2519 results about "Code division multiple access" patented technology

A power amplifier using N-way Doherty structure with adaptive bias supply power tracking for extending the efficiency region over the high peak-to-average power ratio of the multiplexing modulated signals such as wideband code division multiple access and orthogonal frequency division multiplexing is disclosed. In an embodiment, the present invention uses a dual-feed distributed structure to an N-way Doherty amplifier to improve the isolation between at least one main amplifier and at least one peaking amplifier and, and also to improve both gain and efficiency performance at high output back-off power. Hybrid couplers can be used at either or both of the input and output. In at least some implementations, circuit space is also conserved due to the integration of amplification, power splitting and combining.

A system for rapidly acquiring a spreading code, used in a code division multiple access (CDMA) system, comprises a generator for generating a first long code and a second long code, with each long code having a length of N chips. The first long code is different from the second long code. A transmitter transmits the first long code and the second long code at a first phase angle and at a second phase angle, respectively, on a carrier signal over a communications channel using radio waves. The first long code and the second long code may be transmitted at an in-phase (I) angle and at a quadrature-phase (Q) angle, respectively, on the carrier signal. From the communications channel, an I acquisition circuit and a Q acquisition circuit may acquire, in parallel, the first long code and the second long code from the I angle and the Q angle, respectively, of the carrier signal by searching, in parallel, N / 2 chips of the first long code and the second long code.

A multiple access, spread-spectrum communication system processes a plurality of information signals received by a Radio Carrier Station (RCS) over telecommunication lines for simultaneous transmission over a radio frequency (RF) channel as a code-division-multiplexed (CDM) signal to a group of Subscriber Units (SUs). The RCS receives a call request signal that corresponds to a telecommunication line information signal, and a user identification signal that identifies a user to receive the call. The RCS includes a plurality of Code Division Multiple Access (CDMA) modems, one of which provides a global pilot code signal. The modems provide message code signals synchronized to the global pilot signal. Each modem combines an information signal with a message code signal to provide a CDM processed signal. The RCS includes a system channel controller is coupled to receive a remote call. An RF transmitter is connected to all of the modems to combine the CDM processed signals with the global pilot code signal to generate a CDM signal. The RF transmitter also modulates a carrier signal with the CDM signal and transmits the modulated carrier signal through an RF communication channel to the SUs. Each SU includes a CDMA modem which is also synchronized to the global pilot signal. The CDMA modem despreads the CDM signal and provides a despread information signal to the user. The system includes a closed loop power control system for maintaining a minimum system transmit power level for the RCS and the SUs, and system capacity management for maintaining a maximum number of active SUs for improved system performance.

A packet-centric wireless point to multi-point telecommunications system includes: a wireless base station communicating via a packet-centric protocol to a first data network; one or more host workstations communicating via the packet-centric protocol to the first data network; one or more subscriber customer premise equipment (CPE) stations coupled with the wireless base station over a shared bandwidth via the packet-centric protocol over a wireless medium; and one or more subscriber workstations coupled via the packet-centric protocol to each of the subscriber CPE stations over a second network. The packet-centric protocol can be transmission control protocol / internet protocol (TCP / IP). The packet-centric protocol can be a user datagram protocol / internet protocol (UDP / IP). The system can include a resource allocation means for allocating shared bandwidth among the subscriber CPE stations. The resource allocation is performed to optimize end-user quality of service (QoS). The wireless communication medium can include at least one of: a radio frequency (RF) communications medium; a cable communications medium; and a satellite communications medium. The wireless communication medium can further include a telecommunications access method including at least one of: a time division multiple access (TDMA) access method; a time division multiple access / time division duplex (TDMA / TDD) access method; a code division multiple access (CDMA) access method; and a frequency division multiple access (FDMA) access method. The first data network includes at least one of: a wireline network; a wireless network; a local area network (LAN); and a wide area network (WAN). The second network includes at least one of: a wireline network; a wireless network; a local area network (LAN); and a wide area network (WAN).

Multicarrier spreading codes map data symbols to a sequence of orthogonal pulse shapes generated from a superposition of orthogonal subcarriers. The orthogonal subcarriers may include OFDM subcarriers, frequency-hopped subcarriers, or chirped subcarriers. Multicarrier spread spectrum may employ a combination of orthogonal frequency division multiple access, time division multiple access, and code division multiple access. Receivers configured to use multi-user detection may employ a combination of time-domain processing and frequency-domain processing.

A system for facilitating handoff adapted for use with a telecommunications network. The system includes position equipment for determining the location of a mobile transceiver within a region containing a first cell and a second cell. A comparison circuit compares the location with a predetermined handoff area within the region and provides a control signal in response thereto. A handoff initiation circuit initiates handoff of the mobile transceiver between the first cell and the second cell in response to the control signal. In a specific embodiment, the handoff is a hard handoff. The position equipment includes Global Positioning System (GPS) equipment including a mobile unit GPS receiver and signal interface. The comparison circuit includes a positional database that stores latitudinal and longitudinal information corresponding to the predetermined handoff area. The comparison circuit also includes a Code Division Multiple Access selector. The selector begins tracking the position of the mobile transceiver when it is within a predetermined range of the predetermined handoff area. In a specific embodiment, the handoff initiation circuit includes a base station controller. The position equipment includes a base station positional detection system and a mobile unit positional detection system for determining the location of the mobile transceiver. The position database has map information depicting the coverage area of the first and second cells and the predetermined handoff area. The selector runs software for comparing the location to the map information and providing the control signal when the location is within the predetermined handoff area. The base station includes and implements instructions for completing hard handoff in response to the control signal.