KR20000062871A - Dual carrier, three-sector configuration for a cdma transmitter/receiver - Google Patents

Abstract

PURPOSE: A transmitting and receiving subsystem used for a CDMA network in a telephone communication system and method for receiving communication signals in a base station transmitting and receiving subsystem is provided to remove a cable loss by providing a wireless unit easily installed near an antenna and having a small size. CONSTITUTION: A PRU(110) is connected to a PMU(105) through wires or cables. A distance between the PRU(110) and the PMU(105) is more 390 pits. The PMU(105) is designed to be located at the lower portion of a tower building, a pole or an other supporting structure(115). The PRU(110) is located at the top near an antenna(s). For transmitting and receiving signals, the PRU(110) is connected to a tower top installing antenna(120). Wires or cables(122) have an optical cabling between the PMU(105) and the PRU(110). The optical cabling increases a permissive distance between the PMU(105) and the PRU(110).

Description

A base station transceiver system used for a code division multiple access network in a telephony communication system and a method for receiving communication signals from the base station transceiver subsystem {DUAL CARRIER, THREE-SECTOR CONFIGURATION FOR A CDMA TRANSMITTER / RECEIVER}

This application is a continuing application of Application No. 09 / 149,168, filed September 8, 1998, with priority claiming US Provisional Application No. 60 / 055,228, filed September 9,1997.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication systems, and more particularly to base station transceiver systems for use in Code Division Multiple Access (CDMA) networks.

1 is a block diagram showing the configuration of a conventional wireless communication system. As shown, a basic wireless communication system includes a mobile station 10, a base station 20, a reverse link 30 indicating an electromagnetic wave communication link from the mobile station 10 to the base station 20, and the It consists of a forward link 40 representing an electromagnetic wave communication link from the base station 20 to the mobile station 10.

2 is a diagram illustrating a conventional cell grid and cell sites. In a wireless communication system based on general cellular principles, the service area 49 is geographically divided into a number of small areas 50, 52, 54, 56 called cells. Each cell has cell sites 58, 60, 62, 64 equipped with a wireless device known as a base station transceiver system (hereinafter referred to as BTS).

Multi-cell layouts such as macro cells, micro cells, and pico cells are provided in a particular geographic area to create a stepped range. Macro cells have the largest coverage and pico cells have the smallest coverage.

Picocells are used to provide coverage within buildings, to cover specific areas (campus, stadiums, airports, shopping malls) or to temporarily cover areas discovered by accident or by special events or natural disasters. The pico cells also cover a remote location out of the border. The pico cells also complement macro or mini cells with hole filling. The pico cells also increase the capacity of hot spots.

3 is a block diagram of a wireless system network connected to a conventional Public Switching Telephone Network (hereinafter referred to as PSTN) 68. As shown, the BTS 66 provides a link to the mobile subscribers (or mobile stations) 10. Each BTS 66 typically includes two or three antennas 67. The antennas 67 are omni or directional antennas. Omni-directional antenna deployments provide 360 ° coverage. Directional antennas, on the other hand, provide a service area smaller than 360 °, known as a sector.

For example, in a typical directional deployment there are two or three sectors, with each sector of the two sector structure generally providing a 180 ° service area. In addition, each sector in a three sector deployment generally provides a service area of 120 °. Each sector typically has at least two antennas for diversity reception for satisfactory transmission and reception.

3, each BTS 66 is connected to a base station controller (hereinafter referred to as a BSC) 70 (multiple BTSs 66 are connected to a single single BSC 70). Connected. In addition, each BSC 70 is connected to a Mobile Switching Center (hereinafter referred to as MSC) 72, which in turn is connected to a PSTN 68.

4 is a functional block diagram of a conventional BTS. As shown in FIG. 4 above, a typical BTS 66 typically consists of four main functional blocks. That is, each sector RF front-end 74 of coverage, multiple transceivers 76, a large number of modem processors 78 and a controller 80. The controller 80 interfaces with the BSC 70 through the T1 or E1 line 81. The RF front-end 74 is connected to an antenna 67 that is typically mounted on the twist of a tower or pole 67. 5 shows a conventional BTS based on external and ground connected to an antenna mounted on top of the tower.

In a typical system, the four main functional blocks of the BTS 66 shown in FIG. 4 described above are contained in one physical cabinet or housing. The cabinet or housing is proximate to the pole (or tower) 82 at ground level. The long coaxial cable 84 has a length that extends to the top of the pole 82 on which the antennas 67 are mounted. The length of the cable varies from 50 to 200 feet and depends on various mounting scenarios. Cables of these lengths also cause unwanted power losses. About 2 to 4 dB to minimize power loss. or Thin coaxial cables with an inch diameter are used. Minimizing these power losses is very important because such losses in the cable degrade receiver strength and reduce transmit power.

5 shows a conventional BTS unit 66. The BTS unit 66 is coupled via an elongated cable 84 to the antenna 67 at the top of the support structure 82.

