KR100933205B1 - WCDMA physical random access channel demodulation device and demodulation method - Google Patents

Abstract

Disclosed are a physical random access channel (PRACH) demodulation device and a demodulation method according to an asynchronous wideband code division multiple access (WCDMA) protocol. The demodulation device of the present invention can demodulate a physical random access channel (PRACH) transmitted through a reverse channel from a mobile terminal by reproducing a frame sync synchronized with a base station based on information collected from a forward channel and setting various parameters. .

WCDMA, Asynchronous, PRACH, Forward Channel, Frame Sync

Description

Apparatus and Method for Demodulating WCDMA Physical Random Access Channel

The present invention can demodulate a Physical Random Access Channel (PRACH) transmitted through a reverse channel from a mobile terminal based on information collected from a forward channel according to an asynchronous wideband code division multiple access (WCDMA) protocol. The present invention relates to a WCDMA physical random access channel demodulation device and a demodulation method.

Asynchronous Wideband Code Division Multiple Access (WCDMA) is a wireless communication technology applied to the Universal Mobile Telecommunications System (UMTS), one of the third generation mobile communication (3G) technologies standardized by the 3GPP (3 Generation Partnership Project).

The physical layer used in the WCDMA protocol is connected to a medium access control (MAC) layer, which is a higher layer, through a transport channel, and is connected between the medium access control layer and the physical layer through this transport channel. Data is moved.

At the physical layer, a subscriber station (UE) and a wireless network (UTRAN: UMTS Terrestiral Radio Access Network) communicate through a physical channel. The physical channel transmits data divided into predetermined time units called frames.

The physical channel includes a forward channel (downlink) and a reverse channel (reverse channel, uplink), each of which includes a dedicated channel (DCH) and a common channel (Common Channel).

Dedicated channels are commonly used in the forward and reverse channels, and include a dedicated physical data channel (DPDCH) and a dedicated physical control channel (DPCCH).

Common channels of the forward channel include a common pilot channel (CPICH), a primary common control physical channel (P-CCPCH) and a secondary common control physical channel (S-CCPCH). Channel, Synchronization Channel (SCH), Physical Downlink Shared Channel (PDSCH), Acquisition Indication Channel (AICH) and Page indication channel (PICH) do.

The common channel of the reverse channel used by the mobile terminal for transmission to the base station includes a physical random access channel (PRACH) and a physical common packet channel (PCPCH).

Data in the forward channel is channelized by a channelization code called Orthogonal Variable Spreading Factor (OVSF) to maintain orthogonality between different channels, and scrambling used to distinguish one base station from another. It is mixed by a scrambling code and then modulated and sent. However, the sync channel is added to the data stream where channelization and mixing are performed without mixing.

The reverse channel also uses a predetermined scrambling code and channelization code.

An object of the present invention is to demodulate a Physical Random Access Channel (PRACH) transmitted on a reverse channel from a mobile terminal based on information collected from a forward channel according to an asynchronous wideband code division multiple access (WCDMA) protocol. The present invention provides a WCDMA physical random access channel demodulator and a demodulation method.

In accordance with another aspect of the present invention, there is provided a physical random access channel demodulation method, comprising: a first step of extracting a base station parameter and a frame sink from a forward channel radio signal according to Wideband Code Division Multiful Access (WCDMA) protocol; A second step of generating a virtual physical random access channel (PRACH) message based on the frame sync and base station parameters extracted in the first step; Demodulating the virtual PRACH message based on the frame sync; If the demodulation succeeds in the third step, the frame sync is pre-determined for a predetermined time to generate a compensation frame sink that compensates for the delay error, and the steps after the second step are repeated again. Using a fourth step; A fifth step of canceling the last compensation and completing the previous step compensation frame synchro when a demodulation failure occurs while performing the fourth step; And demodulating a PRACH channel received through a reverse channel radio signal based on the compensated frame sync.

According to an embodiment, in the fifth step, when the demodulation of the third step fails without performing the fourth step, the frame sync may be further delayed for a predetermined time to complete the compensation.

Here, the predetermined time is preferably a time corresponding to one chip.

According to an embodiment of the present disclosure, the first step reproduces the frame sync of 10 msec period for demodulation of the third and fourth steps regardless of the period of the extracted frame sync based on a predetermined internal reference clock CLK. It may include the step.

