FI117420B - Subscriber handover between two multi-access communication systems - Google Patents

Description

Λ - 1 1 7420

Subscriber handover between two multi-access communication systems

The invention relates generally to wireless communication systems, and in particular to an improved method and system for performing handover between two mobile communication systems when these mobile communication systems have a different principle of multi-access or channel communication.

10

In order to maximize the use and reuse of radio spectrum, wireless communication systems employ different systems to provide telecommunication capabilities for simultaneous or nearly simultaneous use by multiple users. In mobile phone systems, for example, many mobile subscribers are allowed access to landline communications services (i.e., public cellular network, PSTN) via various air interfaces, which interfaces allow multiple subscriber access.

# · · «« I :: 20 «« «•» 9 .II The multiple access principle can be defined as a set of rules «· that allocate telecommunications resources, such as radio frequency • ·· 1 ·· \ spectrum, by granting various combinations of transmission and reception. * * reception times, channel frequency, channel bandwidth, channel code * * * 25 and, transmitting or receiving locations or the like. For example:. ·. Some of the known multiple access policies are: AMPS (Advanced Mobile Phone System), NAMPS (Narrowband AMPS), TACS (Total).

Access Communications System), GSM (Global System for Mobile * 1.1 Communications), TDMA (Time Division Multiple Access), and • · * 1 * 30 CDMA (Code Division Multiple Access). Many of these multiple access principles are well documented. industry standards, published by the Cellular Telecommunications Industry Association (CTIA), the Telecommunication Industry Association (TIA), and other standardization bodies. An example of such standards is IS-95, which applies to code-5 multiple access communication systems (CDMA).

As newer multi-access principles are developed, the coverage of the new multi-access system is not as wide as that of older, well-established telecommunications systems that employ different multi-access principles. In order to provide subscribers using the new multi-access principle with wide-area telecommunication services, dual-system subscriber devices have been developed to enable subscribers to receive services from the new multi-access system, 15 and when roaming outside the new multi-access system.

, "Let us now refer to Figure X; it describes a typical relationship • · · 9 · «; * 20 new multi-access communication systems • fr «• · ·. * Between one coverage and another multi-access information system 9 · 4 hours. More particularly, * * · 1, * The coverage area 20 of the cellular system of Figure 1 illustrates a system using code division multiple access (CDMA) and is * * · 25 represented by hexagonal cells 22. Figure 1 illustrates, by way of illustration, an alternative multiple access system. fr fr. ··. The system (MP) depicted in circular cells 24. The boundary between the area covered by CDMA • · »t * cells 22 and the area covered by the MP cells 24 of the alternative MP- * * * system is represented by the boundary line 26 drawn pattern with a thick fr · V ·· line.

fr fr · • «♦ · #» * 3 117420

As the subscriber 28 moves between CDMA cells 22, the CDMA base station controller 30 monitors or manages the handover between the CDMA cells. Similarly, as the subscriber 28 moves between the MP cells 24 of the alternative MP system, the alternative MP base station controller 32 monitors or manages the handover between the MP cells 24 of the alternative MP system. Handover is a process of a cellular communication system where a traffic channel is switched from communication with one cell to communication with another cell.

The problem solved by the present invention occurs when the communication system 15 using the first MP wants to transfer the subscriber's responsibility to the communication system using the second MP. This problem occurs in the case of Figure 1 when subscriber 28 moves from CDMA • V * cell 22 over boundary 26 to alternative MP cell 24. Problem Ψ 0 • V. ma may occur without subscriber 28 crossing the boundary 26 pre- • ♦; * · *. 20 characters when the first MP t · '* t • \ J communication system wants to transfer the handheld state to * - * *: *; * · for the alternative MP cell 24 with coverage ♦ within the area covered by the first MP communication. system.

In the prior art, for example, when the first MP is • 9h CDMA, pilot beacon 34 is used to warn CDMA base station controller 30 that subscriber 28 is approaching the edge of the \ CDMA coverage area (i.e., boundary 26). As * 30 used in this context, pilot beacon 34 is a transmitted signal, defined, or typically received by a 4-component, in the first MP, that is, the MP that is the handoff source MP. . For example, when CDMA is a source MP, pilot beacon 34 is a pilot channel beacon that causes 5 alternative MP cells 24 outside and near boundary 26 to look like another CDMA cell 22. This means that subscriber 28 reports the existence of pilot beacon 34 and the strength of the CDMA base station controller in accordance with the rules of the CDMA standard IS-95, so that said. the base station controller is capable of arranging the handover 10 with the alternative MP base station controller 32 via the inter-MP base station controller communication link 36. This is further elaborated in the United States Patent No. No. 5,594,718 to Weaver and Others, issued January 14, 1997.

