KR19990057167A - Transceiver of Multi-sector Base Station in Mobile Communication System - Google Patents

Abstract

1. Fields to which the invention described in the claims belong

The present invention relates to a transmission and reception apparatus of a multi-sector base station in a mobile communication system.

2. The technical problem to be solved by the invention

The present invention can solve the problem of handoff-related signal traffic increase and processing time delay by implementing a base station as a multi-sector in a microcell system, and handling handoffs between microcells by softer handoff. It is an object of the present invention to provide a transceiver for a multi-sector base station that can efficiently use channel resources.

3. Summary of the Solution of the Invention

The present invention provides a transceiver for a multi-sector base station in a mobile communication system in which one macro cell is subdivided into a plurality of microcells, and each of the microcells has an antenna for signal transmission and reception, comprising: cell control means; A plurality of channel modulation means; The plurality of transmission switching means; A number of synthetic means; A plurality of transmission processing means; A plurality of receiving processing means; A plurality of receive switching means; And a plurality of channel demodulation means.

4. Important uses of the invention

Description

Transceiver of Multi-sector Base Station in Mobile Communication System

The present invention relates to a transmission and reception apparatus of a multi-sector base station in a mobile communication system. In a CDMA mobile communication system having a plurality of microcells, microcells are implemented as sectors to implement handoffs between microcells as soft handoffs. A transceiver for a multi-sector base station in a mobile communication system.

In future mobile communication systems, the capacity of wireless channels is required to efficiently accommodate an increasing number of subscribers and to efficiently provide high-speed multimedia services including high-speed data and moving images, as well as voice and low-speed data. In order to increase the capacity of a wireless channel, a new frequency band needs to be allocated, but a frequency band that can be allocated is already limited. Therefore, in order to increase system capacity under a limited frequency band, it is inevitable to replace the existing macrocell with a smaller microcell.

In the following description, a code division multiple access (CDMA) mobile communication system will be described as an example.

In general, as the cell radius decreases, the subscriber demand capacity increases, the shadow area decreases, and the distance between the mobile station and the base station gets closer, thereby extending the battery life of the mobile station.

However, in order to achieve this purpose, two problems must first be solved. First, reducing the radius of a cell means that a huge number of base stations must be installed, which increases initial facility investment and operational management costs. Second, as the radius of the cell is reduced, faster hand-open processing is required. This may lead to degradation of call quality and waste of channel resources.

The first problem can be solved using Hybrid Filber Radio (HFR) technology. That is, each cell site only installs a simplified remote antenna, and almost all functions such as channel processing are concentrated at a central base station, thereby reducing the effort and cost of installing a large number of base stations. On the other hand, the second problem is particularly prominent in CDMA-based mobile communication systems, which is due to the CDMA system's inherent soft handoff processing technique.

In a CDMA-based mobile communication system, for example, a digital cellular system (DCS), a personal communication system (PCS), and an IMT-2000, all base stations in the system use the same common frequency band so that the mobile terminal can simultaneously communicate with multiple base stations. Can be. Therefore, at the time of handoff, the mobile station connects to the new base station and communicates with both base stations at the same time before disconnecting from the current base station. As the signal from the new base station becomes larger than the signal from the current base station, the current base station Soft handoff is possible to disconnect the connection. In the soft handoff process, since the mobile terminal simultaneously communicates with one or more base stations, the call disconnection phenomenon is significantly reduced. However, since a new base station and channel need to be set up, it takes a lot of time for handoff processing, and since it uses channel resources of two base stations at the same time, waste of resources is also severe. In particular, in a microcell environment, this is a very serious problem because the handoff is frequent and the probability that the call is in handoff is much larger than that of the macrocell system.

U.S. Patent No. 5,625,876, "Method and apparatus for performing handoff between sectors of a common base station", proposes a sector-to-sector soft handoff technique of a three sector base station, which reduces the time taken for handoff. It can also reduce waste of resources.

1 shows a cell arrangement diagram when a base station employing three sectors is arranged in a conventional CDMA-based macrocell system. Reference numerals 110, 120, and 130 denote three-sector base stations, and 111, 121, and 131 denote cell areas that base stations 110, 120, and 130 are in charge of, respectively. Reference numerals 112 to 114 and 122 to 124. 132 to 134 represent the beam widths of the sectors (α, β, and γ) of the base stations 110, 120, and 130, respectively.

