| Adaptive receive and omnidirectional transmit antenna array -> Monitor Keywords |
|
|
 
Adaptive receive and omnidirectional transmit antenna arrayRelated Patent Categories: Telecommunications, Transmitter And Receiver At Separate Stations, Distortion, Noise, Or Other Interference Prevention, Reduction, Or CompensationAdaptive receive and omnidirectional transmit antenna array description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060211374, Adaptive receive and omnidirectional transmit antenna array. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATIONS [0001] This application is a continuation of U.S. application Ser. No. 11/076,607, filed Mar. 10, 2005, which is a continuation of U.S. Application Ser. No. 10/386,393 filed Mar. 10, 2003, which claims the benefit of U.S. Provisional Application No. 60/363,144, filed on Mar. 8, 2002. The entire teachings of the above application(s) are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] Code Division Multiple Access (CDMA) modulation and other spread spectrum techniques now find widespread application in wireless systems such as cellular mobile telephones, wireless local area networks and similar systems. In these systems a connection is provided between a central hub or base station and one or more mobile or remote subscriber units. The base station typically includes a specialized antenna for sending forward link radio signals to the mobile subscriber units and for receiving reverse link radio signals transmitted from the mobile units. Each mobile subscriber unit also contains its own antenna, for the reception of the forward link signals and for transmission of reverse link signals. A typical mobile subscriber unit may for example, be a digital cellular telephone handset or a personal digital assistant having an incorporated cellular modem, or other wireless data device. In CDMA systems, multiple mobile subscriber units are typically transmitting and receiving signals on the same carrier frequency at the same time. Unique modulation codes distinguish the signals originating from or intended to be sent to individual subscriber units. [0003] Other wireless access techniques also use spread spectrum for communications between a centralized unit and one or more remote or mobile units. These include the local area network standard promulgated by the Institute of the Electrical and Electronic Engineers (IEEE) 802.11 and the industry developed wireless Bluetooth standard. [0004] The most common antenna used in a mobile subscriber unit is a monopole. A monopole antenna most often consists of a single wire or other elongated metallic element. A signal transmitted from such a monopole antenna is generally omnidirectional in nature. That is, the signal is sent with approximately the same signal power in all directions in a generally horizontal plane. Reception of a signal with a monopole antenna element is likewise omnidirectional. A monopole antenna therefore cannot differentiate between signals originating from one direction versus a different signal originating from another direction. Although most monopole antennas do not produce significant radiation in the elevation plane, the expected antenna pattern in three dimensions is typically a donut-like toroidal shape, with the antenna element located at the center of the donut hole. [0005] Unfortunately, CDMA communication systems are typically interference limited. That is, as more and more subscriber units become active within a particular area and share access to the same base station, interference increases among them, and thus so does the bit error rate they experience. To maintain system integrity in the face of increasing error rates, often the maximum data rate available to one or more users must be decreased, or the number of active units must be limited in order to clear the radio spectrum. [0006] It is possible to eliminate excessive interference by using directive antenna at either the base station and/or the mobile units. Typically, a directive antenna beam pattern is achieved through the use of a phased array antenna at the base station. The phased array is electronically scanned or steered desired direction by controlling the phase angle of a signal input to each antenna element. [0007] However, phased array antennas suffer decreased efficiency and gain as elements become electrically small as compared to the wavelength of the radiated signals. When phased arrays are used or attempted to be used in conjunction with a hand-held portable subscriber unit, the antenna array spacing must be relatively small and therefore antenna performance is correspondingly compromised. SUMMARY OF THE INVENTION [0008] Several considerations should be taken into account when designing an antenna for a hand-held wireless device. For example, careful consideration should be given to the electrical characteristics of the antenna so that propagating signals satisfy predetermined standards requirements such as, for example, bit error rate, signal to noise ratio or signal to noise plus interference ratio. [0009] The antenna should also exhibit certain mechanical characteristics to satisfy the needs of a typical user. For example, the physical length of each element of the antenna array depends upon the transmit and receive signal frequency. If the antenna is configured as monopole, the length is typically a quarter length of a signal frequency; for operation at 800 MegaHertz (MHZ) (one of the more popular wireless frequency bands) a quarter wavelength monopole must typically be in the range 3.7''long. [0010] The antenna should furthermore present an esthetically pleasing appearance. Especially when used in a mobile or handheld portable unit, the whole device must remain