MXPA01000863A - Method and apparatus for allowing cordless communication attempts in a multiple mode system - Google Patents

Abstract

In a multiple mode communication system (29), a radio communication device (22) selectively communicates, using a common pool of channels (42), through a cordless base station (30) and a cellular network having a plurality of cellular base stations (24). The radio communication device (22) determines and stores local station identifiers (88) for the cellular base stations (24) which are broadcasting message streams (48) over control channels (46) in a cordless radio coverage area (26) of the radio communication device (22). The radio communication device (22) transmits a message to the cordless base station (30) when a detected cellular base station identifier (51) matches one of the determined local station identifiers (88). The radio communication device (22) is prevented from transmitting a message when the detected cellular base station identifier (51) matches none of the local station identifiers (88).

Description

METHOD AND APPARATUS FOR ALLOWING INTELLIGENT COMMUNICATION ATTEMPTS IN A MULTIPLE MODE SYSTEM TECHNICAL AREA The present invention relates in general to radio communication devices. More specifically, the present invention relates to radio communication devices that selectively communicate over a cellular network and a wireless network using common radiofrequency channels.

ANTECEDENTS OF THE TECHNIQUE Multiple-mode communication systems use common components for multiple functions. For example, a multi-mode communication system may use a radio communication device, such as a portable radiotelephone apparatus, to communicate both in a wireless mode of operation and in a cellular mode of operation. In the wireless operation mode, typically the apparatus communicates with a low power with a wireless base station having a radio coverage area of a few hundred feet. The wireless base station can REF. NO.126838 connect with one or more local circuits of a public switched telecommunication network (PSTN). Then, the apparatus can communicate in the radio coverage area by means of the wireless base station with telephone devices that are connected to the PSTN.

In the cellular operation mode, the apparatus is typically communicated with moderate energy with a cellular beise station having a much larger radio coverage area in relation to the wireless radio coverage area. Consequently, the apparatus can be located a few miles away from the cellular base station. Typically the cellular base station is connected to the PSTN by means of a mobile telephone switching office (MSTO). In a typical cellular system, multiple cellular base stations provide coverage to a geographic area. Each of these cellular base stations overlaps portions of their coverage to allow non-intervention between cellular base stations to take place. Therefore, in any specific geographic location, confined there is one, and often more than one, cellular base station that provides coverage for that particular location. Then the apparatus can communicate through one of the cellular base stations with telephone devices that connect it to the PSTN.

In a typical situation, a wireless base station can be located near the residence of a user or workplace. Operations in wireless mode are available for the devices when the user is near the user's residence or workplace, and cell operation modes are available in other locations.

The first multiple-mode radiotelephones combined separate wireless transceivers and cellular transceivers in a common device. The wireless and cellular transceivers operated in different frequency bands using different communication protocols. Potential interference between wireless and cellular operations was not a problem. However, the high costs, weight and power consumption of this dual transceiver idea made the idea impractical.

Subsequent generations of multiple-mode radiotelephones use a common frequency band, or a common channel source, and at least compatible communication protocols for wireless mode and cellular mode operations. Since a simple transceiver can be used for both wireless and cellular operations, improvements in costs, weight, and power consumption are obtained. However, there is a potential for interference between wireless mode and cellular mode operations because channels for wireless operations in one location can cause interference with the same channels in use for nearby cellular operations.

A prior art communication system is configured such that a wireless base station monitors conventional reverse cell channels to determine which cellular channels are not in use at the base station location. Once the base station finds a clear channel, it completely consumes the channel by transmitting a pilot signal that mimics a conventional cellular control channel. Unfortunately, the use of a continuous pilot channel prevents the pilot channel from carrying user communications which results in an inefficient use of the frequency spectrum. In addition, the constant transmission of pilot signals from several wireless base stations increases the background noise for all wireless and cellular communications taking place in the surrounding area and further increasing the interference.

Another multiple-mode communication system of the prior art, such as that described in US Patent No. 5,594,782 to Zicker et al., Entitled "Multi-Mode Personal Wireless Communication System", employs wireless operation not piloted to reduce the probability of interference. In other words, the wireless base station does not consistently transmit a radio frequency pilot signal, i.e., the wireless base station is a silent RF unless the communication is first initiated by a radio telephone. Therefore the interference of the piloted signal transmitted constantly is avoided. This prior art system causes the radiotelephone to initiate communication with the wireless base station by transmitting an access message to a wireless base station when the telephone radio determines that it is in a geographical location where the communication with the wireless base station It could be possible.

