Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W84/00—Network topologies
  • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
  • H04W84/10—Small scale networks; Flat hierarchical networks
  • H04W84/14—WLL [Wireless Local Loop]; RLL [Radio Local Loop]
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
  • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
  • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
  • H01Q21/061—Two dimensional planar arrays
  • H01Q21/065—Patch antenna array
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
  • H01Q21/20—Arrays of individually energised antenna units similarly polarised and spaced apart the units being spaced along or adjacent to a curvilinear path
  • H01Q21/205—Arrays of individually energised antenna units similarly polarised and spaced apart the units being spaced along or adjacent to a curvilinear path providing an omnidirectional coverage
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/28—Combinations of substantially independent non-interacting antenna units or systems
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
  • H01Q3/24—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
  • H01Q9/04—Resonant antennas
  • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
  • H04W16/24—Cell structures

Definitions

• the present invention relates to telecommunication systems and, more specifically, to a steerable subscriber station antenna, for a wireless local loop system, that is typically mounted on the exterior of the subscriber premises.
• Wireless local loop (WLL) systems are also expected to become a viable alternative to the wired local loop telephone services offered by the existing local telephone companies throughout North America and other places.
• WLL systems typically include a network of wireless base stations, each serving a plurality of subscribers via radio.
• each subscriber possesses a subscriber station that supports voice services (e.g. telephone) and/or data services (e.g. internet) using wireless communication with one or more of the base stations.
• voice services e.g. telephone
• data services e.g. internet
• Steerable antennas are also known.
• U.S. Patent 4,700,197 to Milne teaches an adaptive array antenna that is adapted for use in mobile terminals that communicate with satellite communication systems.
• Milne teaches the use of over a dozen parasitic elements that require complex controls to steer the antenna, and overall adding extra cost and/or complexity to the mobile terminal, thus making it generally unsuitable for use in a WLL system.
• U.S. Patent 6,037,905 to Koscica teaches a steerable antenna having a plurality of radiating elements that are comprised of a series of diodes connected in series with conductors having a length that is a fraction of the wavelength of the design frequency.
• a basic assumption behind Koscica is that the radiating elements (active or passive) are broken into lengths much smaller than a wavelength in order to make them electrically transparent.
• this design was applied to common cellular telephone applications or a WLL system, the performance of this antenna would be poor because of the losses due to the plurality of diodes.
• Thiel teaches a steerable antenna for use in mobile telephones. Specifically, Thiel teaches an antenna having four equally spaced monopole elements mounted in a symmetric array on the outer surface of a solid cylinder structure. The cylinder has a high dielectric constant, and extends from a conductive ground plane. The monopole elements can be switched by switching elements so that one or more is active, with the others acting as parasitic directors/reflectors being connected to ground, or left in an open circuit to be effectively transparent.
• Thiel One problem with Thiel is that the mounting of the monopole elements within the solid cylinder structure results in an antenna that may be physically robust for the abuse to which a mobile telephone can be subjected, but is unnecessary and/or overly expensive when applied to a WLL subscriber station. Furthermore, Thiel teaches the switching of the elements in order to reduce the exposure of the subscriber to electromagnetic radiation when the cellular telephone is placed near the subscriber's head, a constraint that is not of concern in a WLL subscriber station. Also, Thiel teaches the switching of the driven elements, yet it is believed that switching in this manner can cause unacceptable performance loss in a WLL subscriber station. In general, the configuration of the antenna in Thiel and the method of switching the antenna in Thiel is directed to mobile applications, and is thus unsuitable for fixed wireless applications.
• wireless local loop system for carrying at least one subscriber service between a network and a subscriber terminal via a wireless link
• said system comprising: at least one base station interconnecting said network and said wireless link, said base station operable to transceive said service over said link; and a subscriber station interconnecting said subscriber terminal and said wireless link, said subscriber station being connected by a wired-link to a steerable antenna that is mounted externally to said subscriber station and is operable to be oriented in a direction having a desired transception-quality of said service over said link.
• the subscriber service is typically either a voice service (e.g. telephone calls) and/or a data service (e.g. web-browsing or email) but other types of services are within the scope of the invention.
• the network is a network respective to the type of service, such as a public switched telephone network, private switched telephone network and/or a packet data network.
• the subscriber terminal can be any terminal operable to carry the subscriber service(s), such as telephone, computer, intelligent device, personal digital assistant or the like.
• the antenna is typically electrically steerable and mounted exterior of the subscriber station housing, for example on the exterior of the subscriber premises, and includes a plurality of directional antennas that are oriented in different sectors to each other. Each directional antenna is switchable such that the antenna transceives the radio link in a desired direction.
• the transception-quality can be measured using any suitable metric, such as signal-to- noise ratio, bit error rate, frame error rate, bit rate, power level and frame rate of the wireless link.
• the desired transception-quality can be based on the orientation requiring the least emitted power level from the subscriber station.