Assuming that the service area is divided into hexagonal cells as shown, each cell is adjacent to up to six other cells. Each mobile station is located in one of these cell areas. For example, the mobile station 140 resides in the area covered by the base station 110, more precisely in the area covered by the sector 114 (γ sector) of the base station 110. In a CDMA-based mobile communication system, one mobile station can communicate with more than one base station at the same time because the same frequency band is used in all cells in the system. For example, the mobile station located at 150 is simultaneously in communication with the α sector of the base station 110 and the β sector of the base station 130, and the mobile station located at 160 is the α sector of the base station 110, the base station ( It is possible to simultaneously communicate with the gamma sector of 120 and the beta sector of the base station 130. Therefore, when the mobile station crosses the position 150, a soft handoff is made between the base station 110 and the base station 130, in which case two channel elements are required. In addition, when the mobile station crosses the location 160, a soft handoff is made between the base stations 110, 120, 130, which takes three channel elements. However, a mobile station that traverses the location 170 is in communication with the β and γ sectors of the base station 110 at the same time. The handoff when the mobile station crosses the sectors of the same base station is called softer handoff. Since only one channel element takes care of all three sectors, only one channel element is required. That is, since the change of the channel element is unnecessary at the softener handoff, a gain can be obtained in terms of time required for handoff processing and saving of channel resources.

Figure 2 shows the structure of a channel element for supporting three sector softer handoff according to the prior art.

First, forward transmission will be described. Data passed through cell controller 201 for forward transmission is encoded in encoding logic 202 and then forwarded to distribution port 203. The distribution port 203 transfers these data to one or more modulation logics of the modulation logics 205-1 to 205-3 under the control of the cell controller 201 via the control bus 204. The modulation logics 205-1 to 205-3 are in charge of each sector of α, β, and γ, respectively, and modulate these data using appropriate PN (Pseudo Noise) codes, and then transmit them to a transmission processor (not shown). . Therefore, the same forward channel can be transmitted through any of the sectors α, β, and γ.

On the other hand, in the case of reverse reception, the distribution port 206 receives signals (including diversity signals) from the reception processing unit (not shown) for each sector according to the control signal of the cell controller 201 through the control bus 204. The demodulation logics 207-1 to 207-N and the search logic 208 are distributed. Demodulation logics 207-1 to 207-N generate approximate data 209-1 to 209-K for signals from one mobile terminal. Approximation data 209-1 to 209-N are synthesized by diversity synthesizer 210 to generate one approximation data for data received from a particular mobile station. The data synthesized by the diversity synthesizer 210 is decoded in the decoding logic 211. The demodulation logics 207-1 to 207-N estimate the strength of the signal that they are demodulating and then transfer to the cell controller 201 via the control bus 204. On the other hand, the search logic 208 continuously searches the time domain to find available signals and transmits the information to the cell controller 201 via the control bus 204. The cell controller 201 uses this information to assign or reassign a demodulator. It can be seen that the mobile station is in soft handoff when diversity synthesizer 210 is synthesizing signals from several sectors.

The three-sector base station could be usefully used in a macro cell system, but since the tens or hundreds of micro cell base stations are in charge of the area covered by one of the conventional macro cell base stations, a micrometer having a radius of only tens to hundreds of Km is used. In cell and picocell environments, it is not very effective. For example, when overlaying an existing macrocell area having a radius of 2 km with microcells having a radius of 200 m, the cell radius is so small that handoffs occur frequently between base stations. In the case of using a soft handoff as in the prior art, a communication channel is used. The disadvantage is that the waste of resources is serious.

In order to solve the above problems, the present invention implements a multi-sector of a base station in a microcell system, and increases handoff-related signal traffic by processing handoffs between microcells by softer handoff. And it is possible to solve the problem of degradation of call quality due to processing time delay, etc. It is an object of the present invention to provide a transceiver of a multi-sector base station that can efficiently use channel resources by sharing channels between each microcell.