The prior art system causes the radiotelephone to detect the radiofrequencies of the control channels transmitted by the cellular earth stations in the geographical location in which the radiotelephone is normally located. The radiotelephone is then configured to compare a cellular base station identifier extracted from the detected control channel to a preprogrammed list of cellular base station identifiers, here referred to as local station identifiers, which may be detectable within the coverage area. of wireless radio.

When the radiotelephone finds or matches between the detected base station identifier and a local station identifier from the preprogrammed list, the radiotelephone is capable of transmitting a wireless access message to try to locate its corresponding wireless base station. However, when the detected base station identifier does not match co: none of the local station identifiers of the preprogrammed list, the radiotelephone will not attempt to locate its corresponding wireless base station, thereby eliminating unnecessary transmissions.

In order to generate the preprogrammed list of the local station identifiers, during or before the activation of the radiotelephone, this prior art system compares a proposed geographic location of the wireless base station with computer-modeled predictive propagation traces of the cellular system in order to determine the strongest cellular base stations near the proposed location. The cellular base stations that have been predicted to have the strongest signals, known as best-servers, are then placed in the preprogrammed list of identifiers for the local station.

While this prior art system reduces the likelihood of interference by reducing the unnecessary number of transmissions, this system requires a programming process to be executed per paired unit (i.e., the combination of radiotelephone and wireless base station) for each specific geographic location. in which it is to be used. The programming process introduces additional handling costs, and slows the system supply time because the pairs of units can not be preprogrammed for the operation and placed in reserve. Also, an error is introduced in the processes of predictive modeling and geographic location employed by this prior art system. In addition, the location process employed by the radiotelephony has problems when the operating frequencies are changed or reassigned within the cellular network, or if the cells associated with a particular cellular base station are divided. When the frequencies are altered or when the cells are divided, the radiotelephony may erroneously transmit wireless network access messages and increase the number of unnecessary transmissions or fail to transmit an access message in the appropriate location to allow the subsequent mode of wireless operation.

Therefore, when the frequencies are altered or when the cells are divided, the frequency-dependent localization process must be altered accordingly. This results in significant reprogramming efforts and costs. In addition, there may be a programming delay between the actual frequency changes and the reprogramming of the components, during which the location process may cause the radiotelephone to erroneously transmit access messages to the wireless network or fail to transmit the access messages what are you wishing for Therefore, what is needed is an automatic process for the determination of a list of identifiers of local stations, or identifiers of best-servers, for cellular base stations that have a radio coverage area that covers a coverage area of radio of the wireless base station. Such a system should be able to update this list periodically in order to adapt the changes in the cellular frequency assignments.

BRIEF DESCRIPTION OF THE INVENTION The present invention is carried out in one way by means of a method that allows a radio communication device to attempt communication with a wireless base station. In a multi-mode communication system, the radio communication device is configured to selectively communicate through a cellular network and a wireless base station using a common source of channels. The cellular network has numerous cellular base stations. The method is directed to the selection of local control channels from numerous control channels. Each of the local control channels exhibits a better signal quality than the unselected ones of the control channels. The method is additionally directed to the determination of a local station identifier for each of the local control channels, the local station identifiers identify the cellular base stations that transmit the local control channels. A cellular base identifier is received in the radio communication device, the identifier of the cellular base station being transmitted over one of the numerous control channels. A message is transmitted from the communication device when the cellular base station matches one of the local station identifiers.

The present invention is carried out in another way by means of a radio communication device configured to selectively communicate through a cellular network and a wireless base network using a common source of channels, the cellular network having numerous cellular base stations. The radio communication device includes a controller configured to select the local control channels from numerous control channels. Each of the local control channels exhibits an instantaneous quality signal which is greater than an instantaneous quality station of the non-selected control channels. The controller is further configured to determine local station identifiers for the local control channels, the local station identifiers identify the cellular base stations that transmit the local control channels. A receiver is connected to the controller and is configured to receive a cellular base station identifier transmitted over one of the control channels. A transmitter is connected to the controller and is configured to transmit a message when the cellular base station identifier matches one of the local station identifiers.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a schematic view of an environment in which a radio communication device is located; Figure 2 shows a schematic view in which the radio communication device is included in a multiple mode communication system in a wireless radio coverage area; Figure 3 shows a frequency management table which illustrates an example of a common source of channels used for cellular and wireless operations; Figure 4 shows a block diagram of a portion of an example message flow which is transmitted over a control channel by means of an associated cellular base station; Figure 5 shows a block diagram of the functional equipment included in the radio communication device according to the present invention; Figure 6 shows a flow diagram of a determination process of the local cellular base station performed by the radio communication device; Y Figure 7 shows a flow chart of a wireless registration attempt process performed by the radio communication device.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a schematic view of an environment 20 in which a multi-mode radio communication device 22 is located. The environment 20 supports a cellular network defined by a grid of cells 24 and any number of wireless communication systems defined by the wireless radio coverage areas 26. Environment 20 is illustrated with only two aggregates of seven cells of cells 24 schematically represented as hexagons and only a few wireless radio coverage areas 26 represented schematically as circles. Many more cells 24 and wireless radio coverage areas 26 can be included.

