MXPA96003601A - Station of cellular base of phase formation and associated methods for better energy efficiency - Google Patents

Abstract

A base station includes a radio channel generating circuit for generating a plurality of individual radio channel signals each of a frequency different from the other, and a plurality of individual phase-forming antennas operably connected to the generator's generating circuit. radio channel so that each individual phase training antenna transmits only one individual radio channel signal at a time. Each of the preferential training antennas includes a substrate and a plurality of emitter elements mounted thereon in a predetermined pattern. Each emitter element is rapidly provided by a strip line and the substrate is preferably a circuit board. Correspondingly, another particulity of the base station according to the invention is that the energy emitted by each phase-forming antenna can be selectively controlled to reduce possible interference while maintaining communications with the respective mobile units that are both close as away from the base station. A switch can be provided between the radio channel generating circuit and the phasing array antennas to facilitate cell division. The aspects of the method for operating the water station are also disclosed

Description

"CELLULAR BASE STATION OF FORMATION IN PHASE AND METHODS ASSOCIATES FOR ENHANCED ENERGY EFFICIENCY " FIELD OF THE INVENTION The present invention relates generally to communication systems and, more specifically, to a cellular radio communication system.

BACKGROUND OF THE INVENTION Cellular communication systems are commonly used to provide voice and data communications to a plurality of mobile or subscriber units. Analogue cellular systems such as those designated AMPS, ETACS, NMT-450 and NMT-900, have been successfully deployed throughout the world. More recently, digital cellular systems such as the designated IS-54B system in North America and the pan-European GSM system have been introduced. These systems and others are described, for example, in a book called CeJluJar Radio Systems by Balston et al., Published by Artech House, of Norwood, MA. , in 1993. Frequency reuse is commonly used in cellular technology where groups of Frequencies are assigned for use in regions of limited geographic coverage that are known as cells. Cells containing groups of equivalent frequencies are geographically separated to allow mobile units in different cells to simultaneously use the same frequency without interfering with one another. By doing so, many thousands of subscribers can be served by a system of only several hundred frequencies. In the United States, for example, federal authorities have assigned cellular communications a block of UHF frequency spectrum further subdivided into pairs of narrow frequency bands called channels. The channel pairs result from the double frequency arrangement where the transmit and receive frequencies in each pair are off-center by 45 MHz. Currently there are 832 radio channels of a width of 30 Hz allocated to cellular mobile communications in the U.S. To address the capacity limitations of this analog system, a designated digital transmission standard IS-54B has been provided, wherein these frequency channels are further subdivided into 3 intervals or time slots. As illustrated in Figure 1, a cellular communication system 20 as in the prior art includes one or more mobile stations or units 21, one or more base stations 23, and a mobile telephone switching office 25 (????). Although only three cells 36 are shown in Figure 1, a typical cellular network may comprise hundreds of base stations, thousands of mobile stations and more than one MTSO. Each cell will have assigned to it one or more dedicated control channels and one or more voice channels. A typical cell can have, for example, a control channel and 21 voice / data or traffic channels. The control channel is a dedicated channel used to transmit cell identification and information. Traffic channels carry voice and data information. The MTSO 25 is the central coordinating element of the total cellular network. It typically includes a cellular processor 28, a cellular switch 29 and also provides the interface to the public switched telephone network (PSTN) 30. Through the cellular network 20, a duplex radio communication link can be made between two mobile stations 21 or, between a mobile station 21 and a wireline telephone user 33. The function of the base station 23 is commonly to handle the radio communication with the mobile station 21. In this capacity the base station 23 works mainly as a relay station for data and voice signals. The base station 23 also monitors the quality of the link 32 and monitors the resistance of the signal received from the mobile station 21. A typical base station 23 as in the prior art is illustrated schematically in Figure 2 which shows, as an example, the functional components of model number RBS 882 manufactured by Ericsson Telecom AB, Stockholm, Sweden, for the cellular mobile phone system CMS 8800. A full description of this analog cellular network is provided in the publication number EN / LZT 101 908 R2B, published by Ericsson Telecom AB. A common list now along many roads is the base station 23 which includes a control unit 34 and an antenna tower 35. The control unit 34 comprises the electronics of the base station and is usually placed within a rugged enclosure at or near the base of the tower. Within this envelope are the radio control group 37 or RCG, an interchange radio interface (ERI) 38 and a primary power supply 41 for converting electric power from the alternating current grid to energize the individual components within the base station 23 and a backup power supply 42.