15

There are many problems with the placement of pilot beacons 34 in cells near border 26 and beyond. First, it is * V, expensive. Each pilot beacon 34 requires a transmitter connection »· • V. when mounted on an antenna fixed to a suitable construction. 20 fungus.

9 9 • f 9 9 9 · 9 9 99

9 I

Secondly, it adds to the complexity of the telecommunications system. CDMA pilot beacons must be synchronized with the rest of the system and equipped with a unique timing offset.

: T: 25 Power levels must be set correctly.

··· 9 9 9 9 9 9 9 9 ... ·: Third: additional antenna locations must be rented or purchased. Some of these investment agreements may require negotiation with a mobile * *! . ···, 30 with which to place on the competitor's mast.

• * 99 9 117420 5

Fourth, the pilot beacons may add up to the overall interference surface in a system used by another licensed subscriber in the same radio frequency band.

5 Fifth, the pilot beacon measured by the first MP, i.e. the source MP communication system, may not provide a good indication of the quality of communication in the radio frequency loop using the second MP communication system. That is, the signal quality at the CDMA pilot beacon 10 transmitted from the adjacent AMPS cell and measured at the subscriber location may not accurately reflect the AMPS signal quality at the same subscriber location; There may be some fading in the AMPS signal, which is not the case with the CDMA pilot beacon. This may be caused by differences in signal propagation between the CDMA pilot signal propagating at one frequency and the AMPS signal propagating at another frequency.

As an alternative to using pilot beacons. for these purposes, there are J * ♦ ;; 20 uses a so-called hand-held blind transmission - a transfer from one path i · «· ·, 1 * to another transport system without the source system i« i \ *. i know nothing about the status of the traffic channel in the other MP system • i · • · »! .. *. The result of this option can easily be pu «•« l ·. ' the interruption of the sound. And when more than one cell of another MP information * * * 25 traffic system can handle the traffic channel, there is no intelligent way to choose which # *, · * · is the best candidate for handover.

** · «♦ · ·

For the reasons outlined above, there is a need for an improved method and equipment for handover • * • «· • · · ·

IM

m * • ·

#M

117420 6 communication systems using different multiple access principles.

The novel features of the invention are precisely defined in the appended claims. However, the invention itself and its preferred mode of use, other objects, and their advantages will be best understood by reference to the following detailed description of the illustrative embodiment and accompanying drawings. Of these figures: 10

Figure 1 illustrates a coverage area covered by two communication systems employing two different multi-access principles such that pilot beacons are used for handoffs between the two systems in accordance with prior art, Figure 2 is a general-level schematic of the hardware for performing various multi-access 9 • V. 9 9 • V. In accordance with Method 20, i · 9 9 9 9 9 9 9 9 9 ··· *: T: Figure 3 illustrates an alternative embodiment of the hardware: T: used to perform handoff between various multi-path communication systems according to the invention: T: 25 system, ··· 9 9 9 9 9 9 • 9 illustrates a general-level diagram of a code division ····· multi-access system for performing handover with an alternative MA-1 communication system design, ··· ·. 5 is a more detailed block diagram of a first embodiment of a signal characteristic measuring circuit which may be used in implementing the method and system of the invention, FIG. 6 illustrates a signal characteristic measuring circuit of a second embodiment which may be used in implementing the method of the invention. FIG. 7 is a general flow diagram illustrating a method for performing handover with an alternative MA communication system according to the invention; FIG. 8 is a detailed flow diagram illustrating a subscriber 15 device initialization process according to the invention; FIG. 9 is a detailed flow diagram illustrating a signal property measurement process in an alternative In the MA communication system according to the invention, and FIG. 10 is a detailed flow diagram illustrating the process. in order to configure the receiver to measure the property of the signal fr · · • · · * .. * in the alternative MA communication system # · »... according to the invention.

• fr fr fr * · 25

Reference will now be made to the figures, and in particular to figure 2; it has a 4 fr depiction of a general-level diagram of the apparatus for performing the handover between two different multi-access communication systems in accordance with the method and system of the present invention. As shown in the figure, the subscriber unit 50 generally comprises a first mono-transceiver 52 and a second multi-access receiver 54, both of which are coupled to an antenna 56. The first MP- transceiver 52 is adapted to communicate with cells 5 of the first communication system using the first multiple access principle. Correspondingly, the second MP transceiver 54 is adapted to communicate with cells of the second communication system using a second multiple access principle. Suitable duplexers (not shown in the figure) may be used to distinguish the transmitted signals from received signals. The frequency of the first MP transceiver 52 is controlled by a local oscillator 58 and the frequency of the second MP transceiver 54 is controlled by a local oscillator 60. Each local oscillator 58 and 60 may be set to a selected frequency 15 by a command or signal from control circuit 62.

