HK1033394B - Method and apparatus for automatic channel measurements - Google Patents

Description

Method and apparatus for automatic channel measurement

The present invention relates to a wireless communication device, and more particularly, to a mobile station that more efficiently measures signal strengths of a set of channels in a wireless communication system.

Figure 1 illustrates a typical wireless communication system 2. A plurality of Mobile Stations (MS)10 are located in a geographic service area covered by cells C1-C6 with Radio Base Stations (RBS)4 located in a geographic area covered by cells C1-C6 and serving as an interface between the mobile stations 10 and the wireless communication system 2.

The radio base station 4 is connected by a dedicated wire line to a Mobile Telephone Switching Office (MTSO)6, which is called a mobile services switching center in some radio communication systems. The MTSO 6 is connected to the Public Switched Telephone Network (PSTN)8 and may also be connected to other MTSOs (as shown in dashed lines). This MTSO 6 controls the operation of the connected radio base station 4 in the radio communication system 2, such as establishing a call and coordinating the activities of the radio base station 4. In addition, this MTSO 6 is used as a switch to route calls to/from the appropriate radio base station 4. Other MTSOs similarly control other radio base stations.

The wireless communication system of fig. 1 has only a limited frequency band that is allowed for frequency use. To efficiently use the limited frequency band, the geographic service area of the system is divided into a plurality of cells C1-C6, wherein each cell is allocated a set of channels in the allowed frequency band. Each set of channels is reused every K cells to allocate a disjoint set of channels to adjacent cells to prevent interference. The set of channels for each cell includes control channels and traffic channels. The traffic channels carry voice or data communications and may be analog or digital depending on the particular implementation of the wireless communication system. The control channel may also be analog or digital and is used to provide information to the radio base station 4 and the mobile station 10 and to control various functions of the mobile station 10. These control channels are used, for example, to identify the particular cell in which the mobile station is located, to handle subscriber originated call processing, subscriber registration, and to control other system processes.

When the mobile station moves between cells, the mobile station 10 performs measurement of channels in adjacent cells while determining the best server on a control channel. For digital control channels, the mobile station 10 measures Bit Error Rate (BER) or Word Error Rate (WER) or measures signal strength in decibels. For analog control channels, the measurement of signal strength is performed in decibels. The mobile station 10 may select an analog or digital control channel if capable. In the control channel selection or reselection process, the radio base station 4 transmits the adjacent cell list of the analog or digital control channel to the mobile station 10. The neighbor cell list includes information about control channels of neighbor cells for the mobile station to perform selection and reselection procedures in accordance with the control channels.

If the call is in progress, MTSO 6 assigns a new traffic channel to mobile station 10 (this is called a handoff) without service interruption. The mobile station 10 assists the MTSO 6 in determining traffic channel assignments at the time of handover by measuring the signal strength of the traffic channels in neighboring cells and reporting this data to the MTSO 6, a process referred to as Mobile Assisted Handover (MAHO).

In a digital wireless communication system, such as the system described using the EIA/TIA-IS-36 standard or the IS-54-B standard, the mobile station 10 effectively transmits and receives less than 2/3 time on the traffic channel at the same time. During the idle time period, the mobile station 10 can perform scanning and measurement operations in order to measure channel quality in neighboring cells. For digital traffic channels, signal strength measurements such as Bit Error Rate (BER) or Word Error Rate (WER) are made, while the mobile station makes signal strength measurements in decibels for analog and digital channels.

In order to start radio measurement by a mobile station on a traffic channel, the radio base station 4 transmits a measurement instruction to the mobile station 10, the measurement instruction including a set of channels for the mobile station to perform measurement. During idle periods when the mobile station 10 is neither transmitting nor receiving traffic on the traffic channel, the mobile station 10 performs measurements of the set of channels in the measurement instruction. The mobile station 10 generates a report of the performed measurements and sends this report back to the radio base station 4. MTSO 6 uses this report to determine, among other things, the channel allocation for mobile station 10.

A conventional prior art mobile station 10 is shown in fig. 2. The mobile station 10 includes a controller 12 that controls the functions of the mobile station 10. This controller 12 generally includes a Central Processing Unit (CPU) (not shown), memory (not shown), and I/O ports (not shown). The controller 12 processes voice or data signals to and from the transceiver 14. This transceiver 14 converts voice or data signals from the controller 12 into radio waves and also detects and demodulates received radio waves into voice or data signals. The transceiver 14 is connected to an antenna 16 for radio transmission and reception of radio waves.