Several of the cells 24 can be located close to one another as can also be several of the wireless radio coverage areas 26. In addition, the cells 24 overlap portions of their radio coverage areas, denoted by dotted lines 28, in order to facilitate non-intervention between the cells 24. In addition, the cells 24 and the wireless radio coverage areas 26 overlap one another. Conveniently, each wireless coverage area 26 is substantially smaller than the cells 24. Although not shown, other cellular systems may be covered in the environment 20. In the preferred embodiment, the cellular system is compatible with conventional AMPS standards, Wireless systems also use frequency channels and communication protocols of the AMPS standard. However, nothing prevents the principles of the present invention from being applied to other types of radio communication systems, such as personal communications services (PCS), specialized mobile radio (SMR), and others.

As illustrated in Figure 1, the environment 20 includes any number of multiple mode radio communication devices 22, of which two are shown. In the preferred embodiment, the radio communication devices 22 are radio telephone sets used for voice communications. However, nothing prevents the principles of the present invention from being applied to other types of radio communication devices, such as portable equipment or fixed combinations of data and telemetry used by a wide variety of measurement, alarm, location, and other applications. other diversities.

Figure 2 shows a schematic view in which the radio communication device 22 is included in multiple mode communication systems 29 in one of the wireless radio coverage areas 26. Generally, the system 29 includes a radio communication device 22 and a corresponding wireless base station 30. For clarity of illustration, the radio communication device 22 is hereinafter referred to as apparatus 22. In addition, the wireless base station 30 and the apparatus 22 they are preprogrammed to allow communication to take place between the wireless base station 30 and the apparatus 22. Those skilled in the art will recognize that the system 29 can include any number of devices 22 which are preprogrammed to communicate with the wireless base station 30.

The wireless radio coverage area 26 covers three cells 24 '(BD), the cells 24' being a subset of cells 24. Each of the cells 24 and 24 'includes a cellular base station 34. The terms cellular base station and wireless base station are used here to distinguish one from the other, where "cellular" indicates a significantly larger radio coverage area "wireless". The cellular base stations 34 may be land based systems, satellite based systems, and others. In addition, the wireless base station 30 conveniently avoids operation at frequencies and uses of communication protocols that have historically been used for wireless telephony.

When located in an area where the wireless radio coverage area 26 covers the cell 24 ', the apparatus can communicate via the wireless base station 30 or one of the cellular base stations 34. With momentary reference to Figure 1 , being outside the wireless radio coverage area 26, but still within the cellular network defined by the cells 24, the apparatus 22 can only communicate with one of the cellular base stations 34.

With reference again to Figure 2, the wireless base station 30 is connected to the central telephone office. 36 by means of one or more wire circuits. The cellular base stations 34 are also connected to the central telephone office 36 through a mobile telephone switching office (MTSO) 38 and the appropriate trunks. Through the central telephone office 36, user communications can be provided between the apparatus 22 and other telephone devices connected to the public switched telephone network (PSTN) (not shown) via wireless communications or mode communications. cell phone.

Figure 3 shows a frequency management table 40 which illustrates a common source of example channels 42 used for both cellular and wireless communications. For ease of illustration, Figure 3 illustrates a frequency management table that describes an AMP cellular system. Those skilled in the art will appreciate that the principles discussed below, in connection with Table 40, apply to current AMPS frequency management schemes, as well as to frequency management schemes used by other types of cellular systems. Channel numbers (listed as 1-666 in Table 40 identify discrete radiofrequency channels.) Channels 1-333 are a block designated as A that groups radiofrequency channels consistent with a system assignment A. Similarly, channels 334-666 are a block designated as B that groups radiofrequency channels consistent with a B system assignment.

Conveniently, each channel represents a complete or bidirectional double radio frequency channel which has a forward portion and a reverse portion. The forward portion defines a link connected in the direction of the apparatus 22, while the reverse portion defines a link directed outside the apparatus 22. Consequently, when the apparatus 22 synchronizes a receiver with a channel, they synchronize the receiver with the forward portion of the receiver. radio frequency channel, and when the wireless base station 30 or cellular base station 34 tunes a receiver with a channel, synchronizes the receiver with the reverse portion of the radiofrequency channel .. Each apparatus 22, wireless base station 30, and cellular base station 34 must be configured to communicate on any channel identified in the channel source 42.

