MXPA94005546A - Method for operating a communication system having multiple base stations - Google Patents

Abstract

The present invention encompasses a method for establishing and maintaining communication in a portable telephone system adapted to operate with a plurality of base stations and at least one handset on a plurality of channels. The method generally includes steps of assigning a security code to the handset(s) operating in the portable communication system to enable RF communication between the handset(s) and the plurality of base stations (24);communicating the security code assigned to the handset(s) to the plurality of base stations to maintain within each of the plurality of base stations the security code(s) of the handset(s) operating in the system (26);and aligning the channel of the handset(s) with a channel of a base station to allow for communication between each handset and one of the plurality of base stations (28).

Description

METHOD TO OPERATE A COMMUNICATION SYSTEM THAT HAS MULTIPLE BASE STATIONS $ INVENTORS: JAMES FRANCIS GOEDKEN of United States nationality, resident in: 55 South Vail # 1212, Arlington Heights, Illinois 60005, USA THOMAS PERSZYK of United States nationality, resident in: 192 Jefferson Lane, Bloomingdale, Illinois 60108, USA CHARLES JOHN MALEK of United States nationality , resident in: 915 Camelot Drive, Crystal Lake, Illinois 60014, USA MOTOROLA, INC., American entity, with address at 1303 East Algonquin Road, Schaumburg, Illinois 60196, E. U. A.

SUMMARY OF THE INVENTION The present invention includes a method for establishing and maintaining communication, by means of a portable telephone system adapted to operate with a wide variety of base stations and at least one handset in a variety of channels. The method generally includes the steps for assigning a security code for the operation of the handset (s) in the portable communication system to allow RF communication between the handset (s) and the different stations. base (24); the communication of the security code assigned to the handset (s) to the different base stations in order to keep within each of the different base stations the security code (s) assigned to the handset (s) (s) in operation within the system (26); and aligning the channel of the handset (s) with the channel of a base station to allow communication between each handset and one of the different base stations (28). * * * * * TECHNICAL FIELD The present invention relates generally to communication systems, and more particularly, to a method for operating a wireless communication system having multiple base stations.

BACKGROUND OF THE INVENTION Previously, wireless communication systems provided communication between one or more remote devices and a variety of base stations, including a controller to regulate communication between remote devices and base stations. Generally, the controller provided simultaneous communication between the base stations when necessary. An example of a wireless communication system with a certain number of base stations is the cellular telephone system. Generally, the base stations of the cellular telephone system are controlled by a cellular control station. A wireless telephony system is another example of a wireless communication system that could operate with different base stations. Commonly, wireless telephony systems include one or more wireless remote devices or handsets that are associated with a base station. Each of the handsets can communicate with the base station at a different frequency. Moreover, the communication between the different handsets and the base station can be accommodated. In a wireless telephone system having different base stations it is necessary to allow the handset to communicate with each base station and, at the same time, prevent communication between the base stations and unauthorized handsets. In accordance with the above, it is necessary to assign a security code to each handset and maintain a list of the security codes of all active handsets trained to operate within the system. On the other hand, when a? If the handset is waiting to communicate with a base station, the handset must be on the same base station channel within a range that reduces the time needed to provide a radio frequency (RF) communication link between the base station and the handset. In accordance with the above, it is necessary to align the handset channel with that of the base station ^ which is within a range, even when the handset is not communicating with the base station. further, because the intensity of the radio frequency (RF) communication signals between the handset and the base stations can vary by the location of the handset with respect to the base stations when the handset is communicating with the base station, it is useful to provide a RF communication link between each handset and a base station that has the strongest communication link RF. In accordance with the above, it is necessary to transfer the communication signals between the base stations of a wireless communication system having different base stations. As in any wireless communication system having different base stations, there is a need to regulate the communication between the handset and the base stations. In particular, there is a need to define which base station will communicate with a particular handset. It is good to regulate the communication between a handset and the base stations without separately using a controller of the base stations. Eliminating the need to use an independent controller will reduce both the costs and complexity of the system. In accordance with the above, a method is necessary for the operation of a wireless communication system having different base stations such as a wireless telephone system that eliminates any need for a separate controller for the base stations.