6 is a block diagram showing another conventional BTS structure. As shown, an RF front-end module 74 consisting of a low noise amplifier (LNA) and a power amplifier 74 (hereinafter referred to as LNA / PA unit 74) is mounted on top of the tower. The cable power loss in this structure is not as sharp as the structure described above. This is because cable power loss is compensated for by further amplification. However, it is still necessary to use a fairly thick cable so that the signals between the LNA / PA unit 74 and the transceiver 76 in the BTS 66 are high frequency / radio (RF) signals. Another problem is related to the RF signals transmitted between the LNA / PA unit 74 and the BTS 66. That is, power loss, system noise, mechanical clutter, and so on. In addition, additional complex circuitry is required in the RF front-end module 74 and the transceiver to automatically compensate for the wide range of cable losses arising from differences in installation scenarios for a variety of cable lengths. Problems like this get worse because operating RF frequencies is assigned in higher frequency bands. This is the case for personal communication systems.

In other words, increasing the length of the cable 84 or increasing the frequency transmitted through the cable 84 also increases the power loss between the BTS 66 and the LNA / PA unit 74 and the transceiver 76. . Moreover, the long cable 84 (often exceeding 150 feet or even exceeding 300 feet) used to connect the LNA / PA unit 74 to the BTS 66 causes wide power loss. For example, when there is a 3 dB loss in the cable, the 100 W power amplifier of the base transceiver station transmits only 50 W of power at the antenna. Power loss in cable operation as opposed to good reception reduces the receiver's ability to detect received signals. In addition, for personal communication systems (PCS) operating at high frequencies, power loss in the cable 84 between the LNA / PA unit 74 of the BTS 66 and the transceiver 76 is increased. Thus, RF power loss in both the transmit and receive paths results in the use of relatively thick (high conductance) coaxial cables to further reduce the desired transmission efficiency, lower the desired receiver sensitivity, and minimize the loss.

In general, interference is unavoidable in a wireless environment where radio frequencies are transmitted over air. That is, unless the transmitting antenna is directly in the line-of-site of the receiving antenna, or there are no obstructions such as trees, buildings, stone statues, or water towers on the road, the reflections are fading ( fading) and multipath signals.

Diversity receivers can increase the carrier-to-noise ratio (and / or Eb / No) to minimize fading and multipath effects. Therefore, for each transmit frequency, two antennas are used at the receiver. One antenna is a transmit / receive antenna and the other antenna is used as a diversity receiver used to overcome some of the fading or multipath problems.

Some cell sites with high communication capability need to transmit more than one RF carrier signal. Transmission of multiple RF carriers per sector requires a corresponding number of transmit antennas per sector. If a diversity receiver is used in the system, additional receive antennas are specifically required. Increasing the number of antennas is aesthetically ill and can be harmful to the air (eye-sore), which is undesirable.

Conventional techniques for reducing the number of transmit antennas required for multiple RF carrier transmissions are disclosed in FIGS. 7 and 8.

Referring to FIG. 7, carriers are combined with a high power combiner. Referring to FIG. 8 above, carriers combine at low power and the combined signal is amplified in a multi-carrier power amplifier.

The case illustrated in FIG. 7 is not suitable for use in compact BTS systems due to the high power loss in the combiner, and the case illustrated in FIG. 8 due to multi-carrier linear amplifier requirements.

What is needed is a small BTS system that can handle multiple transmit and receive frequencies without substantially degrading the overall performance of the system or significantly increasing the number of antennas.

It is therefore an object of the present invention to provide a BTS in which a radio unit (RU) is located proximate to the antenna mounting position. The main unit (MU) is located far from the wireless unit and remotely connects with the wireless unit. One or more antennas are connected to the wireless unit. Multiple wireless units are operated at the same or different frequencies.

Another object of the present invention is to minimize the number of antennas required for a multi-frequency BTS system.

Another object of the present invention is to implement a BTS system having two radio units to be connected together to increase the number of operating frequencies without increasing the number of antennas.

Another object of the present invention is to minimize the cost of increasing cell capacity by increasing the calling capability of the BTS without increasing the number of antennas for one cell.

Another object of the present invention is to transmit or receive two frequencies with two antennas and to maintain diversity reception. Diversity receivers try to minimize fading and multipath effects.

The first invention for achieving the above object is a base station transmit / receive subsystem for a telephony communication system, comprising: a first main unit for processing a first transmit / receive frequency pair, and a first cable to the first main unit via a first cable; A first transmitter remotely wirelessly connected, for transmitting a first transmission frequency coupled to the first transmission and reception frequency pair, a first receiver for receiving a first reception frequency coupled to the first transmission and reception frequency pair, the first receiver A first wireless unit having a first diversity receiver for receiving a first reception frequency, and a first for transmitting the first transmission frequency from the first transmitter and receiving the first reception frequency for the first receiver And an antenna and a second antenna for receiving the first reception frequency for the first diversity receiver.

The base station transmit / receive subsystem is remotely wirelessly connected to the first main unit via the second cable, a second transmitter for transmitting a second transmit frequency coupled to the second transmit / receive frequency pair, the second transmit / receive frequency And a second wireless unit having a second receiver for receiving a second reception frequency coupled to a pair, and a second diversity receiver for receiving the second reception frequency, wherein the first antenna further comprises the second diver. Receiving the second reception frequency for a city receiver, the second antenna may transmit the second transmission frequency from the second transmitter and further include the second reception frequency for the second receiver.