The controller 12 is also connected to a microphone 18, a speaker 20 and a user interface 22. The microphone 18 includes an electrodynamic microphone, a condenser microphone, and the like to convert the voice of the user into an electric signal. An analog-to-digital converter (ADC) (not shown) converts the electrical signal to a digital voice signal. This speaker 20 outputs the received voice signal and typically includes a digital-to-analog converter (ADC) (not shown) and an amplifier (not shown). This user interface 22 includes a display such as an LED or LCD and a keypad or other controls. A rechargeable battery 24 provides power to the mobile station 10.

A synthesizer 26 is coupled to the controller 12 and the transceiver 14, the synthesizer 26 generating a variable frequency signal in response to the frequency value input from the controller 12. The generated signal is passed to the transceiver 14 for receiving or transmitting a channel on that frequency. The synthesizer 26 includes a phase detector 28, a loop filter 30, and a Voltage Controlled Oscillator (VCO) 32. A reference crystal 34 is connected to the synthesizer 26 and is set at a set frequency f_rA reference signal 35 is generated. The controller 12 controls the frequency output of the synthesizer 26 by sending a channel data signal 11 to the synthesizer 26 to store the divisor N value in the divide-by-N register 36. The controller 12 then sends a control signal 13 to the synthesizer 26 to latch the divisor N value. In response, the frequency f of the signal 33 output from the VCO 32 is set₀Divided by N. The phase detector 28 compares the phase of the output signal of the divide-by-N register 36 with the phase of the reference signal 35 of the reference crystal 34 to generate an error voltage (Ve) signal 29 proportional to the phase difference between the two signals. The loop filter 30 is a low pass filter that filters the error voltage Ve signal 29 before inputting the signal to the VCO 32. The frequency f of the output signal 33 of the VCO 32₀Is stabilized as f₀＝N*f_rAnd transmitted to the transceiver 14.

The conventional operation of the mobile station 10 of fig. 2 during a measurement operation of a set of channels will now be discussed in connection with fig. 3. In step 38, the mobile station 10 receives a measurement instruction or a neighbor cell list from the radio base station 4 through a traffic or control channel. The controller 12 waits until the next idle state to perform measurements of the indicated channel, as shown in step 39. During the next idle period, the controller 12 determines the number of channels to measure, as shown at step 40. In step (b)At step 42, the controller 12 stores the data for the first channel to be measured in the divide-by-N register 36 of the synthesizer 26 and sends a "latch new channel data" signal 13 to the synthesizer 26 at step 43. In response, the synthesizer 26 divides by the frequency f specified by the channel data in the N register 36₀To generate the VCO output signal 33. This VCO output signal is transmitted in step 44 to the transceiver 14 which then receives the measurement command 15 from the controller 12. The transceiver 14 measures the signal strength of the first channel and transmits a measured signal strength data signal 17 to the controller 12 as shown in step 46.

The controller 12 receives the measured signal strength data, as shown at step 48, and decrements the number of channels to be measured, as shown at step 50. The controller 12 determines in step 52 whether additional channels are to be measured. If there are no additional channels to measure, the controller 12 again enters the idle period and is ready to transmit or receive on the traffic channel or active state, as shown at step 54. Otherwise, the process returns to step 42 and the controller 12 loads the channel data for the next channel to be measured to the combiner 26. If there is not enough time to complete the measurement during the idle period between transmission or reception, the mobile station 10 must wait until the next idle period to continue the measurement.

This conventional process of measuring the signal strength of a set of channels requires a lot of interaction by the controller 12. The controller 12 must separately store the channel data for each channel to be measured in the synthesizer 26, send a latched data signal to the synthesizer 26, and initiate the measurement of each channel by the transceiver 14. As a result, this process requires valuable time and expense of the controller 42.

The measurement operation in the mobile station needs to be performed quickly and efficiently, especially when the mobile station is measuring channels during idle periods, because the time to complete this operation is limited. There is thus a need in the industry for more efficient methods and apparatus for measuring different sets of channels by a mobile station.

