Abstract:
A cellular/wireless foreign subscriber is enabled to use her/his own cellular/wireless telephone instrument in a local cellular/wireless (C/W) network/system by entry of a code and a PIN into the local network/system desired to be used. The local C/W network/system algorithmically responds to the code and PIN by changing characteristics of the radio equipment of the local C/W network/system to accommodate operation of the subscriber&#39;s cellular/wireless telephone instrument with the network/system desired to be used.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 09/384,451, filed Aug. 27, 1999, now U.S. Pat. No. 6,754,490 and incorporated herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to the accessing of different and distinct cellular/wireless (C/W) telephone network/systems with a particular cellular/wireless (C/W) telephone instrument not necessarily adapted to operation in any one of the particular systems. Access is consummated by means of adapting an interface with the system requirements through adaptation of processing procedures of the cellular/wireless network/system alone. In particular the network adaptation process granting access and functionality is attuned for a C/W telephone instrument in response to entries transmitted to the network system from the C/W telephone instrument. 
     BACKGROUND OF THE INVENTION 
     A normal cellular/wireless (C/W) telephone instrument is designed to operate only with a particular cellular/wireless (C/W) communication network/system and as such is designed in accord with interface requirements specific to the network/system sought to be accessed. Such requirements include modulation schemes, format, signal structure, link protocols, signal waveforms and signal frequencies. These are all unique to each network/system and a cellular/wireless telephone instrument designed to work in one cellular/wireless network/system will not function in another C/W network/system having a different operating environment. 
     Traveling subscribers, particularly international travelers are impacted by inoperability of cellular/wireless telephone instruments in a different C/W system, particularly in international travel. In some instances a cellular/wireless telephone instrument is designed to be operative in more than one cellular/wireless/network/system. An example is cellular/cordless telephone instruments which operate in either a cellular or cordless medium. Such a telephone instrument however carries a large overhead of redundant design and feature amenities. As a result such a telephone instrument is expensive and may even be unwieldy in size in order to support all the various features so that the user may properly interact with the different systems. 
     Several prior efforts have been made to accommodate the various dilemma of the traveling telephone user. A common dilemma is the different operating parameters and operating characteristics of C/W telephone instruments associated with different C/W networks. One solution to these dilemma has been to provide a “universal” telephone instrument associated with a network/system that accepts a database encoded on a card (e.g., a smartcard) to control and/or modify telephone instrument operations. This causes the telephone instrument to operate in a manner identical with operations that the user is used to in his home network/system. 
     Universal telephone instruments, for example, are associated with a particular network but can be programmed to mimic responses of a telephone instrument associated with a different telephone network. They often include a smartcard reader to provide a database for such purpose. The foreign user inserts a smartcard into the telephone instrument. It includes all the data as to how the telephone instrument should appear to the user, what language to use, how it should respond and how it is operated in order to make it conform to a telephone instrument that the user is accustomed to. A database of this operational information may be contained solely on the smartcard or it may be included in a database located in the universal telephone instrument. Such a technique is disclosed in U.S. Pat. No. 5,878,124, which also provides an overlay device to the telephone instrument to provide the home appearance and functions that the user is accustomed to. In this arrangement the universal telephone instrument is a specialized telephone instrument which must be provided by the system the user is attempting to access. It does not concern a cellular/wireless telephone instrument, which within the cellular/wireless network/system is personally assigned to the user and likely to be used in another system. 
     Personalized features of a home base network/system are provided to the traveling telephone user in using a telephone instrument in another network/system with a different exchange in which the user enters a code and a personal identification number (PIN) to any telephone instrument of a foreign system. The personalized features are retrieved from a national database, as described in U.S. Pat. No. 4,899,373, and used to provide the telephone user with his specialized features. In another aspect the features are encoded on a card which features are conveyed to the network database. Unfortunately from the point of view of a cellular/wireless telephone instrument the process does not make a C/W telephone instrument operative in a foreign network/system as opposed to providing familiar home type features to the user of a telephone instrument of a different system from the home system. 
     Various approaches have been proposed for making a foreign telephone user feel familiar with local telephone operations by providing features and functions such as they are accustomed to at home, but all have involved using a special “universal” telephone instrument or are limited to providing system features such as are available to a user in his home network/system. Yet to be addressed is the ability of the visitor to the system to use his own C/W telephone instrument in a new different C/W network/system. This is particularly critical in the instance of cellular/wireless, since the user prefers to use his/her own C/W telephone instrument, which he/she is accustomed to. 