The ERI 38 provides signals between the TSO 25 and the base station 23. The ERI 38 receives the data from the RCG 37 and transfers the same to the MTSO 25 in a link 45 dedicated to the MTSO-BS. In the reverse direction, the ERI 38 receives the 5 data of the MTSO 25 and sends the same to RCG 37 for subsequent transmission to a mobile station 21. The radio control group 37 includes the electronic equipment needed to carry out radio communications, a functional diagram of an RCG 37 as in The prior art is shown in Figure 3. The configuration shown illustrates a control channel transmit / receive module (TRM) 51, a number of voice channel TRMs 52 and a signal resistance receiver 53 as it is a typical configuration required to give service to a cell or sector of a cell. Each TRM 51, 52 includes a respective transmitter 54, a receiver 55 and , ^, a control unit 57. The TRMs 51, 52 are typically non-agile in frequency and operate a single predetermined channel instead. The control signals of the ERI 38 are received by the individual control units 57. The voice and data traffic signals are sent through a separate interface to the ERI 38. Each individual transmitter 54 for control and voice 25 is connected to a transmitter combiner 58. The combiner The transmitter combines all the input signals into a single output coupled through a coaxial cable 62 to the transmitting antenna 63. Through the use of combiner 58, up to 16 transmitters 54 can typically be connected to a common transmitting antenna 63. The combiner 58 is used because there is often a need for space in the masts and towers used to support the antennas. In an extreme case, a mast may be required to hold more than 100 radio channels. The individual transmit signals are amplified before being combined and, therefore, the PRMs 51, 52, have relatively high output power to overcome the losses through the transmitter combiner 58 and the interconnecting cable 62. Typical TRMs have average output power levels between 10 and 50 watts. On the receiving side, each of the two receiver antennas 65 is coupled with a respective receiver combiner 66A, 66B, wherein the received signals are separated according to the frequency and passed to the individual receivers 55 in each of the receivers. TRM 51, 52. The two receiver antennas 65 are typically spaced 3 to 5 meters apart in the tower so that they receive signals with uncorrelated fading patterns to thereby provide reception of diversity of space. There are many conventional techniques for both the diversity of pre-detection and post-detection that are described, for example, in chapter 10 of the book called "Mobile Communications Engineer", by William C.Y. Lee, published by McGraw-Hill, in 1992. Usually it is necessary to control the environment inside the envelope for the electronics of the base station, by means of an HVAC equipment, that is, heating, ventilation and air conditioning. On average, the typical envelope of the base station is about the size of a large truck. A visible feature of the typical base station 23 is the antenna tower 35. In order to achieve a reasonable coverage area, the antennas 63, 65 are desirably mounted at some distance above the ground. Referring now also to the schematic plan view illustration of the prior art of Figure 4A, in rural areas, the towers 35 are placed locally in the center of a cell 36, thus providing omni-directional coverage. In an omni-directional cell, the control channel (s) and the active voice channel (s) are broadcast in all areas of the cell - usually from a single antenna. When the base stations 23 are placed more densely, a antenna system in sectors as in the prior art and which is shown by the schematic diagram of Figure 4B. Division into sectors requires directional antennas 70 having, for example, a 120 degree radiation pattern, as illustrated in Figure 4B. Each sector 71 per se is a cell that has its own control channel (s) and traffic channel (s). Note that the term "channel" may refer to a specific carrier frequency in an analog system or to a specific carrier / interval combination in a hybrid TDMA / FDMA system, such as IS-54 and GSM. Figure 5A illustrates a typical antenna system as in the prior art and as discussed above. Figure 5B illustrates two types of antenna of the prior art discussed above - an omni-directional antenna such as a dipole 66, and a directional sector antenna 70 that also includes a reflector 64, for example. It should be understood that the transmitting and receiving antennas are typically of the same type for a given base station. 23 stations of cell bases have been deployed worldwide at cell sites. Currently, the total footprint for a cell site is quite large. Surrounded frequently by a chain link fence, the amount of land required to place a station 23 typical base, can be large. In most urban areas, the cost of the land on which the site is placed is often comparable to the cost of the equipment itself. In addition to the cost of acquiring 5 land, taxes can be a significant operating cost. Therefore, it would be advantageous to reduce the footprint of a typical cell site. Likewise, contributing significantly to the operating cost of a cellular base station is the cost of the energy consumed. In addition to the HVAC equipment for environmental control, the direct current energy requirements for generating radio frequency energy can be quite high. The solid-state power amplifiers placed typically at each TRM 51, 52, operate at between 25 percent to 65 percent of the DC to RF efficiency, > r.f depending on whether the amplifier is linear or saturated. In addition, since the loss of 3 to 4 dB of the typical transmitter combiner 58, there are transmission losses Significant through cable 62 coaxial from RCG 37 up tower 35 and up to transmitting antenna 63. It is not unusual to experience a total loss of 10 dB or more through these paths resulting in only 10 percent of the RF energy generated is actually emitted by the antenna.

The use of training antennas in scanning phase in cellular communications systems has been proposed of course. For example, Stapleton et al., A Cellular Base Phased Array Antenna System, Proceedings of the 93rd IEEE VTC, pages 93 to 96 describe a circular array of monopole emitting elements to provide 360 degree scanning capability. In order to provide diversity of space, the Stapleton antenna is designed in such a way that each emitting element has the potential to transmit on each channel assigned to the cell. The use of phased array antennas for narrow band radar has been widely extended. With emphasis given to highly focused transmissions of short pulse duration, these phase formations called solid state or active usually employ Class C power amplifiers behind each emitter element. In order to develop highly directive beams, a typical formation for a search radar may have hundreds if not thousands of individual broadcast elements. These antennas are discussed extensively in the Skolnik article, Radar Handbook, McGraw-Hill, 1990, chapters 5 and 7. It should be noted that passive microtira formations are also currently obtainable for use eon the cellular base stations. For example, type number 1309.41.0009 manufactured by Huber + Her ner AG of Herisau, Switzerland, is a linearly polarized seven-element flat panel passive antenna with a lifting beam configured for use in cellular base stations. This formation can replace the typical dipole antenna and is more appropriate for locations on the sides of buildings or other flat surfaces. In the application note 20.3, published by Huber + Shuner, it is shown that wide area coverage can be obtained through the use of energy dividers whereby portions of the signals are diverted to different individual panels. Unfortunately, both phase training antennas described above require a multiple carrier energy amplifier or MCPA, for the simultaneous illumination of a specific sector with two or more frequencies as is common in cellular systems. In a multi-carrier system, intermodulation requirements need parasitic noise suppression of more than -65 dB for third-order products. To reduce intermodulation distortion, an MCPA must therefore operate in a highly energy inefficient linear mode, thereby reducing total energy efficiency.