, V. In the embodiment of Figure 2, another MP-t · · V is also shown. a measuring circuit 64 having an input connected to the antenna 56 and * ·! V. 20 measurement outputs connected to the control circuit 62. The second MP- • * measuring circuit also receives control signals through a control line from the control circuit • ·: *; * ·.

i «u * i« i «« a

Referring again to the first MP transceiver 52; : T: 25 downlink traffic 66 departs from the first: T: MP transceiver 52 and can be coupled to control circuit 62 and clock 68. Downlink traffic 66 may include control information, clock or synchronization information, and *, voice, and other data for processing in a subscriber device. circuits not shown in the figure.

ft * tft »117420 9

The uplink traffic 70 is an input signal from the first MP transceiver 52. The uplink traffic 70 may include voice data or other subscriber data and control information from the control circuit 62.

5

The second MP transceiver 54 may include an output for downlink traffic 72 and an input for uplink traffic 74, respectively. Both downlink traffic 66 and 72 and uplink traffic 70 and 74 are handled in parts of the subscriber unit 50 not shown and in a manner known in the art of mobile subscriber equipment. These components provide either telephony or computer data communication services.

15

In operation, the subscriber unit communicates with the subscriber unit of the first multi-access communication system, the transceiver, V. through the transducer 52. The subscriber unit 50 is controlled by a tuning • · · • · .V. The first MP transceiver 52 for a specific frequency * 2V. The control circuit 62 may from time to time receive a command * ·; * · which initiates the process of switching or transferring the power ** · * · to another multi-access communication channel of the system.

Upon receiving such an instruction, the control circuit 62 instructs the operational 2T * 25 MP measuring circuit 64 to measure the signal characteristics of the 2 * 2 * 2 signal from the second MP communication system. Such a characteristic of a signal is typically ·. ··: signal strength. The property of the second MP signal is measured to determine if a successful handover 30 can occur between the first MP communication system and the * t second MP communication system. The measurement of the second MP-117420 10 signal is performed at a predetermined time according to clock 68, preferably at the time of avoiding interruption of downlink traffic 66 or uplink traffic 70. The second MP measurement circuit reports 5 signal characteristic measurement to the control circuit 62. The control circuit 62 then determines whether and how to report the second MP signal characteristic measurement to the first MP base station controller via uplink 70 and the first MP transceiver 52.

10

The measurement frequency of the second MP measuring circuit 64 is controlled by the frequency of the local oscillator 60 which can be set by the control circuit 62.

As soon as the base station controller of the first MP communication system has received reports of measurements of the second MP signal, the base station controller may decide that handover was working. It is appropriate for the MP communication system and luck * # * * * · ll. This decision to hand over may alternatively be made by the subscriber unit, in which case the subscriber requests • ♦ · • · \ *. This is the first MP base station controller to arrange the handoff / • transfer.

• · «* •» · • · ·

The assignment of the subscriber handover to another MP-25 communication system is initiated by the command that receives • · ♦. *: *. via the antenna and the first MP transceiver 52 * · ·. At an agreed point in time, control circuit 62 switches downlink traffic and uplink traffic in subscriber terminal 50 from first transceiver 52 to second MP transceiver ♦ · * • »***** 54 and terminates thus, transferring the handover from the first MP-11 1 1 7420 communication system to the second MP communication system.

Referring now to Figure 3; it describes an alternative embodiment 5 of an apparatus for performing handover between different multi-access communication systems according to the method and system of the present invention. In this embodiment, the measurement of the signal from the second multi-access telecommunication system is performed by the second MP transceiver 80. Such measurement can be accomplished by the RSSI (Receive Signal Strength Indicator) such as is included in the plurality of AMPS transceivers. In order to correctly perform a feature measurement of the second MP signal, control circuit 62 may transfer control information to another MP transceiver 80. Such control information may include gain settings, frequencies, frequency ranges, type of multiple access signal, time slot information, and the timing of the second MP signal measurement.

The embodiment of FIG. 3 also includes a single local oscillator 82. Both transceivers 52 and 80 thus divide the same local oscillator 82, which is a control oscillator 82. · · Under the control of circuit 62. The local oscillator should be able to quickly switch between the two frequencies and settle in a short time so that the second MP signal has the property # * * *. can be measured without interrupting unnecessarily downlink. traffic 66 or uplink traffic 70.

* 9 9 · ···· 30 Reference will now be made to Figure 4; it describes a generic-level ψ · '··· * flash of a code division multiple access system (CDMA-117420 12 system) for performing a handover with an alternative communication system in accordance with the method and system of the present invention. As shown in the figure, the subscriber unit 90 includes an antenna 5 56 for receiving and transmitting signals from both the CDMA system and the alternative MP communication system. In this example, an alternative MP communication system is a communication system that uses a multiple access principle other than CDMA. The CDMA-10 receiver 92 includes a CDMA downlink traffic path, which further includes a down converter 94, gain control 96, filter 98, analog-to-digital converter 100, build circuit 102, and CDMA demodulator 104. CDMA downlink traffic 106 outputs a CDMA-15 demodulator 104.