SUMMARY OF THE INVENTION The present invention includes a method for establishing and maintaining communication, by means of a portable telephone system adapted to operate with a wide variety of base stations and at least one handset in a variety of channels. The method generally includes the steps for assigning a security code for the operation of the handset (s) in the portable communication system to allow RF communication between the handset (s) and the different stations. base; communicating the security code assigned to the (s) handset (s) to the different base stations to keep within each JK > one of the different base stations the security code (s) assigned to the handset (s) in operation within the system; and aligning the channel of the handset (s) with the channel of a base station to allow communication between each handset and one of the different base stations. In another aspect, the present invention includes a method for assigning security codes for the system - ^ communication notebook adapted to operate with multiple handsets and at least one base station. The method comprises the steps to provide the current security code of each handset to the base station; assigning a new security code to each of the handsets; and placing each new security code within the master list of security codes in the base station. The present invention further includes a method for maintaining the communication between a handset and one of the different base stations when the handset is not actively communicating with a base station. Within one aspect of the invention, the method includes, for each handset, the steps for periodically sending a contact request from the handset to the different base stations, and; the change of the handset channel to that corresponding to the base station that returns the contact. Finally, in another aspect of the invention, a method is included to maintain communication in a portable communication system having multiple base stations and at least one handset, when the handset is in active communication with a base station. In particular, the method includes the steps to evaluate the level of the IPSR signal received at a base station from a handset, the instruction to the remaining base stations to report the K level of the IPSR and the operating channel, the selection of the station base that reports the highest level of IPSR signal, the instruction of the handset to activate the operating channel, and provide a contact between the handset and the base station that reports the strongest IPSR signal.In an alternative stage of the method to maintain the communication in a portable communication system that has multiple base stations and at least one handset that is in communication Active with a base station, the method includes steps of evaluating the IPSR level of the signal received at a base station from a handset; by placing the base station on standby, the handset requests to establish contact with the base station that reports the highest level of IPSR signal; providing contact between the handset and the base station that reports the strongest IPSR signal.

BRIEF DESCRIPTION OF THE DRAWINGS • In describing the present invention, reference is made to the following drawings where: Figure 1 is a plan view of a conventional wireless communication system having multiple base stations and multiple wireless handsets using the method of the present invention. Ift Figure 2 is a flow diagram of the method for operating a communication system having multiple base stations in accordance with the present invention. Figure 3 is a flow chart of the method for transferring the codes between the base stations in accordance with the present invention. Figure 4 is a flow diagram of the method for maintaining a channel alignment between the base stations and the handsets, in accordance with the present invention. Figure 5 is a flow chart of the method for establishing a pick-up condition for a handset, in accordance with the present invention. Figure 6 is a flow diagram of the method for executing the distribution among the base stations in accordance with the present invention. Figure 7 is a flow chart of an alternative method for executing the distribution between the base stations in accordance with the present invention. FIGURE 8 is a block diagram of the preferred circuit for the operation of a wireless communication system in accordance with the present invention. Figure 9 is the circuit diagram of the preferred signal transceiver circuit shown in the block diagram of Figure 8.