• a method of orienting a steerable antenna connected to a wireless local loop subscriber station comprising the steps of: determining an appropriate time to orient said antenna; scanning said steerable antenna in a given orientation and measuring a transception- quality of a wireless link in said given orientation; repeating said scanning step until a desired number of orientations have been scanned; and orienting said antenna towards the one said orientation that has a desired transception- quality for a subscriber service transmitted over said link.
• a wireless local loop system includes a wireless base station that communicates with a subscriber station via a wireless link.
• the wireless link can carry a voice service, such as telephone calls, or a data service, such as internet browsing.
• the subscriber station includes a steerable antenna that can be mounted to the outside of the subscriber's premises, or any other location desirable to the subscriber.
• a presently preferred steerable antenna for use with the subscriber station includes a plurality of directional antenna elements each oriented in a different direction to the other.
• the transception can be effected in a desired direction.
• the varying transception-qualities of the link (caused by, for example, moving multipath objects or fading) between the subscriber station and the base station can be compensated for in a dynamic fashion.
• the present invention can, in certain circumstances, obviate the need for the professional installation and manual orientation of a directional external, as the subscriber can mount the antenna himself or herself without being concerned whether the antenna is oriented in the proper direction and/or without requiring special cables and/or cables of fixed lengths.
• This also means that as additional base stations are added to the wireless local loop system, it is unnecessary to reorient the subscriber's antenna, thus saving additional cost and service interruptions of having a professional installer re-attend at the subscriber premises to reorient the antenna.
• a subscriber station for a wireless local loop system that carries at least one subscriber service between a network and a subscriber terminal, said system including at least one base station interconnecting said network and a wireless link, said base station operable to transceive said service over said link, said subscriber station comprising: a microprocessor-assembly interconnecting said subscriber terminal and a modem, said microprocessor-assembly for processing said subscriber service, said modem for modulating and demodulating said service; a radio connected to said modem and for converting said service for transception over said wireless link; and a connection means for attaching a steerable antenna to said radio, said steerable antenna operable to be oriented in a direction that achieves a desired transception-quality of said service over said link.
• an antenna for a wireless local loop subscriber station comprising: a connecting means for attaching said antenna to a radio of said subscriber station; and a plurality of directional antennas each defining a different sector of coverage for said antenna, each of said directional antennas being switchable in relation to each other such that said antenna transceives a radio link in said direction.
• a n antenna for a wireless local loop subscriber station comprising: a connecting means for attaching said antenna to a radio of said subscriber station, said connecting means carrying control signals and radio link signals between said subscriber station and said antenna and carrying power for operating said antenna from said subscriber station; a plurality of directional antennas each defining a different sector of coverage for said antenna; switching means to select one or more of said directional antennas for transceiving a radio link signal; a low noise amplifier to amplify radio link signals received by said one or more directional antennas; a power amplifier to amplify radio signals from said subscriber station radio for transmission on said radio link by said one or more directional antennas; an adjustable attenuator to attenuate radio link signals carried over said connecting means; a signal power level detector; and a controller element operable to:
• the present invention provides a versatile, good performance antenna which can be installed by a typical subscriber without the need for a professional installer.
• cable lengths and qualities are automatically compensated for and a single cable carries the control signals, power for the antenna and radio signals between the subscriber station and the antenna.
• radio signals are sent over the connecting means as intermediate frequency signals which mitigates cable losses of the signals.
• Uplink signals are modulated at the antenna to the required RF frequency for transmission and received RF downlink signals are demodulated at the antenna and sent over the connecting means as IF frequency signals.
• Figure 1 shows a schematic representation of a wireless local loop system
• Figure 2 shows a schematic representation of a base station in the system of Figure 1;
• Figure 3 shows a schematic representation of a subscriber station shown in the system of Figure 1 ;
• Figure 4 shows a perspective view of an antenna in the subscriber station of Figure 3;
• Figure 5 shows a front view of the antenna shown in Figure 4.
• Figure 6 shows a top view of the antenna shown in Figure 4.
• Figure 7 shows the top schematic view of the antenna of Figure 4 shown between the base station of Figure 1 and a multipath object
• Figure 8 shows a flowchart of a method of operating the antenna of Figure 4.
• Figure 9 shows the schematic view of Figure 7 wherein a first of four sectors of the antenna is scanned
• Figure 10 shows the schematic view of Figure 7 wherein a second of four sectors of the antenna is scanned
• Figure 11 shows the schematic view of Figure 7 wherein a third of four sectors of the antenna is scanned
• Figure 12 shows the schematic view of Figure 7 wherein a fourth of four sectors of the antenna is scanned
• Figure 13 shows the schematic view of Figure 7 wherein two of the four sectors are scanned
• Figure 14 shows a block diagram of another embodiment of the present invention.
• Figure 15 shows a block diagram of yet another embodiment of the present invention.
• System 20 includes a radio base station 24 that connects, through appropriate gateways (not shown), to communication networks 28 via one or more backhauls 32.
• networks 28 include the public switched telephone network (PSTN) and/or packet data networks, such as the Internet.
• Backhaul 32 can be any known type of backhaul link between radio base station 24 and network 28, such as a Tl, T3, OC1 or a microwave link.