The present invention relates to a mobile station in a wireless communication system. The wireless communication system includes at least one mobile station interfacing with a wireless base station, wherein the wireless base station transmits a measurement order or a neighbor cell list including a set of channels to be measured by the mobile station. The mobile station includes a controller and a synthesizer for processing the measurement instruction or the set of channels in the neighbor cell list. The synthesizer includes: a memory for storing channel data corresponding to the set of channels; a timing sequence generator for automatically selecting channel data for each channel in the set of channels without controller interaction; and a phase locked loop for generating a frequency signal corresponding to the selected channel data. The mobile station also includes a transceiver for measuring signal strength data corresponding to the frequency signals generated by the synthesizer. The timing sequence generator of the synthesizer includes an output control signal for selecting channel data for each channel of the set of channels and an output measurement signal, wherein the transceiver measures signal strength data corresponding to the frequency signal generated by the synthesizer based on the output measurement signal.

In operation, the controller of the mobile station stores channel data for a set of channels in the memory of the synthesizer. For each channel in the set of channels stored in the memory of the synthesizer, the synthesizer automatically selects channel data for that channel and generates a frequency signal corresponding to the selected channel. The transceiver measures signal strength data for the selected channel based on the frequency signal. Additionally, the transceiver may buffer the signal strength data for the set of channels and send the signal strength data for the entire set of channels to the controller when the signal strength data measurements for the set of channels are completed.

For a more complete understanding of the present invention, and for further objects and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals are used to designate like parts:

FIG. 1 illustrates a wireless communication system in which the present invention may be employed;

FIG. 2 shows a prior art block diagram of a conventional mobile station;

FIG. 3 shows a prior art flow diagram of a conventional process for a mobile station to measure a control channel;

FIG. 4 is a block diagram of a mobile station employing the present invention;

FIG. 5 is a flow chart illustrating operation of a controller in a mobile station in accordance with the present invention;

fig. 6 is a flow chart showing the operation of a synthesizer in a mobile station of the present invention;

fig. 7 is a block diagram of another embodiment of a mobile station of the present invention;

FIG. 8 is a flow chart illustrating operation of another embodiment of a mobile station of the present invention;

FIG. 9 is a flow chart illustrating operation of another embodiment of a mobile station of the present invention;

fig. 10 shows a timing diagram of the operation of the present invention.

In fig. 4, a mobile station 56 employing the present invention is shown. The mobile station 56 may be any type of mobile station suitable for operation in a wireless communication system defined using a different air interface standard, such as the EIA/TIA IS-136 based air interface compatibility 1900MHZ standard. The mobile station 56 includes a controller 58 that controls the functions and operations of the mobile station 56. Similar to the mobile station 10 of fig. 2, the mobile station 56 includes a microphone 60, a speaker 62, and a user port 64. The battery 65 is the power source for the mobile station 56.

The mobile station 56 of the present invention also includes a synthesizer 66 having a signal divider bank 67, an instruction register 61 and a timing sequencer 78. The signal divider bank 67 includes a channel data register bank 68, preferably a plurality of registers, for storing channel data for a set of channels. The register bank 62 is a read/write memory that can reload channel data to different bank channels. The channel data stored in the register set 68 may be a divisor N or the channel data may include the actual frequency value f of the channel (and thus N calculated by the synthesizer 66) depending on the type of synthesizer implemented in the mobile station 56.

The signal divider bank 68 also includes a divider circuit 73 that includes the components necessary to perform signal division based on the channel data stored in the memory 68 a. For example, the division circuit 73 may also include a programmable counter 73a and a coincidence circuit 73b, and the coincidence circuit 73b compares the count value output by the programmable counter 73a with the channel data stored in the register group 68. The coincidence circuit 73b supplies a pulse when the count output of the programmable counter 73a coincides with the channel data stored in the register group 68, and simultaneously supplies a reset pulse to the programmable counter 73a to reset the programmable counter 73 a. As a result, the output of the signal divider bank 69 has a frequency corresponding to the stored channel data.

The divided signal output 69 of the signal divider bank 67 is an input to a phase detector 70, and the phase detector 70 compares the phase of the divided signal output 69 with the phase of a reference crystal 72. Reference crystal 72 provides a constant frequency f_rThe output signal 75. The output signal 71 of the phase detector 70 is an error voltage (Ve) signal proportional to the phase difference between the two input signals. This error voltage Ve signal 71 is input to a loop filter 74.