However, as illustrated by Figures 1 and 3, the apparatus 22, the wireless base station 30, and the cellular base station 34 need to restrict and otherwise manage their use of channels to minimize interference. Figure 11 illustrates a plan for assigning a seven-cell reuse channel well known in the cellular telephone art. The source of channels 42 is divided into various cellular subsets 44, indicated in the form of vertical columns in table 40. Each cellular subset 44 is configured in such a way that its channels are non-contiguous. In other words, two adjacent channels are not included in any single cell subset 44. Cell subsets 44 (marked as AG in Figures 1 and 3) are assigned to different cells 24, and cellular communications can use only channels included in the cell. cellular subset 44 assigned to cell 24 where communications take place. This reuse channel allocation plan maintains a minimum reuse distance between different locations where the same channels are reused. The greater this distance of reuse, the lower the risk of interference. Of course, those skilled in the art will appreciate that many other types of channel assignment plans, sectorization, dynamic channel assignment, channel lending, and the like can be used. In addition, the precise frequencies and numbers of channels included in the channel source 42 are not relevant parameters for the purposes of the present invention.

Table 40 also illustrates cellular control channels 46 (channels 313-354). Each of the cellular base stations 34 (Figure 2) generates a continuous message flow of digital information on one of the control channels 46. The control channels 46 are used to identify the presence of cellular base stations 34, regulate the attempts of access to the cellular network, calls to cellular devices, and for other purposes of signaling.

Figure 4 shows a block diagram of a portion of an example message flow 48 that is transmitted over one of the control channels 46 (Figure 3) by one of the associated cellular base stations 34 (Figure 2). The message flow 48 may include an overload message which provides the device 22 with information in. The cellular network, such as an identification system (SID) 50, and whose access and call channels are available in cell 24 (Figure 1).

The message flow 48 is also configured to include a cellular base station (ID) identifier 51. The cellular base station identifier 51 identifies one of the transmission channels 46 of the cellular base stations 34 (Figure 2). In the preferred embodiment, the identifier of the cellular base station 51 is unique to each of the cellular base stations 34, and is sent in the message flow 48 approximately every eight seconds. Alternatively by convention in cellular systems, the message flow 48 may include a digital coded code (DCC). The digital color code is a two-digit code that distinguishes a particular channel from one at a similar frequency within the common source of channels 42 (Figure 3). The combination of the DCCs and the control channel 46 that is transmitting the particular DCC can be used as a cellular base identifier 51.

Figure 5 shows a block diagram of the functional equipment included in the apparatus 22 in accordance with the present invention. For clarity, standard operating elements well known to those skilled in the art and unimportant to the present invention are not shown in Figure 5 or described here in detail. In general, the apparatus 22 includes a controller 52, which controls the operation of the apparatus 22. Several components are connected or are in data communication with the controller 52, such as a receiver 54, a transmitter 56, a stopwatch 58, a user interface 60, and memory 62. Controller 52 may be, for example, a conventional microprocessor circuit well known in the cellular telephone art.

The receiver 54, which is connected to the controller 52, is configured to receive signaling data and user communications on a selected channel of the channel source 42 (Figure 3). The transmitter 56 is also connected to the controller 52. The transmitter 56 is configured to transmit data associated with cellular telephone operations and user communications. Those skilled in the art will readily recognize that the receiver 54 and the transmitter 56 can be integrated into a transceiver assembly. The timer 58 is connected to a controller 52 and records the passage of time. The user interface 60 is connected to the controller 52 and conveniently includes flat keyboard press buttons, a loudspeaker, a microphone, a display and other user interface devices known in the art. The memory 62 is connected to the controller 36 and stores programming instructions defining the various processes described below. In addition, the memory 612 stores various cellular operation parameters and various tables and lists of data used in the operation of the apparatus 22.

The wireless base station 30 has a block diagram (not shown) similar to that shown in Figure 5. However, the receiver 54 and the transmitter 56 of the apparatus 22 operate in forward and reverse radiofrequency portions, respectively, of channels selected, while a corresponding receiver and transmitter of the wireless base station 30 operates in reverse and forward radiofrequency portions, respectively, of selected channels.

Figure 6 shows a flow diagram of the process 64 of determining a cellular base station executed by the apparatus 22 (Figure 2). The process 64 is executed when the multi-mode communication system 29 (Figure 2) first experiences a manual authorization process. Subsequently, the process 64 conveniently executes automatically each time the apparatus 22 moves within the wireless radio coverage area 26 (Figure 2) after being outside the area 26. In addition, the determination process 64 can be executed in conjunction with other processes of selection of communication channels, such as the selection of free or underutilized channels for voice or data communication.