The down converter 94 performs a frequency conversion from the antenna | from the resulting radio frequency signal to the lower intermediate frequency, which is applied to gain adjustment 96. The local oscillator 108 provides an input reference frequency down-conversion · φ *. to timelle 104.

The gain adjustment 96 can be implemented with an adjustable gain amplifier which operates as a control. 25 for controlling signals from circuit 110.

»I *» M * · • p *

B

*. Analog to Digital Converter 100 Converts Analog Signals *! . a digital word sampled at different times ***; * na.

B

* · B

ΦΙΙ:: 30 117420 13 Such a digital word is output to a build circuit 102, whereby during normal CDMA operation, the digital word is multiplied by a build code obtained from the source code source 112.

5

In accordance with one important aspect of the invention, despreading the selector 114 selects despreader 116 under the control of control circuit 110. When the build code source 112 is selected to provide the build signal 114, the output of the build circuit 102 is directed to a CDMA demodulator 104 which provides a downlink traffic signal 106 for operation in normal CDMA demodulation mode. In the measuring mode, the build signal selector 116 selects the build signal 114 from the alternate signal source 118. Thus, when the signal from the alternative signal source 118 is input to the gain circuit 102, the output of the gain circuit 102 is directed to the signal characteristic measuring circuit 120. sig. The measuring circuit 120 is then input to the control circuit 110.

• 1 2 3 1 • · · · 'Γ 20 Out of the signal characteristic measuring circuit 120, two different •! *. 5 and 6 will now be described

• · t J

♦ M

in connection with.

»1

• M

:::

The control circuit 110 also receives reference levels 124, control 25 signals 126, clock 128 and possibly a measurement signal 130 from an alternate MP transceiver 132 as input.

• · 1i CDMA transmitter 134 is connected to antenna 56 upstream of CDMA. its link to send traffic 136. The CDMA transmitter 134 3 also operates under the control signals * 9 '··· 1 from the control circuit 110.

117420 14

Alternate MP transceiver 132 is coupled to antenna 56 for receiving downlink traffic 138 and transmitting uplink traffic 140 in accordance with 5 alternative MP principles. Alternate MP transceiver 132 operates under control of signals from control circuit 110. Such control signals can control the frequency of the MP transceiver 132, the type of MP used by the alternative MP-10 transceiver 132, and the precise timing of switching downlink traffic 138 and uplink traffic 140, which must be received and transmitted by the alternative MP transceiver 132 through. The control signals may also control other corresponding functions.

In operation, control circuit 110 receives a command via downlink CDMA link traffic 106 to initiate a * · * handover procedure to the alternative MP-JJ 20 communication system. However, prior to the handover, the * * * * * \ \ kernel is made a measurement of the * * * * · · 1., * signal from the MP communication system and reported to the CDMA-ν ': 1 .. base station controller. In the embodiment shown in Fig. 4, the CDMA receiver 92 operates in two modes: nor -... 25 in the form of CDMA demodulation and an alternative MP-

• · i J

• Tue ··· Measurement of the signal in operating mode.

• i »

In the normal CDMA demodulation mode, the converter signal. * Iin selector 116 selects a signal from codec source 30 112 to obtain a composite signal 114 which is output to a *** composite circuit 102. In this embodiment, ordinary downlink traffic 106 of CDMA 117420 is output by CDMA demodulator 104. Such CDMA downlink traffic may include control signals 126, or timing signals or queues that are output to control -5 circuit 110 and clock.

In the alternative MP signal measurement mode, the composite signal selector 116 selects a signal from an alternative signal source 118 to a composite circuit signal 114, which is output to a composite circuit 102. The output of the composite circuit 102 is then used by the signal property measuring circuit 120 to measure the signal characteristic. The resultant signal characteristic value 122 is applied to the result 15 by control circuit 110 and can be compared to a reference level obtained or calculated from reference levels 124. According to agreed reporting criteria, the control unit 110 reports such a comparison to the CDMA base station controller 30 (see FIG. 1). through. After the data required for the 20 * handover of the handheld has been collected, the decision to handover the handheld * * is made either by the subscriber station, the base station controller «« · t «\ *, or another unit elsewhere; the relevant »· · • · I. / place or functional unit making the decision is ♦ · · t i« I .. available to the system designer.

»» »» · · 25

When the subscriber unit 90 is directed to perform handover between communication systems, the subscriber unit 90> m β> · β is switched to use the CDMA downlink traffic * * · 106 and the CDMA uplink traffic 13 6 • »" ** 30 to the downlink link of the alternative MP system, and to the uplink link 140 of the alternative MP system.