COMPENDIUM OF THE INVENTION In view of the foregoing background, it is therefore an object of the present invention to provide a base station of the cellular communication system and an associated method that addresses the practical problems of increased energy efficiency and that reduces the size of the site of the cell. It is also an object of the present invention to provide a base station and an associated method for facilitating the use of active phase-forming antennas, while reducing the emission of parasitic signals, such as intermodulation products. These and other objects, advantages and features of the present invention are provided by the base station including a radio channel generation means for generating a plurality of individual radio channel signals, each at a different frequency from the other, and a plurality of individual phased array antennas operably connected to the radio channel generating means so that each individual phased array transmits only one individual radio channel signal at a time. Therefore, the products of Intermodulation are considerably reduced compared to multiple radio channels, transmitters of the phased array at different frequencies at once. In addition, the present invention allows individual amplifiers to be incorporated into phase forming antennas to thereby significantly reduce the cable transmission losses associated with the delivery of radio frequency energy to a conventional antenna, for example. The total improvement of the frequency of direct current to radio frequency reduces the size of the power supply of the required equipment and reduces the problem of thermal management thus also reducing operating costs and improving the reliability of the system. Each of the preferential training antennas includes a substrate and a plurality of emitter elements mounted thereon in a predetermined pattern. Each emitter element of preference is provided by a strip line and the substrate is preferably a circuit board. Accordingly, another feature of the base station according to the invention is that the energy emitted by each phase-forming antenna can be selectively controlled to reduce the difficulties associated with communication with the respective mobiles whether they are close or withdrawn. from the base station. More specifically, the base station preferably includes a signal quality receiving means for receiving a signal from a mobile unit related to the signal quality received in the mobile unit, and also includes an antenna power control means for selectively operating the predetermined elements of the emitting elements in each respective phase-forming antenna that responds to the quality of the signal received in the mobile unit. Alternatively, the resistance of the signal can be detected at the base station. Therefore, the emitted energy and / or beam width from the antenna can be selectively controlled to maintain a sufficient level of energy received in the mobile unit for good communications, however, it should not provide too much power, particularly for a mobile close, so as to create an unnecessary possibility of interference, for example. The radio channel generating means may preferably be placed adjacent to the lower portion of the tower of the base station antenna and the linking means such as the coaxial cables may be used to supply the radio channel with signals to the antennas of training in phase. Alternatively, the radio channel generating means may be placed in the tower or be made integral with phased array antennas to further reduce radio frequency energy losses. The base station also preferably includes a receiving antenna placed adjacent to the transmitting phase-forming antennas. The receiving antenna is also preferably a phased array antenna capable of receiving a plurality of individual radio channel signals, each at a frequency different from the other from a plurality of mobile units. Accordingly, the receiving antenna may also preferably include a combination network mounted thereon and connected to the elements of the receiving antenna to coherently couple the signals received in this manner, and a low noise amplifier mounted on the antenna and connected with the combination network to amplify a signal of the same. The base station also preferably includes a modulator means for modulating a plurality of radio frequency carriers with the respective input or information signals to thereby generate the plurality of individual radio channel signals. In one embodiment, the input signals may be multiplexed into time division, in repetitive multiple frame time intervals.