The present invention for achieving the above object is a communication signal in a base station transmission and reception subsystem having a first main unit and a first wireless unit disposed far from the first main unit and communicating with the first main unit. In the method of receiving a voice signal, the method comprising: receiving first communication signals from the first antenna, inputting the first communication signals to the first wireless unit, amplifying the first communication signals, Separating power of the first communication signals, providing a first portion of the first communication signals to a first receiver circuit, and providing a second portion of the first communication signals to a first output of the first wireless unit And providing an output signal from the first receiver circuit to the main unit.

The method includes receiving second communication signals from the second antenna, and inputting the second communication signals to one of the first wireless unit or the second wireless unit. Processing the second communication signals as a first diversity signal when input to the first wireless unit; and when the second communication signals are input to the second wireless unit, the second communication Amplifying the signals, separating power of the second communication signals, providing a first portion of the second communication signals to a second receiver circuit inside the second wireless unit, Providing a second portion to a first output of the second wireless unit connected to the first wireless unit, wherein the second portion of the second communication signals is processed as a first diversity signal Can .

1 is a block diagram showing the configuration of a conventional wireless communication system

2 illustrates a conventional cell grid and cell sites.

3 is a block diagram of a wireless system network connected to a conventional wired public switched telephone network

4 is a functional block diagram of a conventional base station transceiver subsystem

5 illustrates a conventional ground based base station transceiver subsystem connected to an antenna mounted on top of a tower.

6 is a block diagram showing a conventional base station transceiver subsystem configuration.

7 illustrates a conventional combined / multi-carrier method using a single antenna to support multiple transceivers.

8 illustrates a conventional combining method using a single antenna to support multiple transceivers.

9 illustrates a configuration of a base station system according to an embodiment of the present invention, connected to a pole-mounted antenna.

10 is a diagram illustrating a structure of a base station transmit / receive subsystem according to an embodiment of the present invention for the overall configuration;

11 is a diagram illustrating a structure of a base station transceiver system according to an embodiment of the present invention for a three sector structure;

12 is a functional block diagram of a base station transmit / receive subsystem configuration according to an embodiment of the present invention, in which selected service systems are disclosed.

13 is a modular level block diagram of a base station transmit and receive subsystem according to an embodiment of the present invention.

14 is a block diagram of a base station transmit / receive subsystem according to an embodiment of the present invention when in a single frequency and three sectors

15 is a block diagram of a base station transmit / receive subsystem according to an embodiment of the present invention when sharing a single frequency, three sectors and an antenna.

16 is a block schematic diagram of duplex and diversity reception channels of a wireless unit system according to an embodiment of the present invention.

17A to 17E are views showing other embodiments of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In the following description, numerous specific details such as components of specific circuits are shown, which are provided to help a more general understanding of the present invention, and it is understood that the present invention may be practiced without these specific details. It will be self-evident to those of ordinary knowledge. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

This embodiment corresponds to the case where the configuration of the pico base station transceiver subsystem is applied. However, it can be applied to any base station transceiver subsystem configuration in a wireless communication system, such as macro or micro base station transmit / receive subsystems.

9 is a view showing a basic idea that forms the basis of the BTS configuration according to an embodiment of the present invention. The BTS is divided into two units, a pico-BTS radio unit 110 and a pico-BTS main unit 105.

As shown in FIG. 9, the Pico-BTS transmits or receives signals via at least one pole-mounted antenna 120, and the PMU 105 via a plurality of wires 122 comprising a coaxial cable. To the Pico-BTS main unit (“main unit system”, PMU or MU) 105 and other supporting structure 115 and Pico-BTS radio unit (“wireless unit system”, PRU or RU) 110 in communication with the Is done.

FIG. 10 is a diagram illustrating a structure of a base station transmit / receive subsystem according to an embodiment of the present invention for omni configuration. The PRU 110 may be connected to the PMU via the wires or cables. The distance between the PRU 110 and the PMU 105 may be greater than 350 feet (current systems are typically spaced about 150 feet apart). This separation is possible because the PMU 105 is designed to be located underneath a tower building, pole, or other support structure 115, and the PRU 110 may be located on top of the antenna s. will be. To transmit and receive signals, the PRU 110 connects one, typically at least two, tower top mounted antennas 120.

Wires or cables 122 may include optical cabling between the PMU 105 and the PRU 110. Cabling on the optics may increase the allowable distance between the PMU 105 and the PRU 110. The reason is that the optical signal has less loss than, for example, an electrical signal in a coaxial cable.

FIG. 11 is a diagram illustrating a structure of a base station transceiver system according to an embodiment of the present invention for a three sector structure. Hardware systems that require redundancy are only redundant in the PRU 110. Therefore, the PMU can interface 1, 2, 3 or make the PRU's more likely.