DESCRIPTION OF THE PREFERRED MODE With reference to Figure 1 there is shown a plan view of a wireless communication system 10 having multiple base stations 11 and multiple handsets 12 using the circuit and the method of the present invention. The base stations 11 are linked by a data link 14 to a single line 16 of a public telephone network system (SPRT) 18, although the method of the present invention could be used in a system of multiple base stations linked to telephone lines . While any number of handsets 12 can be incorporated into the wireless communication system, only one handset is required. The handsets 12 can include any RF communication device with base stations 11. An example of a base station and an associated handset includes a cordless telephone. A cordless telephone that could use the system of the present invention is included in United States Patent Number 5,140,635 assigned to Motorola, Inc., the entire patent is included as a reference. As shown in Figure 1, each base station is in communication with the other base stations by means of a data link 14 (indicated by the lines followed between the base stations). Preferably, the data link can incorporate the common tone and tip lines of the public telephone network system by coupling each base station to the same telephone line 16 of the public telephony network system. Alternatively, the communication between the base stations can be complemented by communication via RF or by an AC power line. Finally, each handset 12 communicates with each base station by means of RF communication signals (shown by dotted lines in Figure 1). "J" Returning to Figure 2, a flow diagram shows the preferred method for operating a communication system having multiple base stations in accordance with the present invention To avoid interference between the base stations and a multi-base system, each The base station is preferably restricted to a certain subgroup of the total available channels, for example, in a 49 Megahertz frequency division multiple access wireless (AMDF) system, there is a total of 10 channels available for use. a system that has two base stations, channels 1-5 can be assigned to the first base station and channels 6-10 can be assigned to the second base station, preferably channels assigned to a single base station should not be assigned be of adjacent frequencies in the spectrum Base stations always communicate with their domain channel 22, except when asked to report their IPSR level on a channel it is specific for the distribution purposes discussed above. When assigning the channel domain to the base stations it is preferable that two base stations can never be in the RF range of the same handset to avoid having intersecting channel domains. That is, while the RF range of the base stations intersects to provide an independent distribution, it is preferable that the base stations having intersected RF ranges do not have intersecting RF channel domains. In accordance with the above, if there are fewer base stations than the total available channels, it is possible to ensure that two domains do not intersect by the exclusive allocation of channels to the base stations. From this, the base stations can be located wherever you want. It should be noted that if there are fewer base stations than available channels, the base stations may have overlapping channel domains if the base stations are located • Kk carefully to prevent channels that have overlapping channel domains from being in the same RF range. In any case, if a system has more base stations than available channels, care should be taken regarding the situation of base stations that have intersecting channel domains. There are various ways of assigning the domains to the base stations in accordance with the present invention. The channel assignment can be assigned manually by using the base station's keyboard to select the channels. Alternatively, the base stations can be preprogrammed at the time of their manufacture. Finally, the base stations can be trained to regulate with others in order to ensure their non-simultaneity with respect to the use of RF channels when the base stations have overlapping radios of RF coverage and when the base stations are within the range of a device specific remote. There are different ways to regulate. For example, base stations can be regulated by RF communication when occupying or vacating an RF transceiver by regulation. Alternatively, the bases can be regulated by an AC power line or the SPRT. The regulation will allow the bases that are servicing a handset to search all the channels (eg. ) of RF available either automatically or through ': jfe request. If a base requires the use of a channel outside of its «Usual channel domain and the channel is not in use at that time, you can simply make an agreement with the base station to which that channel is assigned. This can be done in a short time to give the user access to all available channels. To avoid interference from bases outside the multibase system (eg the neighbor's telephone ^^), the bases that are not periodically serving a handset verify their IPSR levels to know if there is an interference potential . If so, the base explores to find an unoccupied or clean channel within its domain. Alternatively, the base station may agree, if necessary, to move to the unoccupied channel. Then, when a handset searches for a base it moves to the domain of the base, it's as if the connection were established in an unoccupied channel without requiring communication * by some busy channel. Having established the channel domain of the base station 22, the security codes can be assigned to the handsets as in step 24. Normally, the security codes are assigned to ensure that only the handsets that are part of the system are allows to communicate with the base stations of the system. Accordingly, a handset associated with a foreign base station in the vicinity of