This loop filter 74 is preferably a low pass filter to pass the DC error voltage Ve signal to the VCO 76. In response to the error voltage Ve signal, the VCO76 output has a voltage equal to nxf_rFrequency f of₀Signal 77 of (a). Thus, in settling, the VCO output signal 77 has a frequency f corresponding to channel data of a selected register among the register set 68₀. The synthesizer 66 sends the VCO output signal 77 to the transceiver 80, the transceiver 80 having a center frequency f₀Transmit or receive data and voice signals.

The programmable counter 73 is also triggered by the feedback of the VCO output signal 77 by the signal divider bank 68 and thus forms a feedback loop. The timing sequencer 78 controls the input of channel data from the register bank 68. The timing sequencer 78 includes a programmable counter and a register that outputs control signals to select channel data in the register bank 68. The synthesizer is shown in dashed lines to indicate that the various parts may not be located in the same chip. For example, the VCO76 is preferably a chip separate from the loop filter 74 and the phase detector 70 so that the required sensitivity can be obtained.

The timing sequencer 78 and the instruction register 61 of the synthesizer 66 control the different operations of the synthesizer 66. The timing sequencer 78 controls the timing of the channel data selection while the command register 61 passes commands from the controller to the timing sequencer 78 and other components of the synthesizer 66.

The operation of the mobile station 56 during scanning and measuring a set of channels is now described with reference to fig. 5 and 6. In fig. 5, the operation of the controller 58 is explained, while the operation of the synthesizer 66 is explained in more detail in connection with fig. 6. In the embodiments of fig. 5 or 6, the mobile station 10 performs measurements of a set of channels during call processing, for example, in response to a neighbor cell list or measurement instructions. Those skilled in the art will understand that: the present invention is applicable and beneficial when the mobile station 10 must measure a set of channels during any call processing.

In fig. 5, the mobile station 10 is on a traffic channel during a call when the radio base station 12 transmits a measurement order or neighbor cell list comprising a set of channels to the mobile station 56 on a traffic or control channel. The set of channels to be measured will vary depending on the geographic location of the mobile station 56 and the channel allocation of the wireless communication system. In step 84 of fig. 5, the mobile station 56 enters an idle period. For example, when on a traffic channel, the mobile station will enter an idle period when not transmitting or receiving on the traffic channel and will leave the idle period in order to transmit or receive voice or data traffic. When on the control channel, the mobile station enters an idle period or park state when no function is performed and will leave the idle period in order to handle various functions or instructions, such as a user-originated call. In response to entering the idle period, controller 58 determines the number of channels in the set of channels to measure, as shown in step 86. The set of channels may include one, two or more channels according to the measurement operation.

The controller 58 then loads the channel data for the set of channels into the register set 68 of the signal divider set 67 at step 88. The load operation may be a write operation to the I/O port address of register set 68 as is known in the art. If the idle period has a known duration, such as the duration between paging channels, the controller 58 may determine the number of channels that can generally be measured during the known duration and load only that number of channels in the set of channels into the register set 68. Otherwise, for example, if the idle period has an unknown duration, such as in a parked state, the controller 58 may load the entire set of channels into the register set 68 and send an interrupt instruction to the instruction register 61 in the synthesizer 66 when another function needs to be performed.

Once the channel data is loaded into the register set 68, the timing sequencer 78 begins to perform synthesis of the frequency signals corresponding to the channel data in the registers of the register set 68. The timing sequencer 78 automatically sends the channel select signal 83 that selects the channel data for the first register in the register bank 68 as an input to the divider circuit 73 without controller interaction such as latching the channel data signal or other control signal from the controller 58. The timing sequencer 78 waits a predetermined period of time for the synthesizer 66 to output a stable VCO output signal 77 corresponding to the selected channel data, as shown at step 90. The timing sequencer 78 then generates a stable interrupt signal 79 that may be sent to the controller 58, as shown at step 92.