12 is a functional block diagram of a base station transmit / receive subsystem in accordance with an embodiment of the present invention, illustrating components of the PMU 105 and the PRU 110. The PRU 110 is connected to a transmit and receive interface 135 (hereinafter referred to as a T / R interface) that is the end of the PMU 105 via a set of cables 122. The transmit and receive interface 135 is connected to the channel elements 130. The channel elements 130 are where the CDMA signal is modulated or demodulated. The PMU 105 provides a global positioning receiver that provides accurate clock and frequency signals to the main controller module 125, the channel elements 130, the T / R interface 135 and the PRU (s). It includes. In addition, the PMU 105 includes a power supply system 145 and a temperature control service system 150.

13 provides further details of the PRU 110 and the PMU 105 subsystems. As shown in FIG. 13, each PRU 110 is originally composed of two modules. One is transmit module 155 (XCVR) and the other is antenna interface module 160 (AIF). However, these modules can be combined into one or more modules. Therefore, the antenna interface module 160 may include a transmission power amplifier PA, two low noise amplifiers (LNA, not shown), a duplexer module, and a receiver filter Rx. The transmit power amplifier PA amplifies the signal to the level required for the desired cell range. The two low noise amplifiers amplify the received signal to maximize receiver sensitivity. The transceiver module 155 is a synchronization circuit, a transmission circuit, and two receiver circuits (common to refer to a system-owned transmitter and receiver circuit, collectively referred to as a "transceiver").

The PRU 110 also includes a microprocessor and nonvolatile memory (not shown). The nonvolatile memory stores measurement data and provides real time temperature operating variable compensation to the transceiver. Therefore, no mobile station or mobile simulator is required for the measurement. And system measurements in the field are no longer needed.

The PRU 110 preferably accommodates the duplexer and receive filters in a shared cavity. This is essentially three filters (two receive and one transmit) coupled to one aluminum cavity. By combining a conventional duplexer cavity with a conventional diversity receiving cavity, a very useful space is provided inside the unit, which can be used for other circuits, and the cost is lower.

In this embodiment the duplexer / receiver filter cavity of the PRU 110 is designed to allow connectors on the filter to protrude directly through the cover of the unit and to remove any coaxial cable bulkhead connectors. This approach again requires some small parts in the unit to free up valuable space and lower costs.

As shown in FIG. 13, the PMU 105 includes six functional subsystems. That is, Pico-BTS main controller card 125 (PMCC), Pico-BTS channel card 130 (PCC), transmit and receive interface card 135 (TRIC), time and frequency card 140 (TFC), And a power supply assembly 145 (PSA) for distributing direct current to alternating current and distributing direct current power throughout the PMU 105 and the PRU 110. For simplicity, the temperature management subsystem 150 is not shown in FIG. 13.

In operation, the PMCC 125 includes an external interface module and a communication control module, often referred to as a packet engine, monitors of all cards in the BTS structure 100. The PMCC 125 also routes traffic and signaling packets between the base station controller (BSC, see FIG. 3) and the PCCs 130.

Similarly, the TRIC 135 provides an interface between the transceiver module 155 and the PCCs 130. The TRIC 135 provides connectivity to the PRU 110 through internal connection cables 122.

Baseband analog signals and intermediate frequency (IF) signals in the frequency range of about 1 KHz to 700 MHz are carried in a cable 122 connecting the PRU 110 and the PMU 105. A better IF frequency range is 2.39MHz with a bandwidth of 1.26MHz and signal strengths from -50dBm to -70dBm. The advantage of this approach is that the modulated signal is routed over a redundant, inexpensive standard RG-58 coaxial cable. Other signals to be transmitted between the units include a 48V power supply, a 10 MHz reference, and RS-422 control lines.

Separation of the PRU 110 and the PMU 105 allows the PRU 110 to be mounted close to the antenna 120. Since the power loss in the antenna cable lowers receiver sensitivity and reduces the transmit power at a 1: 1 ratio (dB per dB), placing the PRU 110 in close proximity to the antenna 120 is a performance of the BTS 100. Maximize. The location of the PRU also reduces signal loss through power and cables. This will save energy and increase efficiency.

It is undesirable to have all the wires and coaxial cables jumbled into one polymer jacket. Therefore, one multi-wire / coaxial connector is used at both ends of the cable. The resulting cable is usually assembled as a single item that is easy to install and replace in the field. Therefore, as in indoor applications (requires a turning corner), it is easy to keep the cable diameter below 0.75 inches.

The coaxial cables entering the PRU 110 are transformers connected to the transceiver and eliminate the realization of ground loops (and their corresponding ground noise). And ensure that the PRU 110 can be located more than 150 feet from the PMU 105. Moreover, if the PRU 110 is connected to a pole or other grounded conductive structure, the system performance is degraded because of noise coupling. Power at 24 and 48, or higher VDC or alternating voltage, is sent to the top of the tower with a separate return. This reduces power loss in the power wires and makes the system efficient.

The signals transmitted by the cable 122 between the PRU 110 and the PMU 105 operate most effectively over a range of about 1 KHz to 20 MKHz. Low signal attenuation results from the use of thinner and less expensive cables.