     SUMMARY OF THE INVENTION 
     A cellular/wireless (C/W) foreign subscriber/user, when roaming beyond a local cellular/wireless (C/W) network/system, compatible with his/her telephone instrument, is enabled to use her/his own cellular/wireless telephone instrument by entry of a code and a PIN into the foreign network/system desired to be used. The local serving C/W network/system algorithmically responds to the code and PIN by changing signal processing characteristics of the radio equipment of the network/system to accommodate operation of the subscriber&#39;s cellular/wireless telephone instrument with the foreign network/system desired to be used. 
     In a particular embodiment of the invention, the foreign user has been assigned an InterSystem Roamer Access Code Number (IRACN) and Personal Identification Number (PIN). This permits use of the C/W network/system upon application, followed by validation, to a C/W network/system designed to accommodate foreign subscriber telephone instruments. The radio communication system responds to the transmitted IRACN and PIN by adjusting its interfacing and signal processing equipment to interact with the cellular/wireless telephone instrument of the subscriber. 
     In operation the local C/W network/system receives the IRACN and PIN and upon validation detects and characterizes the signals transmitted by the subscriber&#39;s C/W telephone instrument and adjusts the receiver of the radio system to change the received signal to a format and character adjusted to the network/system operation requirements. Once identity and authentication is established the call may proceed normally. Reply downlink signals are changed to a format and character acceptable to the C/W telephone instrument prior to transmission. 
     In a specific embodiment, a foreign C/W subscriber requests service in the local C/W network/system, by using the cellular/wireless access channel and transmits the PIN and the IRACN to the central office (CO) of the local C/W network/system. The received signal is detected and characterized. A determination is made if it is a foreign or US (local) C/W service request, depending upon the C/W telephone instrument used. For US based C/W telephone instrument calls the process of registration and authentication proceeds as normal. For calls made using a foreign C/W telephone instrument, the received signal is characterized to determine if it is a GSM, TDMA, FDMA, PCS, etc. The signal is channeled to the appropriate radio system for that particular modulation and processing scheme. The uplink signal is frequency translated, and demodulated; it is decrypted and decoded, protocol converted, and deframed; it is subsequently structured and framed, modulated, frequency translated and adapted to NA (North American)-digital or analog radio system requirements in the local Central Office (CO). 
     Registration and authentication is initially performed to validate the subscriber PIN, IRACN and his/her identity. Transmitters of Invalid PIN and IRACN numbers are asked to check the numbers and try again. Valid subscriber entries are given a request acknowledgement to access the network and start transmitting. For a US based call, with a C/W telephone instrument designed for the local C/W network/system, registration and authentication follows normal operating procedure. 
    
    
     
       DESCRIPTION OF THE DRAWING 
         FIG. 1  is a block diagram illustrating the process of adapting the local cellular/wireless network/system to process signals supplied from a foreign non-system cellular/wireless telephone instrument; 
         FIG. 2  is a block diagram illustrating an algorithmic framing process in adapting radio signals to allow the local network/system to provide service to a foreign cellular/wireless telephone instrument; 
         FIG. 3  is a schematic portrayal of frames structured by the process of  FIG. 2 ; 
         FIG. 4  is a block schematic of a radio system of a cellular/wireless telephone network/system incorporating the principles of the invention; and 
         FIG. 5  is a schematic of a signal processor used in the circuitry of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
     An algorithmic process for adapting a foreign cellular/wireless telephone instrument for operation with a new/local cellular/wireless telephone network/system is shown in the flow chart of  FIG. 1 . A subscriber traveling within an area other than his/her home/foreign area wishes to use a cellular/wireless telephone instrument in a new area serviced by a local cellular/wireless telephone network/system different in operation and location from his/her normal home/foreign area. The process is initiated with a service request as indicated in block  101 . The service request is transmitted over the access channel used by cellular/wireless network/systems for this purpose. The receiving network/system accepts/detects the signal and as indicated in the block  103  detects and characterizes the request signal as to its format, frequency, modulation, framing, etc. Whether the request for service is from a local or foreign cellular/wireless telephone instrument (i.e., foreign vs. US) is determined as indicated by decision block  105 . If the request is from a US/local C/W telephone instrument the flow proceeds to process registration, authentication for US/local processing as indicated in decision block  107 . 