In accordance with another aspect of the present invention, an apparatus for demodulating a physical random access channel includes an antenna for receiving a forward channel signal and a reverse channel radio signal between a base station and a mobile terminal according to a WCDMA protocol, a first down converter, a forward link receiver, and a PRACH generator. And a delay controller, a second downconverter, and a demodulator.

The first down converter converts the radio signal of the forward channel into a baseband signal, and the forward link receiver extracts base station parameters and frame sinks from the signal converted by the first down converter.

 The PRACH generation unit generates a virtual PRACH message based on the frame sink and the base station parameters extracted by the forward link receiver, and the demodulator demodulates the virtual PRACH message based on the frame sink.

The delay controller determines whether the demodulator demodulates success, and if successful, generates a compensated frame sink that compensates for the delay error by advancing the frame sync a predetermined time and provides the demodulator to repeat the demodulation.

The second down converter converts the radio signal of the reverse channel into a baseband signal and provides the demodulation unit.

When the demodulation failure of the demodulator fails, the delay controller completes the compensation by delaying the frame sink used for the demodulation by one chip time, and the demodulation unit is provided from the second downconverter based on the compensated frame sink. The PRACH channel included in the baseband signal is demodulated.

The WCDMA Physical Random Access Channel (PRACH) demodulation device according to the present invention can interwork with a base station to reproduce a frame sync of the base station without compensating information directly from the base station and compensate for the delay error.

Accordingly, the demodulation device can demodulate the physical random access channel of the terminal having various delay errors without the help of the base station. Furthermore, the analysis apparatus using the demodulation device of the present invention can effectively analyze traffic such as a repeater even in a stand-alone state without direct connection with a base station.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a block diagram of an apparatus for physical random access channel demodulation according to an embodiment of the present invention. Referring to FIG. 1, a physical random access channel (PRACH) demodulator (hereinafter, simply referred to as a demodulator) 100 includes an antenna 101 and a first down converter 103. And a forward link receiver 105, a frame sink 110, a second down converter 131, and a demodulator 133.

The demodulation device 100 is a base station (UE) through a reverse channel of an asynchronous mobile communication network according to the Wideband Code Division Multiful Access (WCDMA) protocol (UE: User Equipment) (hereinafter, simply referred to as a 'terminal') A physical random access channel (PRACH) transmitted to the Node-B may be demodulated. To this end, the demodulation device 100 must set the same settings as the air interface of the base station and use the same frame sync as the base station Node-B. Information related to such configuration is extracted from the forward channel from the base station to the terminal.

The first down converter 103 receives the radio signal of the forward channel transmitted from the base station to the terminal from the antenna 101, converts it into a baseband signal, and provides it to the forward link receiver 105.

The forward link receiver 105 demodulates the frame sync by demodulating the main-sink channel (P-SCH) and the sub-sink channel (S-SCH) included in the signal provided from the first down converter 103, and -Demodulate the Node-B Parameter by demodulating the common control physical channel (P-CCPCH) and the sub-joint control physical channel (S-CCPCH).

The frame sync is extracted through the main sync channel (P-SCH) and the sub-sync channel (S-SCH). The master sink channel informs the slot starting point for a terminal having no synchronization information. The main-sink channel consists of 10 ms frame units containing 15 slots, and each time slot is repeated with a so-called 'Generalized Hierachical Golay Sequence Code' of 256 bits in length. Is sent. This code is the same for all base stations.

The forward link receiver 105 searches for a sub-sync channel (S-SCH) after slot synchronization by searching for a main-sync channel having the best signal. The sub-sync channel (S-SCH) uses a different code for every slot. The codes used for the sub-sync channel (S-SCH) are 64 orthogonal codes having a length of 256 chips, and the forward link receiver 105 is a combination of orthogonal codes assigned to each slot and is used for main-scrambling of its base station. Identify the Primary Scrambling Code Group.

Since only one primary scrambling code is included in one code group, the forward link receiver 105 checks the main scrambling code assigned to the base station based on the extracted main scrambling code group.

The forward link receiver 105 demodulates the main common control physical channel (P-CCPCH) by using the obtained master scrambling code, and transmits the broadcast channel through the primary common control physical channel (P-CCPCH). BCH: demodulates a broadcast channel to obtain various base station parameters. The broadcast channel (BCH) is one of transport channels, which is an interface between a physical layer and a media access control (MAC) layer, and is transmitted through a master-joint control physical channel (P-CCPCH).