• system 20 can have additional base stations 24, as desired, and that communications between multiple base stations 24 and subscriber stations 36 can be managed using known handoff techniques. Additionally, base station 24 can be multi-sectored, each sector being defined by directional antennas, as is known by those of skill in the art.
• a wireless link 40 composed of various communications channels, can be established between base station 24 and one or more of a plurality of subscriber stations 36. Utilizing one or more communication channels, wireless link 40 allows information to be transferred between base station 24 and respective subscriber stations 36, as needed.
• the radio-communication multiple access technique employed over wireless link 40 is CDMA, however, other types of techniques and/or protocols, such as GSM, FDMA, OFDM, or TDMA are also within the scope of the invention.
• data transmitted on wireless link 40 is formed into packets and the implementation/type of packet communication employed is not particularly limited, and can include IP (with TCP or UDP) and/or modifications thereof or any other packet implementation as will occur to those of skill in the art. While the present embodiment is directed to digitally-based radio communications, it will be understood that the present invention can be modified to accommodate analog based radio communications, such as that found in analog cellular telephone networks.
• each subscriber station 36 is fixed within a subscriber's premises. However, it is also contemplated that the present invention can be applicable, with appropriate modifications to mobile and/or nomadic subscriber stations.
• Each subscriber station 36 is operable to connect to one or more voice terminals 44 (e.g. a telephone) to provide voice services, and to connect to one or more data terminals 48 (e.g. a computer) to provide general data services.
• voice terminals 44 e.g. a telephone
• data terminals 48 e.g. a computer
• each voice terminal 44 and its respective data terminal 48 can be separate devices or can be combined into a single intelligent device, such as a telephone with a built-in web browser or any other intelligent device that is operable to process both voice and data.
• each voice terminal 44 is operable to process voice telephone calls carried over a PSTN portion of network 28, while data terminal 48 is operable to process general data applications carried over a packet switched data network portion of network 28. It is to be understood that in other embodiments of the invention, subscriber station 36 and system 20 can be modified to provide different types of services, or to only provide voice or data services.
• Base station 24 comprises an antenna 100 for receiving and transmitting radio-communications over wireless link 40.
• antenna 100 is connected, via any suitable connecting means, to a radio 104 and a modem 108.
• Modem 108 is connected to a microprocessor-router assembly 112.
• a suitable microprocessor would be a SPARC processor system manufactured by SUN Microsystems. It will be understood that assembly 112 can include multiple microprocessors, as desired.
• the router within microprocessor-router assembly 112 is connected to backhaul 32 in any suitable manner, which in turn connects base station 24 to network 28 via appropriate gateways (not shown). Other suitable configurations of base station 24 will occur to those of skill in the art.
• Subscriber station 36 is shown in greater detail. Subscriber station 36 is attached to a steerable antenna 200 for receiving and/or transmitting ("transceiving") radio-communications over wireless link 40. Station 36 and antenna 200 are connected via a wired-link 202, that carries power signals, antenna control signals, and signals transceived over wireless link 40 between subscriber station 36 and antenna 200.
• wired link 202 is connected to a radio 204 within subscriber station 36 and to antenna control sources, such as microprocessor-assembly 212, and a power supply (not shown). Radio 204 then connects to a modem 208, which in turn is connected to microprocessor- assembly 212.
• antenna 200 is mounted distal to subscriber station 36.
• antenna 200 can be mounted substantially vertically outside of the subscriber's premises, either directly to the premises or proximal thereto.
• a protective radome such as a plastic cylinder, is also typically included to protect antenna 200 from weather elements, while still allowing transception over wireless link 40. It is also contemplated that antenna 200 can be mounted within a subscriber's premises, for example in an attic, if desired.
• Antenna 200 is mounted any suitable mechanical hardware as will occur to those of skill in the art, although preferably as part of a kit mechanical hardware is provided that would allow a subscriber to mount the antenna him or herself, without the need for a professional installer.
• wired-link 202 is preferably a single piece of dual conductor cable, such as coaxial cable used in CATV installations.
• subscriber station 36 and antenna 200 are designed such that power signals, antenna control signals, and transceived signals from/to wireless link 40 are all carried over different frequencies within the coaxial cable, with appropriate circuitry at each end of wired-link 202 to differentiate between each signal carried on link 202.
• wired-link 202 can include separate cables for one or more signals.
• the remaining components of subscriber station 36 are housed within a chassis. For safety reasons, such a housing can be configured to restrict access by the subscriber to the components of subscriber station 36.
• Microprocessor-assembly 212 which can include, for example, a Strong ARM processor manufactured by Intel, performs a variety of functions, including implementing A/D-D/A conversion, voice codecs, filters, encoders, data compressors and/or decompressors for packet assembly/disassembly. As seen in Figure 3, microprocessor-assembly 212 interconnects modem 208 and a pair of ports 214, 216. Accordingly, microprocessor-assembly 212 is operable to process voice services for voice terminal 44 (connected to port 214), and data services for data terminal 48 (connected to port 216).
• Antenna 200 comprises a plurality of elements 258a, 258b, 258c and 258d.