Still another advantageous feature of the present invention is that it can be provided in a switch between the radio channel generating means and the phasing array antennas in such a manner as to facilitate cell division. More particularly, the burner is movable between first and second positions so that in the first position, the switch is coupled together with two or more predetermined phasing antennas to increase the energy of the antenna emitted for a radio channel signal respective. In the second position, the switch decouples the two or more predetermined phase-forming antennas and facilitates increasing the capacity of the radio channel for the base station, i.e., the division of the cell. The aspects of the method of the present invention relate to the operation of the base station as described above. One method is to operate the base station for improved energy efficiency and includes the steps: generating a plurality of individual radio channel signals each at a different frequency from the other; and operating each individual phase training antenna to transmit only one individual radio channel signal at a time. Accordingly, active phase-forming antennas can be used to reduce losses typically associated with the supply of radio frequency energy from the ground to an antenna mounted in a tower, as in conventional cellular communications systems. Another aspect of the method relates to controlling the output power emitted from the phasing antennas and includes the steps of: generating a plurality of radio channel signals and transmitting them through at least one training antenna in phase, receiving a signal from a mobile unit related to the quality of the signal received in the mobile unit and selectively operating predetermined elements of the emitting elements in response to the resistance of the signal detected from the mobile unit. Accordingly, a desired amount of energy or a desired beam shape can be produced to secure communications, while reducing the possibility of unnecessary interference. Another aspect of the method relates to facilitating the division of the cell as is typically required as the number of mobile units in a given cell increases. The method includes the steps of: generating a radio channel signal and supplying the same to two or more predetermined phase formation antennas coupled together to increase the energy of antenna emitted for the radio channel signal; and subsequently decoupling the two or more predetermined phase-forming antennas and operating the two or more predetermined phase-forming antennas with the respective different radiofrequency channels to thereby increase the capacity of the radio channel for the base station.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features and advantages of the present invention will become readily apparent to a person skilled in the art of the following written description, read in conjunction with the drawings in which: Figure 1 is a schematic functional diagram illustrating the basic components of a cellular communication system, such as in the prior art; Figure 2 is a schematic functional diagram illustrating the functional components of a cellular base station as in the prior art; Figure 3 is a functional schmatic diagram illustrating the functional elements of the control group radio of a base station, as in the prior art; Figure 4A is a schematic plan view illustrating an omni-directional cellular pattern as in the prior art; Figure 4B is a schematic plan view illustrating a cellular pattern in sectors as in the prior art; Figure 5A is a schematic side view illustrating a typical cellular antenna system as in the prior art; Figure 5B is a schematic side view illustrating an omni-directional antenna and a sector antenna as in the prior art; Figure 6 is a schematic functional diagram illustrating a base station of the cellular communication system in accordance with the present invention; Figure 7 is a schematic functional diagram of a transmitter / receiver module used in the base station in accordance with the present invention; Figure 8 is a schematic plan view illustrating a typical arrangement of the antennas according to the invention having three sectors that they are served by one, two and three carrier frequencies each; Figure 9 is a schematic plan view of the theoretical downlink coverage patterns, as produced by the arrangement shown in Figure 8; Figure 10 is a schematic functional diagram illustrating the relationship between intervals, frames, transmission of multiple frames in GSM as in the prior art; Figure 11 is a schematic functional diagram of a modaliad of the base station according to the invention illustrating how capacity and emitted energy can be negotiated to facilitate cell division; Figure 12 is a schematic functional diagram of a base station embodiment according to the invention, illustrating a method for effecting control of the emitted energy; and Figure 13 is a schematic diagram of a base station embodiment according to the invention illustrating a method for effecting the coupled energy by changing the light beam shape of a phased array antenna.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The present invention will now be described more fully below with reference to the accompanying drawings, wherein the preferred embodiments of the invention are shown. This invention, however, may be encompassed in many different forms and should not be construed as being limited to the embodiments set forth herein. Instead, these embodiments are provided so that this disclosure is complete and complete and fully conveys the scope of the invention to those skilled in the art. Equal numbers refer to the same elements. 15 Even though the proposed invention can be used with any cellular or mobile radio transmission standard "?, Known terrestrial, it is visualized that it may be particularly appropriate for use with the pan-European GSM system: Therefore, where appropriate, the specific examples presented here will all be directed towards an implementation of the GSM system. This is done to ensure that the description of the preferred embodiments will be readily understood by those skilled in the art, while Those skilled in the art will appreciate that the present invention can easily and quickly adapt to different transmission standards. First, a proposed base station according to the invention will be described. After this, a detailed description illustrating the way to advantageously use the proposed base station in a cellular communication system will be provided. Referring first to FIGURE 6, a mode of the base station 80 according to the present invention is shown, configured for an exemplary arrangement that covers a sector with three carrier frequencies. This specific provision is selected due to its simplicity and is not intended to be limiting. It is visualized for example that a typical base station may have eight or more carriers and therefore, eight or more transmit antennas per sector / cell. From the following description of this example, those skilled in the art will be able to easily expand these exemplary configurations that have many carriers and / or many sectors / cells. The base station 80 includes an antenna system 81, an inter-installation link 82 (IFL) 82, and the radio control group (RCG). The RCG 83 is preferably a grid-mounted assembly that in a mode is physically separated from the antenna system 81 through the IFL 82. The RCG provides the radio channel generating means for generating a plurality of individual radio channels at different frequencies. The IFL 82 provides a link means and preferably includes a bundle of coaxial cables, power cables and is typically a few tens of meters in length. It is visualized that the base station 80 in this mode will have the RCG 83 placed on the ground and housed in an environmentally protected enclosure. The antenna system 81 will typically be placed in a tower 86 or otherwise raised above the ground. It is also possible to have an RCG 83 placed intermediate in the tower or incorporated per se in the antenna system 81. If RCG 83 is to be placed in this manner, careful consideration must be given to provide adequate protection against lightning, as will be readily understood by those skilled in the art. In any arrangement, the RCG outputs 85 are interconnected with a conventional interchange ray interface (ERI) 90 and subsequently with the MTSO 91 and with the rest of the network through a conventional means as will be easily understood by those skilled in the art. in the technique. In fact, it is envisioned that the proposed base station 80 can be used to improve existing cellular systems by replacing a system of existing antenna, IFL and conventional RCG with the components as described herein. Again RCG 81 can therefore be plugged directly into the inputs of an existing ERI. The base station 80 in accordance with the present invention utilizes a single carrier by active formation. As shown in the embodiment illustrated in FIGURE 6, the base station 80 includes three antennas or panels 95A, 95B and 95C of separate active formation to transmit each of the three frequencies assigned to the sector / cell. Base station 80 also includes a single receiving antenna 96 capable of receiving all transmitting frequencies. Each active training panel includes a plurality of radiofrequency energy amplifiers 101 each coupled through a filter 102 with an individual emission element 103. The energy is distributed to each power amplifier 101 through the energy divider network illustrated schematically only for the active A formation 95A by the irradiated ion block 105. In this embodiment, the components mentioned above are preferably manufactured using a strip line or microtira techniques on a mounting substrate such as a board glass-epoxy printed circuit as will be readily understood by those skilled in the art. The power divider 105 is a network for distributing the radio frequency energy from a single input to several outputs and preferably it can be a Wilkinson power divider, a branch guide divider or coupled on the edge, or other devices for dividing well-known energy, such as described in Chapter 5 of the Bahl article, and others, Microware Solid State Circuit Design, Wiley & Sons., 1988. The power divider 105 is preferably designed to provide coherent phase outputs to each power amplifier 101. The input energy can be divided equally and in phase between all the inputs of the power amplifier 101; This is known as uniform illumination and produces a symmetrical emission pattern. Alternatively, small and / or off-center phase energy imbalances may be provided if one wishes to configure the emission pattern in accordance with basic training theory. A discussion of energy imbalances and phase offsets can be found in Brookner Part 2, Practical Phased-Array Antenna Systems, Artech House, 1991. Another reference on the basic theory of training can be found in Chapter 7 of the Skolnik article, Radar Handbook Second Edition, McGraw Hill, 1990. In the illustrated embodiment, power amplifier 101 may preferably be a 1-2 watt device such as part number GT-1867 manufactured by GigaTec, Inc. of 942-1 Shimosatomi Haruna-machi Gunma-gun Gunma-ken 370-33 Japan. The power amplifier 101 desirably is suitable for integration with a microtraft circuit it can be operated in a linear saturated mode depending on whether the modulation of the radio frequency signal is respectively a constant or non-constant envelope. For an analog system that uses frequency modulation, the amplifier can be operated as a saturated class C device that has high direct current to radio frequency efficiency. For certain digital modulations, for example, DQPS shifted in // / 4, the amplifier 101 is preferably operated as a linear Class A device having lower RF direct current efficiency, but which produces an amplified duplicate of the variations of the envelope of the input signal. The power amplifiers 101 can produce broadband noise outputs at frequencies that overlap the receiving frequency band. These can be of a level such as to degrade the noise figure of the amplifier 110 receiver. To improve the spectral purity of the transmitted signal, the output of each power amplifier 101 is preferably coupled with a respective filter 102. The filter 102 is preferably a microtire notch filter, such as that described in Chapter 6 of the Bahl article, and others, Microwave Solid State Circuit Design, Wiley & Sons, 1988. Filter 102 preferably attenuates signals that overlap the receiving frequency band. Depending on the system bandwidth and the frequency assignment, the filter 102 may preferably be a bandpass filter with the passband centered around the transmitting frequency. Alternatively, a low pass or high pass filter may also be appropriate. The output of each filter 102 is illustratively coupled with a respective emission element 103 which can preferably be a linearly polarized microtire correction antenna as described on pages 7-1 to 7-14 of Johnson's article, and others. , Antenna Engineering Handbook - Second Edition, McGraw-Hill, 1984. Alternatively, a polarized circulating correction antenna, as described on pages 7 to 14 to 7 to 16 of the aforementioned reference, may be used equivalently.In the illustrated embodiment of the base station 80, the panels 95A, 95B and 95C of transmitting active formation preferably are identical. The receiver training panel 96 preferably is an antenna array formed of the microstrip correction elements 97. As with the transmitting active training panels, the receiver panel 96 is preferably constructed of a glass-epoxy circuit board using strip or microtire line techniques, as will be readily understood by those skilled in the art. The antenna elements 97 again preferably are microtire correction radiators as described above. Preferably correction antenna elements 97 are linearly polarized correction antenna elements. It is preferred if both transmitter and receiver panels exhibit the same polarization - the normally vertical linear polarization. The receiver antenna elements 97 are coupled with a common transmission line 98, through a combination network 99. Basically, the inverse of the power divider network 105, the combining network 99 coherently couples the signals received from the training elements 97 into a common output. As above, the combination network 99 can introduce phase offsets or tapered coupling in order to effect the configuration of the beam of light or reduce the side lobes. The output of the combination network 99 is illustratively coupled with a low noise amplifier 110 (LNA). Traditionally, a similar LNA was placed in the RCG of a conventional base station, and, correspondingly, the received signal suffered from 2 to 4 dB of transmission loss through the IFL cable. By placing the LNA 110 in the receiver antenna panel 96, in accordance with another advantage of the present invention, the losses before the amplification are reduced thereby benefiting the total system noise figure and allowing the receiving antenna gain to be reduce in this way. The amplified receiver signal of the LNA 110 is also preferably filtered to remove unwanted signal components, such as those generated by the power amplifiers 101. Therefore, the output of the LNA 110 is preferably coupled with the bandpass filter 112. The bandpass filter 112 may preferably be a microtray edge coupled filter, as described in Chapter 6 of the Bahl article, and others, Microwave Solid State Circuit Design, iley & Sons, 1988. Depending on the bandwidth of the system and the separation of the channel, it can also be a low pass filter, or a high pass filter acceptable as will be readily understood by those skilled in the art. Both the transmit signals and the receiver signals are coupled with / of the antenna system 81 through an inter-installation link (IFL) 82. In the illustrated embodiment, the IFL preferably comprises a bundle of coaxial cables 154, and power cables (not shown) to provide power to the power amplifiers 101 and the LNA 110. The radio control group 83 preferably includes a plurality of transmitter / receiver modules (TRM) 120. Referring now further to FIGURE 7, explains the TRM 120. The TRM 120 preferably comprises the radiofrequency hardware and the electronics necessary to effect the conversion of an information signal to a radio frequency output and vice versa for a receiving signal. The preference information signal is digitized to a bitstream comprising a digital phase sequence and / or phase and amplitude information and is received from the ERI by conventional means. For cellular GSM systems, the information signal represents a GMSK waveform.

