implementation across multiple networks is difficult. Some standardization is required so that all network poiots understand and support the language protocol of the scheme being used. 
       FIG. 4  is a conceptual diagram illustrating QoS management according to an embodiment of the present invention. 
     It is the intention of the inventor to provide a new, one-sided QoS implementation from the clients side to the other end of the pipe, namely router  410 . This is accomplished in embodiments of the invention either with firmware that is embedded in NV MEM  103 , or via a software application  501  installed in system memory available in unit  100 . In this embodiment, an instance of application  501  also resides in router  410 . The application provides a fixed algorithm that always prioritizes DNT data both in unit  100  and in router  410 . In this way, DNT data, as real time data, is always assured sufficient bandwidth. If another data type such as data from file transfer is initiated while simultaneously engaging in a DNT call, all such packets are held until there is a pause in the speech wherein no DNT data is being transferred. The transferring of files initiated by unit  100  takes place only during data gaps in the prioritized DNT communication. This is a one directional feature that only effects the communication link between unit  100  and router  410 , and the instances of application  501  at each end operate independently of the other. In other embodiments the unique uni-directional QnS routine may be used only at one end of the pipe or the nther, either in router  410  or in the user&#39;s hand-held unit. 
     Dynamic Address Translation 
     In yet another embodiment nf the present invention, a method is provided whereby a user may roam away from and out of range of a transceiver such as transceiver  400 , and be smoothly and efficiently logged onto another transceiver in system  99 . 
       FIG. 5  is a block diagram illustrating dynamic address translation according to an embodiment of the present invention. Three transceiver regions  97 ,  98  and  99  are shown provided by separate transceivers spaced apart from each other but with overlapping areas, as is known in the art for such wireless systems; as is done in cell-phone systems, for example. Together, reginns  97 ,  98 , and  99  define a sub-net  404 . Sub-net  404  is, in this case, serviced by a single router  410 . Such a case may represent, for example, a technical campus. Each unit  100  is capable of operating on one or another of defined channels in each of regions  97 - 99 , and RF tuning in the hand-held units is a matter of apparatus and procedures that are all well-known in the art. 
     Router  410  in this embodiment is a lower-level router in a multilevel routing system connected to a higher-level router  415  via link  413 . In this embodiment router  415  is a Master router for the wireless system, and is linked to Net  500 . Master router  415  may be linked as well to other lower-level routers such as router  417  in another subnet  405  equivalent to subnet  404 , which in turn controls three transceivers, such as transceiver  418 . 
     It will be apparent to the skilled artisan that there is a broad variety of architectures that might be implemented comprising routers in hierarchical levels, interconnection among routers, and connection of routers to transceivers to accomplish coverage of an area for such a wireless communication system. The architecture illustrated here is one of many possibilities, and is used for exemplary purposes to illustrate improved tracking of users across subnets in an embodiment of the present invention. 
     Generally speaking, when incoming DNT calls arrive at master router  415 , they are routed appropriately hased on routing tables in the several routers. In the overall system, cach user may have a home lncation served by a particular transceiver connected to a particular router. A particular user may, for example, typically be found in region  99  served by transceiver  403  connected to router  410 . This user will then be listed on the routing table of router  410  and the table of Master router  415 . If a call comes in tn Master router  415  for this particular user, the call will be quickly routed to the proper end router and transceiver by virtue of the routing list entries. Each satellite transceiver such as transceiver  403  has a fixed number of channels, and a channel is assigned to each user. 
     The purpose of a distributed system of the sort illustrated in embodiments of the present invention, is to provide communication for all users regardless of the particular region (transceiver), and to allow users to move from region to reginn while maintaining communication. 
     As an example, the user nf unit  100 , shown in  FIG. 5  as resident in region  99 , has decided to roam to region  97  covered by transceiver  402 . In the system of various embodiments, locatinn negotiation is periodically executed by each unit in operatinn with the nearest transceiver. As long as a user does not move from one region to another, the routing tables do not change. As the user of unit  100  enters region  97 , negotiation communication will occur with both transceivers  403  and  402 . At some point the system will determine that the user is to be handed off to transceiver  402 , at which time the routing tables are updated, deleting the particular user from transceiver  403  and assigning the user to transceiver  402 . 
     Each hand-held unit tunes to the system-assigned channel, and unit  100  will initially negotiate with router  410  through transceiver  402  on the same channel that was assigned to the unit in region  99  served through transceiver  403 . There may, however, be one or more users in region  97  assigned to the same channel, and once the routing tables are updated, the channel assignment may change in the newly-entered rcginn. Each transceiver, for example may have more channel capability than users expected at any one time to be in that reginn, and therefore may have unused channels at any point in time that may he assignable to users newly entering the particular region. 
     In this example, router  410  services both regioos  99  and  97  through transceivers  403  and  402  respectively, making this a relatively simple example of ripple. However, if the user of unit  100  were to roam to subnet  405 , where the transceivers are controlled by router  417 , then unit  100  would ping that new rnuter through the closest satellite transceiver, and negotiate entry into the new subnet. In this case the user would be moved frnm the routing table in router  410  to the routing table in router  417 , rather than just updating the routing tahle in router  410  to a new transceiver and region. 
     In the process of rippling, users throughout the overall area covered by a wireless system are tracked, and their location relative to the network of transceivers is noted. Routing lists at each router are updated as users move from region to region in the manner described above, wherein the minimum change is made with minimum impact on the stored and updated data for the system. 