• antenna 200 is used within the spectrum of from about 1850 Megahertz ("MHz") to about 1990 MHz (referred to herein as the "PCS band").
• Each element 258 is sized and configured to be responsive within the PCS band. More particularly, the frequency range of from about 1850 MHz to about 1910 MHz is reserved for transmitting from subscriber station 36 to base station 24 (i.e. the "uplink” or "forward link") over wireless link 40.
• antenna 200 can be designed to operate in any frequency range, as desired and, for example, antenna 200 can also be constructed for operation in the MMDS and/or WCS bands.
• each element 258 is effectively a directional antenna, oriented in different directions in relation to each other.
• each element 258 is oriented on antenna 200 at an angle of ninety degrees to the adjacent elements 258, thereby providing four directions, or sectors, of potential coverage, with the availability of additional coverage patterns by using two or more elements 258 in combination.
• the base of each element 258 is defined by one of the four sides of a substantially square tubular substrate 262.
• Substrate 262 is preferably hollow, made from a thin gauge of aluminum that is rigid enough to support each element 258, yet light enough to reduce the overall weight of antenna 200 for considerations such as reduced materials cost, ease of assembly, ease of mounting, and/or ease of transport.
• Each element 258 is characterized by a first sub-element 264 ⁇ and a second sub-element 264 2 .
• elements 258a, 258b, 258c and 258d each have a first sub- element 264a l5 264b l5 264c l5 and 264d j and a second sub-element 264a 2 , 264b 2 , 264c 2 and 264d 2 , respectively.
• Each sub-element 264 is characterized by an inner patch 270, adjacent to substrate 262 and an outer patch 274.
• Each patch 270, 274 is substantially the same octagonal shape and of substantially the same size.
• a fastener-and-spacer assembly 276 is used to mechanically secure each inner patch 270 and outer patch 274 to substrate 262.
• first sub- elements 264a j , 264b l5 264c l5 and 264d ! each have an inner patch 270a l5 270b l3 270c l5 and 270d x and an outer patch 274a l5 274b 1; 274c l5 and 274d 1? respectively.
• second sub- elements 264a 2 , 264b 2; 264c 2 and 264d 2 each have an inner patch 270-- 2 , 270b 2 , 270c 2 , and 270d 2 , and an outer patch 274a 2 , 274b 2 , 274c 2 , and 274d 2 , respectively.
• Each element 258 also includes a trace 278 that connects at one end to a switching means 282 resident on a cap portion 286, best seen in Figure 6, that closes tubular substrate 262.
• Each trace 278 runs along the surface of cap portion 286 to its periphery, at which point each trace 278 extends perpendicularly to cap portion 286 so that each trace 278 runs parallel to its respective element 258.
• each trace 278 runs along its respective element 258, interconnecting both inner patches 270 of the respective element 258 along the path of trace 278.
• Traces 278 and sub-elements 264 are all preferably made from aluminum, but any suitable conducting material for antennas can be used, for example traces 278 and sub- elements 264 can also be made from a suitable gauge of copper.
• each trace 278 and the inner patches 270 that it interconnects are stamped or otherwise cut from a single piece of aluminum, thereby offering a simplified manufacturing process.
• the portion of trace 278 running parallel to cap portion 286 and the portion of each trace 278 running parallel to its respective element 258, and the junction thereof, are all impedance-matched to facilitate the manufacture of trace 278 from a single piece of aluminum and thereby help reduce the cost and/or complexity of antenna 200.
• switching means 282 interconnects each trace 278a, 278b, 278c, 278d.
• switching means 282 includes four PIN-diodes, where one PIN-diode is respective to each trace 278.
• Switching means 282 further includes a controller element that connects to wired link 202.
• wired link 202 enters through the hollow opening of tubular substrate 262 and passes through the interior of substrate 262 to terminate at switching means 282 on cap portion 286.
• a controller element within switching means 282 is operable to extract power supplied by wired-link 202, as well as to receive a control signal carried within wired link 202.
• the controller element within switching means 282 is operable to activate the appropriate PIN diode, or diodes, and thereby activate the corresponding element or elements 258, according to the extracted control signal. Furthermore, the controller element within switching means 282 is operable to transmit signals received, over wireless link 40, by a given element or elements 258 over wired link 202 to subscriber station 36, and to deliver signals received from subscriber station 36 to a given element or elements 258 for transmission over wireless link 40.
• antenna 200 is shown intermediate base station 24, and a multipath object 300.
• base station 24 is transceiving wireless link 40.
• the term transceiving means transmitting and/or receiving.
• wireless link 40 actually exists as two wireless links, 40 LOS and 40 ⁇ .
• wireless link 40 LOS is a line-of-site instance of wireless link 40 between base station 24 and antenna 200
• wireless link 40 ⁇ is a multipath instance of wireless link 40 between base station 24 and antenna 200.
• Multipath object 300 can be any object that causes multipath interference signals to exist between base station 24 and antenna 200, such as trees, rocks, buildings, walls and/or can be mobile objects such as trucks or other vehicles.
• wireless link 40 ⁇ can change depending on the location of object 300.