The determination process begins with task 66. Task 66 causes the device 22 to verify that it is located within the wireless radio coverage area 26 (Figure 2). The verification task 66 can be performed for the authorization of the system 29 (Figure 2) by the manual input of commands in the user interface 60 (Figure 5) by the user. In an authorization process, the apparatus 22 is physically placed near the wireless base station 30 (Figure 2). At this point, the wireless base station 30 is silent RF. In other words, it is not transmitting a pilot signal. Instead, task 66 causes the device 22 to transmit a message addressed to the wireless base station 30 to attempt registration. In response to the registration attempt message, the wireless base station 30 returns an acknowledgment message to the device 22. Following an authorization and while operating in cellular mode, the apparatus 22 periodically transmits a message to attempt wireless registration following the expiration of predetermined durations measured by the timer 58 (Figure 5) in response to a call attempt, and so on.

In connection with the verification task 66, a query task 67 is executed. The inquiry task 67 causes the apparatus 22 to determine whether the verification is successful. The verification task 66 is successful when the apparatus 22 receives a recognition message from the wireless base station 30 (Figure 2) in response to the registration attempt message sent by the device 22. If an acknowledgment message is not received, the apparatus 22 is not in the wireless radio coverage area 26 (Figure 2), and process 64 ends. Although not shown in Figure 6, a consequence of the failure of the verification tasks 66 and (57 is that the apparatus 22 may remain in its cellular operating mode where it routes the communications through the cellular base stations 34 (FIGS. 1-2).

However, when the inquiry task 67 determines that the apparatus 22 is in a wireless radio coverage area 26, the program control proceeds with a task 68. At this point, the apparatus 22 is operated in its wireless mode, in where future communications will be routed through the wireless base station 30. The task 68 causes the receiver 54 of the apparatus 22 to tune to one of the control channels 46 (Figure 1) in a preferred range of control channels. For example, the apparatus 22 may be tuned to one of the twenty-one control channels 46 assigned for use in a type A cellular system.

In response to task 6T, a task 70 causes the apparatus 22 to check a signal quy of the tuned control channel 46. In the preferred embodiment the signal quy is determined by measuring an instantaneous signal strength or relative signal strength indicator. (RSSI)., In an analog communication system, the RSSI provides an instantaneous take of the signal quy of the control channel 46 tuned by measuring the radio frequency energy of the detected control channel 46. However, in a digital communication system , the task 70 can cause the apparatus 22 to measure signal quy by detecting a bit error rate in the tuned control channel 4. (5) In addition, those skilled in the art will recognize that other techniques exist for the determination of the signal quy of the tuned control channels 46.

The task 70 also causes the apparatus 22 to retain the signal quality measurements. For example, the signal quality measurements may be retained in a temporary array 72 in the memory of the apparatus 62 (Figure 5). An exemplary time arrangement 72 is illustrated in Figure 6 showing a preferred block of the control channels 46 in association with a measured RSSI value 74.

Next to task 70, a query task 76 determines whether another of the control channels 46 exists in the temporary array 72 for which the RSSI value 74 will be measured. When the inquiry task 76 determines that another of the channels 46 exists , the program control returns to task 68 to tune to one of the control channels 46 and the subsequent RSSI 74 measurements. Then, tasks 68, 70, and 76 cause the apparatus 22 (Figure 5) to sequentially tune to the receiver 54 for each of the control channels 46 and measure the current or instantaneous RSSI 74 when the receiver 54 tunes to one. specific control channels 46.

When the inquiry task 76 determines that there is no other control channel 46, in other words, when the receiver 54 has been tuned to each of the control channels 46 and the RSSI 74 has been measured, the program control proceeds to a task 78. The entire programming cycle, which includes tasks 68, 70, and 76, can be completed quickly because instantaneous signal quality measurement quickly takes place for each simple control channel 72.

Task 78 causes the controller 52 (Figure 5) of the apparatus 22 to select a subset of control channels 46 from temporary array 71 which exhibits an RSSI 74 that is larger than the unselected control channels 46 of the temporary array 72. The task 78 causes the controller 52 to identify control channels 46 as local control channels 46 'and to assemble the local control channels 46' in an update list 80. In the preferred embodiment, the update list £ 0 includes up to eight local control channels 46 '. However, the number of local control channels 46 'is system specific and greatly depends on the number of cells 24 having cell coverage areas 28 (Figure 1) which can overlap each other in a geographic location within a environment 20 (Figure 1). In addition, the update list 80 need not be separated from the buffer 72. Instead those control channels 46 that are identified as local control channels 46 'can be marked or otherwise denoted from the non-selected control channels 46. in arrangement 72.