     When a user moves from region to region as has been described, and routing lists are updated, there will be instances wherein a user is receiving real-time data packets for DNT as the user&#39;s location is updated. At the time that the user is relisted io a new region, there may well he data packets delivered to the rnuter where the user was previously listed. In this instance real-time data packets, or for that matter any data packets, that are left behind io this manner, are retrieved and forwarded immediately to the router serving the region to which the user has been moved, so there is no apparent loss in the data stream for the roaming user. 
     It will be apparent to the skilled artisan that there may be a varying number of routers such as router  410  assigned a varying number of satellite transceivers without departing from the spirit and scope of the present inventioo. There may also be, in more sophisticated systems, several hierarchical levels of routers. There are many possibilities for system architecture. 
     Personal Router io Client 
     In yet another embodiment of the present invention a software application known to the inventor as a personal router application is employed for flexibility in routing. Complete and enabling detail for such a personal router system is taught in U.S. Pat. No. 6,148,074, assigned to the assignee of the present patent application. 
     Io the personal router system a user, through an executable application at the hand-held unit, may, among other capabilities, program alternative actions for incoming calls. For example, a user may need to leave an area, and a co-worker is selected to cover the first user&#39;s responsibilities. ln this case, the first user can program through the hand-held unit and the personal router applicatioo, for incomiog calls to the first user to be re-routed to the alternate. A hroad range of other alternatives is available, including automatic answering with pre-recorded messages, call-holding, and many others. ln a preferred embodimeot a user interface is provided whereio incoming calls are represeoted by icons on the user&#39;s screen, which the user may select to manipulate calls. 
     In one embodimeot the bulk of the personal router applicatioo is resident at the system routers, and each user has an interface whereby he/she may access the application on the system router in a client-server fashion, and edit routing rules on the router to effect the manner in which incoming calls for the user are handled. The rules that may be invoked in this manner are limited only by system capabilities and the user&#39;s needs. 
     The personal router application provides maximum flexibility to the user without requiring additional equipment. A user need not be resident in any one voice/data system in order to apply his personal routiog rules. By having an instance of the router application at each of the routers in the oetwork, a user may roam without losing access to personal routing capability. By utilizing a hierarchy of routers, personal routiog capability may be scaled up to cover a large geographical area such as routing calls to other sub-nets and so on. 
     It will he appareot to one with skill in the art that the personal routing applicatioo may be used in conjunctioo with other routing applicatioos that may be implemeoted separately from individual units without departing from the spirit and scope of the present invention. For example, as a DNT telephony application, routing software may be stored at a machine dedicated to ioterfacing with routers so that mnre complicated routing rules may be observed. 
     Practicing DNT Wireless Telephony on a CSMA/CD Type Network 
     All of the embodiments of the prescot invention as previously taught herein are applicable to assigned the typical bandwidth types of wireless networks such as TDMA and CDMA oetworks. However, successful practice of the present invention in various embodiments can be further enhanced by implemeoting a wireless protocol betweeo traosceivers and users based on the characteristics of carrier-sensed multiple-access oetworks including collisioo detection (CSMA/CD). This type of oetwork is most often employed as a hard-wired or wireless LAN architecture such as Ethernet. 
     In CSMA/CD all data is transmitted over a shared channel and each registered device that attempts to transmit data oo the network must first listen to see if the network is free (carrier seose). Each device has a preset priority to use the available baodwidth over the network (multiple access). If two devices attempt to transmit at the same time, a collision occurs which is detected by all devices on the network (collision detection). Each device typically plans it&#39;s second-attempt transmissioo at a random amount of time after a collision is detected. As all of this takes place in a matter of micro-seconds, CSMA/CD provides a means of efficiently utilizing available bandwidth in a wireless shared system. 
     Baodwidth-on-demand meaos that no device transmits during the transmissioo of another device on the network. Instead of iodividual channels of dedicated baodwidth being assigned to each unit, all incomiog DNT communications are broadcast over the oetwork wherein each unit picks up it&#39;s own coded informatioo via addressing within the packet frame. 
     CSMA/CD in wireless mode operates virtually the same as in hard-wired mode except that the network architecture with respect to linked devices would be closer than would be the case with a wired network. The inventor koows of no wireless CSMA/CD network that curreotly practices DNT. For purposes of the present inveotion the wireless CSMA/CD implementation could use existing wireless LAN technology with the replacement of RF/NIA adapters such as module  109  of  FIG. 1  with existing LAN type oetwork adapters. 
     It will be apparent to one with skill in the art that the methods and apparatus of the preseot invention as taught by the various presented embodiments allows DNT iocluding IPNT to be practiced efficiently and economically oo a wireless narrow-band network having dedicated chaonels as well as a wireless network having a shared channel with carrier sense capability and collisioo detection capability without departing from the spirit aod scope of the present invention. For example, the methods aod apparatus of the present may be implemented in various networks such as TDMA, CDMA, Global System Mobile (GSM), and other similar networks as well as CSMA/CD type networks. 
     It will also be apparent to one with skill in the art that such a wireless network enhanced by methods and apparatus of the present inventioo may comprise a plurality of voice/data systems belnnging to one of a plurality of sub-nets each controlled by a router with each router linked to a LAN, a WAN, including but not limited tn, the lnternet. There are many other architectural possibilities with regards to building such networks. The spirit and scope of the present invention is limited only by the claims that follow.