In response to receiving the stable interrupt signal, the controller 58 generates a make measurement signal 61 to the transceiver 80 at step 94. In response to this make measurement signal, the transceiver 80 measures the signal strength of the selected channel corresponding to the frequency of the VCO output 77. The transceiver 80 sends the measured signal strength data to the controller 58 in step 96 to select channel data. Controller 58 decrements the number of channels to be measured in step 98.

In step 99, the controller 58 determines whether signal strength data has been collected for all channels loaded into the register bank 68 in the previous step 88. If all signal strength data has been collected, the controller 58 generates a measurement report of the measurement result to the radio base station 4 in step 102. The mobile station 56 may then be used in the active state, as shown in step 104.

If the mobile station 56 does not complete the measurement of the signal strength data for the set of channels loaded into the register set 68, but the idle period is over, the mobile station 56 stops the measurement by sending an interrupt signal to the instruction register 61, as shown in step 101. The mobile station 56 transmits or receives as required and completes the measurement process as needed during the next idle period. During the next idle period, controller 58 may generate a restore signal to instruction register 61 to continue measuring the remaining channels in register set 68 without reloading the channels.

In the above process, the controller 58 needs to load the channel data only once at the start of the measurement operation. The controller 58 loads the channel data for the entire set of channels into the register bank 68 instead of loading the channel array for one channel at a time, which avoids the controller 58 performing multiple I/O writes that typically take up a lot of processor time.

The operation of the synthesizer 66 during the measurement operation of fig. 5 will now be described in more detail in connection with fig. 6. In step 106, the synthesizer 66 receives a set of channel data from the controller 58 and stores the channel data in the register set 68 located in the signal divider set 67. The channel data received from controller 58 may include a set of N values, where the frequency f of VCO output signal 77₀Is equal to f₀＝N*f_r. Each register in register set 68 includes a separate value of N corresponding to the channel for which the measurement is to be made. Alternatively, depending on the type of combiner implemented, this channel data may include the conversion by combiner 66 into each channelThe actual frequency values of a set of channels of N values.

Once the channel data is loaded into the register set 68, the timing sequencer 78 automatically selects the channel data from the first register of the register set 68 without controller interaction, such as latching or other control signals from the controller 58, as shown at step 108. The timing sequencer 78 waits a predetermined period of time for the VCO output signal 77 to settle to the frequency corresponding to the selected channel data, as shown at step 110. This predetermined time period may vary depending on the PLL used to implement synthesizer 66 and the frequency selected. Once stabilized, the timing sequencer 78 generates a stabilized interrupt signal 79 that is sent to the controller 58, as shown at step 112. This stable interrupt signal 79 informs the controller 58 to: the transceiver 80 can now make measurements.

In step 114, the timing sequencer 78 determines whether all registers in the register bank 68 containing channel data have been selected. If so, the synthesizer 66 waits for the next set of channel data or other instructions from the controller 58, as shown at step 115. If additional channels are present, the timing sequencer 78 determines whether an interrupt signal has been received from the controller 58 in step 116. If not, the timing sequencer 78 waits a predetermined period of time in step 118 for the transceiver 80 to complete its current measurement. Alternatively, the transceiver 80 may notify the synthesizer 66 to: the measurement is completed. The program then returns to step 108 and the timing sequencer 78 automatically selects the channel data for the next register without controller interaction such as control from the controller 58 or latching a new data signal in step 116. If synthesizer 66 receives an interrupt signal from controller 58, timing sequencer 78 no longer selects a channel and waits for a resume signal from controller 58 or for controller 58 to load a new set of channels into register set 68, as shown at step 117.

Thus, as described in the measurement operation of fig. 5, this controller only needs to load the entire set of channels into the register set 68 at one time, rather than loading the channel data for each channel separately. The timing sequencer 78 automatically selects the channel data for each channel in the set of channels without latching new data or other control signals from the controller 58. As a result, the interaction of the controller 58 necessary for the conventional method of fig. 3 is reduced. This reduced controller interaction increases the efficiency and speed of this measurement operation.

A second embodiment of the mobile station 56 is shown in fig. 7. In this embodiment, the transceiver 80 of the mobile station 56 includes a buffer 120 for storing measured signal strength data. In addition, the synthesizer 66 outputs a make measurement signal 119 to the transceiver 80 without outputting the stable interrupt signal 77 to the controller 58. The operation of the second embodiment of the mobile station 56 is described in connection with fig. 8 and 9.