For IS-54 systems, the information signal represents a DQPSK waveform shifted by // / 4. The The generation of both of these types of signals can be easily understood by those skilled in the art as well as the other modulation techniques. The information signal is coupled with a modulator 121 wherein the amplitude and / or the phase and the amplitude information are printed at a reference frequency to create a baseband signal coupled with a mixer 123 where it is mixed with a the predetermined radio frequency carrier frequency generated by a reference oscillator 127 and a channel synthesizer 128. The reference oscillator 127 is also coupled to the modulator 121 through the multiplier 129 in the illustrated mode. The frequency of the radiofrequency carrier is selected in response to the commands that are obtained from the ERI. The output of mixer 123 is coupled with a transmitter filter 124 to remove unwanted mixer products. After filtering, the modulated radiofrequency carrier is coupled through the coaxial cable 115 illustratively defining the IFL 82 with the transmission line 116 in the active forming panel 95A where it is emitted as described above (FIGURE 6). An identical process occurs on a separate carrier frequency in each of the other TRMs.

Still referring to FIGURE 7, signals received from receiver training panel 96 are coupled to a receiver circuit 130 where the modulated radio frequency carrier is converted to a baseband signal and demodulated by the illustrated arrangement of the first and second mixers 132, 134, respectively, driven respectively through a local oscillator and the associated local oscillator filter 135 and through a second synthesizer 137 of the local oscillator, respectively. Three IF filters 141 and 142 are also shown in the illustrated embodiment to downwardly convert the receiver signal to the baseband and demodulate the downconverted signal. Accordingly, two signals are generated: an IF signal and a signal indicating the resistance of the received signal (RSSI) as illustrated. In FIGURE 7 an appropriate arrangement for demodulating an LDQPSK signal shifted by rr / 4 is shown. An example of this demodulation technique is described, for example, in U.S. Patent No. 5,048,059 entitled "Log-Polar Signal Processing" issued to Dent and assigned to the present concessionaire, the disclosure of which is incorporated herein by reference. A person skilled in the art can easily observe that the GMSK demodulator, or another, can be used of course. The output of the receiver circuit 130 is an information signal that can be processed in the TRM 120 or passed through the ERI for subsequent processing in accordance with conventional techniques. FIGURE 8 is a schematic plan view illustrating an exemplary arrangement for using the proposed base station 80 described above. This arrangement provides an omni-directional coverage by dividing a cell into three sectors each having, for example, a different number of assigned frequencies. The active phase forming antennas 151, 152, 153, 155, 156 and 157 are placed in a triangular assembly 160 and oriented to provide coverage in sectors. A conventional dome 162 provides protection of the environment. The sector 1 is defined as approximately that region between the line 165 and the line 166 and is illuminated by the antenna 151 of phase formation. Sector 2 is defined as approximately that region between line 166 and line 167. Sector 2 is illuminated by three antennas of enfase formation. 155, 156 and 157. Sector 3 is defined by that region between lines 167 and line 165 and illuminated by two antennas 152 and 153 of phase formation.

