KR20010003804A - appratus and method for searching pilot signal using memory in cdma terminal equipment - Google Patents

Abstract

PURPOSE: A search device and method using a memory in the CDMA communication terminal is provided to search by storing real-time data in a memory only in a short time interval and to search pilot signals by off-line processing. CONSTITUTION: A switch(311) transmits receiving chip sample data to a memory(312). The memory(312) stores the receiving chip sample data and outputs them under the control of a controller. The first multiplexer(313) inputs the output of an auto gain amplifier and the output of the memory(312) and outputs selectively one of the two inputs by a selection signal of the control of the controller. An on-line PN generator(314) generates a PN code to correlate the chip sample data presently received under the control of the controller. An off-line PN generator(315) generates a PN code to correlate the data stored in the memory(312). The second multiplexer(316) inputs the output of the on-line PN generator(314) and the output of the off-line PN generator(315) and outputs selectively one of the two inputs by a selection signal of the controller. A searcher(317) correlate the output signal of the first multiplexer(313) with the PN code output from the second multiplexer(316) to carry out search operation.

Description

Apparatus and method for searching pilot signal using memory in cdma terminal equipment}

The present invention relates to a pilot signal search apparatus and method of a code division multiple access communication terminal, and more particularly, to a search apparatus and method using a memory.

1 shows a block configuration of a general code division multiple access communication terminal.

Referring to FIG. 1, the radio frequency (111) unit down converts a radio signal received through an antenna to an intermediate frequency IF, converts the radio signal into a baseband signal, and outputs the converted baseband signal. The amplifier 112 amplifies and outputs the output signal of the RF receiver to match the dynamic range of the A / D converter under the control of the automatic gain regulator. The A / D converter 113 converts the output signal of the amplifier 112 into a digital signal through sampling and quantization and outputs the digital signal. The automatic gain adjuster 114 adjusts the gain of the amplifier 112 so that the output signal range of the amplifier 312 maintains a constant level. The fingers 115-135 receive, despread, and output a signal related to a corresponding phase, respectively. The searcher 116 searches for the received signal while changing the phase, and controls the fingers 115-135 according to the result. The combiner 117 combines and outputs signals output from the fingers 115-135. The message processor Demodulator 118 restores the signal output from the combiner 118 to the original data through a decoding process and outputs the original data.

As described above, the signal received from the antenna is converted into respective I / Q channel baseband signals through the RF stage and the IF stage. The baseband signal is analog / digital converted and input to the fingers 115-135 and the searcher 116. Here, the searcher 116 searches for a received signal while changing the pn phase and controls the fingers according to the result. The detailed configuration is the same as that of FIG. 2.

2 shows a detailed block diagram of the searcher 116 according to the prior art.

Referring to FIG. 2, the correlator 211 correlates the output chip sample data of the automatic gain amplifier 114 with a PN code provided for a predetermined period of time and outputs the result. The energy meter 212 calculates and outputs energy with respect to the value output from the correlator 211. The threshold comparator 213 processes the software algorithm or the like, and controls the PN generator 214 to output the corresponding PN code to the correlator 211. Here, the threshold comparator 213 is a controller (cpu) or a digital signal processor (dsp). As described above, after obtaining the energy value for the PN phase having the current constant sequence, the input clock of the PN generator 214 is adjusted to change the phase of the PN generator 214 by one chip, and the newly changed PN. Correlate again in phase to find the energy. Therefore, energy is calculated for a predetermined number of PN phases through the searcher and transferred to cpu / dsp. Here, the number of pn phase changes by the predetermined number is referred to as a search window size.

As described above, in the conventional method, the search is performed using chip sample data input in real time. The problem with this approach is that the analog / digital converted receive chip sample data required for the search is still needed during the search. On the battery side, this results in a constant current pass from the RF stage to the baseband stage, resulting in much current consumption. That is, the conventional search structure does not need to demodulate data, and even in the case of only searching, all the paths from the RF stage to the baseband stage are turned on and current consumption continues.

In addition, in order to support the interfrequency handoff proposed by the next generation mobile communication system (IMT-2000), RF paths of different frequencies for searching are opened at a given short time, about 1 to 2 ms. The search with a simple structure of serial correlator is impossible.

Accordingly, an object of the present invention is to provide a search apparatus and method for storing real-time data in a memory only in a short time period for a predetermined time in a code division multiple access communication terminal, and performing a necessary search using the same.

Another object of the present invention is to provide an apparatus and a method for searching a pilot signal by offline processing in a code division multiple access communication terminal.

Another object of the present invention is to provide a search apparatus and a method for increasing a waiting time in a code division multiple access communication terminal.

Another object of the present invention is to provide an apparatus and method for performing a search using a memory even in an environment where data can be obtained only in a short time such as an inter-frequency handoff in a code division multiple access communication terminal.

A search apparatus of a code division multiple access communication terminal for achieving the above objects includes a memory for storing received chip sample data, a first switch for selectively outputting the output data of the memory and the currently received real time data, and an online search. An on-line PN generator operating in the mode, an off-line PN generator operating in the offline search mode, a second switch for selectively outputting the outputs of the on-line PN generator and the off-line PN generator, and data transmitted from the first switch. And a search unit that performs a search operation in correlation with the P / N code output from the second switch.