relatively small and light with a shape that allows it to be easily carried. The antenna therefore must be mechanically simple and reliable. [0011] In CDMA systems in particular, another consideration involves controlling the capacity of the overall network. Some have provided for adaptive antenna arrays for use on a reverse link of a CDMA system in a handset. These directional antenna arrays can be used to increase system performance by decreasing interference from surrounding base-stations and/or other handsets. However, employing directional antennas on the reverse link complicates the performance of power control systems. That is, as in most wireless communication systems, the power level of signals radiated from handsets must be carefully controlled in order to avoid interference to other handsets so that the signal powers arrive at the base or other central site within a known power level range. [0012] The present invention comes about from realizing the advantages of a mobile-subscriber device that uses a directional or other adaptive antenna array together with a separate transmit antenna. The directional adaptive antenna array, which is used only to receive signals, may typically consist of a number, N, of monopole antenna elements. These monopole elements can be formed as conductive segments on a portion of a dielectric substrate such as a printed circuit board. To complete the array, at least one element is designated as an active antenna element which is also disposed on the same substrate as one or more passive elements. In a preferred embodiment, the active element is disposed in the center of the array and the number of passive elements is two. [0013] The separate transmit antenna may be integrated with the receive array. In a preferred embodiment, the transmit antenna is an omnidirectional element. [0014] In other embodiments, the transmit antenna may be physically separated such as on the opposite side of the housing. That is, the receiver array may be positioned on the top of the handset with the transmit antenna on the lower portion thereof. In either case there is a separate receive and transmit interface port to the two antennas. [0015] By utilizing a horizontally polarized transmit and vertically polarized receive array, isolation between the two antennae is improved. [0016] CDMA based systems that exist today, such as IS-95 and IS-2000, have a capacity limitation problem. The limitations largely occur on the forward link, and result from some channel interference. This interference originates from both adjacent cells as well as from users within the same cell. Indeed, the difference in capacity between the forward and reverse links can be estimated to be as high as 50 to 100%. For voice and circuit switched data systems, the number of users that can be simultaneously supported is defined by the less capacious of the two links. Therefore, the limitation on the forward link actually limits the total number of users, and the excess capacity of the reverse link is wasted. [0017] The use of an adaptive antenna in the subscriber unit on the receive side has the potential to increase the forward capacity to levels equal to or greater than the reverse capacity. This allows for a significant increase in the overall number of users without directly increasing the reverse capacity. [0018] It is also envisioned that other types of systems, such as Time Division Duplex (TDD) systems, may also advantageously use the adaptive array for receive but to steer in an omnidirectional mode during transmit periods. The effect is achieves a similar result. It is also expected that when TDD systems are in a stationary or slow moving environment, a directional transmit may also be able to be utilized. [0019] In accordance with its key aspects, the present invention consists of an antenna system in which an adaptive array is used for receiving signals and an omnidirectional antenna is used for transmitting. In preferred embodiments, the adaptive antenna is integrated into the housing of a handheld wireless communication unit, such as a mobile telephone unit, personal digital assistant or the like. [0020] The adaptive array used for receive mode is preferably an array that uses parasitic, passive elements to achieve directionality. [0021] In further aspects, the omnidirectional transmit antenna is physically and/or electrically separated from the receiver array. The omnidirectional transmit antenna may be integrated at a different polarity. For example, a vertically polarized receive array may have a horizontally polarized transmit element. In other instances, the separation can be provided by a physical distance such as by integrating the transmit antenna and the base of a handheld telephone unit. Continue reading about Adaptive receive and omnidirectional transmit antenna array... Full patent description for Adaptive receive and omnidirectional transmit antenna array Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Adaptive receive and omnidirectional transmit antenna array patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Adaptive receive and omnidirectional transmit antenna array or other areas of interest. ### Previous Patent Application: Coexistence techniques in wireless networks Next Patent Application: Dual purpose multi-brand monopole antenna Industry Class: Telecommunications ### FreshPatents.com Support Thank you for viewing the Adaptive receive and omnidirectional transmit antenna array patent info. IP-related news and info Results in 0.11926 seconds Other interesting Feshpatents.com categories: Canon USA , Celera Genomics , Cephalon, Inc. , Cingular Wireless , Clorox , Colgate-Palmolive , Corning , Cymer , 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