Fig. 8 shows a flowchart of the operation of the controller 58 in fig. 7. In the example of fig. 8, the radio base station 12 transmits a neighbor cell list or a measurement instruction having a set of channels to be measured to the mobile station 56. Moreover, those skilled in the art will appreciate that: the present invention may be beneficial for measuring a set of channels during other operations. In step 122, mobile station 123 enters an idle period. In response to entering the idle period, the mobile station 56 performs measurements of the channels in the received neighbor cell list or measurement order. The controller 58 performs an I/O write operation to the register set 68 for storing channel data for the set of channels, as shown at step 124. Also, if the duration of the idle period is known, controller 58 may only load a subset of this channel into the register set that can be measured in the allocated period. In step 126, the controller 58 waits for signal strength data from the transceiver 80. If the idle period has elapsed before the measurement is completed, the controller 58 may send an interrupt signal to the synthesizer 68.

While the controller performs other operations or waits, the transceiver 80 measures the signal strength of each channel (as described in more detail in connection with fig. 9) and buffers this signal strength data in a buffer 120. Once the signal strength data for the entire set of channels has been measured and buffered in buffer 120, transceiver 80 sends an interrupt signal 121 to the controller, as shown at step 128. The controller 58 may access the buffer 120 at the address indicated in the interrupt signal 121 to read the signal strength data for all channels, as shown in step 130. Alternatively, the transceiver 80 may send the signal strength data to the controller 58 as part of the interrupt signal 121. Thus, the controller 58 receives signal strength data for the entire set of channels at once. Controller 58 generates a measurement report back to wireless base station 12 as shown at step 132 and prepares for a valid status as shown at step 134.

The operation of the synthesizer 66 and transceiver 80 during the measurement operation of fig. 8 is described in more detail in connection with fig. 9. In step 136, the combiner 66 receives channel data for a set of channels from the controller 58 and stores the channel data in the register set 68. The timing sequencer 78 automatically selects channel data for the first register in the register set 68 without controller interaction in step 138 and waits a predetermined period of time for the output 77 of the synthesizer 66 to settle to a frequency corresponding to the selected channel data, as shown in step 140. Once the predetermined period has expired, the timing sequencer 78 generates a make measurement signal 119 to the transceiver 80 in step 142 without the need for synthesizer or controller interaction between the transceivers. In the first embodiment of fig. 4, the synthesizer 66 sends a steady interrupt signal 79 to the controller 58, and the controller 58 then sends a make measurement signal 61 to the transceiver 80. In contrast, in this embodiment, the synthesizer 66 sends a make measurement signal 119 directly to the transceiver 80 and does not generate the stable interrupt signal 79 to the controller 58.

In response to the make measurement signal 119 generated by the timing sequence generator 78, the transceiver 80 measures the signal strength of the selected channel. The transceiver 80 stores the signal strength data in the buffer 120, as shown in step 144. The transceiver 80 then waits for another measurement signal 119 from the synthesizer 66. The timing sequencer 78 determines whether channel data for all registers in the register set 68 has been selected in step 146. If not, the process returns to step 138 and the timing sequencer 78 automatically selects the channel data for the next register. Alternatively, if the synthesizer receives an interrupt signal from the controller 58, the timing sequencer 78 will not select another channel until a recovery signal is received or another set of channels is loaded into the register set 68. If no additional measurements need to be performed, the transceiver 80 sends the measured signal strength data for the entire set of channels to the controller 58 along with the interrupt signal 121.

The embodiment of fig. 7 requires less controller interaction than the embodiment of fig. 4. Once the channel data for a group of channels is loaded into combiner 66 by controller 58, controller 58 need only wait until transceiver 80 sends the measurement data for the entire group of channels to controller 58 along with interrupt signal 121. The timing sequencer 78 automatically selects the channel data for each register and generates a make measurement signal 119 for transmission to the transceiver 80. In response, the transceiver 80 performs the measurements and buffers the measured signal strength data without requiring a measurement signal or other control signal from one of the controllers 58. Once the measurement of the entire group of channels is completed, the transceiver transmits the signal strength data to the controller. Alternatively, after each signal strength measurement, the transceiver 80 may send an interrupt signal to the controller 58 along with the signal strength data for that channel without buffering the signal strength data in the buffer 120.