Referring now to Figure 5; it illustrates a detailed block diagram of a first embodiment of a signal characteristic measuring circuit which may be used to implement the method and system of the present invention. As illustrated, the signal characteristic measuring circuit 120 includes a narrowband filter 150, a power measuring function 10, and an integrator 154. The output of the signal characteristic measuring circuit 120 may thus be an estimated power level integrated over a period of time. Such a power level value can be compared to a reference level in the control circuit 110. If the signal characteristic measuring circuit 120 measures a signal from one of the 15 channels of the AMPS communication system, the narrowband filter 150 can be tuned to an AMPS channel bandwidth of 30 kHz.

Referring now to Fig. 6, another embodiment of a signal characteristic measuring circuit which can be used to implement the method of the present invention is described; As shown in the figure, this second embodiment of the signal property measuring circuit 120 includes a * · "* wideband filter 156 and a frequency analysis circuit, ···, 25 158. In operation, the wideband filter 156 may be set. for example, receive a frequency range that covers • * * •. multiple AMPS channels. Frequency analysis circuit 158 may be used to perform a Fourier transform of the filtered signal. Fou- • *. The rier conversion can reveal multiple AMPS frequencies from multiple · · · :•• 2 30 AMPS base stations, each of which can be selected as a target »··:: ψψψ 117420 17 when moving from CDMA to AMPS.

Before performing the measurement on the signal eigenvalue measurement 5 circuit 120 shown in either Figure 5 or Figure 6, it may be necessary to set the appropriate gain with gain control 96 (see Figure 4). Depending on which measurement circuit is used and which multiple access system is to be measured, control circuit 110 may set gain control in a suitable manner so that a valid measurement can be made.

Referring now to Figure 7; it describes a generic logic flow diagram illustrating a method of performing a handover with an alternative communication system according to the invention. As shown in the figure, the process begins at block 200 and then continues to block 202 where the process initializes the subscriber unit. This initialization process includes. . includes the transfer of parameters and conversation protocols between the base station controller and the subscriber unit. Such an initialization process is described in detail in connection with the description of Fig. 8.

• t ·

• I

Next, the subscriber unit measures the signal property of the signal, which is obtained by the alternative multi-access communication system 25 as shown in block 204. This measurement> · · can be implemented by an alternative MP of the subscriber unit. - •. a transceiver as shown in Figure 3, or • * # an alternative MP measuring circuit of a subscriber unit such as • * • shown in the example of Figure 2. Yet another way to handle the measurement of 30 alternate MP signals is to use the current MP receiver, as shown in Figure 4, where the CDMA-117420 18 receiver can be configured to measure the signal in the alternative MP. system, such as AMPS.

After measuring the alternative MP signal, the subscriber device may possibly measure the signal characteristic of the signal coming from the current MP communication system, as described in block 206. In some communication systems, this step may be an extra feature because the signal characteristic of the current MP system signal may be irrelevant for the purpose of the delegation decision. However, some systems may be designed to measure the signal property of both the signal coming from the alternative MP system and the signal coming from the current MP system. 15

After making appropriate signal measurements, the subscriber unit reports these signal characteristic measurements to the base station controller,. . as outlined in block 208. Signal property reporting criteria * * · ♦ · * 'can be discussed in the initialization procedure in block 202. Some measurements are reported in * *! possibly only if the measurements exceed a certain threshold, · ··, ·. / n, and the omission of the signal measurement report • ♦? . * ·· such that the value is below the threshold.

• * J

Note that the phase 08 block 2 may not be necessary if the system is • designed to be subscriber *. decide when and where the handover takes place.

• · we · In this case, the subscriber may request a handover instead of reporting the values of the signal measurements.

···: 30 iti • ♦

* I

··· 19 1 1 7420

After all signal characteristic measurements have been reported to the current MP base station controller, the process determines whether to attempt a handover to the alternative MP communication system, as described in block 210.

5 If handover is not required for any reason, the process repeatedly returns to block 204 to update the signal measurements. If the system determines that handover must be made from the current MP communication system to the alternative MP-10 communication system, the process next determines whether the alternative MP system is capable of accepting subscriber traffic, as described in block 212.

If the alternative system is unable to accept subscriber traffic, the process repeatedly returns to block 204 where the measurements are updated. If the alternative MP communication system is able to accept the subscriber traffic, the process will coordinate the handover option! - <«· • * * l with its MP communication system as described in block 214. This step can be accomplished with the current MP »» »»

I I

by means of communication between the base station controller and the alternative MA base station controller via communication between the MP base station controllers * · * *, ···, kennel 36 (see Figure 1). The handover • · · «coordination may include parameters such as the target frequency of the alternative 25 MP communication system channel and the time of handover.

** ϊ ί

After coordinating the handover, the process completed · * ·. provides a handover for the subscriber from the current MP-* a 30 communications system to an alternative MP-* »'* ·· * communications system, as shown in block 216.

