L-3 Communications Corporation

Lee A Butterfield

Thomas R Giallorenzi

Dan M Griffin

Johnny M Harris

Philip L Stephenson

Eric K Hall

Richard B Ertel

L Andrew Gibson

Steven B Perkins

Michael J Hurst

Samuel Charles Kingston

Alan E Lundquist

Leon L Nieczyporowicz

Ronald B Arthur

Kyle L Henderson

R William Steagall

William T Ralston

Rolf K Thompson

A communications system employs the use of both synchronous CDMA and FDMA to provide a variable bandwidth waveform with multiple bonded transmitters and receivers that are agile in both frequency and PN code to permit a variable bandwidth and variable rate multiple access system. In a first aspect the teachings provide the use of both CDMA and FDMA together to enable an improved concentration efficiency by making a larger pool of bandwidth available to each user. In a second aspect these teachings enable channel bonding across both code space and frequency space, thus making the system capable of operating within a variable (not necessarily contiguous) bandwidth and at a finely variable rate.

Two-dimensional channel bonding in a hybrid CDMA/FDMA fixed wireless access system to provide finely variable rate channels

A method is disclosed for operating a wireless communications system, such as a DS-CDMA communications system, by transmitting a waveform that includes a plurality of repeating frames each having x header training base symbols in a header training symbol field (TH) and y tail training base symbols in a tail training symbol field (TT). The frame is received and functions as one of a plurality of different types of frames depending on the content of at least TT. In the preferred embodiment the frame functions as one of a normal traffic frame, a termination frame, or a legacy frame providing backwards compatibility with another waveform. A given one of the frames includes four equal-size data fields separated by three equal-sized control fields, the header training symbol field (TH) and the tail training symbol field (TT).

Adaptive, multi-rate waveform and frame structure for a synchronous, DS-CDMA system

A method and apparatus for constructing a series of PN code sets that can be used for multirate synchronous and quasi-synchronous CDMA systems. The construction technique produces PN codes that are balanced, and that furthermore do not require any synchronization of neighboring base stations. The method is a non-recursive method that uses a permuted orthogonal matrix to modulate permuted orthogonal matrices to create PN codes that support multirate operation. Furthermore, the codes constructed using the method have very good spectral properties (if chosen properly) when the code length, n, is reasonably large.

Non-recursively generated orthogonal PN codes for variable rate CDMA

A method is disclosed for operating a synchronous Code Division Multiple Access (S-CDMA) radio frequency communication system having a host transceiver unit and a plurality of user transceiver units. The method includes an initial step of defining a super-frame to be comprised of N sequential frames of data. In the preferred embodiment N is equal to three. For a user transceiver unit that obtains access to the host transceiver unit a next step of the method receives frames of data transmitted by the host transceiver unit and initially aligns a receiver timing and a transmitter timing of the user transceiver unit to a super-frame boundary of the received frames. A next step transmits frames of data from the user transceiver unit to the host transceiver unit using the initial timing alignment. A further step of the method detects at the host transceiver unit a difference between the arrival of the transmitted frames of data and a super-frame boundary and then transmits a timing correction parameter, preferably expressed in symbols, from the host transceiver unit to the user transceiver unit in order to align the transmitted frames of data to the super-frame boundary.

S-CDMA fixed wireless loop system employing subscriber unit/radio base

Disclosed is a method for transmitting information in a CDMA communication system, the method including steps of (a) multiplexing data and control information into a data stream; (b) encoding the data stream to form a stream of encoded I/Q symbol pairs; (c) inserting synchronization information into the stream of encoded I/Q symbol pairs; and (d) spreading the encoded I/Q symbol pairs and the inserted synchronization information using a same pseudonoise (pn) spreading code prior to transmission as a frame. The preferred frame structure includes an unencoded synchronization field followed by a plurality of multi-byte data fields. Individual ones of the plurality of data fields are separated by a control message field. Individual ones of the control message fields contain a single byte of a multi-byte control message frame.

Waveform and frame structure for a fixed wireless loop synchronous CDMA

Disclosed is a method for generating I/Q waveforms for transmission over a CDMA radio channel. The method includes steps of (a) summing, for each of a plurality N of channels, the state of I bits to form an Isum value having a sign bit, the state of Q bits to form a Qsum value having a sign bit, and a total number of active channels to form a channel sum value; (b) applying the Isum value and sign bit, the Qsum value and sign bit, and the channel sum value to an input of a multiplexer; and (c) time multiplexing the inputs to generate first and second sets of output bits. The first set of output bits includes a subset of the Isum value bits, a subset of the Qsum value bits, the I sign bit, and the channel sum value bits. The second set of output bits includes the subset of the Isum value bits, the subset of the Qsum value bits, the Q sign bit, and the channel sum value bits. A next step of the method sequentially applies the first and second sets of output bits to a lookup table memory device for sequentially outputting an I value and a Q value for application to a digital to analog converter for generating I/Q waveforms that are predetermined to reduce transmission power and distortion. In the preferred embodiment of this invention the lookup table memory uses the LSB of the channel sum value as the LSB of the I value and the LSB of the Q value.

Fixed wireless loop system having baseband combiner predistortion

Users or subscribers of a multi-user communications system, such as a spread spectrum communications system, provide signals to the central station or base unit of that system, and receive signals therefrom. Avoidance of interference among those users' signals is needed to ensure proper operation of the system. To do so, the data of each user is individually scrambled to randomize the data that different users are transmitting, in order to improve tracking performance at a receiver. The data of each user is scrambled independently, in a manner unique to that user in the system, in order to improve tracking performance and detection performance of a receiver. This scrambling makes the multi-user interference zero mean, and makes it possible to integrate out or average out the multi-user interference. The pattern or sequence used for this scrambling, and the pattern or sequence used for spreading here, are preferably identical except in frequency.

Growing community of inventors

West Jordan, UT, United States of America

Lee A Butterfield