KR100288197B1 - Apparatus for extending traffic coverage in mobile communication system - Google Patents

Abstract

The present invention relates to a communication area expansion device in a mobile communication system in which a cell communication area is expanded by supplying a base station modem ASIC by changing a system reference clock. The present invention relates to a system obtained from a time and frequency generation unit (TFU). The clock is differentially delayed to generate a plurality of system clocks corresponding to each communication zone, and each digital processor in the digital processing section selectively takes one of the plurality of system clocks and expands the coverage area. In addition, each digital processor uses a clock generator to differentially delay the system clock to generate multiple system clocks, each channel element in the channel card being selectively picked and used by one channel card. Extended area transmit and receive signal processing is also possible.

Description

Apparatus for extending traffic coverage in mobile communication system

TECHNICAL FIELD The present invention relates to extension of a call area in a code division multiple access (CDMA) mobile communication system. In particular, a call area extension device in a mobile communication system in which a cell communication area is expanded by supplying a base station modem ASIC by changing a system reference clock It is about.

In general, in a CDMA mobile communication system, all mobile stations (terminals) and base stations are time-synchronized based on the CDMA system reference time. Here, the base station synchronizes time with the CDMA system reference time received from the GPS receiver, and the mobile station obtains the long code timing of the CDMA system and the time information of the system timing from the synchronization channel message sent by the base station. Synchronize the timing and system timing with the long code timing and system timing of the mobile station. This synchronization allows the mobile station to recover the signal transmitted from the base station and the base station to recover the signal transmitted from the mobile station.

Herein, the mobile station obtains time information through a message transmitted from the base station and sets a reference time to synchronize with the base station.

The forward link (base station to mobile station) has a pilot channel, a synchronization channel, a calling channel and a forward call channel, and the reverse link (mobile station to base station) has an access channel and a reverse call channel. The mobile station first acquires a pilot channel and acquires a synchronization channel (synchronization channel message) in synchronization with the obtained pilot channel. The mobile station obtains time information from the system time data (SYS_TIMEs) included in the sync channel message, where the system time data (SYS_TIMEs) obtains the pilot PN offset at 320 ms past the end of the last 80 ms super frame of the sync channel message received by the mobile station. It means the system time when subtracted.

At this time, the reference time set by the mobile station is delayed due to the signal propagation delay from the base station to the mobile station and the signal processing delay at the mobile station compared to the base station reference time. The mobile station having set the reference time as described above transmits a signal in accordance with the set reference time. The mobile station sets the reference time and transmits the signal in synchronization with the set reference time because the CDMA system generates and extracts the signal based on the time. This reverse link signal is delayed by the propagation delay and received by the base station. That is, the base station transmits according to the system reference time, but the reverse link signal is received with a time delay (hereinafter, referred to as a "bidirectional propagation delay") compared to the system reference time.

In a CDMA system, the maximum allowance of this bidirectional propagation delay (416.5us) is limited by hardware of the base station modem ASIC. That is, the maximum possible cell call radius in timing is limited to 62.5 km (= 416.5us * (3 * 10 ⁸ m / s)), which leads to low density of traffic and unnecessary base stations in large areas. A problem arises. In addition, when the base station is difficult to install, such as at sea, it causes a limit of the service radius. It is assumed here that there is no limit of cell radius due to propagation loss.

The conventional Extended Coverage Base Station (BTS), which was developed to solve the timing problem, delays and supplies the GPS reference timing to the CDMA modem, thereby compensating the bidirectional propagation delay by the delay time. The CDMA modem can demodulate from a delayed GPS reference timing to a signal with a bidirectional propagation delay of 416.5us.

For example, suppose that Modem 1 supplies normal reference timing, Modem 2 supplies 416.5us delayed GPS reference timing, Modem 1 demodulates signals up to 62.5 km from the base station, and Modem 2 provides 62.5 km from the base station. To demodulate signals up to 125 km. Therefore, the radius of the base station can be extended as desired by adjusting the GPS reference timing supplied to the modem according to the radius of the base station.

In other words, the conventional extended coverage base station apparatus as described above generates normal and delayed GPS reference clocks from a TFU (Time & Frequency Unit), which is a sub-system of the base station, and supplies them to a channel card with a built-in CDMA modem.