In an environment where heavy communication traffic is typically done, it is beneficial to connect the two PRUs together and use both carrier frequencies. In this embodiment, two PRUs may be connected together, and two carrier frequencies may be transmitted and received without minimizing signal degradation and increasing the number of antennas required. This is useful because additional services can be obtained from the PRU by doubling the effective communication traffic capability without compromising the aesthetics and harming the public with the installation of additional antennas.

14 is a block diagram of a base station transmit / receive subsystem according to an embodiment of the present invention in the case of single frequency and three sectors. Referring to FIG. 14, duplexers and diversity channels for one PRU are described in a single carrier frequency structure. In single carrier mode the service provider is required to install only one PRU for each sector. The PRU-A 110 has two antennas, a duplex antenna 200 and a diversity antenna 210. The duplex antenna 200 is shared by the transmitter circuit 212 and the duplex receiving circuit 214. The transmitter circuit 212 transmits at the operating frequency T1. The duplex and diversity antennas 200, 210 will be tuned to receive the frequency R1. The two frequencies T1 and R1 thereby form a duplexed frequency pair. The frequencies T1 and R1 are preferably separated by about 80 MHz, thereby forming a frequency pair. PRUs in sectors 2 and 3 are substantially the same as PRU-A 110. Note that the transmitter circuit 212 and the duplex receiver circuit 214 are shared with the duplex antenna 200.

The diversity antenna 210 is not connected to the transmitter circuit 212. Received signals arrive at the diversity antenna 210 and are provided to a diversity receiver 216. Duplexer and Diversity The received signals couple to a demodulator located in the PMU 218 to reduce signal fading effects.

The combination of PRU-A 110, PRU-B and PRU-C covers 360 ° or three sectors for the cell tower. The single PRU 110 can be used in omni-directional mode so there are two omni-directional antennas for the duplex and diversity antennas 200 and 210, respectively. In short, FIG. 14 illustrates a PRU 110 for transmission and diversity according to an embodiment of the present invention.

15 is a block diagram of a base station transmit / receive subsystem according to another embodiment of the present invention. A dual carrier frequency three-sector architecture for CDMA transmitters and receivers is disclosed where only two antennas per sector are required and diversity reception is maintained. An additional demand for dual carrier mode for each sector that exceeds dual carrier mode for each sector that exceeds a single carrier mode for each sector is an additional PRU per sector and an additional PMU for site location. No additional antenna is required at this time.

The duplex antenna 200 is divided by the transmitter circuit 212A of the PRU-A 110A and the diversity receiver 216B of the duplex receiver 214A and the PRU-B 110B. Diversity antenna 210 is divided by diversity receiver 216A of PRU-A 110A and duplex receiver 214B and transmitter 212B of PRU-B 110B. After being input to the duplex receivers 214A and 214B, each signal is distributed by a power divider (see FIG. 16). In practice, half of the signal is provided to the diversity receivers of other PRUs. More specifically, the signal delivered to the duplex receiver 214A is distributed by a 3 dB power divider. One output of the power divider is provided to the duplex receiver 214A and the other output is provided to the diversity receiver 216B of the PRU-B 110B.

The duplex receiver signal of the PRU-B 110B is distributed in the same configuration as that transmitted in the PRU-A 110A. The PRU-A 110A will operate in frequency pair # 1 and the PRU-B 110B will operate in frequency pair # 2. The signal from the duplex antenna 200 distributed and provided to the duplex receiver 214A is processed by the duplex receiver 214A and becomes a duplex signal for frequency pair # 1 (DXA1). The signal from the diversity antenna 210 provided to the PRU-B 110B is distributed at the duplex receiver 214B and provided to the diversity receiver 216A of the PRU-A 110A. Therefore, the signals processed by the duplex receiver 214A and the diversity receiver 216A are actually the same as those found in the single carrier mode. Here, the duplex antenna 200 transmits a signal to the duplex receiver 214A, and the diversity antenna 210 provides a signal to the diversity receiver 216A. Therefore, the signals to be transmitted by the output signals DXA1 and RXA1 and the transmitter 212A all combine with the same frequency pair # 1. RXA1 is a diversity signal combined with DXA1.

As for the PRU-B 110B, the diversity antenna 210 is used to transmit the transmission signal for the frequency pair # 2 through the transmitter 212B. Moreover, the signal received from the diversity antenna 210 is distributed such that a 3 dB signal is provided to the duplex receiver 214B and the diversity receiver 216A. Therefore separate antennas are used for receive duplex and diversity receivers. Moreover, frequency pair # 2 is transmitted and received by the PRU-B 110B. The output signals DXA2 and RXA2 are provided to the PMU B via a combined cable like the diversity and duplex signals.

Receive diversity is maintained as well as two PRUs A & B that provide independent received signals back to their respective PMUs. An advantage of the configuration according to the embodiment of the present invention is that the capability is doubled as if two frequencies are currently being used. The most important point here is that the capacity is doubled without additional antennas. Moreover, no hardware reconfiguration is required inside the PRUs. A further advantage is that the scalability provided by embodiments of the present invention saves on non-recurring engineering and installation costs. The PRUs will require additional external cabling modifications to achieve a dual carrier structure. Sectors 2 and 3 may be formed in a configuration similar to sector 1 according to an embodiment of the present invention.