one of the user's base stations will not be allowed to communicate with the user's base station. Preferably, the security code assigned to each handset can be assigned when the handset is received at the base station. The assignment of the security codes can be completed by a physical connection between the handset and the base station. However, it is possible to assign security codes by means of RF communication signals. For additional security, an access code may be required by the user before the security code is assigned to the handset. The security code assigned by a base station to any given handset must be communicated to the remaining base stations in the system according to step 26 to allow the handset to communicate with any of the J ^ base stations in the system. Preferably, the security codes assigned to the handsets must be transferred between the base stations by means of the data link which is described in the United States of America patent application of the invention of James Mielke entitled "CIRCUIT AND METHOD FOR OPERATING A WIRELESS COMMUNICATION SYSTEM "(case number CE00811R) this request being assigned to the assignee of the present invention and filed on the same date hereof. The aforementioned patent application V, describes in general terms a method and a circuit for the transfer of security codes to a signal of 30 KHz on a data link connected to the Telco line. The circuit is described in detail with reference to Figures 8 and 9. Alternatively, the security codes can be preprogrammed at the time of manufacture or manually programmed using the base and / or the handset keypad, or randomly once (or several times JK via user request) through the handset and then transferred to each base via a single-use physical connection (eg via the load contacts). This would eliminate the need for base-based communication, thus reducing the complexity and cost of the system. In step 28, the base stations maintain a channel alignment with the handsets to ensure that an RF communication link can be established between each handset and a base station. Generally, each handset will periodically request a contact with a base station via the RF communication link on a designated channel. If the contact request is not successful, the handset will continue to request contact on different channels until it is recognized by the base station. Accordingly, in response to a call signal or when the handset is picked up to initiate a call, the handset will be on an unused associated channel with a base station that is within the range of the handset. While channel alignment is beneficial in a system that has a single base station, maintaining channel alignment is particularly important in a system that has multiple base stations. When a handset moves within the area covered by the base stations, the handset is able to communicate on an unoccupied channel with the base stations within its range. • A pick-up request is then made to establish communication with the base station as shown in step 30. The pick-up request can be made in response to a call signal or when a call is being made. After the connection to the base station is established, the RF communication link is maintained with the base station until the distribution is required in step 32. The distribution is necessary when the user moves within the region of the stations. base stations. The user may travel outside the range of a base station and within the range of another base station requiring the distribution of the other base station. At the end of the conversation, the handset hangs as in step 34. After being hung, the handset maintains a channel alignment with the base stations as described in step 28. Returning to Figure 3, a detailed Flowchart shows the preferable operation of assigning security codes to the handsets (as shown in block 24 of Figure 2). Initially, the handset detects that it has been placed in the charging cradle of the base and sends a security code request to the base station via RF or through the charging contact in step 40. Preferably, the request includes a copy of the current security code of the handset (eg the original). Then, the base station checks a list of all the known security code numbers to determine if it has previously communicated with the handset in step 42. The base station generates a new temporary security code as in step 44 and sends it to the handset. The base station waits to receive the handset signal recognition in step 46 indicating that the new security code has been received. If the base station does not receive handset recognition, the base station determines whether the handset continues at the base station in step 48. If the handset continues at the base station, the base station generates a new code as in step 44 and sends it to the handset. In any case, if the handset is not in the base station, the base station proceeds to step 50. Alternatively, if the security code is sent via RF, the base station generates a new temporary security code as in step 44 as shows the dotted line if the acknowledgment is not returned from the handset as in step 46. If the base station receives handset recognition indicating that the new security code has been received from the base station as in step 46, the station The base checks the list of the security codes assigned to the handsets to determine if the code of Kfe- original security of the handset is listed in step 52. If the original security code is in the list, the base station replaces the original security code with the new security code assigned as in step 52 and outputs to step 50. However, if the original security code is not in the list, the base station determines if there are any white spaces in the list in step 56. If there are free spaces in the list, the base station replaces the blank space for the new security code in step 58. However, if there are no blank spaces in the base station, the base station