• Figure 7 is a simplified example of links, 40 LOS and 40 ⁇ and that more complex, and multiple multipath links 40 ⁇ can exist between base station 24 and steerable antenna 200.
• subscriber station 36 can be positioned in relation to base station 24 such that no line-of-site link 40 LOS instance is available to subscriber station 36, and that in such cases only one or more multipath links 40 ⁇ may be available to subscriber station 36.
• a link 40 may be subject to Rayleigh fading or other phenomena which result in significant changes to its transception characteristics with time.
• antenna 200 is operable to be oriented in a direction of having a desired transception-quality of a service over available links 40 such as the two links 40 LOS and 40 ⁇ shown in Figure 7.
• subscriber station 36 is operated normally. Normal operation can include any number of states. For example, normal operation can be where subscriber station 36 is powered-on, and conducting an initialization sequence of loading operating system software and performing self-diagnostics, and preparing to attempt to establish communications with base station 24 over wireless link 40 using pilot channels or other signaling channels transmitted from base station 24 to subscriber station 36.
• subscriber station 36 may be carrying one or more voice telephone calls between voice terminal 44 and base station 24.
• subscriber station 36 may be carrying one or more data services, (i.e. web- browsing, email) between data terminal 48 and base station 24.
• Another example of normal operation is when subscriber station 36 has already established communications with base station 24 over wireless link 40, but is in an idle state where it is not carrying any service.
• step 410 it is determined whether an appropriate time has been reached in which to orient (or reorient) antenna 200. This determination can be made based on any number of criteria, which would generally reflect the state of normal operation of subscriber station 36 at step 400 just prior to the advancement of the method to step 410.
• step 400 subscriber station 36 is attempting to establish initial communications with base station 24, then at a predetermined point during such initialization the determination at step 410 will typically determine that 'yes', now is an appropriate time to orient antenna 200, in order to allow subscriber station 36 to acquire a desired signal from base station 24.
• step 400 subscriber station 36 is engaged in a voice telephone call using voice terminal 44, it is generally believed that this would be an inappropriate time to reorient the antenna from an existing orientation, due to the risk of "dropping" the voice call. (although presently less preferred, it is to be understood that there can be situations where it may be desired to reorient antenna 200 during a voice call.)
• subscriber station 36 is carrying a data service between data terminal 48 and base station 24, then at step 410 it may be desired to reorient antenna 200 if the bit-rate (or other metric of transception-quality) has fallen below a certain threshold. For example, where subscriber station 36 has been able to achieve a higher bit-rate when carrying previous data services between data terminal 48 and base station 24, yet at the time the method reaches step 410 this bit-rate has dropped to some appreciable amount below that higher bit-rate, then it can be desired to reorient antenna 200 in an attempt to increase the bit-rate.
• subscriber station 36 can, at predetermined time intervals, attempt to reorient itself in relation to wireless link 40 in an attempt to secure a more desirable signal with base station 24, especially where subscriber station 36 is aware of a drop in uplink or downlink bit-rate, signal-to-noise ratio, or other measurement of transception-quality with respect to wireless link 40.
• Other criteria for determining, at step 410, whether an appropriate time for orienting (or reorienting) antenna 200 has been reached will occur to those of skill in the art and are within the scope of the invention.
• step 410 it is determined that it is not an appropriate time to orient (or reorient) antenna 200, then the method returns back to step 400 where normal operation of subscriber station 36 continues. However, if it is determined that an appropriate time has been reached to orient antenna 200, then the method advances to step 415.
• an initial sector in which antenna 200 can be directed is scanned and a measurement of transception-quality is taken.
• This initial sector can be randomly selected, a fixed pattern of sectors to be scanned can be employed, the sector which previously provided the best transception can selected, or any other selection criteria can be used.
• subscriber station 36 it is contemplated that the first sector 310 scanned at step 410 will be that sector 310 which is presently being used by subscriber station 36.
• the first sector that is scanned is sector 310a, which corresponds to element 258a.
• sector 310a is scanned by sending a control signal along wired-link 202 to switching means 282 that switches the PIN diode corresponding to element 258a into the active state, thereby capturing any signal entering sector 310a and/or transmitting any uplink signal from subscriber station 36 into sector 310a.
• the remaining elements 258b, 258c and 252d are switched into the inactive state, rendering them inactive.
• the transception-quality of wireless link 40 in sector 310a is measured and this measure is stored for later consideration.
• Any metric for transception-quality can be used. For example, signal-to-noise ratio, received power level, bit error rate, frame error rate or combinations thereof in the uplink and/or the downlink of wireless link 40 can be used.
• base station 24 can also, or instead, report an appropriate metric to subscriber station 36 indicating how well it has received a transmission from subscriber station 36 transmitted through a sector 310.
• the transception measure referred to above can be performed by the subscriber station 36, the base station 24 or both.
• the measurement of transception-quality in sector 310a will be extremely poor, as neither wireless link 40 LOS or wireless link 40, ⁇ is present in sector 310a.