In addition to this main-scrambling code, the base station parameters include a T-Cell, which is a timing delay associated with a base station frame number (BFN) in a cell. In addition, the base station parameters include a preamble scrambling code, a preamble scrambling code, a preamble signature, and a physical random access channel (PRACH) slot format 'RACH Slot Format' and a RACH Subchannel Numbers. , Puncture Limit, Preamble Threshold, Minimum Spreading Factor (SF) available, Transmit Format Set (RACH TFS), Transfer Format Combination Set (RACC TFCS), and Acquisition Indicator Channel (AICH) Transmission Timing. These can be extracted from the System Information Block (SIB) of the broadcast channel (BCH).

The forward link receiver 105 provides the extracted frame sync and base station parameters to the frame sync 110. In addition, the forward link receiver 105 provides the extracted base station parameters to the demodulator 133.

The frame sync unit 110 includes a frame sync play unit 111, a PRACH generator 113, and a delay controller 115, and demodulates the unit 133 regardless of the period of the frame sync extracted by the forward link receiver 105. Reproduces a stable frame sync of 10 msec required by the N) and provides it to the demodulator 133, and simultaneously reproduces the compensated frame sync for demodulating the physical random access channel of the demodulator 133. Here, the compensated frame sync refers to a frame sync that compensates the delay error to the maximum within a demodulated range of the physical random access channel received from the mobile terminal.

Since asynchronous WCDMA does not require strict synchronization, demodulation of the physical random access channel (PRACH) of the demodulator 133 may be possible even when the frame sync unit 110 is not corrected. As a result, the frame sink unit 110 can reproduce a frame sink capable of receiving and demodulating a physical random access channel including the maximum delay possible.

The frame sync regenerator 111 reproduces the stable frame sync of 10 msec required by the demodulator 133 regardless of the period of the frame sync extracted from the forward link receiver 105 based on the internal reference clock CLK, thereby delaying the controller. Provide to 115. To this end, a phase-locked loop (PLL) for fixing an internal reference clock CLK having a high frequency oscillation frequency may be used.

In addition, according to an embodiment, the frame sync playback unit 111 determines whether the frame sync provided from the forward link receiver 105 is in units of 10 ms. When the frame sync received from the forward link receiver 105 is not in a 10 ms unit (eg, 80 ms), the frame sync reproducer 111 acquires the frame sync obtained from the forward link receiver 105 using the reference clock CLK. Reproduces the frame sync in units of 10 ms and provides the delay control unit 115.

The PRACH generation unit 113 generates a 'virtual PRACH message' using the frame sink and base station parameters provided from the forward link receiver 105 and provides the demodulator 133 to the frame sink by the delay controller 115. Enable fine correction of The 'virtual PRACH message' generated by the PRACH generating unit 113 replaces the PRACH message sent by the mobile station to the base station, and is a message in which channelization and mixing just before being finally modulated into a radio signal are performed. In addition, the virtual PRACH message corresponds to a state that does not include a delay in the air (Air) from the mobile terminal to the base station or repeater.

The virtual PRACH message includes a data part and a control part in the same manner as the data of the physical random access channel transmitted on the reverse channel. The PRACH generation unit 113 spreads the binary control and data parts at chip rates with channelization codes Cc or Cd, respectively, and then quantizes them using a gain factor β. The PRACH generating unit 113 combines the data parts into one complex stream using the I-branch and the control part as the Q branch and then mixes them using a predetermined scrambling code to mix the virtual PRACH message. Create

The PRACH generation unit 113 generates a virtual PRACH message periodically or aperiodically and provides the demodulation unit 133 until the frame sync correction by the delay controller 115 is completed.

The delay controller 115 provides the demodulator 133 with a compensated frame sink compensated for the delay error of the frame sync based on the information on whether the virtual PRACH message demodulation succeeded from the demodulator 133 is successful. Let 133 demodulate the 'virtual PRACH message' based on the compensation frame sync. The delay control unit 115 repeats this operation until it reproduces the compensated frame sync.

