KR20000074010A - Apparatus for extending traffic coverage in mobile communication system - Google Patents

Abstract

PURPOSE: An apparatus for expanding speech areas in a mobile communication system is provided to divide the speech areas to compensate a system clock according to numbers of the divided speech areas, and to make many system clocks to supply the system clocks to a digital processor as synchronous clocks so as to expand the speech areas. CONSTITUTION: A time/frequency generator(200) receives a 10Mhz clock signal, a time of day(TOD) signal, and a 1 pulse per second(PPS) signal from a global positioning system(GPS) receiver, and generates a system clock. A clock generator(400) differentially delays the system clock, and generates many system clocks corresponding to each speech area. A digital processor(500) is synchronized with the system clocks to modulate a transmission signal, and demodulates a reception signal. A high frequency processor(600) converts the forward transmission signal into a high frequency signal to deliver the converted transmission signal through a transmit antenna(710), and converts the reverse reception signal into an intermediate frequency(IF) signal to transmit the converted reception signal to the digital processor(500).

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 in accordance with the system reference time, but the reverse link signal is received with a time delay (hereinafter referred to as "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.

That is, the conventional extended coverage base station apparatus as described above generates normal and delayed GPS reference clocks from a time and frequency unit (TFU), which is a sub-system of the base station, and supplies them to a channel card having a 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,

Divides the call area by dividing the call radius by a certain unit for a wide call radius B above the call radius A which is limited in timing by the base station modem ASIC (call areas B ', B ", ..... B ⁿ Then, base station modem ASICs are allocated separately so that signals can be independently demodulated for each divided call zone, and an even second clock is supplied to the base station modem ASICs assigned to each call zone. The maximum allowable two-way propagation delay of the base station modem ASIC and the maximum two-way propagation delay of each communication zone are considered, and the transmitter uses the existing shape without dividing the call area. Extend the call radius by the maximum possible bidirectional propagation delay.

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;

4 (a) to (d) are timing diagrams for explaining generation of differential system reference clocks according to a calling area in a base station clock generator of a CDMA mobile communication system.

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

110, 120, 130, 140: call zone

300: system clock

400: clock generators 410 to 440: first to fourth clock generators

500: digital processing unit 510 to 540: first to fourth digital processors

550: forward link signal 560: reverse link signal

600: high frequency processing unit

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

1 is a block diagram of a call area extension device 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 processed by the digital processor 500 is up-converted to a high frequency and transmitted through a transmission antenna 710, and the reverse link signal received by the reception antennas 720 and 730 is down-converted to an intermediate frequency. It is composed of a high frequency processing unit 600 for transmitting to the digital processing unit 500.

In the above description, the clock generator 400 generates the first to fourth clock generators 410 to 410 to make the system clocks obtained by the time and frequency generator 200 into the first to fourth system clocks corresponding to the respective communication zones. 440).

In addition, the digital processor 500 modulates a forward link signal in synchronization with a first system clock generated by the clock generator 400, and first digital processor 510 for demodulating a reverse link signal, and the clock. A second digital processor 520 that modulates only a signal corresponding to its own call area among the forward link signals and demodulates only a signal corresponding to its own call area among the reverse link signals in synchronization with a second system clock generated by the generator 400. And a third digital that modulates only a signal corresponding to its own communication area among forward link signals and demodulates only a signal corresponding to its own communication area among reverse link signals in synchronization with a third system clock generated by the clock generator 400. In synchronization with the fourth system clock generated by the processor 530 and the clock generator 400, only a signal corresponding to its own call area among the forward link signals is modulated. And the reverse link is composed of the fourth sinhojung digital processor (520) for demodulating only signals corresponding to their call region.

Referring to Figures 1 to 4 attached to the operation of the communication zone expansion device in the mobile communication system according to the present invention configured as described above in detail as follows.

First, as shown in FIG. 2, in the CDMA mobile communication system, the call radius is set in a predetermined unit for the wide call radius 145 or more, which is limited in time by the hardware of the existing base station modem ASIC. Divide the call zones 110, 120, 130, and 140 separately. 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 Figure 3 (a) and (b), 10Mhz from the Global Positioning System (GPS) receiver in the TFU (Time & Frequency Unit) of the base station, TOD (Time Of Day) 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, 130 and 140 are allocated to the first to fourth digital processors 510 to 540 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 first to fourth clock generators 410 to 440 in the clock generator 400 correct the system clocks 300 respectively input in consideration of the cell radius, and then correct each of the system clocks 450 to 450 as shown in FIG. 4. 480 is transmitted to the digital processing unit 500.

Here, the system clock 450 generated by the first clock generator 410 is an original system clock synchronized with 1PPS received from the GPS receiver, and the system clock 460 generated by the second to fourth clock generators 420 to 440. 480) is an even-second clock delayed by the maximum bi-directional propagation delays 126, 136, 146 for the entire coverage area 120, 130, 140, respectively.

In addition, the first to fourth digital processors 510 to 540 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 base station mobile signal at the base station) 550 in synchronization with the original even second clock 450 obtained by the first clock generator 410, and reverse link. Demodulate the signal (from mobile station to base station) 560. In other words, the first digital processor 510 processes both the forward link and reverse link signals in the call area 110, 120, 130, 140. In addition, the second digital processor 520 is synchronized with the even-second clock 460 which is delayed by a predetermined time as shown in FIG. 4 (b) obtained by the second clock generator 420. Only the corresponding reverse link signal is demodulated. The third digital processor 530 is synchronized with the even-second clock 470 delayed by a predetermined time as shown in FIG. Only the corresponding reverse link signal is demodulated. In addition, the fourth digital processor 540 synchronizes with the even second clock 480 which is delayed by a predetermined time as shown in FIG. 4 (d) obtained by the fourth clock generator 440. Only the reverse link signal corresponding to &lt; RTI ID = 0.0 &gt;

This will be described in more detail as follows.