• the method then advances to step 420, where it is determined whether all sectors have been scanned. At this point of the present example, not all of the sectors of antenna 200 have been scanned, and the method moves to step 425 and antenna 200 is advanced to a next sector. This advancement is represented in Figure 10, where sector 310d is now shown as being scanned.
• sector 3 lOd is accomplished in a manner similar to that for sector 310a, namely sector 310d is scanned by sending a control signal along wired-link 202 to switching means 282 that switches the PIN diode corresponding to element 258d in the active state.
• switching means 282 that switches the PIN diode corresponding to element 258d in the active state.
• the remaining PIN diodes for elements 258a, 258c and 252d are switched into the inactive state, rendering them inactive.
• any signal entering sector 3 lOd is captured and/or any uplink signal from subscriber station 36 if transmitted in sector 3 lOd.
• the method then returns to step 415, at which point the transception-quality of sector 310d is measured and stored for later use.
• the measurement of transception-quality in sector 310d is extremely poor, as neither wireless link 40 LOS or wireless link 40 ⁇ is present in sector 310d.
• step 420 it is determined whether all sectors have been scanned.
• two of the sectors 310b and 310c of antenna 200 remain unscanned, and so method moves to step 425 and a next sector is selected.
• This selection is represented in Figure 11, where sector 310c is now shown as being scanned.
• the scanning of sector 310c is accomplished in a similar manner to that described above for sectors 310a and 31 Od.
• the method then returns to step 415 , at which point the transception- quality of sector 310c is measured and stored for later use.
• the measurement of transception-quality in sector 310c will detect the presence of wireless link 40 ⁇ in sector 310c. It is to be understood that while wireless link 40 ⁇ is a multipath instance of wireless link 40, this fact is unknown to subscriber station 36, which simply takes a measurement of link 40 ⁇ , using the appropriate metric.
• step 420 the method then returns again to step 420, where it is determined whether all sectors have been scanned.
• sector 310b of antenna 200 remains unscanned, the method moves to step 425 and antenna 200 is advanced to that sector, as represented in Figure 12, where sector 310b is now shown as being scanned.
• the scanning of sector 310b is accomplished as described above for the other three sectors 310.
• step 415 the transception-quality of sector 31 Ob is measured and stored for later use.
• the measurement of transception-quality in sector 310b detects the presence of wireless link 40 LOS in sector 31 Ob. It is to be understood that while wireless link 40 LOS is a line- of-sight instance of wireless link 40, this fact is unknown to subscriber station 36, which simply takes a measurement of link 40 ⁇ using the desired metric.
• step 430 The method then returns again to step 420, where it is determined whether all sectors have been scanned. This time, it is determined that all sectors 310a, 310b, 310c and 3 lOd have been scanned, and accordingly, the method advances to step 430.
• antenna 200 is oriented in a desired direction. This orientation is made using a selection criteria that considers the transception-quality measurements taken at step 415.
• the simplest selection criteria is to simply select the sector 310 with the best transception- quality, for example, where the transception-quality is measured in terms of signal-to-noise ratio (SNR), then the sector with the highest SNR will be chosen. According to the examples shown in Figures 9-12, it is generally expected that sector 310b, shown in Figure 12, would have the highest SNR, as sector 310b captures a line-of-sight instance of wireless link 40 (i.e. wireless link 40 LOS ).
• SNR signal-to-noise ratio
• any selection criteria can be used, and such criteria are expected to be more complex where there are additional multipath objects 300, no line-of-sight link exists, and/or where there are multiple base stations 24 and additional subscriber stations 36 all attempting to carry voice and/or data services.
• one selection criteria for the uplink can be to choose whichever sector 310 (or, in other words, orientation) allows subscriber station 36 to operate at the lowest possible level of transmission power thereby reducing interference with adjacent subscriber stations 36.
• This criteria can be useful, for example, where subscriber station 36 is simply uploading data to base station 24 over wireless link 40, and not utilizing the downlink of wireless link 40, however, where both the downlink and uplink of wireless link 40 are being utilized, more complex selection criteria can be used to achieve desired operating functionality of system 20.
• the appropriate sector 310b is scanned by sending a control signal along wired-link 202 to switching means 282 that switches the PIN diode corresponding to element 258b in the active state thereby capturing any signal entering sector 310b and/or transmitting any uplink signal from sector 310b.
• the remaining elements 258a, 258c and 252d are switched into the inactive state, rendering them inactive.
• step 400 where normal operation of subscriber station 36 resumes.
• the steps 400-430 are repeated as necessary to reorient antenna 200 in a direction that provides optimal and/or desired operation of subscriber station 36, or until wireless link 40 is broken, terminated by either subscriber station 36, base station 24 or some other multipath object 300 that causes wireless link 40 to break.
• each elements 258 is switched with a PIN diode, such switching may be accomplished in other ways, such as through the use of GaAs FETs.
• steerable antennas for use with a wireless local loop subscriber station 36
• other types of steerable antennas can be used in conjunction with wireless local loop subscriber station 36, and that such other types are within the scope of the invention.
• the present invention can include multiple steerable antennas attached to subscriber station 36. For example, one steerable antenna can be used for transmitting on the uplink, whereas the other antenna can be used for receiving over the downlink, and whereby each antenna can be oriented in different directions according to desired transmission-quality for the uplink, and reception-quality for the downlink.