replaces the last security code used with the new security code in the list in the step 60. In accordance with the above, the base station will maintain a list of all active handsets within the system. As stated above, an identical list of security codes is maintained at each of the base stations to allow A communication between each handset and any of the base stations. Returning to Figure 4, the preferable method for maintaining channel alignment (shown in block 28 of Figure 2) is described here. After having assigned the security codes to the handsets, the method of the present invention maintains a channel alignment between each handset and a given base station. In particular, it I initiates a channel alignment procedure periodically each time a certain period of time expires in step 70. Then, the handset randomly selects a channel search pattern (eg, 2, 4, 9, 1, 3, 5, 8, 6, 10, 7) in step 72. The random distribution of channels is beneficial for a communication system that has multiple handsets. In particular, it is a simple method to avoid collisions when more than one handset is found simultaneously searching for a base station for a channel alignment or for picking up. The handset places the channel in operation on the first N channel in the pattern (eg N = 2). Preferably, the first channel in the pattern is located in which the handset was previously aligned with the base station. This can reduce the time the channel is occupied by this procedure in case the handset ^ ¡^ ^ ¿¿¿¿^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ Remain aligned. Then, the handset sends a contact request to the base via the RF link on the N channel in step 74. Then, the method determines if there is a base in the N channel that is within the range in step 76. If there is a base on the N channel that is within the range, the handset is aligned with the base. In accordance with the above, the base sends an acknowledgment in step 78. If the handset receives the acknowledgment in step 78, the handset returns to step 70 to wait for the time period to expire to complete another channel alignment. If there is no base that is in the range of the N channel in step 76 or the handset does not receive the base recognition in step 80 within a predetermined period of time, the handset advances to the next channel number in the pattern in step 82. The handset determines if all the channels in the pattern have been used, in step 84. If all the channels have not been used, the handset sends a contact request to the base via RF link in a new one. channel N as in step 74. However, if all the channels in the pattern have been used, the handset returns to step 72 to randomly select a new channel search pattern and start the channel alignment procedure again . Optionally, the handset can be aligned to the base with the highest IPSR level.

In accordance with the foregoing, the channel alignment procedure described with reference to Figure 4, maintains a channel alignment of the handset with the base station by periodically sending a contact request to the base on a certain channel and increasing the channel if you do not receive a contact signal back from the base. The handset will align with the base station even when the handset moves from one position to another within the range of the base stations while it is hung. Going back to Figure 5, a flow chart describes the preferred pick-off operation (as shown in block 30 of Figure 2) in accordance with the method of the present invention. In particular, the user initiates the connection in step 90. The handset randomly selects a channel search pattern with a uniform distribution of channels (eg 2, 4, 9, 1, 3, 5, 8, 6 , 10, 7) in step 92. The handset places the handset channel equal to the first channel N in the pattern (eg N = 2). Preferably, the first channel in the pattern is located in the channel that was previously determined during the alignment procedure (described in detail with reference to Figure 4) to reduce the time needed for the hook-up connection. Then, the handset sends to the base a pick-up request via the RF link on the N channel in step 94. Then the handset determines whether there is a 'B ~ base on channel N that is within the range in step 96. If there is a base within the range found on channel N, the handset in any case determines whether the base is serving a handset in step 98. If the base is not servicing a handset, the base sends a recognition signal and picks up on the N channel in step 100. If the handset receives the acknowledgment in step 102, the connection is made in the N channel in the step 4É 104 output. If the base is serving a handset, the base ignores the request of the handset in step 106. Likewise, if there is no base in the N-channel which is in the range, as in step 96 or the handset does not receive the In step 102, the handset advances to the next channel number in the pattern in step 108. If all the channels in the pattern have not been used in the ~ At step 110, the handset sends a pick-up request to the base via the RF link on the next channel in the list as in step 94. However, if all the channels in the pattern have been used, the handset randomly selects a new search pattern with a uniform distribution as in step 92 to start the pick-up request again. Returning to Figure 6, a method for implementing the function of block 32 of Figure 2 is shown. Having established a connection with a base station, the station 1 (? Original base (eg the base station connected before any distribution to a new base station) will be determined periodically by establishing an exit period if a distribution is required in step 120. The original base station will determine if The original base station or the IPSR of the handset have fallen below a certain threshold in step 122. If the original base station and / or handset IPSR have dropped below the threshold, the original base station instructs all the base stations