However, such an extended coverage base station has a disadvantage in that it is impossible to supply various kinds of delayed GPS reference clocks generated by the change of the cell radius to each channel card.

In addition, the conventional extended coverage base station apparatus as described above is impossible to provide a reference clock for each channel element (CE) in one channel card.

Accordingly, the present invention has been proposed to solve various problems occurring in the conventional extended coverage base station apparatus as described above.

SUMMARY OF THE INVENTION An object of the present invention is to provide a call coverage extension device in a mobile communication system in which a cell coverage area is expanded by changing and supplying a system reference clock to a base station modem ASIC.

The present invention for achieving the above object,

The hardware of the base station modem ASIC divides the call area by dividing the call radius by a predetermined unit for a wide call radius over the call radius limited in timing. Then, the base station modem ASICs are allocated separately so that the signals can be independently demodulated for each divided call area. The even second clock supplied to the base station modem ASICs assigned to each call zone is changed in consideration of the maximum allowable bidirectional propagation delay of the existing base station modem ASIC and the maximum bidirectional propagation delay of each call zone. At this time, the transmitter does not divide the telephone area and uses the existing shape. This extends the call radius due to the maximum allowable bidirectional propagation delay of the existing base station modem ASIC.

1 is a block diagram of a call area expansion device in a mobile communication system according to the present invention;

Figure 2 is a call-zone segmentation diagram in the present invention,

3 (a) and (b) are timing diagrams for explaining the base station system time in a CDMA mobile communication system;

Figure 4 is a block diagram showing another embodiment of a telephone area expansion device in a mobile communication system according to the present invention.

<Explanation of symbols for the main parts of the drawings>

110, 120, 130: call zone

300: system clock

400: clock generator

500: digital processing unit

510 to 530: first to third digital processors

511: clock generator

512-1 to 512-n: Channel element 1 to channel element n

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention according to the technical spirit as described above in detail.

<Example 1>

1 is a block diagram of a first embodiment of a call area extension apparatus in a mobile communication system according to the present invention.

As shown, time and frequency generator 200 for receiving a 10Mhz clock, TOD, 1PPS signal from the GPS receiver to generate a system clock; A clock generator 400 which differentially delays the system clock obtained by the time and frequency generator 200 to generate a system clock corresponding to each communication zone; A digital processing unit (500) for modulating a transmission signal and demodulating and processing a reception signal in synchronization with a system clock generated by the clock generation unit (400); The forward link transmission signal 610 processed by the digital processor 500 is up-converted to a high frequency and transmitted through the transmission antenna 810, and the reverse link signal 620 received by the reception antennas 820 and 830 is It is composed of a high frequency processing unit 700 for converting down to an intermediate frequency to pass to the digital processing unit 500.

In this case, the digital processor 500 modulates the forward link signal in synchronization with the first system clock 410 generated by the clock generator 400, and first digital processor 510 for demodulating the reverse link signal. And a second system clock 420 generated by the clock generator 400 to modulate only a signal corresponding to its own communication area among forward link signals and to demodulate only a signal corresponding to its own communication area among reverse link signals. 2 in synchronization with the digital processor 520 and the third system clock 530 generated by the clock generator 400, modulates only the signal corresponding to its own call area among the forward link signals, And a third digital processor 530 that demodulates only the corresponding signal.

When described in detail with reference to Figures 1 to 3 attached to the operation of the communication zone expansion device in the mobile communication system according to the present invention configured as described above are as follows.

First, as shown in FIG. 2, in the CDMA mobile communication system, the call radius is determined in a predetermined unit with respect to the wide call radius 135 over the call radius 115 limited in time by the hardware of the existing base station modem ASIC. Divide into currency zones 110, 120, and 130. Here, the unit is less than or equal to the maximum bidirectional propagation delay allowed by the existing base station modem ASIC. The number of call zones classified according to the call radius is variable.

In addition, the present invention, as shown in (a) and (b) of Figure 3, 10Mhz, TOD (Time Of Day) from the GPS (Global Positioning System) receiver in the TFU (Time & Frequency Unit) of the base station It receives a 1PPS (Pulse Per Second) signal and generates an even-second clock 10 that is a system clock. Considering the even-second clock 20 with a total time delay 30 of the even-second clock 10 generated, the base station system time at time 40 in the system using the even-second clock 10 is A time, the delayed even-second seconds In a system using clock 20, the base station system time becomes A at time 45. That is, by advancing or delaying an even second clock, the system time used by the base station can be advanced or delayed from the absolute CDMA system time. Accordingly, the present invention utilizes the principle that the base station system time in a CDMA mobile communication system is synchronized to an even second clock, which is a system clock, so that the system time varies from an absolute value by a time variation of the even second clock.