Following task 78, a task 82 causes the receiver 54 (Figure 5) of the apparatus 22 to tune to one of the local control channels 46 'from the update list 80. When tuned, the receiver 54 is configured to receive the message flow 48 (Figure 4) that is continuously being transmitted on one of the local channels 46 'by one of the cellular base stations 34 (Figure 2).

In connection with the task 82, a task 84 causes the controller 52 to determine the cellular base station identifier 51 (Figure 4) in the message flow 48 of the local control channel 46 'tuned. The determination of the identifier 51 of the message flow 48 for a simple local control channel 46 'takes more time than the single determination of the signal quality for that channel. However, typically a few control channels 46 'need to be evaluated, and the overall effect is slight.

Next to task 84, a task 86 causes the controller 52 to dial or otherwise denote the determined cellular base station identifier 51 as a local station identifier 88 in the update list 80 and the associated local station identifier 88. with its local control channel 46 '. The local station identifier 88 is then a best-server identifier corresponding to a best-service cellular base station 34 for which a signal quality measure (RSSI 74) is better than the other base station control channels. cellular 46. Therefore, better-server cellular base stations have a portion of their cellular radio coverage area 28 (Figure 2) that covers the wireless radio coverage area 26 (Figure 2).

Following task 86, a query task 90 determines whether another of the control channels 46 'exists in the update list for which a local station identifier 88 will be determined. When there is another of the local control channels 46' , the process 64 returns to the task 82, in such a way that the tuning, which determines, and associates the tasks 82, 84, and 86 is performed for another of the control channels 46 '. Therefore, tasks 82, 84, 86, and 90 cause the apparatus 22 (Figure 5) to sequentially tune the receiver 54 with each of the control channels 46 'and determine its associated local station identifier 88. In the preferred embodiment, the cellular base station identifier 51 (Figure 4) is sent approximately every eight seconds. Consequences, the receiver 54 tunes to each local control channel 46 '"for up to eight seconds to allow sufficient time for the local station identifier 88 to be determined.

When the inquiry task 90 determines that there are no other local control channels 46 'for which a local station identifier 88 will be determined, the process 64 proceeds to task 92. Task 92 causes the controller 52 to store the list of update 80 in memory 62 (Figure 5). If a list of local station identifiers still exists in the memory 62, from a previous iteration of the determination process 64, or from an activation session, discussed previously, the controller 52 overwrites the preprogrammed list in memory 62 with the list update 80. Following task 92, the process (54 ends.

Process 64 is executed because system 29 is not preprogrammed for a specific geographic location. Therefore, the system 29 has no prior knowledge of which of the base stations 34 can be a local cellular base station until the activation of the system 29. Since, the wireless base stations and the apparatuses do not need to be preprogrammed by the provider for a specific customer, the systems 29 are by far less complex than the previous systems, less expensive, and the response time for the supply is faster. In addition, since the process 64 is executed each time the device 22 returns to its wireless radio coverage area 66, the apparatus 22 is able to automatically adapt to changes in the cellular network, such as changes in the radio frequency assignment and cell division 34.

Figure 7 shows a flowchart of a wireless registration attempt process 94 executed by the apparatus 22 (Figure 2). The process 94 is executed by the apparatus 22 to attempt wireless communication with the wireless base station 30 (Figure 2). The wireless base station 30 is substantially silent RF. In other words,. the wireless base station does not continuously transmit a pilot signal which, when detected by the apparatus 22, could indicate to the apparatus 22 that it is located in the wireless coverage area 26 (Figure 2). Therefore, the base station 30 remains with silent RF unless it responds to a request initiated by a device or unless the device 22 is called. Consequently, the process 94 is executed by the device 22, while operating in the mode cell, to determine if it can be in the wireless radio coverage area 26. The process 94 occurs every time the device 22 is initialized, when the device 22 operates in cellular mode and attempts a call, when the device 22 loses the ability to reliably decode the selection of the current control channel (usually due to the declining strength of the signal), or upon expiration of a predetermined duration established by the operation of the timer 58 (Figure 5).

The process 94 begins with the task 96. The task 96 causes the apparatus 22 to electronically track and detect the radiofrequency of a continuous transmission of the control channels 46 (Figure 3) in the geographic location in which the apparatus 22 is normally located . When one of the control channels 46 is detected in the task 96, the process 94 proceeds to a task 98.

The task 98 causes the apparatus 22 to receive a cellular base station identifier 51 (Figure 4) of: transmission of the message flow 48 (Figure 4) on one of the detected control channels 46. As discussed with respect to the message flow 48, the identifier of the cellular base station 51 is conveniently a unique identifier code of the cellular base station. Alternatively, the station identifier 51 is a combination of the detected control channel 46 and a digital color code.