In a one carrier system per channel, such as the United States AMPS system, i.e., ??? 553, is preferably assigned to a frequency to each phase training antenna according to the invention. For this example, a first frequency is assigned to the antenna 151, a second, third and fourth frequency are each assigned to the antennas 155, 156 and 157 respectively, and a fifth and a sixth frequency are assigned to the antennas 152 and 153 , respectively. The frequency assignment is determined by the MTSO which provides control signals through the ERI to the respective TRM associated with each antenna as described above. Even though it is possible that the individual frequency assignments can be changed dynamically, each antenna does not transmit more than one frequency at any moment in time. In FIGURE 9, a theoretical coverage pattern produced by the antenna system of FIGURE 8 is shown, wherein the respective coverage areas for each transmitter are indicated by the respective antenna numbers with a subscript "A". In accordance with the present invention, a le station 171 can receive downlink signals at a first frequency transmitted from the antenna 151. The uplink signals transmitted from the le station 171 will be received by a phase-forming antenna 150. Note that the patterns (not shown) of the receiving antennas 150, 154 and 158 preferably have a sufficient beam width to cover their respective total sectors. In Sector 2, the mobile station 172 can receive downlink signals from all three antennas in this sector. Therefore, the mobile station 172 can be tuned to receive a downlink signal at a second frequency from the antenna 155, a third frequency from the antenna 156 or a fourth frequency of the antenna 157. The mobile station 173 is shown outside of the coverage area of the antenna 157 so that it must be tuned to receive a downlink signal or a second frequency from the antenna 155, or a third frequency from the antenna 156. The uplink signals transmitted by the stations 172 and 173 both mobile are received by receiving antenna 158. The received signals are coupled with the TRMs in the RCG and processed as described in greater detail above. In a TDMA system, such as the pan-European GSM system, each carrier is divided into several time intervals 179. An illustration of the structure of the GSM frame of the prior art is shown in FIGURE 10 and includes a multiple frame 181 divided into a series of frames 180, of TDMA, divided in turn into a series of time intervals 179, as will be readily understood by those skilled in the art. As shown in TDMA table 180 there are eight time slots numbered 0 to 7. Therefore, up to eight mobile stations can occupy a given carrier frequency. In FIGURE 9, for example, the mobile station 171 and seven other mobile stations (not shown) can be serviced from the antenna 151. Similarly, in the sector, three mobile stations 174 and 175 can occupy different intervals of the same frequency transmitted from the antenna 152 or the antenna 153. It may also be noted that the mobile station 174 may occupy for example a time interval transmitted on the first frequency by the antenna 152 and that the mobile station 175 may also occupy the same interval of time transmitted on a second frequency by the antenna 153. In FIGURE 11, another aspect or particularity according to the present invention is shown. Therein is illustrated an arrangement of two transmitting phase forming active antennas 95A and 95B connected through a single shot single pole switch 190 or SPDT. The upper antenna 95A and the lower antenna 95B may be identical to the description above. provided. For reasons of clarity, the IFL 82 and the RCG83 are not shown in FIGURE 11. There are also two TRM 120 as described above which are connected to the ERI. It will be readily appreciated by those skilled in the art, that the effective emitted isotropic power or EIRP, for a phased array antenna is a function of the energy transmitted by each emitting element 103, the number of elements and the gain of the antenna . For example, if each emitter element 103 has a power amplifier 101 of 600 milliwatts coupled thereto, and the emitting element has 11 dBi of gain, then each of the upper and lower antennas 95A, 95B, respectively, have approximately 100 Watts of EIRP. Connected together as when the switch 190 closes, they effectively form a single antenna having approximately 400 Watts of EIRP. In the initial deployment of the new cell coverage there are often relatively few cell sites each having large coverage regions, i.e. large cell diameters. As the number of subscribers increases, cell division is desirable. Cell division is a process by which cell sizes are decreased and increased frequency reuse. The general approach is described for example on pages 301 to 306 of W.C.Y. Lee, Mobile Cellular Telecommunications Systems, McGraw Hill Book Company, 1989. In the initial deployment of a cellular communications system, a base station 80 that includes an antenna configuration as shown in FIGURE 11 can be mounted. The system will first be designed with relatively large cell sizes. In this situation, for example, a single frequency with a high EIRP is required and the switch 190 preferably has an arm coupled with the pole thereby connecting the upper and lower antennas 95A, 95B together with a TRM as shown by the position of the dotted switch, thus effectively forming an antenna having a higher EIRP. As the number of subscribers increases, the base station 80 has the integral capacity to change the size of the cell for capacity. This is achieved by adding another TRM shown on the left of FIGURE 11 in the RCG and moving the switch 190 to the position indicated by the continuous line. In this configuration, the left TRM 120 is connected to the upper antenna 95A and the right TRM is connected to the lower antenna 95B. Each TRM is tuned to a different transmitting frequency as described above. In doing so, without requiring any change to the antenna system, other than readjusting switch 190, a single antenna having 400 Watts of EIRP is changed to two antennas each having 100 Watts of EIRP. As will be readily apparent to a person skilled in the art, increasing the number of frequencies and reducing the transmitting power increases the capacity of the system user. In any cellular communications system there is a so-called "near / far" problem. For example, referring again to FIGURE 4A, two mobile stations 21 are shown in cell 36. One mobile station is positioned near the base station while the other is positioned at the periphery of the remotely removed cell from the base station. To reduce the interference, it is desirable to transmit downlink (and uplink) signals with just enough energy to fill the sensitivity requirement of the respective receivers. It is therefore desirable to transmit a much lower power level to a nearby mobile station than to a remote mobile station. In a cell phone system that employs digital communications, the quality of the signal may be a more important factor than the resistance of the received signal. A distinct advantage in TDMA systems, such as IS-54B and GSM, is that a mobile station can carry out signal quality measurements during otherwise inactive time intervals. More often, these measures are used to determine whether a delivery to another sequence is necessary or not. This method is known as assisted delivery by mobile unit, or MAHO and is well known to those skilled in the art and is described for example in section 3.4.6 of the IS-54B Specification. In accordance with another aspect of the present invention, the signal quality measurements carried out by the mobile station can also form the basis for determining the amount of energy required that is transmitted by the base station. Of course, since it is the quality of the signal and not the resistance of the signal that is typically measured, the energy transmitted by the base station can be brought to the optimum if these signal quality measures are used. The signal quality measurements are carried out in the usual manner and the transmitting energy of the training antenna can be adjusted as will be described below. The manner in which the large changes in the transmitting energy of the aforementioned antenna system are effected has been shown. However, control of practical downlink power requires smaller increments of power adjustment. One modality of invention shown in Figure 12 illustrates a base station 80 to do so. Figure 12 shows the addition to the structure of Figure 11 of a power supply 195 controlled by a microprocessor. For understanding, the individual supply lines 196a-196h to each power amplifier 101 are likewise shown. It is also possible that there are individually steerable power supply lines which are serviced from a common bus supply. In any case, the controllable power supply 195 is capable of connecting and disconnecting the direct current energy to each individual power amplifier 103 in response to the signals received from the ERI. In this example, the next and distant mobile stations of Figure 4A are in the coverage region of the antenna system shown in Figure 12, and both are rendered service by different time slots transmitted at the same frequency from the radio system. antenna. Again referring to Figure 10, it is further assumed that the next mobile station occupies the time slot five of the DMA frame 180 and that the more distant mobile station occupies the time slot three of the TDMA frame. It can be shown that the output energy (ie, EIRP) of the antenna is proportional to the number of active elements squared by: EIRP < N2 (Gain) < PT) If as above, each power amplifier is capable of producing an output of energy, PT of 600 milliWatts and that each element has a gain of 11 dBi, 5 then, the energy values emitted in TABLE 1 that is presented to then they can be built. TABLE I ESSUMINIS¬ , - l 0 TADO TRO OF ACTIVATED? ENERGY 1 196a YES YES YES YES YES YES YES YES YES 2 196b NO YES YES YES YES YES YES YES YES 3 196c NO NO YES YES YES YES YES YES 4 196d NO NO NO YES YES YES YES YES 5 196e NO NO NO NO YES YES YES YES 6 196f NO NO NO NO NO YES YES YES 7 196g NO NO NO NO NO NO YES YES 8 196h NO NO NO NO NO NO NO YES EIRP 7 .5 30.2 67.9 120.8 188.8 271.9 370.1 4Í 33.4 (Watts) For example, if it is required to transmit to the mobile station next 30 watts, then during the time interval five of the power supply lines 196a and 196b of the TDMA board are activated and all others are deactivated. If it is required to transmit to the distant mobile station with the full 480 watts, then during the three time interval of the TDMA board all the supply lines are activated. Other combinations may be used as desired. If the intermediate energy levels are required, they can be obtained by varying the number of power supply lines that are activated during any given time interval. As the number of elements in a phase-forming antenna decreases, the width of the radiation beam increases. This has the advantage that can be exploited in the present invention. In Figure 13 an antenna 95A of phase formation according to the present invention is shown. When transmitting to more distant mobile stations, such as a mobile station 177, it is required to activate a relatively large number of the active elements 103 available. In doing so, the vertical beam width of the antenna 95A and which is schematically illustrated by the dashed line 178, is also decreased, thereby providing a beam of direction towards distant mobile station 177. When it is transmitted to the nearest mobile station 176, it is required that fewer active elements 103 be activated. Since the mobile station 176 can be very close to the antenna tower, it would normally be in a poor coverage region for an antenna having a beam width 178. However, since the decrease in the number of elements 103 active in the antenna has the effect of increasing the vertical beam width indicated by line 179 of dashes, the mobile station 176 is found to be in an acceptable coverage region without having to resort to electronic or mechanical steering of the antenna 95A. Many modifications and other embodiments of the invention will occur to a person skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it should be understood that the invention should not be limited to the specific embodiments disclosed and that the modifications and modalities are intended to be included within the scope of the appended claims.