I___ 117420 20

As with handover between cells in any telecommunication system, handoffs between different MP telecommunication systems should occur quickly so that the subscriber traffic channel 5 is not unnecessarily temporarily interrupted.

The process of performing the handover from the first multi-access communication system to the second multi-access communication system 10 is terminated in block 218.

Referring now to Figure 8; there is illustrated a detailed flow diagram illustrating the subscriber device initialization process 15 according to the invention. As shown in the figure, the initialization process begins at block 300 and then continues to block 302, where the process sends an alternative type of MP communication system to the subscriber. This step may * * '1 Γ be optional if the subscriber unit is designed to * * f, 11' 20 allow only one handoff to take place; · · An alternative type of communication system. Optional * # **, ···, another type of communication system can be defined ** * such as AMPS system, TDMA system, GSM system or any other standardized multi-function system. system.

• * · ** • · i • I ·

Once the process has received an alternate type of MP · * * system, it will send a frequency list or frequency *** '! the range of hair used by the alternative MP communication system * * * 30 as shown in block 304. The frequency list may:: .......

"* contains a list of frequencies for control channels used in different base stations, for example, in an AMPS system. Alternatively, a frequency range can be defined, whereby signal strength or other characteristics of the signal at multiple frequencies within the range are reported back to the base station controller.

Next, the UE receives from the alternative MP communication system reporting criteria for reporting signal measurements as described in block 306.

Such reporting criteria may include, as a guideline, not reporting the signal property of an alternative MP signal below the threshold. Thus, if a response to the reporting request is not received, the base station controller may interpret it as a measurement value that is below the agreed threshold. The reason for such reporting criteria may be to reduce the reporting traffic between the UE and the base station controller.

* The process then discusses the timing of the alternate MP signal measurements at the current MP-

: V

• * · I · / 308. The result of such a discussion may be that • · · 9 * β · »· β measurements are made at predetermined intervals, or that measurements are made only. on application.

25V ·

The initialization process is now complete as reported in block * I · 310.

* * * • «• Now referring to Figure 9; it describes a detailed ♦ • f ··· * 30 ti flow chart showing an alternative MP • u

• J

··· 'signal characteristics of a signal from a communication system according to the method of the invention. As shown in the figure, the process begins at block 400 and then continues to block 402, where the process determines whether time is available to measure the signal property of the signal from the alternative MP communication system. If no time is available for measurement, the process rotates repeatedly until time to make measurements of dawn. Measurements can be made at predetermined intervals or upon request from the current MP-10 communication system base station controller. The alternate communication system measurement time can be negotiated during the initialization process, as described in connection with the description of Figure 8.

If it is time to measure the signal property of the signal from the alternative MP system, the process configures the subscriber unit to measure the alternative MP signal, as described in block 404. In some embodiments of the present invention, this configuration * the signal characteristic circuit 120 filters, · · · * *, 11 to perform the measurement and can also set various filtering *, *, and gain adjustments so that the measuring circuit can perform the * • 4!,. * This process of performing the subscriber con fi guration is described in detail below in connection with the description of Fig. 10.

* * * • * *

Next, the process measures the signal characteristics * * of the signal from the alternative MP data communication system, as shown in block 406. In the preferred embodiment of the * * "* 30, the signal characteristic is the strength of the signal. Depending on the architecture of the subscriber device, the signal measurement can be made by special configuration of the current MP demodulator, or by a dedicated receiver which receives alternative MP signals, or by the receiver part of the alternative MP transceiver. These various subscriber device architectures are described with reference to Figures 2-4.

After performing the signal feature measurement, the process reconfigures the subscriber unit for normal operation in its instantaneous MP communication system, as described in block 408. If the circuit used to measure the signal feature is not completely independent of the current MP transceiver, blocks 404 to 408 should be kept as short as possible so that the T-15 broadband is not unduly interrupted.

After reconfiguring the subscriber unit for normal demodulation in the current MP communication system, the * * \ V process determines whether the alternative MP measurement * * \ V 20 was valid, as shown in block 410. If the measurement was * · * ί. * Valid , the process terminates as described in "return block" 412. Alternatively, if the measurement was not good, the process adjusts the measurement configuration parameters, such as the filter and gain settings as described in block 25414. then the process repeatedly returns to block 402 ϊ * *, \ Y to wait for the next measurement moment, most obviously the subscriber unit returns to normal operation while it waits for the next opportunity to make a measurement.

Referring now to Fig. 10, a detail flow diagram illustrating a process for illustrating a receiver to measure a signal characteristic in an alternative MP communication system according to the present invention is now described. As shown in the figure, the process begins at block 500 and then continues to block 502, where the process rejects code division multiple access in speech and Listening, i.e., modulation and demodulation. It should be noted that the process described in connection with the description of FIG. 10 relates specifically to a CDMA receiver used to perform a signal property measurement on a signal coming from an alternative MP communication system. Such a receiver is, for example, the receiver shown in Figure 4.