16 is a block schematic diagram of duplex and diversity receive channels of a PRU according to an embodiment of the present invention. This structure is one of many possible structures and can be used to perform the same function. In embarking on this design, it is new that both the duplexer and diversity receivers operate in near-ideal performance in single or dual carrier modes. Another feature of this undertaking is that no additional circuitry is required inside the PRU to support dual carrier mode.

The foregoing features are made possible by appropriate selection of topology and RF elements to achieve nearly the same performance in both receivers and modes. The gain, noise shape, and third order intercept point of each step are carefully managed. According to FIG. 16, receivers are practically ideal.

The main difference between the two receivers is that dual carrier signals are input to or output from the receiver. The duplex receiver employs a 3dB power divider to obtain two ideal signals from the duplexer antenna. Since the RX gain stages in front of the distributor are always optional, in contrast to the switch, the distributor is needed.

The duplexer antenna is always used for reception. However, diversity receivers use a switch to accommodate the dual carrier input midstream. Dual diversity inputs do not enter through the diversity antenna. In duplex mode, the RX gain stages at the end of the diver's receiver will be turned off to conserve power. Attenuators and switches around the divider are used to equalize the path gain through the receivers regardless of the mode of operation. The amplifier's bias and switch control circuitry is controlled through software to select the desired operating mode. For dual carrier mode, the diversity antenna operates as a TX / RX antenna as the duplex antenna does.

As noted above, many alternative configurations achieve the same result as far as possible. Others include the use of directional couplers and / or circulators instead of distributors and / or switches. Such items are substantially identical to those currently embodied. Dual carrier inputs / outputs are also rerouted to enter and / or exit other points in the receiver circuit.

16 is divided into a duplex receiver portion and a diversity receiver portion within the PRU 110 according to an embodiment of the present invention. Referring to the duplex receiver section, the duplex antenna 200 receives a signal and provides the received signal to the receiver gain stage 300. The signal is provided to the RF divider 302. As the RF divider, a 3 dB power divider is preferable. A portion of the signal is passed to first attenuator 304 and to another receiver gain stage 306. The output signal from the receiver gain stage 306 is down converted and provided as a received duplex signal RxIF_DUP.

If the PRU is installed for dual carriers, two PRUs are commonly used, and part of the signal is output from the RF divider 302 to the attenuator 308. The output is provided as an input to another PRU.

Referring to FIG. 16, in the diversity portion of the PRU according to the embodiment of the present invention, when the PRU is configured for single carrier frequency processing, an RF signal is received by the diversity antenna and is received in the reception gain stage portion 310. Is provided. The signal is provided to an attenuator 311 and to a single pole double throw (SPDT) switch 312. The SPDT switch 312 is controlled by a switch control circuit 314 which is in turn controlled by a PMU coupled with an amplifier bias.

When the SPDT switch 312 is in the "1" position, essentially, the signal is transmitted from a diversity antenna to the other gain end portion 316 via the SPDT switch 312. The signal is then transmitted via mixer 318 to the IF circuit of the diversity receiver portion in the PRU and eventually to the PMU.

Conversely, if the PRU according to the embodiment of the present invention is in the dual carrier frequency mode, the diversity antenna 210, the gain stage 310 and the attenuator 311 are not used. Instead a diversity signal is received from another PRU unit (see FIG. 15). The signal is provided to a unique PMU (shown as RXIF_DIV) which is received at pole 2 SPDT switch 312 and provided to gain stage 316 and mixer 318.

17A through 17E are diagrams illustrating other embodiments of the present invention showing another coupling between one or more PRUs and one or more PMUs. In addition, it illustrates a connection between PRUs for sharing an antenna in dual carrier operations.

17A shows a full or sector range configuration with a single carrier frequency. Both antennas provide receive diversity to reduce signal fading. One of them transmits a transmission signal to minimize the number of antennas. The PRU is easy to handle and install It is connected to the PMU using a single cable smaller than inches. It consists of a number of smaller cables carrying signals, reference frequency and direct current power and wrapped in a single jacket. GPS antenna access is provided from the PMU. And it can be mounted wherever the GPS signal is received at the appropriate intensity.

FIG. 17B shows a full or sector range configuration with two carrier frequencies to double the service capability over the signal carrier frequency configuration. Both PRUs are combined into a single PMU. If desired, two PMUs can be used. Thus a single PRU is combined into a single PMU and other PRUs are connected to other PMUs. Connectivity between PRUs provides a means for antenna sharing. Thus, as in single carrier frequency operation, only two antennas are required for dual carrier frequency operation.

17C shows a full or range configuration with two or three sector carrier frequencies. PRUs combine together for antenna sharing purposes, where they provide the same area range with two carrier frequencies. The third PRU may also provide the same area range with different carrier frequencies or provide a range in another area using one of the two carrier frequencies used by the two first PRUs. The device has four antennas. It is possible to reduce the number of antennas to three by bringing one PRU-to-PRU connection to the third PRU instead of an unduplicated antenna in three PRUs for the same area range for all three carrier frequencies.