The frame sync extracted from the forward link receiver 105 or reproduced by the frame sync regenerator 111 includes a delay error as much as a delay in the air than the frame sync of the base station Node-B. to be. However, the demodulation device 100 based on the asynchronous method may demodulate the physical random access channel of the terminal despite such a delay error. Therefore, the delay control unit 115 needs to compensate the delay error as much as possible within the range capable of demodulating the physical random access channel of the terminal. The physical random access channel transmitted by the terminal in a real environment may also include a delay error, and thus the compensated compensated frame sync is effective for all terminals in the cell environment to which the physical random access channel is to be demodulated.

When the delay control unit 115 reproduces the compensated frame sync, the delay control unit 115 provides the corresponding compensated frame sync to the demodulator 133 so that the actual physical random access channel is demodulated.

The second down converter 131 receives the radio signal of the reverse channel transmitted from the terminal to the base station from the antenna 101, converts the radio signal into a baseband signal, and provides the demodulation unit 133.

The demodulator 133 is based on a base station parameter provided from the forward link receiver 105 and a frame sink (or a compensated frame sink) provided from the delay controller 115. It demodulates the PRACH message and provides the delay control unit 115 with success in demodulation so that the delay control unit 115 finds the compensated frame sink.

The demodulator 133 demodulates the physical random access channel (PRACH) included in the signal provided from the second down converter 131 when receiving the compensated frame sync from the delay controller 115.

Based on the above configuration, the demodulation device 100 demodulates the physical random access channel.

According to an embodiment, when the demodulation device 100 is installed in a wireless repeater or the like, and the wireless repeater includes a configuration corresponding to the antenna 101, the first down converter 103 or the second down converter 131, demodulation The apparatus 100 may use a configuration corresponding to the antenna 101, the first down converter 103, or the second down converter 131 included in the wireless repeater.

2 is a flowchart provided to explain a physical random access channel demodulation method according to an embodiment of the present invention. Hereinafter, the physical random access channel demodulation method of the demodulation device 100 will be described with reference to FIG. 2.

The first down converter 103 of the demodulation device 100 converts the radio signal of the forward channel received from the antenna 101 into a baseband signal and provides the signal to the forward link receiver 105. The forward link receiver 105 extracts the base station parameter and the frame sink included in the signal provided from the first down converter 103, provides the extracted frame sink to the frame sync playback unit 111, and restores the extracted base station parameter. The grandfather 133 is provided. In addition, the forward link receiver 105 provides the frame sync and base station parameters to the PRACH generator 113 (S201).

The frame sync regenerator 111 reproduces and provides the stable 10msec frame sync required by the demodulator 133 to the delay controller 115 regardless of the period of the frame sync received from the forward link receiver 105. The delay controller 115 resets the compensation coefficient N for delay error compensation to '0' (S203).

The PRACH generator 113 generates a 'virtual PRACH message' based on the frame sync and the base station parameters provided by the forward link receiver 105 and provides the demodulator 133 to the demodulator 133 (S205).

The demodulator 133 sets various parameters related to demodulation of the physical random access channel to base station parameters provided from the forward link receiver 105 and uses a frame sink (or a compensated frame sink) provided from the delay controller 115. In step S207, the PRACH generation unit 113 attempts to demodulate the 'virtual PRACH message'.

The delay controller 115 receives the demodulation result of the 'virtual PARCH message' from the demodulator 133 and determines whether the demodulation succeeded (S209). If the demodulation is successful, the delay controller 115 provides the demodulator 133 with a compensated frame sync, which is compensated by preceding the frame sync in a predetermined time unit (for example, one chip unit). The demodulation apparatus 100 returns to S205 and repeats the frame sync delay error compensation procedure again. Therefore, the delay controller 115 continuously compensates for the compensation frame sink until the compensation completed frame sink is made (S211, S213).

If the demodulator 133 fails to demodulate the 'virtual PARCH message' in step S209, the delay controller 115 determines that excessive compensation has been made for the delay error of the frame sync. Therefore, the delay controller 115 determines the previous frame (N = N-1) compensation frame sync as the compensated frame sync, and provides the corresponding compensated frame sync to the demodulator 133 to input from the second down converter 131. The demodulation of the actual physical random access channel is performed. As a result, the rewarded frame sink corresponds to one of the compensated frame sinks capable of demodulating the virtual PRACH message, and may preferably correspond to the most rewarded (S215).

In this manner, the physical random access channel demodulation of the demodulation device 100 is performed. In the example of FIG. 2, steps S211 to S215 are examples in which compensation for a delay error is made in units of one chip, but it is not necessary to compensate in units of one chip.