Next, the process sets the frequency of the local oscillator to receive the frequency of the alternative MP-15 communication system as shown in block 504. This step can be used to set the local oscillator 108 with a control signal obtained from the control circuit 110 of the subscriber device 90 shown in FIG.

After setting up the local oscillator, the process sets up the ** signal gain and filters to receive the signal * · * '; e' from an alternative MP communication system, such as the · * Ten are described in block 506. Correspondingly, control circuit 110 may send signals to gain control 96 and filter ... 25 98 in preparation for measuring the signal from an alternative MP communication system.

• i ·

It should be noted that steps 504 and 506 may be called to configure a tuner to receive a signal from an MP system having an exchange of ... T30. Such a tuner is shown ** with reference numeral 142 in Figure 4. Next, the process selects the 117420 25 alternative build signal for use in the CDMA build circuit, as shown in block 508. With reference to Figure 4; this step may be accomplished by switching the aggregate signal selector 116 to a position corresponding to the source of the alternative 5 signal so that the aggregate circuit signal 114 comes from the alternative signal source 118. The alternate signal source 118 may be a series of zeros and ones forming a constant value signal. This signal interrupts the build operation in the build circuit 102.

10

After selecting an alternate aggregate signal, the process activates an alternate MP signal property measuring circuit as described in block 510. This step may be accomplished by clearing the registers or otherwise resetting the sig-15 signal property measuring circuit 120. Thereafter, the configuration process terminates as shown in block 512.

In order to configure a subscriber ***** ***** device with the architecture shown in Figure 3, the process may execute blocks .V.

• V 20 502, 504, 506, and then jump to block 510 to improve the measuring circuit ak ··· * * * • · * in the second MP transceiver 80. In a subscriber device having the architecture shown in Figure 2. *! * · J * e *, the measurement configuration process can perform • i ** ** * step 506 and then jump to step 510 to make a measurement ... 25 with another MP measuring circuit 64. Local oscillator! Setting is not necessary because the measuring circuitry uses an independent local oscillator 60.

* • *

In summary, the invention described above, "H * 30, permits handover from a first multicast communication system to a second multicast communication system, whereby a two-way subscriber unit assists in handover by measuring signals from another subscriber system. Multiple pilot beacons that send signals on the MP principle of the first multi-access communication system 5 are not required, which reduces the cost of the infrastructure required for inter-system handoffs.

Although some of the above specific examples relate to 10 handovers from a CDMA system to an AMPS system, the principles and basic architectures of the present invention can be used to perform handover from any MP communication system to any other MP communication system.

15

Various means for measuring the property of an alternative MP signal have been described above. These include: a subscriber system using an independent measuring circuit V, a subscriber unit in which transceivers of various MP systems share a common local oscillator circuit • i »9 · 9 f •. *, And a subscriber unit which uses a reconfigured CDMA receiver to measure the signal characteristics of the signal. · • # 'le, which comes from an alternative MP communication system ·· # • «» * ·' *. Such a CDMA receiver can be set to e # e 25 such that the build function is interrupted and an alternate signal passing through the build circuit can be analyzed by integrating power over a narrow band, or by analyzing a broadband frequency spectrum.

In some embodiments of the present invention, the alternative signal source 118 may be a special signal, 117420 27, which improves the measurement of the alternative MP signal, or signals having known characteristics. For example, such a signal may include a plurality of discrete frequencies that may be used to detect the power of a plurality of alternative MP-5 signals.

The foregoing description of the preferred embodiment of the invention is provided for purposes of illustration only. It is not intended to be exhaustive or to limit the invention to any particular form. Changes and alternatives are possible in the light of the above. The embodiment was chosen and described to provide the best possible description of the principles of the invention and its practical applications, and to enable one of ordinary skill in the art to use the invention in various embodiments and variations according to the particular application. All such modifications and variations are intended to be within the scope of the invention as defined in the exact claims as interpreted by <a, ** · * 20 to the extent that is correct in law, reasonableness and: v: \ \ according to equity.