Claims (33)

CLAIMS:

1. A base station for a cellular communication system, the base station comprises: a radio channel generating means for generating a plurality of individual radio channel signals, each at a frequency different from the other; and a plurality of individual phased array antennas connected to the radio channel generating means so that each individual phased array antenna transmits only one individual radio channel signal at a time.

2. A base station according to claim 1, wherein each of the phased array antennas comprises a substrate and a plurality of emitter elements mounted thereon, in a predetermined pattern.

A base station according to claim 2, further comprising a signal quality receiving means for receiving a signal transmitted from a mobile unit related to the quality of the signal received in the mobile unit, and further comprising a means of antenna energy control connected to the signal quality receiving means and the antennae of phase training for selecting predetermined operating elements of the emitting elements in each respective phased array antenna in response to the quality of the signal received in the mobile unit.

4. A base station according to claim 2, further comprising a signal resistance means for detecting the resistance of the signal received from a mobile unit, and further comprising an antenna energy control means connected to the signal strength means and phasing array antennas in order to selectively operate predetermined elements of the emitting elements in each respective phased array antenna with response to the resistance of the detected signal.

5. A base station according to claim 2, wherein each emitter element comprises a strip line and wherein the substrate comprises a circuit board.

6. A base station according to claim 2, further comprising a respective amplifier connected to each emitter element and mounted on a substrate so that each phased array antenna defines an active phase training antenna.

7. A base station according to claim 1, further comprising a receiving antenna placed adjacent to the phasing array antennas to receive from the mobile units a plurality of individual radio channel signals each at a different frequency from the other.

A base station according to claim 7, wherein the receiving antenna comprises a receiving phase-forming antenna that includes a substrate and a plurality of receiving antenna elements mounted therein, in a predetermined pattern.

9. A base station according to claim 8, further comprising: a combination network means mounted on the substrate of the receiving antenna and connected to a plurality of receiver antenna elements for coherently coupling the signals received in this way; and an amplifying means mounted on the substrate of the receiving antenna and connected to the combination network means for amplifying a signal therefrom.

10. A base station according to claim 1, wherein the generating means of the radio channel further comprises a modulating means for modulating a plurality of radiofrequency carriers with radio signals. respective inputs to thereby generate the plurality of individual radio channel signals.

11. A base station according to claim 1, further comprising a switch means connected between the radio channel generating means and the phase and movable formation antennas between the first and second positions so that the switch when it is in the first position couples together two or more predetermined phase formation antennas to increase the antenna energy emitted for a respective radio channel signal, and so that the switch when in the second position decouples the two or more predetermined phase-forming antennas to increase the capacity of the radio channel for the base station.