that are not currently serving any handset to go to their channel in step 124. In addition, the original base station instructs each base station that it is not currently servicing any handset to report (i) the IPSR level of the handset and (ii) the channel that will be operating in step 126. All the base stations are instructed to go to their original channels and the base station The original selects the base station with the highest IPSR signal level in step 128. The original base station also sends an order to "go to channel X" to the handset. Then, the handset initiates contact with the new base and waits for the return of the contact in step 130. If there is no return of the contact, the handset returns to the original base station in step 132. If in spite of the return the handset does not can restore communication with the original base station, the handset will search for a new M base station using the same search patterns described in detail in the reference in Figure 5 for * hook off. In any case, if there is a return of the contact request, the new base station will send a hanging order to the original base station in step 134. In accordance with the above, if there is a basic communication based on the line TELCO; an AC line or an independent RF communication are possible, and j 'is possible to complete the pick-up procedure with a small interruption in communication. Turning now to Figure 7, there is shown an alternative method for implementing block 32 of Figure 2. In particular, Figure 7 describes a method for off-hooking in a system that does not have independent base-to-base communication. The original base station establishes an exit time period in step 140. If the station The original base Wk determines that the IPSR level of the original base station and / or the microtrephone falls below a certain threshold in step 142, the original base station is put on hold and the handset initiates the pick-up request in step 144. The pick-up request is identical to the pick-up request described in the reference to Figure 5. and will not be repeated here in detail. If the handset is unable to find another base station in the ^^^ g step 146, the handset returns to the original base station (tt and it places itself out of standby in step 148. In any case, if the original base station detects that the new base station is placed on off-hook when detecting a change in the resistance of the TELCO line in step 150, the original base station is placed on itself to hang in. Returning now to Figure 8, it shows a preferred circuit for communication between base stations.A block diagram for the base stations 10 shows the relevant parts of the base station for providing information signals between the base stations by means of the data link Each base station generally includes a transceiver 220 for the transmission of communication RF signals and for the reception of communication RF signals from each remote device 12 The radio transceivers are well known in the art and could be used in the present invention.

MK using the transceiver circuit described in the aforementioned United States Patent 5,140,635. The RF communication signals include the frequency or channel occupied by the remote device, a security code assigned to the remote device to allow the remote device to operate in the wireless communication system 10 and in any message signal. The message signals may depend on the remote device but may include some voice signals, facsimile data or computer data. (tt The radio transceiver 220 provides communication signals to a line 22 that is linked to a signal transceiver circuit 224. The signal transceiver circuit 224 includes an ordinary telephone company interface (Telco) circuit 226 for the transmission of communication signals The ordinary Telco circuits are well known in the art and provide communication signals to ordinary inputs and tone lines of the public telephone network system (SPRT) 231. The radio transceiver 220 also generates an information signal to the line 222. The information signal could include a receiver signal power indication (IPSR) signal and an associated security code for the remote device The IPSR signal indicates the power of the RF communication signals received from the remote device 12 In a system that has multiple remote K devices, an IPSR signal is generated by each remote device 12 and it is identified by a security code associated with the remote device. The IPSR signal may be an on / off indicator or may represent a discrete level within a predetermined range of levels representing the signal strength. Information signals that include an IPSR signal are provided by a microprocessor 228.

The microprocessor 228 in each base station 10, maintains ß an IPSR signal to indicate the power of the RF communication signal received from each remote device 12. In addition, the microprocessor 228 communicates with the signal of the transceiver circuit 224 to transmit the signals of IPSR to other base stations and receive the IPSR signals of other base stations by means of the data link 14. As will be described in detail in the reference to the operation of the circuit of the present invention, the microprocessor 228 of (tt) each active base station compares the associated IPSR signals to a given remote device from the base stations to determine if another base station is receiving a stronger RF communication signal The signal transceiver circuit 224 generally includes a transmitter circuit 230 and a receiver circuit 232. The microprocessor 228 provides an IPSR signal to the signal of the transceiver circuit 224 for coupling the two signals to the contacts and tone lines of the SPRT via the data link 14. Preferably, the circuit Transmission 230 transmits information signals at a frequency of approximately 30 KHz. A frequency of 30 KHz is selected to optimize the transmission of information signals., the 30 KHz signal is outside the range