The pilot, sync, and paging channels of the forward link signal 550 are digitally modulated by the first digital processor 510 and then transmitted to the high frequency transmitter 610 in the high frequency processor 600. The signal is input, and amplified by the high frequency transmitter 610 and then amplified and transmitted to the outside through the base station transmit antenna 710. These pilot channels, sync channels, and call channels are received by all users in all call zones 110, 120, 130, and 140.

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 channel access channel to attempt a connection, the access channel transmits a base station receive antenna 720, 730. After it is received through the radio frequency receiving unit 600 is input to the high frequency receiving unit 620. The high frequency receiver 620 amplifies the received signal and down-converts the received signal and inputs the reverse link signal 560 to the first to fourth digital processors 510 to 540. 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 560 of the user is detected and demodulated only in the first digital processor 510 and not detected and demodulated in the second to fourth digital processors 520 ˜ 540 due to a timing relationship.

In addition, when a user in the coverage area 120 receives the pilot channel, the synchronization channel, and the call channel, and transmits the reverse link access channel to attempt connection, the access channel is transmitted through the base station receive antennas 720 and 730. After the reception, the signal is transmitted to the high frequency receiver 620 in the high frequency processor 600. The high frequency receiver 620 amplifies and down-converts the input received signal and transmits the reverse link signal 560 to the first to fourth digital processors 510 to 540 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. And assigns a lower channel element in charge of the call channel in the second digital processor 520 to detect and demodulate the reverse link call channel of the user at that channel element. In this process, the reverse link signal of the user is detected and demodulated only in the second digital processor 520 in relation to timing, and the remaining digital processors, that is, the first digital processor 510, the third and fourth digital processors 530 ( It is not detected and demodulated at 540.

Similarly, the user's access channel signal in the call area 130 is detected and demodulated only in the third digital processor 530, and the user's access channel signal in the call area 140 is detected and demodulated only in the fourth digital processor 540.

According to the present invention described above, the first digital processor 510 processes all forward link and reverse link signals in the coverage area 110, 120, 130, and 140, and the second digital processor 520 processes the reverse link in the coverage area 120. Only the signal is processed, and the third digital processor 530 processes only the reverse link signal in the call area 130, and the fourth digital processor 540 is configured to process only the reverse link signal in the call area 140.

Alternatively, however, the first digital processor 510 may process both the pilot channel, the synchronization channel, the call channel of the forward link and the access channel and the call channel of the reverse link, and the second to fourth digital processors 520. 540 may process the talk channel of the forward link and the access channel and talk channel of the reverse link. In this case, the communication channel of the forward link transmitted from the second to fourth digital processors 520 to 540 is delayed by the even-second clocks 460, 470, and 480. The delayed talk channel of each forward link is advanced by each delayed time using a timing compensation register in the base station modem ASIC.

Meanwhile, the clock generator 400 according to the present invention implements the first to fourth clock generators 410 to 440 as an example in order to explain the case where the telephone area is divided into four (110, 120, 130, 140).

However, alternatively, one independent clock generator can be used, and one independent clock generator can be implemented to generate all the system clocks corresponding to the corresponding number of call zones.

As described above, the present invention divides the telephone area into a predetermined number, corrects the system clock corresponding 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. Since the call area can be extended, high-quality service can be provided in a call area other than the call area due to the hardware limitation of the existing base station modem ASIC.

In addition, by generating various system reference clocks, channel cards and channel elements in the digital processor can be efficiently used.

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 clock obtained by the time and frequency generator to generate a system clock corresponding to each communication area; A digital processing unit for modulating a transmission signal and demodulating and processing a received signal in synchronization with a system clock generated by the clock generation unit; The forward link transmission signal processed by the digital processor is converted to a high frequency and transmitted through a transmitting antenna, and the reverse link signal received by the receiving antenna is converted to an intermediate frequency and a high frequency processor configured to transmit the digital processor. Call area expansion device in a mobile communication system, characterized in that. The clock generator of claim 1, wherein the clock generator comprises first to fourth clock generators that make the system clocks obtained from the time and frequency generators into first to fourth system clocks corresponding to respective communication zones. Telephony Area Expansion Unit in Mobile Communication System. 3. The clock generator 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 which modulates only a signal corresponding to its own call area in a forward link signal and demodulates only a signal corresponding to its own call area in a reverse link signal in synchronization with a second system clock generated by the second system clock; A third digital processor for synchronizing with the generated third system clock and modulating only a signal corresponding to its own call area among the forward link signals and demodulating only a signal corresponding to its own call area among the reverse link signals; Synchronized with the fourth system clock, modulates only the signal in the forward link signal corresponding to its own call area Effort link sinhojung currency region expansion device in a mobile communication system, characterized in that consisting of the fourth digital processor for demodulating only signals corresponding to their call region. The mobile communication apparatus according to claim 1 or 2, wherein the clock generation unit differentially delays an input system clock using one independent clock generator to generate a system clock corresponding to the number of communication zones. Call-zone extension in the system.