On the other hand, the divided call zones 110, 120 and 130 are allocated to the first to third digital processors 510 to 530 in the digital processor 500 of FIG. Here, one digital processor consists of one or more channel elements or channel cards. The channel element includes a set of base station modem ASICs to modulate and demodulate the digital signal, and the channel card consists of one or more channel elements and a channel card processor.

In this state of allocating the digital processors corresponding to the divided communication zones, the time and frequency generator 200 supplies the even-second clock received from the GPS receiver to the clock generator 400 as the system clock 300. .

Then, the clock generator 400 adjusts the system clocks 300 respectively input in consideration of the cell radius, and then transfers the adjusted system clocks 410 to 430 to the digital processor 500.

In the above description, the first system clock 410 generated by the clock generator 400 is an original system clock synchronized to 1PPS received from the GPS receiver, and the second and third system clocks 420 to 430 are the entire telephone area. Maximum bidirectional propagation delays for 120 and 130 are even-second clocks delayed by 126 and 136, respectively.

In addition, the first to third digital processors 510 to 530 in the digital processing unit 500 respectively modulate and demodulate the forward link or reverse link signals in synchronization with an input system clock.

That is, the first digital processor 510 modulates the forward link signal (the mobile station direction signal at the base station) 610 in synchronization with the original even second clock 410 obtained from the clock generator 400, and reverse link signal. (620 to demodulate the base station from the mobile station).

In addition, the second digital processor 520 corresponds to the call area 120 of the reverse link signal 620 in synchronization with the even second clock 420 delayed by a predetermined time from the even second clock 410 obtained by the clock generator 400. Demodulate only the reverse link signal.

And the third digital processor 530 is in communication with the reverse link signal 620 in synchronization with the even-second clock 430 which is delayed by a predetermined time more than the predetermined time-delayed even-second clock 420 obtained by the clock generator 400. Only the reverse link signal corresponding to the region 130 is demodulated.

This will be described in more detail as follows.

The pilot channel, sync channel, and paging channel of the forward link signal 610 are digitally modulated by the first digital processor 510 and then transmitted to the high frequency transmitter 710 in the high frequency processor 700. The signal is input, and amplified by the high frequency transmitter 710 and then amplified and transmitted to the outside through the base station transmit antenna 810. These pilot channels, sync channels, and call channels are received by all users in all call zones 110, 120, 130.

In addition, when a user in the coverage area 110 receives the pilot channel, the synchronization channel, and the call channel, and transmits a reverse link access channel to attempt a connection, the access channel is connected to the base station receive antennas 820 and 830. After it is received through the high frequency receiver 700 in the high frequency processor 700 is input. The high frequency receiver 720 amplifies the received signal, down-converts the received signal, and inputs the reverse link signal 620 to the first to third digital processors 510 to 530. The access channel is detected and demodulated in the channel element responsible for access channel demodulation in the first digital processor 510. The channel card processor in the first digital processor 510 assigns a channel element that is responsible for the call channel, transmits a forward link call channel to the user at the channel element, detects and reverses the reverse link call channel of the user. Demodulate In this process, the reverse link signal 620 of the user is detected and demodulated only in the first digital processor 510 and not detected and demodulated in the second and third digital processors 520 ˜ 530 due to timing.

In addition, when a user in the coverage area 120 receives the pilot channel, the synchronization channel, and the call channel, and transmits a reverse channel access channel to attempt connection, the access channel is transmitted through the base station receive antennas 820 and 830. After the reception, the signal is transmitted to the high frequency receiver 720 in the high frequency processor 700. The high frequency receiver 720 amplifies and down-converts an input received signal and transmits the reverse link signal 620 to the first to third digital processors 510 to 530 in the digital processor 500. The received access channel is then detected and demodulated only at the channel element responsible for access channel demodulation in the second digital processor 520. The channel card processor in the second digital processor 520 allocates one channel element that is responsible for the call channel of the first digital processor 510 and transmits a forward link call channel to the user in the assigned channel element. A channel element in charge of the call channel in the second digital processor 520 is assigned to detect and demodulate the reverse link call channel of the user. In this process, the reverse link signal of the user is detected and demodulated only by the second digital processor 520 in relation to timing, and the other digital processors, that is, the first digital processor 510 and the third digital processor 530, are detected and demodulated. It doesn't work.