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Claims (16)

A method for performing a switchover (216) in a cellular communication system for a subscriber (28) from a first multi-access communication system to a second multi-access communication system, characterized in that it comprises the following steps: in a subscriber device communicating with said first multi-access communication system , (206) a signal characteristic of a signal from the second multi-access communication system is measured to produce a signal value, said subscriber device is configured on the basis of said signal value to communicate with said second multi-access communication system, and the switchover (216) is performed for the subscriber (28). ) from said first multi-access communication system to said 9 · · ** '. other multi-access communication systems. • i • · • * «« 9 A method for performing a switchover (216) for a subscriber (28) according to claim 1, characterized in that the method comprises said signal; characteristics of the signal strength. · * «• * * • · •« M · Method for performing a switchover (216) for a subscriber (28), characterized in that in the method, said first multi-access communication system is made by a CDMA communication system and said subscriber device * · * ··· * contains a collection circuit which uses a collection signal, and in which method the step of measuring (206) the signal value contains the following steps: an alternative collection signal is selected for use in said collection circuit, signal from said second multi-access communication system is transmitted through said collection circuit, and a signal characteristic of a signal from said second multi-access communication system is measured (206) to produce a signal value. 4. A method for performing a subscriber (286) switchover (28) according to claim 3, characterized in that, in the method, said alternative interconnect signal contains a constant value interconnect signal. »» • * * • «* * ·; V. 5. A method for performing a switchover (216) for a subscriber (28) according to claim 3, characterized in that, in the method, said alternative interconnection signal contains a signal with a plurality of: * · *: preselected discrete frequencies for measuring the power of multiple signals in said second multi-access communication system of different frequencies. »· ♦ * · • 9 ·· * ·. 6. Procedure for performing a transfer (216) for • *. «··. a subscriber (28) according to claim 3, characterized in that the method comprises said step of measuring (206) a characteristic of a signal from a signal from *** said second multi-access communication system for producing a signal gene value further that a frequency analysis of a signal from said second multi-access communication system is performed to produce signal power values within a frequency range. Method for performing a subscriber (286) switchover (28) according to claim 1, characterized in that in the method, said step of configuring the subscriber device comprises communicating with said second multi-access communication system on the basis of said signal value further, said subscriber device is configured to communicate with said second multi-access communication system on the basis that said signal value exceeds a predetermined threshold value. Method for performing a switchover (216) for a subscriber (28) according to claim 1, characterized in that the method further comprises the following steps: 44 from said subscriber device is measured. (206) a signal characteristic of a signal from said second multi-*: * access communication system to produce a signal intrinsic value for the first system. to »4 4 4 4« «: <ie: said signal value is compared with said first signal value, and 4 4« Il 4 4 in the 4 * 4 4 subscriber device is configured to communicate with 4. m ·. * said second multi-access communication system on base 4 Thereof if said signal value exceeds said first signal value. A method of performing a subscriber (286) switchover (216) according to claim 1, characterized in that, in the method, said step of configuring the subscriber device comprises communicating with said second multi-access communication system on the basis of said signal value. that the subscriber device's uplink and downlink traffic is coupled from a first multi-access transceiver (92) to a second multi-access transceiver to communicate with a second multi-access communication system on the basis of said signal value. A method in a CDMA subscriber device for measuring (206) a characteristic of a signal from an alternative multi-access communication system, characterized in that said method comprises the following steps: A tuner is configured to receive said signal from said alternative multi-access communication system, an alternate collection signal is selected for use in the CDMA subscriber device collection circuit , Said signal from said alternative multi-access communication system is passed through said collection circuit, and said ft characteristics of said signal from said signal from said W Alternative multi-access communication systems are fed (206). «·· ft · •« ··· 39 1 1 7420 The method of a CDMA subscriber device according to claim 10, characterized in that, in the method, said step of configuring a tuner to receive said signal from said alternative multi-access communication system further that a frequency is installed, an amplification is installed. and a filter is installed, each of the same installs so that said signal is received from said alternative multi-access communication system. The method of a CDMA subscriber device according to claim 10, characterized in that in the method said alternate collection signal is a constant value signal. The method of a CDMA subscriber device according to claim 10, characterized in that the method comprises said step of measuring (206) of said: V: characteristics of said signal from said alternative: Y: multi-access communication system further that a frequency: analysis for said signal from said alternative multi- / access communication system is performed. • * · • «i Device for receiving a CDMA signal and for measuring (206) a signal value of a signal from an alternative multi-access communication system, may be characterized by the device comprising: »♦ * ·« · φ • ♦ • #, ···. A collection circuit with a signal input, a collection input, and a collection circuit output, · · · *? A signal source for a collection code, a source for an alternate collection signal, a collection circuit signal selector with inputs connected to said collection code signal source and said alternative collection signal source, and an output coupled to said collection input, a tuner with a tuner an output coupled to said signal input, a signal value measurement circuit coupled to said collection circuit output, and a control circuit coupled to said tuner and said collection circuit signal selector for configuring said device, for receiving said CDMA signal, or for measuring a signal value (206) signal from an alternative multi-access communication system. * ♦ • · · • · 9 Device according to claim 14, characterized in: v. of the said alternate collection signal output being * *: a constant value signal source. Device according to patent claim 14, characterized in that said alternative collective signal output generates. A signal with many preselected discrete frequencies. • Λ · mmm mmm m m m m m m m m m m m m m m m m m m m m m m m m m m m m m m m m m m m mmm