of audible signals and will not be heard by the user of the remote device. In addition, a signal of 30 KHz is the lowest frequency outside the audible range and thus allows a greater signal amplitude in the Telco line. Finally, a signal of 30 KHz will be filtered by the public telephone network system. While a signal of 30 KHz is preferred, any other signal that is outside the audible range can be used and will be filtered by the public telephone network system. The signal transceiver circuit 224 further includes a receiver circuit 232 for receiving information signals from other base stations via the data link 14. Preferably, the receiver circuit 232 includes a bandpass filter to pass signals from 30 KHz transmitted on the data link by the transmitting circuits of other base stations. The information signals are coupled to the microprocessor where they are stored. Because each base station receives the information signals from another base station, none of the base stations will be able to function as an active base station and determine which base station is receiving the strongest RF communication signal with respect to a device. private remote. Finally, an answering machine 233 can be incorporated into one of the base stations. Preferably, the answering machine should be a digital answering machine. Turning now to Figure 9, the preferred transceiver circuit 224 (shown in tt block form in Figure 8) found in each station is shown in detail. * base 11. Transmitting circuit 230 includes an AND gate 234 (y) having a first input 236 coupled to receive a square wave of 30 KHz and a second input 238 coupled to receive data. The data should include information signals that describe the remote device, the channel or frequency of operation and the IPSR signal generated by the radio transceiver as described above. The data must be transmitted by placing in AND (y) a square wave of 30 MHz and a square wave signal of 30 MHz. Alternatively, the data can be provided by the microprocessor as a 30 MHz signal. The output 240 and the AND gate (y) 234 are coupled by a capacitor 242 to the TIP line. Preferably, the capacitor 234 should be approximately 200 picofarads. The output 240 and the AND gate 234 are also coupled by an inverter 244. The output 246 of the inverter 244 is coupled by a capacitor 248 to the TONE line. The capacitor 248 should preferably be 200 picofarads. The Telco circuit 226 is shown in detail in Figure 9. The Telco circuit 226 includes a transformer 252 for transmitting and receiving audio signals from the transceiver. The transformer is coupled to the relay 254. The relay 254 is controlled by a transistor 256 which is activated or deactivated by the voltage of a control ttf electrode 258 coupled by an input transistor 260. The relay 254 is coupled by a bridge circuit 262 and a node 264. The nodes 266 and 268 of the bridge circuit 262 are coupled to the TIP and Tone lines. In addition, the bridge circuit 262 receives signals from the TIP and TONE lines through the nodes 266 and 268. Finally, the node 270 is coupled to the transformer 252 to transmit signals from the TIP and TONE lines to the radio transceiver. Finally, the signal transceiver circuit 224 includes a receiver circuit 270. The receiver circuit acts as a bandpass filter to pass the telephone network public service information signal. Preferably, the receiver circuit 270 will pass the 30 MHz information signals that are transmitted by the transmitter circuits 230 of the other base station. The receiver circuit 270 includes a differential jtt amplifier circuit 272 having a positive input 274 and a negative input 276. The positive input 274 is coupled to the TONE line by a capacitor 278 and a resistor 280 which form a low pass filter. Preferably, the capacitor 278 must be 620 picofarads and the resistor 280 must be 10 KO. In addition, the output 274 is coupled to a parallel RC network comprising a capacitor 282 and a resistor 284 to form a high pass filter. Preferably, the capacitor 282 must be 20 pf and the resistor 284 must be 220 KO. The negative input 276 of the differential amplifier is further coupled to the capacitor 286 in series with the resistor 288 forming a low pass filter. Preferably, the capacitor 286 must be 620 pf and the resistor 288 must be 220 KO. In addition, the parallel configuration of the capacitor 290 and the resistor 292 are coupled between the negative input 276 and the output 294 of the differential amplifier. Preferably, the capacitor 290 must be 20 pf and the resistor 292 must be 220 kO. The signal transceiver circuit 224 is shown in detail in Figure 9 and is an example of the type of circuit that can be used. However, it should be clear that other signal transceiver circuits for transmitting and receiving information signals of about 30 MHz can be used in the data link from the scope of the present invention. In particular, the present invention establishes and maintains communication in a portable telephone system adapted to operate with multiple base stations and at least one handset in a variety of channels. In general, the method assigns security code (s) for the operation of the handset (s) within the portable communication system and provides copies of the security codes to each of the base stations to allow communication

Claims (10)

1. RF between the handset (s) and the base stations. -jttr In addition, the method aligns the channel of the handset (s) with the channel of the base station to allow communication * between each handset and one of the different base stations. In particular, when a particular handset is not in use, the method maintains a channel alignment with a base station within the range. Moreover, during RF communication with the handset, the base station will distribute the signal between the base stations ^ fi in order to maintain communication. The distribution can be made by means of the communication between the different base stations.