     If the request is from a foreign cellular/wireless telephone instrument, as determined by the instructions of decision block  105 , the flow proceeds to determine the type of modulation, as per decision block  111 , that the requesting foreign cellular/wireless telephone instrument is using. For illustrative purposes three types of modulation are illustrated although it is to be understood that the invention is not limited to the three designated modulation types. If the detected modulation scheme is time division modulation (i.e., TDMA,GSM) the flow process proceeds all the way through blocks  113   a ,  115   a ,  117   a  and  119   a . The system processing frequency is adjusted to the signal frequency and the demodulation scheme of the transmitting telephone instrument, as per block  113   a . The protocol of conversion is adjusted as per block  115   a  to accommodate the transmitting telephone instrument. Appropriate formatting and structuring is performed in accord with the instructions of block  117   a  and frequency translation of the signal to the network/system values is performed as per block  119   a . A Mux/Demux process  121  (multiplexer and demultiplexer) provides bi-directional connection between the appropriate processing circuitry and the requesting telephone instrument. 
     The Mux/Demux process  121  is coupled to a decision block  107  concerned with registration and authentication. If the codes (IIRACN and PIN) entered are approved the flow proceeds to call processing as shown in the block  109 . The requesting telephone instrument may now communicate through the network/system. The process flow (b and c) for amps and PCS is similar to that for TDMA/GSM and hence it is not necessary to discuss. 
     If the origin of the calling telephone instrument is unknown to the network/system. The decision process of block  105  the flow returns to the state of block  101 . 
     When, as discussed above with reference to  FIG. 1 , an International Roamers Access Radio System (IRARS) participant requests service, the received signal frequency is determined, and the IRACN and PIN are verified for validity. The signal undergoes frequency adjustment, demodulation and carrier recovery, decoded and de-interleaved. It is deframed; the deframing process removes all the overhead bits by the Decision circuitry and stores it in the RAM. Only the information bits remain. Protocol conversion takes place, after bandwidth/time slot adjustment, channel spacing, and rate adjustment are made in the processor. The outputs of the protocol converter, as discussed below, are looped back to the modulator where signal is modulated with pi/4DQPSK, to adapt to NA-TDMA type modulation. The processor sends the modulated signal to the framer where the information is structured and adapted to NA-TDMA. It is encoded and interleaved such that the final bit count and the bit pattern is equal to 1944 bits (972 symbols) per frame and is similar to the NA-TDMA frame structure. 
       FIG. 2  shows the framing algorithm to accomplish this structuring, and the bit patterns for the framing transformation are shown in the diagram of  FIG. 3 . For example, if the GSM system is chosen for processing,  FIG. 2  shows the transformation algorithm for this modulation scheme. The invention is not limited to GSM framing and framing for other modulation schemes is included within the scope of the invention. 
     Framing processing starts with the number of bits N of the incoming frame being determined as indicated in block  201 . If the number of bits N is less than 1944, as per decision block  203 , the process proceeds to a block  205  whose instruction is to add the difference between the number of bits and 1944. If the number of bits now equals 1944 as per decision block  209  the process proceeds to the framing process of block  217  from whence the frame is transmitted to an encoder. 
     If the number of bits N is not less than 1944 as per decision block  204  a subsequent decision (decision block  207 ) determines if the value of N exceeds 1944. If it doesn&#39;t then at this point in the process N should equal 1944, which is what decision block  211 , determines. If n=1944 the process proceeds to framing step of block  217  and if not the process returns to the start block  201 . 
     If the decision of block  207  determines that N exceeds 1944 a subsequent instruction of block  213  subtracts the difference from N. N should now equal 1944 and this is checked in decision block  215 . If N=1944 the process proceeds to the framing of block  217  and if not the process returns to block  213  to repeat the subtraction step of block  213 . 
     The results of the framing process are detailed graphically in the  FIG. 3  diagram. The GSM frame  301  is shown comprising a total of 1248 bits with 8 slots each slot including 156 bits and a time duration of 4.615 ms. The content of each GSM slot  303  includes three tail bits  303   a ; fifty eight information bits  303   c ; a training sequence  303   e  of twenty six bits; fifty eight more information bits  303   g ; three tail bits  303   h  and a guard section  303   j  of eight bits. Each slot  303  has a total of 156 bits for a duration of 0.577 ms. 
