Abstract:
An illustrative embodiment of the present invention supports the transmission of data to a user on an as-needed basis over multiple allocated data channels. Data packets are transmitted in time-slots of the allocated data channels to corresponding target receivers without the need for explicitly assigning particular time-slots to a target user well in advance of transmitting any data packets in the time-slots. Instead, each data packet transmitted in a time-slot includes a header label or preamble indicating to which of multiple possible receivers a data packet is directed. The preamble also preferably includes decoding information indicating how a corresponding data payload of the data packet is to be processed for recapturing transmitted raw data.
Abstract:
A system and method for encoding/decoding data channels in a CDMA system having data channel interference cancellation, wherein data channel interference cancellation is used to remove unwanted non-orthogonal pilot signal components which are present within a demodulated data signal. This is accomplished by regenerating interference terms with respect to the non-orthogonal pilot signal and subtracting them from the demodulated data signal.
Abstract:
A varactor based phase shifter that increases phase shift range using a lower characteristic impedance between quadrature ports than is used at its input/output ports. The circuit makes use of a four port coupler arrangement that imbeds a quarter wave impedance transformation between the input port and the quadrature ports as well as between the quadrature ports and the output port. The characteristic impedance across the quadrature ports is therefore less than the characteristic impedance across the input and output ports. In one implementation, reducing a characteristic input/output impedance of 50 to a 20 ohm quadrature port impedance results in a phase shift range increase of more than 50%.
Abstract:
A directive antenna includes plural antenna elements in an antenna assemblage. A feed network connected to the antenna elements includes at least one switch to select a state of one of the antenna elements to be in an active state in response to a control signal. The other antenna elements are in a passive state, electrically coupled to an impedance to be in a reflective mode. The antenna elements in the passive state are electromagnetically coupled to the active antenna element, allowing the antenna assemblage to directionally transmit and receive signals. The directive antenna may further include an assisting switch associated with each antenna element to assist coupling the antenna elements, while in the passive state, to the respective impedances. The antenna assemblage may be circular for a 360° discrete scan in N directions, where N is the number of antenna elements. The directive antenna is suitable for use in a high data rate network having greater than 50 kbits per second data transfer rates, where the high data rate network may use CDMA2000, 1eV-DO, 1Extreme, or other such protocol.
Abstract:
A phased array antenna provides a subscriber unit with an ability to transmit and receive signals in different directions to allow for optimum gain in both directions, simultaneously. In this way, refraction and multipath effects resulting from communication signals operating at different frequencies can be compensated for to improve gain in both the forward and reverse links. Frequency selective components are coupled to respective antenna elements. At least two weighting structures are coupled to the frequency selective components to produce independently steerable beams having spectrally separated signals. The weighting structures may include phase shifting elements to steer the beams independently and include at least one variable gain amplifying component to independently amplify the signals received by or transmitted by the respective antenna, thereby optimizing the respective shapes of the beams. By having independently steerable and shapable beams, the directive antenna is attractive for use in a multi-band and/or multipath environment, same frequency or spread spectrum network.
Abstract:
A dipole antenna for use with a mobile subscriber unit in a wireless communications system. The antenna is fabricated with printed circuit board (PCB) photo-etching techniques for precise control of the printed structure to mass produce antenna elements with repeatable features. The antenna includes a planar substrate made of dielectric material. A conductive planar element layered on one side of the substrate, and a conductive planar ground patch is located on the other side of the substrate. The conductive planar element is located in an upper region of the substrate, while the location of the planar ground patch is offset from the conductive planar element in a lower region of the substrate. A feed strip is connected to the conductive planar element, extends from the element to a bottom edge of the substrate, and terminates at a bottom feed point. The conductive planar ground patch includes two portions. One portion extends from the midsection of the other portion to the bottom edge of the substrate and provides a connection point for coupling the conductive planar ground patch to a ground plane which is aligned orthonormally to the substrate. Capacitive coupling between the conductive planar element and the conductive planar ground patch creates a junction which provides an upper dipole feed point in a mid-region of the substrate such that the conductive planar element acts as a first element of an unbalanced dipole antenna and the conductive planar ground patch acts as a second element of the unbalanced dipole antenna. The unbalanced dipole antenna forms a beam which may be positionally directed along a horizon that is substantially parallel to the ground plane.
Abstract:
A method for setting optimal phase settings for a plurality of antenna elements of a subscriber unit in a CDMA cellular telephone system includes the steps of detecting a received pilot signal at each of the plurality of antenna elements, combining the received pilot signal detected at each of the plurality of antenna elements with a summation circuit to produce a combined received pilot signal, determining a quality metric for the combined received pilot signal and adjusting phase settings of at least one of the plurality of antenna elements on the subscriber unit in response to the quality metric of the received pilot signal. These steps are repeated until the determined quality metric of the combined received pilot signal reaches a maximum.
Abstract:
An antenna apparatus which can increase capacity in a cellular communication system. The antenna operates in conjunction with a mobile subscriber unit and provides a plurality of antenna elements, each coupled to a respective programmable phase shifter. The phase of each antenna element is programmed for optimum reception during, for example, an idle mode which receives a pilot signal. The antenna array creates a beamformer for signals to be transmitted from the mobile subscriber unit, and a directional receiving array to more optimally detect and receive signals transmitted from the base station. By directionally receiving and transmitting signals, multipath fading is greatly reduced as well as intercell interference. Various techniques for determining the proper phase of each antenna element are accommodated.
Abstract:
A method and a wireless transmit/receive unit perform a handoff to a target base station having enhanced capabilities. A dual mode manager triggers a capabilities query for information regarding enhanced capability of the target base station, wherein the enhanced capability includes transmission in accordance with a high speed data mode. A generator sends the query to a server connected to the Internet via a first base station not having enhanced capability. The dual mode manager receives from the server via the first base station information regarding the enhanced capability. A handoff to the target base station is initiated by the dual mode manager on a condition that the received information indicates that the target base station has enhanced capability. The dual mode manager deactivates a first mode of operation for communication with the first base station and activates the high speed data mode for communication with the target base station.
Abstract:
In a wireless communication system, there are several wireless channels used for communication between users and a base station. Channel characteristics may be defined by whether a channel is carrying traffic data and the timing of the channel transmissions with respect to channels not carrying traffic data. Different power levels between channels carrying traffic data or not may be defined and individual power levels of each channel may be amended based on individual power level command responses.