In addition, the present invention can implement a multi-sector base station while minimizing changes to the components of the conventional macrocell system using a switching module, and concentrates the performance of transmission processing on the central microcell base station. It is an object of the present invention to transmit and receive a multi-sector base station that can save channel resources by varying the number of channels allocated according to the call volume of each microcell.

1 is a three sector base station layout of a CDMA based macrocell system according to the prior art.

2 is a structural diagram of a transmission apparatus for three-sector softer handoff according to the prior art;

Figure 3 is an exemplary cell arrangement of a microcell system to which the present invention is applied.

4 is a structural diagram of an embodiment of a multi-sector base station in a CDMA mobile communication system according to the present invention;

5 is a structural diagram of an embodiment of a forward channel transmission apparatus according to the present invention of FIG.

Figure 6 is a detailed view of one embodiment of a switching module according to the present invention of Figures 4 and 5.

Figure 7 is a detailed view of one embodiment of a transmission switch according to the present invention of Figure 6;

Figure 8 is a detailed view of one embodiment of a receiving switch according to the present invention of Figure 6;

* Explanation of symbols for major reference symbols

401, 601: cell controller

402-1 to 402-N, 511-1 to 51 m-n: transformer demodulator

402-3 to 403-N, 521-1 to 52 m-n: switching module

404-1 to 404-K and 502-1 to 502-k: digital synthesizer

405-1 to 405-K, 503-1 to 503-k: Transmission processor

407-1 to 407-K: Receive processor 406-1 to 406-K: Transmit antenna

408A-1 to 408A-K, 408B-1 to 408B-K: receiving antenna

409: parallel transmit bus 410: parallel receive bus

602, 603-A, 603-B: switches

In order to achieve the above object, the present invention provides a transmission and reception apparatus of a multi-sector base station in a mobile communication system in which one macro cell is subdivided into a plurality of micro cells, and each of the micro cells is provided with a sector antenna for signal transmission and reception. Cell control means for centrally controlling the plurality of microcells, the cell control unit being located at the center of the macrocell; A plurality of channel modulating means for performing encoding and modulation / demodulation on the signal output from the cell control means; A plurality of transmission switching means for switching the signals output from the channel modulation means to transmit to the plurality of microcell base stations under control of the cell control means; A plurality of combining means for receiving and synthesizing a signal corresponding to each sector among the signals output from the switching means; A plurality of transmission processing means for receiving the signal output from the synthesizing means and performing digital / analog conversion and frequency rising conversion to output to each sector antenna; A plurality of reception processing means for performing frequency down conversion and analog / digital conversion on the signals received from the sector antennas and transmitting them to the central base station; A plurality of reception switching means for receiving a signal output from the plurality of reception processing means and switching the output; And a plurality of channel demodulation means for demodulating and decoding the signal received from the switching means and outputting the demodulated signal to the cell control means.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 3 to 8.

3 is a diagram illustrating an example of cell arrangement in a microcell system to which the present invention is applied, and illustrates a cell arrangement when cells and a macrocell are overlaid in a microcell system using a CDMA-based multisector base station. Reference numeral 301 denotes a macro cell base station, 302 denotes a cell area that the macro cell base station 301 is responsible for, reference numerals 311-1 to 311-K denote omni-type microcell base stations, and 312-1 to 311-K respectively. A sector antenna for each sector of a CDMA-based multisector base station provided by the present invention is shown.

4 is a diagram illustrating an embodiment of a multi-sector base station in a CDMA mobile communication system according to an embodiment of the present invention.

In the figure, there are N channel elements (where N is a natural number) and a total of K (where K is a natural number) sectors supporting a three sector structure. Reference numerals 406-1 to 406-K denote transmission antennas, and 408A-1 to 408A-K / 408B-K correspond to the microcell base station 311-K shown in FIG. Reference numeral 401 denotes a cell controller, 402-1 to 402-N are channel elements, 403-1 to 403-N are switching modules corresponding to each channel element, and 404-1 to 404-K combine outputs to respective sectors. Digital synthesizers, 405-1 to 405-K, denote transmission processors for each sector, and 407-1 to 407-K denote receivers for each sector.

The channel elements 402-1 to 402 -N receive the signal output from the cell controller 401 (for forward transmission) or the switch 403-1 to 403 -N (for reverse transmission) to encode and modulate Is provided to the switches 403-1 to 403-N or the cell controller 401.