The invention is particularly beneficial for reducing the time and improving the efficiency of this type of measurement operation, since there is only a limited time to perform the measurement operation of the neighbor table during the idle period. For example, fig. 10 shows a timing diagram of a measurement operation performed in response to receiving a measurement instruction. Between times T1 and T2, the mobile station 56 is active and transmitting or receiving traffic on the traffic channel at frequency f 1. At T2, the mobile station 56 enters an idle period until the next active period. If the mobile station 56 receives a measurement instruction to measure the signal strength of the adjacent channel f2-fn, the mobile station 56 must perform the measurement before returning to the active state at time T3.

The present invention reduces the overhead and time of the controller 58 by automatically performing the measurement of the signal strength of the set of channels f 2-fn. The functions performed by the controller 58 in the prior art mobile station 10 (such as storing each channel data, latching each new channel data, triggering signal strength measurements of each channel by the transceiver, and recording the controller interaction of each measured result) are eliminated in the present invention. By reducing the time required to perform signal strength measurements for a set of channels, measurement instructions or neighbor cell lists may be issued more frequently, or more channels may be measured during measurement operations, which advantageously increases the likelihood that mobile station 56 will use the cleanest channel to communicate with wireless base station 12.

Although the present invention is described above in the case of measuring the signal strength of a set of channels in accordance with reception of a neighboring cell list or a measurement instruction from the radio base station 4, the present invention is applicable whenever a set of channels needs to be scanned or measured, such as at power-up, subscriber registration, and call origination. For example, at power up, the mobile station 56 scans the channels for an acceptable digital or analog control channel. The mobile station 56 will often scan for certain frequencies based on a set of predetermined probabilities of finding an acceptable control channel on those frequencies. If the mobile station 56 finds a candidate control channel, it is determined from the service viewpoint whether this control channel meets the signal strength criteria and is appropriate. If not, the mobile station 56 continues to look for another candidate control channel. The mobile station 56 may store a set of candidate control channels in the register set 68 and perform other operations until an interrupt signal is received from the transceiver 80 along with the requested signal strength data for the set of channels.

In another embodiment, the mobile station repeatedly monitors the Synchronization Channel (SCH) of neighboring cells between transmit and receive bursts. The mobile station can then calculate any timing advance required by the neighboring synchronized cells prior to handoff, which will speed up the handoff process. This set of neighboring SCHs can be loaded into the register set 68 and monitored sequentially with little controller interaction using the present invention.

It is believed that the operation and construction of the present invention will be apparent from the foregoing description, and although the invention has been shown and described herein with respect to particular embodiments thereof, changes and modifications may be made without departing from the scope of the invention as defined in the following claims.

Claims (22)

1. A method of measuring signal strength of a set of channels, comprising the steps of:

storing channel data for a set of channels in a memory (68);

for each channel in the set of channels stored in the memory (68):

automatically selecting channel data for the channel without controller (58) interaction;

generating a frequency signal corresponding to the selected channel; and

the signal strength data of the selected channel is measured in response to the frequency signal.

2. The method of claim 1, further comprising the steps of:

generating a stable interrupt signal to a controller (58) in response to the step of generating a frequency signal corresponding to the selected channel; and

a measurement signal is generated to the receiver (80) in response to the stable interrupt signal.

3. The method of claim 2, further comprising the steps of:

in response to said step of measuring the selected channel signal strength data in response to the frequency signal, sending an interrupt signal containing the selected channel signal strength data to the controller (58).

4. The method of claim 1, further comprising the steps of:

transmitting a measurement signal without controller (58) interaction in response to said step of generating a frequency signal corresponding to the selected channel; and

wherein said step of measuring signal strength data comprises measuring signal strength data of the selected channel in response to the frequency signal and the measurement signal.

5. The method of claim 4, further comprising the steps of:

in response to said step of measuring signal strength data for the selected channel, an interrupt signal containing the signal strength data for the selected channel is sent to the controller (58).

6. The method of claim 4, further comprising the steps of:

for each channel in the set of channels, storing measured signal strength data for the selected channel in a buffer (120); and

in response to measuring the signal strength data of all selected channels in the set of channels, an interrupt signal containing the signal strength data of all selected channels in the set of channels is sent to the controller (58).