17D shows a full or range configuration with three carrier frequencies without antenna sharing. This configuration can provide a three sector range with a single carrier frequency. In this case, antenna sharing is not possible.

17E illustrates a full or range configuration with six carrier frequencies using antenna sharing. This configuration can provide three sector range with two carrier frequencies using antenna sharing. Each PMU is connected to three PRUs. Two PRUs providing the same area range with different carrier frequencies combine together for antenna sharing. 17 (e) shows two GPS antennas-an antenna of each PMU, but only one GPS antenna connected to the two PMUs can be used.

Therefore, embodiments of the present invention represent different combinations of connections between the PMU and the PRU to provide special configurations for satisfying different range and capability requirements in a given area. They also represent PRUs with the ability to allow connections between multiple PRUs to achieve antenna sharing purposes without compromising performance. In a nutshell, the present invention allows a service provider to upgrade a cellular (PCS) communication system using a minimum number of antennas for all or three sectors of single carrier frequency operation, dual frequency operation, and the difference between operation possibilities. Allow. In particular, the PMU provides a simple upgrade capability from the whole to two sectors (or all with two carrier frequencies), three sectors (or all with three carrier frequencies) configurations with a simple connection of additional PRUs only. These capabilities provide key advantages in cellular (PCS) technology with flexibility and easy upgradeability.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention virtually eliminates cable losses by providing a wireless unit that is easy to mount close to the antenna and has a small size. Cable losses reduce the sensitivity of the receiver and reduce the transmit power. Therefore, the present invention allows a low power amplifier with a relatively low power and provides an equivalent transmit power level to a high power amplifier used with conventional BTS.

The inclusion of a transceiver in a wireless unit allows for a lower frequency interface than the RF interface typically used for main units in the prior art. The low frequency interface allows for the use of inexpensive and small diameter internal connection cables between the radio unit and the main unit since the cable loss is low.

As at other frequency bands and at different transmit power levels, as only the wireless unit needs to be modified, the separation of the RF elements and the dependencies of those elements are necessary for the BTS design to support different RF operating environments or situations. Facilitate adaptation The same applies to the main unit. This also results in the main unit having a small size to facilitate processing and mounting. This also requires less space if no RF elements are mounted. At the same time, less heat is generated in the main unit which must be kept cool.

This structure allows BTS to be formed to support full or partial operations or to upgrade partial operations from the whole when a traffic request goes up. This is particularly important in CDMA systems where softer handoffs are supported between sectors. For two or three sector structures, two and three radio units are required, respectively. The three radio units may operate on the same frequency within the three sector structure or on different frequencies within the three carrier overall configuration.

The present invention also allows the coupling of different sets of three radio units connected to their own main unit to the same antenna without using a combiner.

By placing the transceiver module in the wireless unit, only low frequency signals need to be passed from the transceiver module and the main unit. On the receiving side, the transceiver module converts the high frequency signal into a low frequency signal. On the transmitting side, the transceiver module converts the low frequency signal from the main unit into a high frequency signal for transmission. Therefore, only low frequency signals are passed between the radio unit and the main unit, whereby power consumption in the cables connecting the two units is minimized. This gives the ability to use smaller diameters, resulting in lower cables.

In addition, by removing the transceiver subsystem from the main unit has the advantage that the physical size of the main unit is smaller and lighter. This not only makes it flexible to meet the technical requirements for meeting environmental considerations or operating instructions, but also makes installation and management easy.

In addition, small and light BTSs are particularly convenient for pico-cell applications or micro-cell applications where a larger number of BTSs are required than are needed for macro-cell implementations.

Since the entire transmission functionality is included in the radio unit, the radio unit only receives baseband signals for transmission data. And perform both amplification and up-conversion in the wireless unit. This eliminates the need to send RF signals to the wireless unit. This allows the radio unit to operate at higher efficiency than the unit where the RF signal must travel the length of the pole. Since the up-conversion takes place in the wireless unit, direct conversion reduces the complexity of the transmission signal line, and a significant cost reduction can be obtained for a system in which the transmission signal climbs the pole and up-converts back to RF. Compared to the prior art, the present invention requires fewer RF elements. An output power calibration can be performed at the factory and the wireless unit can be programmed to be used for any Mean unit. The wireless unit not only reduces the power setting in the local memory but also stores the full power setting. Therefore, cell size adjustment from the wireless unit is made from the wireless unit instead of the BTS.

The increase or decrease of attenuation can be made in the wireless unit rather than in the BTS. Output power detection is also performed in the wireless unit and can be used to confirm the integrity of the entire signal transmission path.

All wireless units or main units can be replaced, making system upgrades easier. In addition, similar elements can be formed together so that board or device level upgrades can be made easier than for traditional BTS units.