2. NOVELTY OF THE INVENTION
3. Having described the foregoing invention, it is considered as a novelty, and therefore, the content of the following is claimed as property:
4. CLAIMS 1. A method for establishing and maintaining communication in a portable radiotelephone system that includes a variety of base stations adapted to communicate via a variety of radio channels with at least one remote device, characterized in that it contains the steps of assigning a security code to at least one
5. A remote device to allow communication between at least one remote device and the multiple base stations; the communication of the security code assigned to at least one remote device to the multiple base stations to maintain within each of the multiple base stations the security code assigned to at least one remote device operating in the system and; the channel alignment of at least one remote device with the radio channel of one of ^ the multiple base stations to allow communication between at least one remote device and at least one of the multiple base stations. 2. A method according to claim 1 in claim 1 characterized in that it establishes and maintains the communication in a portable radio communication system adapted to operate with multiple remote devices and the assignment of a security code characterized by the mk assignment of a security code. different security to each one of the multiple remote devices. 3. A method for establishing and maintaining communication in a portable radio communication system according to claim 1, characterized in that it is adapted to operate with multiple remote devices and the communication of the security codes is characterized by the generation of a list of security codes for the multiple remote devices in each of the multiple base stations. 4. A method for establishing and maintaining communication in a portable radio communication system and the steps for assigning a security code in accordance with claim 1, characterized in that the steps provide the current code of the remote device to the station base; the assignment of a new security code to the remote device; and the status of the new security code in the master list of security codes. 5. A method for establishing and maintaining communication in a portable radio communication system in accordance with claim 4, characterized in that the steps to provide the current security code and the assignment of a new security code are completed by communication of RF
6. 6. A method for assigning a security code for a portable radio communication system that includes multiple remote devices adapted to communicate by means of at least one radio channel with at least one of the multiple base stations characterized because it provides the current code security to each of the multiple remote devices; the assignment of a new security code to each of the multiple remote devices and; places the new security code in the master list of security codes in at least one base station.
7. 7. A method for maintaining communication with a remote system within a radio communication system that includes at least one base station adapted to communicate through multiple radio channels with at least one remote device, a method characterized in that it periodically sends a contact request from at least JK one of the remote devices to at least one of the base stations; waiting for the return of contact from at least one of the base stations and; changing the channel of at least one of the remote devices to correspond to the channel of at least one base station that returns the contact message.
8. 8. A method for maintaining communication with a remote device in accordance with claim 7, characterized in that it is adapted to operate with multiple base stations and the multiple base stations are maintained in different channels.
9. 9. A method for maintaining communication in a portable radio communication system that includes multiple base stations adapted to communicate over multiple radio channels with at least one remote device that is in active communication with a base station of the multiple base stations, a method characterized in that it includes the evaluation steps of the signal power indicator level of the receiver of the signal received in the base station from at least one remote device; instruction from a base station to the remaining base stations to report the receiver signal strength level and a channel in operation; the selection of the base station that reports the signal of the highest signal power indicator level of the receiver. ttjr
10. 10. A method for maintaining communication in a portable radio communication system that includes multiple base stations adapted to communicate over multiple radio channels with at least one remote device that is in active communication with a base station of the multiple base stations , a method characterized in that it includes the evaluation steps of the signal power indicator level of the receiver of the signal received in the 4 k base station from at least one remote device; the status of the standby base station; the contact request from at least one remote device to establish contact with the base station that reports the strongest signal of the signal strength level of the receiver; providing contact between at least one remote device and the base station that reports the strongest signal from the receiver's signal strength indicator. In testimony of which I sign the present in this City of Mexico D. F. to July 20, 1994. NDUI. P131294MX- - '- «• *