     The frame  305  in process has a bit pattern in each slot in which all the overhead bits except the tail bits have been removed. This leaves 120 bits in each slot or a total of 960 bits per frame. The in-process frame is now adjusted to adapt the signal to the NA-TDMA format and structure to be ready for encoding and interleaving. 
     The NA-TDMA frame  307  has 1944 bits or 972 symbols in which each slot  309  had 324 bits at a rate of 48.6 kbps or 6.67 ms/slot. This is the NA-TDMA frame and down link structure processed by the network/system. 
     When the subscriber is receiving signals the bit pattern is adapted to GSM standards, shown by frame  309 , which the subscriber&#39;s cellular/wireless telephone instrument is able to receive. While GSM NA-TDMA transition is shown the invention is not so limited. Other transitions fall within the purview of the invention. 
     A radio transceiver used in the network/system, which illustrates the invention, is shown in the  FIG. 4  and includes a RF front end; an IF section and a Baseband section. Uplink signals are received at a receiving antenna  401  and are coupled to a bandpass filter (BPF)  403 . 
     A frequency detector is coupled to the input of BPF  403  and detects the frequency of the uplink signal as well as the type of system in use (i.e., GSM, PCS, FDMA, etc.) and IRARS and PIN validity. This frequency determination and other information determined is coupled to the IRARS processor  501  discussed below with reference to  FIG. 4 . 
     The filtered signal output of BPF  403  is amplified in amplifier  405  and mixed in mixer  407  with the reference signal frequency of local oscillator  409  to achieve the IF signal. After further filtering and amplification the signal is bifurcated to form I (In-phase) and Q (Quadrature-phase) signals. The I and Q signals are applied to mixers  413  and  415  for demodulation and referencing by a second reference signal (by local oscillator  417 ) to achieve baseband frequency, respectively. The signal is further processed, to recover original signal information, in both paths by an A/D converter  419  to recover a digital signal format and in various processes the carrier is recovered  421 , and de-interleaved  423 , decoded  425  (to recover original information) and deframed  427  (to remove overhead bits). These signals are applied to the processor  501  discussed in reference to  FIG. 5 . These signals are also processed in path  451  to adjust to signal characteristics of the local C/W network/system connected to lead  453 . 
     Downlink I and Q signals, as processed in processor  501 , are framed  431 , encoded  433 , interleaved  435  and converted from digital to analog format in D/A converter  437 . Framing reinserts the overhead bits and structures the packet into a suitable format. The signal is modulated in mixer  439  and upped to IF frequency in mixer  441  to produce a modulated IF signal for the front end. After filtering and amplification the signal is converted to RF, suitable for the foreign subscriber&#39;s telephone instrument, in mixer  443  amplified in amplifier  445  filtered by BPF  447 , for spectrum control, and applied to a transmitting antenna  449 . 
     Processing to adjust the various uplink and downlink signals to the requirements of the cellular/wireless network/system processing the calls to the requirements of the subscriber&#39;s instrument are performed by the processing circuitry  501 . Processor  501  accepts both I and Q incoming signals from the subscriber, on leads  502  and  503 , and in a pair of switches  504  and  505  selects subsequent circuit connections to (in the example) enable processing of GSM or NA-TDMA processing. Time slot control GBW (Gaussian Modulation Shift Keying BW)  541  applies a control signal to a GSM channel  514  or  516  and changes the time slots and framing of the GSM incoming signal. The I and Q signal has the rate appropriately adjusted in mixers  518  and  520 , respectively, in response to control signals provided by a variable rate generator  526  which is controlled by a processor  530 . 
     The same type process is used for NA-TDMA and other modulation schemes. This process is known to those skilled in the art and its implementation is not discussed. 
     A second channel is included to provide North American TDMA (NABW) control to a NA-TDMA channel  524  and  526  also under control of processor  530 , through time slot control  543 . 
     Outgoing signals (downlink) intended for the C/W telephone instrument of the foreign user are modulated to its operating requirements in mixers  551  and  552  and output on leads  561  and  562  to the radio output circuitry shown in the  FIG. 4 . 
     Signals for C/W network/system processing are output on leads  571  and  572 .