In the case of forward transmission, the switches 403-1 to 403-N switch the signals output from the channel elements 402-1 to 402-N under the control of the cell controller 401, and thus, multiple sectors (microcells). The base station). In the case of reverse transmission, the signals received from the reception processors 407-1 to 407-K are switched and output to the channel elements 402-1 to 402-N under the control of the cell controller 401.

The digital synthesizers 404-1 to 404-K receive and synthesize a signal corresponding to each sector among the signals output from the switches 403-1 to 403-N of the central base station.

The transmission processors 405-1 to 405-K receive the synthesized signal from the digital synthesizers 404-1 to 404-K, and perform digital / analog conversion and frequency up conversion. Output through K).

The reception processors 407-1 to 407-K receive signals from the reception antennas 408A-1 to 408A-K and 408B-1 to 408B-K to perform frequency down conversion and A / D conversion to output the signals. .

An operation process of forward transmission and reverse transmission according to an embodiment of the present invention will be described.

In the case of forward transmission, each channel element 402-1 to 402 -N performs encoding and modulation on forward data to be transmitted from the cell controller 401 to each mobile station, and then outputs each of α, β, and γ sectors. do. One switching module 403-1 to 403-N corresponds to each channel element 402-1 to 402-N. That is, the switching module 403-1 corresponds to the channel element 402-1, and the switching module 403-N corresponds to the channel element 402-N. Each of the switching modules 403-1 to 403-N switches the output of each sector of the channel elements 402-1 to 402-N for each of K destination sectors under the control of the corresponding cell controller 401. . That is, the switching module 403-1 switches the sector-specific outputs 415A-1 to 415C-1 of the channel element 402-1 in accordance with the control signal 413-1 of the cell controller 401, thereby switching K pieces. The output is output to three of the outputs 441-1 to 4141-K corresponding to each sector. Similarly, the switching module 403-N switches the sector-specific outputs 415A-N to 415C-N of the channel element 402-N in accordance with the control signal 413-N of the cell controller 401 to switch K pieces. Three of the outputs 417N-K to 417N-K corresponding to each sector are output.

The output of each switching module switches the digital synthesizers 404-1 to 404-K for each destination through the parallel bus 409 to receive the outputs 417N-K to 417K-N corresponding to the K sectors. These are digitally synthesized. That is, the digital synthesizer 401-1 receives the output signals 41-11-1 to 4141-N for the first sector of each switching module output and digitally synthesizes them. Similarly, the digital synthesizer 404-K receives the output signals 417K-1 to 417K-N for the Kth sector among the outputs of each switching module and digitally synthesizes them.

The digital synthesizer outputs each sector antenna 406-1 through frequency conversion to the common air interface (CAI) band by D / A conversion and transmission processor 405-1 to 405-K in each sector. 406-K, 408A-1 to 408A-K, and 408B-1 to 408B-K). That is, the transmission processor 405-1 receives the output of the digital synthesizer 404-1 and outputs it to the transmission antenna 406-1 of the first sector through D / A conversion and frequency up conversion. Similarly, the transmission processor 405-K receives the output of the digital synthesizer 404-K and outputs it to the transmission antenna 406-K of the first sector through D / A conversion and frequency rising conversion.

On the other hand, in the case of reverse transmission, it is assumed that the antenna diversity scheme using two reception antennas for each sector. However, the same can be applied whether or not the antenna diversity technique is applied.

The reverse radio interface signals received through two reception antennas for each sector are subjected to frequency down conversion and A / D conversion by the reception processors 407-1 and 407-K in charge of the sectors, and then form digital samples. On the high-speed parallel receive bus 410. That is, the reception processor 407-1 receives the signals of the reception antennas 408A-1 and 408B-1, performs frequency down conversion and A / D conversion, and then outputs the lines 418A-1 and 418B-1. It is loaded on the high speed parallel receive bus through Similarly, the receiving processor 407-K receives signals from the receiving antennas 408A-K and 408B-K, performs frequency down conversion and A / D conversion, and then outputs the lines 418A-K and 418B-K. It is loaded on the high speed parallel receive bus through