• one element 258 could be activated for the uplink, while the other activated for the downlink, in the event that different directions could prove to be optimum for each link. For example, this could occur in systems with multiple base stations, where one element 258 is oriented towards one base station 24, while another element is oriented towards another base station 24. In this case, transception could be accomplished with the use of both base stations 24.
• the present invention can be used to allow a subscriber station 36 to steer its antenna towards the most desirable signal available from one of those base stations.
• the foregoing aspect of the invention can be utilized with soft-handoff or other types of handoff techniques.
• the present invention can be modified to provide a wireless local loop subscriber station with one or more steerable antennas that are steerable in multiple planes: for example, steerable in both horizontal planes and vertical planes, in order to allow the antenna to be directed in both the horizontal and vertical planes to achieve a desired transception-quality.
• each element 258 in the embodiments shown in Figure 4-6 can be described as a double-coupled patch antenna. It is to be understood, however, that each element 258 could be configured differently, depending on the desired characteristics of antenna 200.
• each outer patch 274 serves as a parasitic element to its respective inner patch 270, thereby improving performance over entire the entire PCS band. It is to be understood, however, that the use of such a parasitic element is optional.
• the utilization of two sub-elements 264 in the vertical plane can narrow, in relation to the use of one sub-element 264, the elevation plane in which a particular element 258 operates.
• additional or fewer sub-elements 264 in either the horizontal or vertical planes can be chosen to provide a desired aperture of each element 258.
• another embodiment of antenna 200 can have a single sub-element 264 per element 258 to reduce the vertical size of antenna 500, albeit at a likely cost in terms of the performance of antenna 200.
• antenna 200 can have additional or fewer elements 258, as desired. It is also to be understood that other types of elements 258 can be used. For example, the embodiments discussed herein elements 258 are essentially four individual directional antennas, yet in other embodiments there could be a single active antenna element with a plurality of parasitic elements that could be switched in or out, to influence the radio signal in relation to the active element.
• the present invention could be offered as kit in addition to the wireless local loop subscriber station having an internal steerable antenna, as taught in the above-mentioned co-pending application.
• additional circuitry would be provided within subscriber station 36 to accommodate the attachment of the external antenna 200 shown in Figures 4-6, allowing subscriber station 36 to switch between utilization of its own, internal antenna, or an external steerable antenna 200 of the like discussed herein.
• FIG 14 shows a block diagram of another embodiment of an antenna 500 in accordance with the present invention.
• This embodiment is intended to be used as an option with a standard subscriber station 36.
• antenna 500 can be employed.
• antenna 500 is connected to subscriber station 36 by a user installable wired-link 202 such as RG6 coaxial cable.
• wired-link 202 can vary in length and in a present embodiment, wired-link 202 can be up to forty-five meters in length.
• cables such as RG6 which are reasonably priced and/or are easy for a user to self install, suffer from significant line losses (represented in Figure 14 at 504).
• line losses represented in Figure 14 at 504
• RG6 cable at the PCS band frequencies of from about 1.8 GHz to about 2.0 GHz a signal traversing a forty-five meter length of RG6 cable can experience a 15db loss.
• Antenna 500 is intended to compensate for the loss of signal in wired-link 202.
• antenna 500 includes a switching means 282, as described above, and a controller element 508.
• controller element 508 is operable to extract from and/or insert control signals and radio signals on wired-link 202 and to extract power 512 supplied to antenna 500 from wired-link 202.
• Power 512 is regulated and set to appropriate levels required by the various components of antenna 500, such as the low noise amplifier (LNA) 516 and the power amplifier 520.
• LNA low noise amplifier
• a radio signal path extends bi-directionally from wired-link 202 through controller element 508, a step-wise attenuator 524, a power level detector 528 and a first duplexer 532.
• First duplexer 532 duplexes downlink radio signals amplified by LNA 516 onto the radio path and provides uplink signals to power amplifier 520.
• a second duplexer 536 duplexes downlink signals from switch means 282 to LNA 516 and output uplink signals amplified by power amplifier 520 to switch means 282 which connects in turn to at least one of elements 258 to complete the radio path.
• Controller element 508 provides a control signal 540 to step-wise attenuator 540 and a control signal 544 to switch means 282. Controller element 508 is responsive to a control signal 548 output by power level detector 528 and to control signals from subscriber station 36 over wired-link 202.
• Controller element 508 controls step-wise attenuator 524, as described in more detail below, to ensure that the combination of the actual cable loss 504 and the attenuation of step-wise attenuator 524 totals 15db.
• step- wise attenuator 524 will be set to provide additional attenuation to that provided by cable loss 504 so that the amplitude of signals into subscriber station 36 do not exceed design expectations and that signals applied to power amplifier 520 also do not exceed design specifications.
• antenna 500 When a subscriber station 36 is powered on, it determines if it is connected to antenna 500, in which case antenna 500 will be selected for radio operations by subscriber station 36. If no antenna 500 is detected, then subscriber station 36 will default to using its internal antenna.