After task 98, a task 100 is executed. Task 100 causes the apparatus 22 to compare the identifier of the received cell base station 51 with the update list 80 (Figure 6) of the local station identifiers 88 which is stored in the memory of the apparatus 62 (Figure 5).

In connection with task 100, a query task 102 is executed. Query task 102 determines whether a match is found between the identifier of the cellular base station 51 and any of the identifiers 88 in the update list 80. A match between a cellular base station identifier 51 and the local station identifiers 88 indicates that the apparatus 22 may be in a wireless radio coverage area 26.

When a match is found in the inquiry task 102, a task 104 is executed. The task 104 causes the apparatus 22 to attempt communication with the wireless base station 30. In other words, the apparatus 22 is allowed to transmit a message of intent registration on a portion of one of the radio frequency channels of the channel source 42 (Figure 3), known and tracked by the wireless base station 30. The location of the apparatus 22 in the wireless radio coverage area 26 is checked if the base station 30 recognizes the attempted registration message transmitted. Accordingly, the wireless registration attempt process 94 is an antecedent, or previous operation, that is executed before and because of the initiation of communication with the wireless base station 30.

In addition, the registration attempt process 94 is executed as an antecedent, or a previous operation, when the process of determining local base station 64 is repeated (Figure 6). In other words, the determination process 64 is repeated when the apparatus 22 moves within the wireless radio coverage area and re-establishes contact with the wireless base station 30.

When a match is not found in task 102, a task 106 is executed. Task 106 prevents the apparatus 22 from transmitting a wireless registration attempt message to the wireless base station 30. Therefore, the apparatus 22 communicates to through one of the cellular base stations 34 (Figure 2) of the cellular network. Since the transmission of an access message from the wireless base station from the apparatus 22 is prevented when the apparatus 22 can not be in the wireless coverage area 26, unnecessary and interfering radio frequency transmissions are avoided.

After task 104 or 106, process 94 terminates, and the apparatus communicates through the wireless base station 30 (Figure 2) or the cellular base station 34 (Figure 34) using conventional cellular communication protocols.

In summary, a method and system is provided to allow a radio communication device in a multi-mode communication system to attempt communication with a wireless base station. The method and system reduces the likelihood of interference imposed on the cellular network by the wireless operation of the radio communication device by preventing the radio communication device from transmitting an attempt to register the wireless base station when the device determines that it is not in a radio coverage area of the wireless base station. The radio communication device plays an active role in determining which cellular base stations are transmitting control channels in the wireless radio coverage area., and detects one of those control channels before the transmission of a message to the wireless base station. In addition, the radio communication device automatically repeats the determination process each time it re-enters the wireless radio coverage in such a way that it can adapt to changes in the frequency assignments of the cellular network.

Although the preferred embodiments of the invention have been illustrated and described in detail, those skilled in the art will readily appreciate that various modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims. For example, an alternate embodiment of the present invention may include more than one radio communication device. In this alternate mode, a radio communication device can be a "master" device and the others can be "slave" devices. The master device executes the determination process of the local base station, and transfers the list of the local station identifiers to the wireless base station. The wireless base station can then bring this list to the slave devices in such a way that each of the radio communication devices is programmed with the same update list of the local station identifiers.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (1)