Each of the switching modules 403-1 to 403-N is a bus line corresponding to a sector used by the channel element 402-1 to 402-N which is in charge of each sector on the high speed parallel receiving bus. Select only to be input to the channel elements 402-1 to 402-N. That is, the switching module 403-1 selects only those corresponding to sectors used in the channel element 402-1 among the signal lines of the high speed parallel receiving bus 410 to form the types 416A-1 to 416F-1. To the channel element 402-1. Similarly, the switching module 403-N selects only those corresponding to the sectors used in the channel elements 402-N among the signal lines of the high-speed parallel receiving bus 410 in the form of 416A-N to 416F-N. It is input to the channel element 402-1.

Each channel element 402-1 to 402 -N transfers data obtained by performing diversity synthesis, demodulation, decoding, etc. on the six received signals to the cell controller 401.

FIG. 5 illustrates a structure diagram of a forward channel of a multi-sector base station in the CDMA mobile communication system according to the present invention of FIG.

In FIG. 4, a digital synthesizer having N input lines, which is the number of channel elements, is difficult to implement in practice and is difficult to implement as the number of channel elements is expanded. In addition, in the actual implementation, since channel elements are implemented in the form of a channel card and several channel elements are implemented in one channel card, as shown in FIG. 5, by digitally synthesizing the forward output for each channel card and then synthesizing them again. Reduce system scalability and implementation complexity. Reference numerals 501-1 through 501-m denote m channel cards. Considering only the forward channels, each channel card consists of channel elements, switches, and digital synthesizers. That is, the channel card 501-1 has n channel elements 511-1 to 511-n, n switches 521-1 to 521-n, and k synthesizers corresponding to k sectors. 1-531-k, the channel card 501-m likewise has n channel elements 51m-1 to 51m-n, n switches 52m-1 to 52m-n, and k each Digital synthesizers 53m-1 to 53m-k corresponding to sectors are provided. Each of the digital synthesizers 531-1 to 531-k and 53m-1 to 53m-k in the channel card combines the outputs of all the channel elements in the channel card for each destination sector.

These channel card outputs are once again synthesized by the digital synthesizers 502-1 through 502-K, and then subjected to D / A conversion and frequency up conversion by the transmission processors 503-1 through 503-K for each sector. The transmission antennas 504-1 to 504-K for each sector are sent out over the radio interface.

Figure 6 is a detailed view of one embodiment of a switching module according to the present invention of Figures 4 and 5.

The switching module has control ports 604, 605-A, 605-B, one 3xk transmit switch 602 and two 3xk receive switches 603-A, 603-B. Each switch 602, 603-A, 603-B operates under the control of the cell controller 601 through the control ports 604, 605-A, 605-B.

The transmit switch 602 outputs 606-1 to 606-3 for three sectors of α, β, and γ of the channel element under the control of the cell controller 601 through the control port 604 for the K sectors. Map to outputs 608-1 to 608-K. The two receive switches 603-A and 603-B have the same structure and operation. However, the reception switches 603-A and 603-B are in charge of the main reception signal and the diversity reception signal in a system providing reception diversity using two reception antennas. The reception switch 603-A transmits the reception signals 609A-1 to 609A-K from each sector reception processing section to three sectors of the channel element under the control of the cell controller 601 through the control port 605-A. To the inputs 607A-1 to 607A-3.

Similarly, the receive switch 603-B receives the received signals 609B-1 to 609B-K from each sector receiving processor under the control of the cell controller 601 through the control port 605-B. Maps to diversity inputs 607B-1 through 607B-3 for the sector.

7 is a detailed diagram of an embodiment of a transmission switch according to the present invention of FIG.

The transmission switch includes three single pole multithrow (SPMT) switches 702-1 to 702-3. The inputs 704-1 to 704-3 of the transmit switch correspond to the outputs for three sectors α, β, and γ of the channel element, and the outputs 705-1 to 705-i and 706-1 to 706-i of the switch. , 707-1 to 707-i are outputs corresponding to k (= 3 x I) sectors. The switch 702-1 is operated by the control of the control port 701 through the selection logic 703-1 and outputs one signal 704-1 of the outputs for three sectors α, β, and γ of the channel element. Maps to one signal 705-1 to 705-i of outputs for k / 3 (= m) sectors.