• Detection of the presence of antenna 500 is performed by subscriber station 36 assuming an antenna 500 is connected and sending an interrogation signal to it over wired-link 202. If antenna 500 is connected to subscriber station 36, controller element 508 will extract the interrogation signal, which is a defined control signal that it recognizes, and will send a reply signal, comprising for example a model number or other identifier, to subscriber station 36 over wired-link 202. If subscriber station 36 does not receive a suitable reply message within a defined maximum time period, as for example when wired-link 202 and antenna 500 are not present, it will default to using its internal antenna.
• a control signal is sent over wired-link 202 and is received by controller element 508 which will turn the amplifiers (e.g. - LNA 516 and power amplifier 520) in antenna 500 to an OFF state.
• a signal is sent by subscriber station 36 to controller element 508 to set step-wise attenuator 524 to the maximum amount of attenuation.
• step- wise attenuator 524 can provide 0 to 15db of attenuation, in ldb steps.
• the subscriber station 36 sends a signal of known power over wired-link 202 to antenna 500.
• this signal should be selected carefully, taking into consideration the RMS transmit power levels of the inphase and quadrature signals and typically, to some extent, the temperature of the radio components.
• this signal is transmitted over wired-link 202 at the midpoint of the intended uplink and downlink frequency range so that it characterizes cable loss 504 at a relevant operating condition.
• Controller element 508 notes the control signal 548 output to it by power level detector 528 which represents the power level of the signal after attenuation by the combination of cable loss 504 and step-wise attenuator 524.
• This detected power level is transmitted back to subscriber station 36, along with the present setting of step- wise attenuator 524, over wired-link 202 and, if the detected power level is within the tolerances selected for the total attenuation of cable loss 504 and step-wise attenuator 524, then the process completes, as described below. If the detected power level is lower than desired, subscriber station 36 signals controller element 508 to set step-wise attenuator 524 to the next lower level of attenuation and the process repeats until the desired power level is detected at power level detector 528.
• subscriber station 36 can commence normal operations.
• a signal is sent from subscriber station 36 to controller element 508 over wired-link 202 which controller element 508 responds to by placing the amplifiers (e.g. - LNA 516 and power amplifier 520) in antenna 500 to the ON state and then normal operation, including the steering process described above, commences.
• amplifiers e.g. - LNA 516 and power amplifier 520
• FIG. 15 shows another embodiment of an antenna 600 which is similar to that discussed above with respect to Figure 14.
• IF intermediate frequency
• antenna 600 when IF frequency signals are sent over wired-link 202, antenna 600 includes a modulator 576 (to modulate IF signals received from subscriber station 36 to the desired RF frequency) and a demodulator 580 (to demodulate RF signals received at an element 258 to an IF frequency to be sent to subscriber station 36 over wired link 202). It is presently contemplated that a local reference oscillator signal 584 will be provided to antenna 500 from subscriber station 36 over wired-link 202 and that the modulator and demodulator will be provided with their respective frequencies from a local oscillator 590 which uses the reference signal 584.
• a local reference oscillator signal 584 will be provided to antenna 500 from subscriber station 36 over wired-link 202 and that the modulator and demodulator will be provided with their respective frequencies from a local oscillator 590 which uses the reference signal 584.
• the present invention provides a novel antenna for a wireless local loop system.
• the present invention provides a steerable antenna that adds spatial diversity to a radio link between a base station and a subscriber station in a wireless local loop.
• the antenna is external to the premises of the user of the subscriber station, but the steerable nature of the antenna can obviate or mitigate the requirement for professional installation, as required with prior art external antennas found in existing wireless local loop systems.
• the present invention obviates the need for professional remounting of the antenna when new base stations are added to the wireless local loop system, or where new structures arise that create unacceptable multipath interference. Additionally, since the direction of the antenna can be dynamically changed, the present invention allows for redirecting of the antenna according to changing system requirements.
• the antenna can be changed between these two directions according to whether the subscriber stations is predominantly engaged in uplink transmission or downlink reception.
• the use of an omnidirectional antenna can be placed in a location subject to destructive interference from multipath signals, the present invention allows the antenna to be reoriented so as to minimize the effects of the destructive interference.
• the use of two steerable antennas, one for transmission and one for reception, as taught in certain embodiments of the invention can allow for each antenna to be oriented in different directions in order to achieve desired transmission-qualities and reception-qualities, respectively.
• the present invention provides a system and method whereby an antenna with good performance may be installed, without requiring professional installers, and will self configure itself with the subscriber station 36. Requirements for expensive cables and/or fixed lengths of cable are avoided by automatically compensating for cable loss.

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• 2002
  • 2002-02-01 WO PCT/US2002/002759 patent/WO2002063895A1/en not_active Application Discontinuation
  • 2002-02-01 CA CA002471303A patent/CA2471303A1/en not_active Abandoned
  • 2002-02-01 EP EP02706084A patent/EP1362488A4/de not_active Withdrawn
  • 2002-02-01 CN CNB028078993A patent/CN100438641C/zh not_active Expired - Fee Related

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