Similarly, the user's access channel signal in call zone 130 is detected and demodulated only at third digital processor 530.

Meanwhile, the clock generator 400 of the present invention implements three system clocks in one independent clock generator in order to explain the case where the telephone area is divided into three (110, 120, 130). In many cases, a single clock generator can generate as many system clocks as the number corresponding to the calling area.

In addition, the present invention provides one system clock to one digital processor so that several channel cards in the digital processor are synchronized with the same system clock.

<Example 2>

4 is a block diagram showing another embodiment of a call area extension device in a mobile communication system according to the present invention.

This is not only using the first system clock 410 in the first digital processor 510 synchronized with one system clock generated by the clock generator 400, for example, the first system clock 410. The internal clock generator 511 generates a multi-system clock delayed by a predetermined time from the first system clock 410.

The first system clock 410 and the multi-system clock generated by the clock generator 511 are separately supplied to each channel element (channel element 1 to channel element n) to process transmit and receive signals. do.

That is, one digital processor has a plurality of channel cards, and one channel card has a plurality of channel elements again. In the first embodiment, a system clock is shared by a plurality of channel elements. On the other hand, in <Embodiment 2>, one system clock is changed to generate multiple system clocks, and one channel clock and multiple system clocks are input differently from each other.

For example, channel element 1 uses the system clock 410 obtained from the clock generator 400, and channel element 2 uses one of the multiple system clocks 411-1 generated by the clock generator 511. The channel element n uses another multi-system clock 411-n among the multi-system clocks generated by the clock generator 511.

This allows one channel card to process both the user's reverse channel signals and forward channel signals in the coverage areas 110, 120, 130.

In another method of the present invention, there may be a method in which several channel elements are grouped into one channel element group, and each channel element in the channel element group shares and uses one system clock.

As described above, the present invention divides the telephone area into a predetermined number, adjusts the system clock to correspond to the divided number of the telephone area, creates a plurality of system clocks, and provides them as a synchronous clock to the corresponding digital processor. Expansion of the monetary domain is possible.

In addition, by providing a different system clock for each channel element in the channel card, one channel card can also effect signal processing in an extended area of the call other than the existing area of the call.

Claims (4)

A base station apparatus of a CDMA mobile communication system, A time and frequency generator for receiving a 10 MHz clock, TOD, and 1PPS signal from a GPS receiver to generate a system clock; A clock generator for differentially delaying the system clocks obtained by the time and frequency generators to generate a plurality of system clocks (first to third system clocks) corresponding to respective communication zones; And a digital processor for modulating and demodulating and transmitting a transmission signal in synchronization with a plurality of system clocks generated by the clock generation unit. The digital processor of claim 1, wherein the digital processor is configured to modulate a forward link signal in synchronization with a first system clock generated by the clock generator, and to demodulate a reverse link signal. A second digital processor for synchronizing with the second system clock to modulate only a signal corresponding to its own call area among the forward link signals and to demodulate only a signal corresponding to its own call area among the reverse link signals, and a third signal generated by the clock generator; Call area expansion in a mobile communication system, comprising: a third digital processor configured to modulate only a signal corresponding to its own call area among the forward link signals in synchronization with the system clock and to demodulate only a signal corresponding to its own call area among the reverse link signals. Device. 3. The digital processor of claim 2, wherein each digital processor in the digital processor generates a multiple system clock by differentially delaying a system clock obtained from the clock generator by a predetermined time, and obtains the multiple system clock and the clock generator. And a channel clock for each channel element. 3. The digital processor of claim 2, wherein each digital processor in the digital processor generates a multiple system clock by differentially delaying a system clock obtained from the clock generator by a predetermined time, and bundles a plurality of internal channel elements. A channel area extension apparatus in a mobile communication system, which is formed of a group of channel elements, and uses one of a plurality of generated system clocks and a system clock obtained from a clock generator.