7. The method of claim 6, further comprising the steps of:

receiving a set of channels to be measured from a radio base station; and

wherein said step of storing channel data for a set of channels in a memory of a synthesizer comprises storing the channel data for the set of channels received from the radio base station in a memory (68) of a synthesizer (66) of the mobile station (56).

8. The method of claim 7, wherein said storing step is performed in response to an idle period of the mobile station (56).

9. The method of claim 8, further comprising the step of generating a measurement report including signal strength data for all selected channels in the set of channels.

10. An apparatus for measuring signal strength of a set of channels, comprising:

a memory (68) for storing channel data for different sets of channels;

a controller (58) for loading channel data for different sets of channels into the memory (68);

a synthesizer (66) for automatically selecting channel data for each channel of the set of channels stored in the memory (68) without controller interaction and generating a frequency signal corresponding to each selected channel; and

a transceiver (80) for measuring signal strength data for each channel in the set of channels in response to the frequency signals generated by the synthesizer (66).

11. The apparatus of claim 10, further comprising:

a buffer (120) for storing signal strength data of the set of channels measured by the transceiver (80); and

wherein the transceiver (80) communicates the signal strength data for the set of channels to the controller (58) in response to completing the signal strength data measurements for the set of channels stored in the memory (68).

12. A device according to claim 11, wherein said memory (68) for storing channel data for a group of channels is a register bank (68) in said combiner (66).

13. The apparatus of claim 12, wherein said synthesizer (66) for automatically selecting channel data for each channel of the set of channels stored in said memory (68) and generating a frequency signal corresponding to each selected channel comprises:

a timing sequencer (78) for automatically selecting channel data for each channel (68) in the set of channels stored in the register bank (68); and

a phase locked loop for generating a frequency signal corresponding to each selected channel.

14. The apparatus of claim 13, wherein said timing sequencer (78) for automatically selecting channel data for each channel of the set of channels stored in said register bank also generates an output control signal and an output measurement signal for selecting a register of said register bank.

15. The apparatus of claim 14, wherein said transceiver (80) measures signal strength data for each channel in the set of channels in response to outputting the measurement signal.

16. The apparatus of claim 14, wherein the phase locked loop for generating the frequency signal corresponding to each selected channel is characterized by:

a phase detector (70) for comparing the phase of each selected channel with the phase of the reference signal and generating an error voltage signal proportional to the phase difference; and

a voltage controlled oscillator (76) for generating a frequency signal corresponding to the selected channel in response to the error voltage signal.

17. The apparatus of claim 16, wherein the apparatus is a mobile station (56) in a wireless communication system.

18. A wireless communication system, comprising:

a wireless base station (4);

at least one mobile station (56) that interfaces with said radio base station (4), wherein said radio base station (4) transmits a set of channels to said mobile station (56), and wherein said mobile station (56) comprises:

a controller (58) for processing the set of channels for which measurements are to be made;

a synthesizer (66) comprising:

a memory (68) for storing channel data for the set of channels for which measurements are to be made;

a timing sequencer (78) for automatically selecting channel data for each channel of the set of channels stored in said memory (68); and

a phase locked loop for generating a frequency signal corresponding to the selected channel data; and

a receiver (80) for measuring signal strength data corresponding to the frequency signals generated by the synthesizer.

19. The wireless communication system of claim 18, wherein the receiver (80) includes a buffer (120) for storing the signal strength data for the set of channels measured by the receiver (80), and wherein the receiver (80) transmits the signal strength data for the entire set of channels to the controller (58) upon completion of the signal strength data measurement for each channel.

20. The wireless communication system of claim 19, wherein said timing sequencer (78) of said combiner (66) further generates an output control signal and an output measurement signal for channel data selection for each channel of the set of channels.

21. A wireless communication system according to claim 18, wherein said timing sequencer (78) of said synthesizer (66) generates an output control signal for channel data selection for each channel of the set of channels and an output stabilization signal indicative of frequency signal generation corresponding to the channel data selected by the phase locked loop.

22. The wireless communication system of claim 21, wherein the controller (58) generates an output measurement signal in response to the output stabilization signal, wherein the transceiver (80) measures signal strength data corresponding to the frequency signal generated by the synthesizer (66) in response to the output measurement signal.