Demodulation device 100 of the present invention can be used in combination or included in a variety of devices.

For example, the demodulation device 100 may be used in a system for monitoring traffic of a wireless repeater based on WCDMA protocol. The demodulator 100 is coupled to the wireless repeater to demodulate the physical random access channel provided from the terminal to the base station to provide the information to the analysis device directly coupled with the demodulator 100, or external traffic coupled through the network It can be provided to an analysis server (not shown).

In the conventional traffic analysis system, a device in charge of demodulating a physical random access channel uses a method in which various information about a base station is provided from an external analysis server. However, even if there is no network with an external analysis server, the analysis device directly coupled to the demodulation device 100 of the present invention can analyze the traffic of the corresponding relay by demodulating the access channel by obtaining information about the base station from the direct forward channel. It becomes possible.

The invention can be implemented in methods, devices and systems. In addition, when the present invention is implemented in computer software, the components of the present invention may be replaced with code segments necessary for performing necessary operations. The program or code segment may be stored in a medium that can be processed by a microprocessor and transmitted as computer data coupled with carrier waves via a transmission medium or communication network.

The media that can be processed by the microprocessor include electronic circuits, semiconductor memory devices, ROMs, flash memory, electrically erasable programmable read-only memory (EEPROM), floppy disks, optical disks, and hard disks. (Hard) Includes the ability to transmit and store information such as disks, fiber optics, wireless networks, and the like. Computer data also includes data that can be transmitted over electrical network channels, optical fibers, electromagnetic fields, wireless networks, and the like.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the above-described specific embodiment, the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1 is a block diagram of an apparatus for physical random access channel demodulation according to an embodiment of the present invention; and

2 is a flowchart provided to explain a physical random access channel demodulation method according to an embodiment of the present invention.

Claims (6)

Extracting a base station parameter and a frame sync from a forward channel radio signal according to Wideband Code Division Multiful Access (WCDMA) protocol; A second step of generating a virtual physical random access channel (PRACH) message based on the frame sync and base station parameters extracted in the first step; Demodulating the virtual PRACH message based on the frame sync; If the demodulation succeeds in the third step, the frame sync is pre-determined for a predetermined time to generate a compensation frame sink that compensates for the delay error, and the steps after the second step are repeated again. Using a fourth step; A fifth step of canceling the last compensation and completing the previous step compensation frame synchro when a demodulation failure occurs while performing the fourth step; And And a sixth step of demodulating a PRACH channel received through a reverse channel radio signal based on the compensated frame sync. The method of claim 1, In the fifth step, when the demodulation of the third step fails without performing the fourth step, physical random access channel demodulation may be completed by further delaying the frame sync for a predetermined time. Way. The method of claim 1, The predetermined time is a physical random access channel demodulation method, characterized in that the time corresponding to one chip (Chip). The method of claim 1, The first step includes reproducing a frame sync of 10 msec periods for demodulation of the third and fourth steps regardless of the period of the extracted frame sinks based on a predetermined internal reference clock CLK. And a physical random access channel demodulation method. An antenna for receiving forward channel and reverse channel radio signals between a base station and a mobile terminal in accordance with Wideband Code Division Multiful Access (WCDMA) protocol; A first down converter converting the radio signal of the forward channel into a baseband signal; A forward link receiver extracting a base station parameter and a frame sink from the signal converted by the first down converter; A PRACH generator configured to generate a virtual physical random access channel (PRACH) message based on the frame sync and base station parameters extracted by the forward link receiver; A demodulator for demodulating the virtual PRACH message based on the frame sync; A delay control unit for determining whether the demodulation unit is successful and, if successful, generating a compensation frame sink for compensating a delay error by advancing the frame sink a predetermined time and providing the demodulation unit to repeat the demodulation; And A second downconverter converting the radio signal of the reverse channel into a baseband signal, When the demodulation failure of the demodulator occurs, the delay controller delays the frame sync used for the demodulation by one chip time to complete compensation. And a demodulator demodulates a PRACH channel included in a baseband signal provided from the second downconverter based on the compensated frame sync. The method of claim 5, And a frame sync reproducing unit for reproducing the frame sync of 10 msec periods and providing the demodulation unit and the delay control unit regardless of the period of the frame sink extracted by the forward link receiver based on a predetermined internal reference clock CLK. A physical random access channel demodulation device.

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