12. A base station for a cellular communication system, the base station comprises: a radio channel generating means for generating a plurality of radio channel signals; at least one phase-forming antenna connected to the radio channel generating means, at least one phase-forming antenna comprises a plurality of emitter elements; a signal quality receiving means for receiving a signal transmitted from a mobile unit related to the quality of the signal received in the mobile unit; and an antenna power control means connected to the signal quality receiving means and at least one phased array antenna in order to selectively operate the predetermined elements of the emitting elements responsive to the quality of the received signal in the mobile unit.

13. A base station according to claim 12, wherein at least one phase forming antenna further comprises a substrate on which the plurality of emitter elements are mounted.

14. A base station according to claim 13, wherein each emitter element comprises a strip line, and wherein the substrate comprises a circuit board.

15. A base station according to claim 13, further comprising a respective amplifier connected to each emitter element and mounted on the substrate so that at least one phased array antenna defines an active phase training antenna.

16. A base station according to claim 15, wherein the antenna energy control means comprises a microprocessor that operates under the stored program control in order to selectively operate some of the predetermined amplifiers.

17. A base station of a cellular communication system, the base station comprises: a radio channel generating means for generating a plurality of radio channel signals; a plurality of phased array antennas connected to the radio channel generating means; and a switch connected between the radio channel generating means and the phase and movable formation antennas between first and second positions so that the switch when in the first position couples together two antennas or more of predetermined phase formation to increase the energy of the emitting antenna for a respective radio channel signal, and so that the switch when in the second position decouples the two or more predetermined phase-forming antennas to increase the capacity of the radio channel for the radio station. base.

18. A base station according to claim 17, wherein each of the phased array antennas comprises a substrate and a plurality of emitter elements mounted thereon in a predeterminated pattern.

19. A base station according to claim 18, further comprising a signal quality receiving means for receiving a signal transmitted from the mobile unit related to the signal quality received in the mobile unit, and further comprising a means for controlling the antenna power connected to the signal quality receiving means and phase forming antennas to selectively operate the predetermined elements of the emitting elements in each respective phased array antenna which responds to the quality of the signal received in the unit mobile.

20. A base station according to claim 18, further comprising a signal resistance means for detecting the resistance of the received signal from a mobile unit further comprising an antenna energy control means connected to the signal strength and phasing array antennas to selectively operate predetermined elements of the emitting elements wherein the respective phased array responds to the resistance of the detected signal.

21. A base station according to claim 18, wherein each emitter element comprises a strip line, and wherein the substrate comprises a circuit board.

22. A base station according to claim 21, further comprising a respective amplifier connected to each emitter element and mounted on the substrate so that the phased array antenna defines an active phase training antenna.

23. A base station according to claim 17, wherein the radio channel generation means further comprises a modulator means for modulating a plurality of radiofrequency carriers with the respective signal inputs to thereby generate the plurality of individual radio channel signals.

24. A method for operating a base station for a cellular radio communications system of the type including a plurality of individual phased array antennas, the method comprising the steps of: generating a plurality of individual radio channel signals each at a different frequency from the other; and operating each individual phase training antenna to transmit only one individual radio channel signal at a time.

25. A method according to claim 24, wherein each of the phased array antennas includes a plurality of emitter elements, and further comprises the step of receiving a signal transmitted from a mobile unit related to the quality of the signal received in the unit, and selectively operate predetermined elements of the emitting elements in each respective phase-forming antenna in response to the quality of the signal received in the mobile unit.

26. A method according to claim 24, further comprising receiving from the mobile units a plurality of individual radio channel signals each at a different frequency from the other.

27. A method according to claim 24, wherein the step of generating the plurality of individual radio channel signals comprises modulating a plurality of radiofrequency carriers with respective input signals.

28. A method according to claim 24, wherein the step of generating a plurality of individual radio channels comprises time division multiplexing a plurality of input signals at predetermined time intervals of repetitive multiple frames.

29. A method according to claim 24 further comprising the step of coupling together two or more phased array antennas. predetermined to increase the energy of the antenna emitted for a respective radio channel signal.

30. A method according to claim 29, further comprising the steps of subsequently uncoupling the two or more formation antennas in predetermined phase and operating the two or more predetermined phase formation antennas with respective different radio frequency channels. to increase the capacity of the radio channel for the base station.

31. A method for operating a base station for a cellular radio communications system of the type that includes at least one phased array antenna comprising a plurality of emitting elements, the method comprising the steps of: generating a plurality of radio channel signals and transmitting the plurality of radio channel signals from at least one phased array antenna; receiving a signal transmitted from the mobile unit related to the quality of the signal received in the mobile unit; and selectively operating the predetermined elements of the emitting elements in response to the quality of the signal received in the mobile unit.

32. A method according to claim 31, wherein at least one phase-forming antenna further comprises respective amplifiers associated with each of the emitting elements, and wherein the step of selectively operating predetermined elements of the emitting elements comprises controlling selectively the energy supplied to the respective amplifiers.

33. A method for operating a base station for a cellular radio communications system of the type that includes a plurality of phased array antennas, the method comprising the steps of: generating a radio channel signal and providing the same in a plurality of predetermined phase-forming antennas coupled together to increase the power of the antenna emitted to the radio channel signal; and subsequently decoupling the plurality of predetermined phase-forming antennas and operating the predetermined phase-forming antennas with different radio frequency channels to increase the capacity of the radio channel for the base station. SUMMARY OF THE INVENTION A base station includes a radio channel generating circuit for generating a plurality of individual radio channel signals each of a different frequency from the other, and a plurality of individual phase-forming antennas operably connected to the generator's generating circuit. radio channel so that each individual phase training antenna transmits only one individual radio channel signal at a time. Each of the preferential training antennas includes a substrate and a plurality of emitter elements mounted thereon in a predetermined pattern. Each emitter element is provided provided quickly by a strip line and the substrate is preferably a circuit board. CorrespondinglyAnother unique feature of the base station according to the invention is that the energy emitted by each phased array antenna can be selectively controlled to reduce possible interference while maintaining communications with the respective mobile units that are both close to and far from the base station. A switch can be provided between the radio channel generator circuit and the phase-forming antennas to facilitate the division of the cell. The aspects of the method for operating the base station are also disclosed.