1. CLAIMS One method, in a multi-mode communication system in which a radio communication device is configured to selectively communicate through a cellular network and a wireless base station using a common source of channels, said cellular network having numerous cellular base stations, which allows said radio communication device to attempt communication with said wireless base station, said method characterized in that it comprises the steps of: selecting local control channels from numerous control channels, each of said control channels exhibiting a better signal quality than the non-selected ones of said control channels; determining a local station identifier for each of said local control channels, said local station identifiers identifying said cellular base stations transmitting said local control channels: reception of a cellular base station identifier in said radio communication apparatus, transmitting said cellular base station identifier on one of numerous control channels; and transmitting a message from said radio communication device when said transmission of the received station identifier matches one of the local station identifiers. A method according to claim 1, characterized in that said selection and determination steps occur in a radio coverage area of said wireless base station. A method according to claim 1, characterized in that said selection and determination steps are performed by means of said radio communication device, and said method additionally comprises the step of verifying that said communication device is in said area of radio coverage before said selection and determination steps. A method according to claim 1, characterized in that said signal quality is an instantaneous signal strength for one of the detected control channels and said selection step comprises the steps of: sequential tuning of a receiver with each of said numerous control channels, each of said control channels being continuously transmitted by each of said cellular base stations; and measuring said instantaneous signal strength of said control channel for each of said control channels, said instantaneous signal strength being the radiofrequency energy detected by said receiver, and said instant signal strength identifying said one of said channels of control that are said local control channels. A method according to claim 1, characterized in that said step of determining comprises the steps of: sequential tuning of a receiver with each of said local control channels; and for each of said control channels, the detection of said local station identifier from a flow of messages transmitted on said local control channel. A method according to claim 1, characterized in that said determining step comprises the step of programming a memory element of said radio communication device with said local station identifiers. A method according to claim 1, characterized in that it additionally comprises the step of preventing the transmission of said message from said communication device when said transmitted and received station identifier matches said local station identifiers. A method according to claim 1, characterized in that said radio communication device is configured to communicate through said cellular network when said radio communication device moves outside said coverage area of said wireless station, and said method additionally comprises the step of repeating said selection and determination steps when said radio communication device moves within said wireless radio coverage area. A method according to claim 8 (characterized in that said radio communication device includes a memory element within which said local station identifiers are programmed, and said step of repeated determination comprises the step of replacing the programmed local station identifiers with said updated local station identifiers. A radio communication device configured to selectively communicate through a cellular network and a wireless base station using a common source of channels, said cellular network having numerous cellular base stations, and said device comprising: a controller configured to select local control channels to from numerous control channels, each of said local control channels exhibiting an instantaneous signal quality which is greater than the instantaneous signal quality for the non-selected control channels, and in addition said controller being configured to determine station identifiers local to said local control channels, said local station identifiers identifying said cellular base stations transmitting said local control channels; a receiver connected to said controller and configured to receive a cellular base station identifier transmitted over one of numerous control channels; and a radiocommunication transmitting device connected to said controller and configured to transmit a message when said cellular base station identifier matches one of said local station identifiers. A radio communication device according to claim 10, characterized in that the controller diaphragm is additionally configured to prevent transmission of said message when said cellular base station identifier matches said local station identifiers. A radio communication device according to claim 10, characterized in that it additionally comprises a memory element connected to said controller, said memory element being configured to store said local station identifiers. A radio communication device according to claim 10, characterized in that said radio communication device is configured to communicate through said cellular network when said radio communication device moves outside of a radio coverage area of said wireless base station, and said controller is additionally configured to update said local station identifiers when said communication device moves within said radio coverage area. A method, in a multi-mode communication system in which a radio communication device initiates communication with a substantially silent RF wireless base station after said device determines that it is located within a range of radio coverage of a cellular base station, a method for adapting said device and said wireless base station to said cellular base station comprising: electronic detection of a cellular base station control channel which exhibits a better signal quality within an area of radio coverage of said wireless base station than other cellular base station control channels, said detected control channel being transmitted by a better-server cellular base station; and verifying that said device is within the range of radio coverage of said best-server cellular base station as an antecedent to initiate communication with said cellular base station. A method according to claim 14, characterized in that said detection operation is performed in said device. A method according to claim 15, characterized in that it additionally comprises the operation of verifying that said device is within the range of radio coverage of said wireless base station as an antecedent to repeat said detection operation electronically. A method according to claim 13, characterized in that it additionally comprises a best-server identifier for said best-server cellular base station. A method according to claim 14, characterized in that said detection operation detects numerous cellular base station control channels each of which exhibits a better signal quality within said radio coverage area of said base station than other channels control of cellular base station; said device determines numerous best-server identifiers corresponding to said numerous control channels; said device forms an updated list of best-server identifiers in response to said numerous best-server identifiers; and said verification operation is performed on said device in response to said updated list of best server identifiers. A method, in a multi-mode communication system in which a radio communication device is configured to selectively communicate through a cellular network and a wireless cellular base station using a common source of channels, said cellular network having numerous base stations cellular, to allow said radio communication device to attempt communication with a wireless base station, said method comprising the steps of: a) tuning a receiver with each of the numerous control channels, each of said control channels being continuously transmitted by each of said cellular base stations; b) measurement of an instantaneous signal strength of said control channel, for each of said control channels, said measured instantaneous signal strength being the radiofrequency energy detected by said receiver; c) selection of local control channels from numerous control channels, each of said control channels exhibiting an instantaneous signal strength greater than the instantaneous signal strength for said non-selected control channels; d) tuning said receiver with each of said local control channels; e) determining a local station identifier from a transmission of the message flow on said control channel, for each one of said control channels, said local station identifier identifying one of said cellular base stations transmitting one of said stations. said local control channels; f) reception of a cellular base station identifier in said radio communication device, said cellular base station identifier being transmitted over one of said numerous control channels; and g) transmission of a message from said radio communication device when said cellular base station identifier matches one of said local station identifiers. A method according to claim 19, characterized in that said radio communication device is configured to communicate over said cellular network when said radio communication device moves outside said coverage area of said wireless base station, and said method includes the repetition of the steps a) - e) when said radio communication device moves within the wireless radio coverage area.