Claims (22)

A base station transmit / receive subsystem for a telephony system, A first main unit for processing the first transmit / receive frequency pair, Is wirelessly connected to the first main unit via a first cable, A first transmitter for transmitting a first transmission frequency coupled to the first transmission / reception frequency pair, A first receiver for receiving a first reception frequency coupled to the first transmission / reception frequency pair, A first diversity receiver for receiving the first reception frequency A first wireless unit having: A first antenna for transmitting the first transmission frequency from the first transmitter and receiving the first reception frequency for the first receiver; And a second antenna for receiving the first reception frequency for the first diversity receiver. 2. The base station transmit / receive subsystem of claim 1 wherein the telephony communication system is a code division multiple access communication system. The method of claim 1, Is wirelessly connected to the first main unit via a second cable, A second transmitter for transmitting a second transmission frequency coupled to the second transmission frequency pair, A second receiver for receiving a second reception frequency coupled to the second transmission / reception frequency pair, A second diversity receiver for receiving the second reception frequency Further provided with a second wireless unit having, The first antenna receives the second reception frequency for the second diversity receiver, the second antenna transmits the second transmission frequency from the second transmitter and the second receiver for the second receiver And a base station further comprising a frequency. 2. The base station transmit / receive subsystem of claim 1 wherein the first and second antennas are substantially positioned near the first wireless unit. The method of claim 1, And circuitry for separating the received signal from the first receiver and providing the separated portion of the received signal to the second wireless unit. 2. The base station transmit / receive subsystem of claim 1 wherein the first diversity receiver comprises circuitry for receiving the first reception frequency from the second radio unit. A base station transmit / receive subsystem for a telephony system, With the first antenna, With the second antenna, A first wireless unit connected to the first antenna and transmitting a first transmission frequency through the first antenna and receiving first and second reception frequencies; A second wireless unit connected to the second antenna and transmitting a second transmission frequency through the second antenna and receiving first and second reception frequencies; And the first wireless unit provides the received second reception frequency to the second wireless unit, and the second wireless unit provides the received first reception frequency to the first wireless unit. Subsystem. 8. The base station transmit / receive subsystem of claim 7, wherein the second receive frequency provided by the first wireless unit to the second wireless unit is used as a diversity signal within the second wireless unit. 8. The base station transmit / receive subsystem of claim 7, wherein the first received frequency provided by the second wireless unit to the first wireless unit is used as a diversity signal within the first wireless unit. 8. The base station transmit / receive subsystem of claim 7, further comprising a first main unit remotely connected to the first wireless unit. 12. The base station of claim 10, wherein at least another radio unit is located away from the first main unit to communicate with the first main unit for transmitting the first transmission frequency and receiving the first reception frequency. Sending and receiving subsystem. 8. The base station transmit / receive subsystem of claim 7, further comprising a second main unit remotely connected to the second wireless unit. 8. The base station transmit / receive subsystem of claim 7, wherein the first and second wireless units are substantially identical. 8. The base station transmit / receive subsystem of claim 7, wherein the telephony communication system is a code division multiple access communication system. 8. The base station transmit / receive subsystem of claim 7, wherein the first and second antennas are omnidirectional antennas. 8. The base station transmit / receive subsystem of claim 7, wherein the first and second antennas are arranged to transmit and receive within a predetermined sector. A base station transmit / receive subsystem for a telephony system, A first main unit for processing the first communication frequency pair; Remotely connected to the first main unit through a first cable, A first transmitter for transmitting a first transmission frequency coupled to the first transmission / reception frequency pair, A first receiver for receiving a first reception frequency coupled to the first transmission / reception frequency pair, A first wireless unit having: And a first antenna for transmitting the first transmission frequency from the first transmitter and for receiving the first reception frequency for the first receiver. 18. The base station transmit / receive subsystem of claim 17, wherein the telephony communication system is a code division multiple access communication system. The method of claim 17, A first main unit for processing a second communication frequency pair; Remotely connected to the second main unit via a second cable; A second transmitter for transmitting a second transmission frequency coupled to the second transmission frequency pair, A second receiver for receiving a second reception frequency coupled to the second transmission / reception frequency pair A first wireless unit having: And a second antenna for transmitting the second transmission frequency from the second transmitter and receiving the second reception frequency for the second receiver. The method of claim 19, wherein the first wireless unit, And a first diversity receiver for receiving said first frequency from a signal path connected to said second antenna. A method for receiving communication signals in a base station transmission / reception subsystem having a first main unit and a first wireless unit disposed far away from the first main unit and communicating with the first main unit, Receiving first communication signals from the first antenna; Inputting the first communication signals to the first wireless unit; Amplifying the first communication signals; Separating power of the first communication signals, providing a first portion of the first communication signals to a first receiver circuit, and providing a second portion of the first communication signals to a first output of the first wireless unit Process, Providing the output signal from the first receiver circuit to the main unit. 22. The method of claim 21, further comprising: receiving second communication signals from the second antenna; Inputting the second communication signals to one of the first wireless unit or the second wireless unit, Processing the second communication signals as a first diversity signal when the first communication signals are input to the first wireless unit, When the second communication signals are input to the second wireless unit, Amplifying the second communication signals; Separating power of the second communication signals, providing a first portion of the second communication signals to a second receiver circuit inside the second wireless unit, and providing a second portion of the second communication signals to the second portion; And providing a first output of the second wireless unit connected to the wireless unit, wherein the second portion of the second communication signals is processed as a first diversity signal. .