FIG. 8 is a detailed view of an embodiment of a receive switch according to the present invention of FIG.

The receiving switch has a control port 801 and a kx3 switch 802. The switch 802 includes k SPMT (1 × 3) switches 805-1 through 805-K. The outputs 803-1 to 803-3 of the receive switches correspond to the inputs for three sectors of α, β, and γ of the channel element, and one more such receive switch is used for the reception diversity signal.

On the other hand, inputs 804-1 to 804-K of the reception switch correspond to received signals corresponding to K sectors. The SMPT switches 805-1 to 805-K in charge of each sector distribute the input signals from each sector to three outputs 803-1 to 803-K corresponding to the input of each channel element. In charge.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

The multi-sector base station structure of the CDMA-based mobile communication system according to the present invention can significantly increase the number of sectors that can be handled by handoff off, and in particular, signal traffic, which is a problem when miniaturizing a cell in a microcell system, etc. There is an effect of mitigating the increase and enabling a quick handoff process.

Therefore, by using a multi-sector base station structure, a cell can be miniaturized to increase the use efficiency of radio resources and to increase subscriber capacity, and to provide a microcell system capable of accommodating various high-speed multimedia (voice, data, and video services). There is an effect that can be built efficiently.

In addition, the multi-sector base station of the CDMA-based mobile communication system has the effect of increasing the resource utilization efficiency by centrally managing the base station resources.

Claims (7)

In the transmission and reception apparatus of a multi-sector base station in a mobile communication system in which one macro cell is subdivided into a plurality of micro cells, and each micro cell is provided with a sector antenna for signal transmission and reception, Cell control means for centrally controlling the plurality of microcells, the cell control unit being located at a central portion of the macrocell; A plurality of channel modulating means for performing encoding and modulation / demodulation on the signal output from the cell control means; A plurality of transmission switching means for switching the signals output from the channel modulation means to transmit to the plurality of microcell base stations under control of the cell control means; A plurality of combining means for receiving and synthesizing a signal corresponding to each sector among the signals output from the switching means; A plurality of transmission processing means for receiving the signal output from the synthesizing means and performing digital / analog conversion and frequency rising conversion to output to each sector antenna; A plurality of reception processing means for performing frequency down conversion and analog / digital conversion on the signals received from the sector antennas and transmitting them to the central base station; A plurality of reception switching means for receiving a signal output from the plurality of reception processing means and switching the output; And A plurality of channel demodulation means for demodulating and decoding the signal received from the switching means, and outputs to the cell control means Transceiver of a multi-sector base station comprising a. The method of claim 1, And subdividing said one macro cell into at least three microcells, each combining means, transmission processing means, and receiving processing means of a number corresponding to the number of cells. The method of claim 1, A plurality of reception processing means for performing frequency down conversion and analog / digital conversion of the diversity signal received from the reception antenna and transmitting to the central base station; A plurality of reception switching means for receiving a signal output from the plurality of reception processing means and switching the output; And Multiple channel demodulation means for performing diversity synthesis, demodulation and decoding on the signal received from the switching means and outputting the signal to the cell control means Transmitting and receiving apparatus of a multi-sector base station further comprising. The method of claim 1, And the data transmission between the transmission switching means and the reception switching means and the microcell base station is via a parallel common bus. The method according to any one of claims 1 to 3, The transmission switching means, A plurality of control ports for receiving control signals from the cell control means; And Transmission switch for switching the signal output from the channel modulation means in accordance with the control signal from the control port for transmission to a plurality of base stations Transmitting and receiving apparatus of a multi-sector base station comprising a. The method according to any one of claims 1 to 3, The reception switching means, A plurality of control ports for receiving control signals from the cell control means; And Receiving switch for switching the signal received from the base station according to the control signal from the control port for transmission to the channel demodulation means Transmitting and receiving apparatus of a multi-sector base station comprising a. The method of claim 5, The transmission switch, A selection unit for receiving and outputting a control signal from the control port; And Single input multiple output switch for switching to one of the outputs for the sector in accordance with the control signal output from the selector Transmitting and receiving apparatus of a multi-sector base station comprising a.