1 is a block diagram of a general communication terminal.

Figure 2 is a block diagram of a search apparatus according to the prior art.

3 is a block diagram of a search apparatus according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding the reference numerals to the components of each drawing, the same components have the same reference numerals as much as possible even if displayed on different drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The online search mode described below refers to a mode for receiving data in real time and performing a search operation. The offline search mode stores a short time of real time data in a memory and uses the same. Refers to a mode for performing a search operation.

The search apparatus proposed by the present invention includes a memory capable of storing real-time data for a predetermined time and a separate dedicated PN generator. That is, the search apparatus has a structure capable of supporting both the online search mode and the offline search mode.

The configuration of the searcher according to the present invention described above is shown in FIG.

Referring to FIG. 3, the switch 311 is switched under the control of a controller (not shown) to transfer the received chip sample data to the memory 312. The memory 312 stores the received chip sample data transferred from the switch 311 and outputs the data under the control of the controller. The first multiplexer 313 inputs the output of the auto gain amplifier and the output of the memory 312, and selects and outputs one of the two inputs according to a selection signal of the controller. The online PN generator 314 generates a PN code for correlating the chip sample data currently received under the control of the controller in the online search mode. The offline PN generator 315 sets the state stored in the internal register of the online PN generator 314 provided by the controller to the initial state in the offline search mode, and then, in the memory 312 under the control of the controller. Generates a PN code to correlate the stored data. The second multiplexer 316 inputs the output of the online PN generator 314 and the output of the offline PN generator 315, and selects and outputs one of the two inputs according to a selection signal of the controller. The search unit 317 correlates the output signal of the first multiplexer 313 with the PN code output from the second multiplexer 316 to perform a search operation.

The operation according to the present invention based on the above configuration will be described in detail.

The searcher as the configuration of FIG. 3 proposed in the present invention supports the online search mode and the offline search mode as described above. In the online search mode, a search operation is performed by inputting data output from the automatic gain amplifier 114 to the search unit 317 in the conventional manner.

In the offline search mode, on the other hand, the controller first sets the offline search mode flag. At the time of storing the chip sample data of the memory 312, the state of the shift register of the online-only PN generator 314 is read and stored. The memory 312 stores data of a predetermined synchronization cumulative interval, and notifies the controller when the data storage is completed.

Then, the controller generates a search command and initializes the state value of the register read from the online dedicated PN generator 314 to the offline PN generator 315. The search unit 317 notifies the controller of the PN phases as large as the size of the search window received at the search command.

Then, the controller reads the search result, performs an algorithm related to the search, and generates the next search command. At this time, the controller loads and initializes the shift register state value read from the online dedicated PN generator 314 to the offline dedicated PN generator.

The search unit 317 reads the same data from the memory 312 and calculates each energy for PN phases equal to the size of the search window. As described above, the offline search is repeatedly performed as necessary using the chip sample data stored in the memory. And at the end of the search the controller clears the offline search mode flag.

Therefore, the search mode automatically switches to the online search mode. At this time, the input data of the search unit 317 is real-time data from the RF stage through the baseband stage, and the PN generator that correlates the data is also an online dedicated PN generator.

As described above, the present invention stores the real-time data currently received by the code division multiple access communication terminal in the memory and searches for the pilot signal using the same. As a result, there is no need to turn on the power of the baseband data path at the RF stage during the search, thereby reducing current consumption. In addition, even in an environment where data can be obtained only in a short time such as an inter-frequency handoff, the memory can be effectively searched.

Claims (4)

A search apparatus for a code division multiple access communication terminal, A memory for storing the received chip sample data; And a search unit configured to perform a search operation by correlating the data stored in the memory into a plurality of P & N codes. A search apparatus for a code division multiple access communication terminal, A memory for storing the received chip sample data; An offline PEN generator that operates in the offline search mode and generates the PEN code; And a search unit configured to perform a search operation by correlating the data stored in the memory with the P / N code outputted from the offline PN generator. A search apparatus for a code division multiple access communication terminal, A memory for storing the received chip sample data; A first switch for selectively outputting output data of the memory and real-time data currently received; An online PN generator operating in the online search mode, An offline PEN generator operating in the offline search mode, A second switch for selectively outputting the outputs of the online PN generator and the offline PN generator; And a search unit configured to perform a search operation by correlating the data transmitted from the first switch with the P / N code output from the second switch. A search method of a communication terminal having a memory for storing received chip sample data and an offline PEN generating unit operated in an offline searching mode and generating a corresponding PEN code, Reading the shift register state value of the on-line PEN generator in the off-line search mode and setting the initial state value of the off-line PEN generator; Calculating the value of each energy value by correlating the data stored in the memory with the number of P & Cs of the search window output from the offline PN generator; Performing an algorithm related to the search with the calculated energy value; And after performing the algorithm, returning to the initial state value setting process of the offline PEN generator and performing the following steps again.