Abstract: In simultaneous reception of overlapping signals sharing a single spreading sequence, packet start times are found by separately demodulating, low pass filtering and despreading in-phase and quadrature components. Despread in-phase and quadrature signals are provided to sychronization filters connected in parallel and arranged in two identical pairs. Outputs from filters in different pairs are added, and the sums are squared. The squared signals are added. An exceeded threshold of the output from the last adder delineates a packet start. Knowing packet start times facilitates separating the overlapping inbound signals.

Abstract: The present invention is a match filter architecture that is used in the Spread ALOHA Multiple Access (SAMA) receiver to facilitate the separation of individual user's data from the incoming SAMA sample “chip” stream. The filter outputs the convolution of the incoming signals with the matched filter impulse response at the same rate as the sampling of incoming chips, thus providing a means to detect more than one user within one match pattern interval. The filter operates completely synchronously with a high frequency filter clock, which is used to generate the sample clock. Incoming chip samples are loaded in the delay shift register at the sample clock rate. The samples are shifted at the filter clock frequency. Each bit in the chip trickles down through serial adders, with one clock period of delay for each serial adder. At the final accumulator, the serial sum bits are collected for parallel presentation to output registers at the sampling frequency.

Abstract: A SPREAD ALOHA Multiple Access (SAMA) channel uses distinct chip phases to label portions of a common SAMA channel and to reserve specific phases by means of a random access packet in the same SAMA channel. In the new SAMA reservation channel protocol, reservations consisting of the specification of a given chip phase are transmitted in a random access mode in a common SAMA channel. After a given user has reserved a given chip phase, that chip phase can be used on a reserved basis by that user to guarantee a certain quality of service. The reservation can be made by a user who simply initiates transmissions with a given chip phase and continues to use that chip phase if the user's first packet (the packet making the reservation) is received correctly. The SAMA hub broadcasts a list of reserved chip phases or broadcasts a list of free chip phases to ensure that other transmitters do not use the reserved chip phase. Alternately, the hub requires a transmitter to adjust chip phases of its transmitters.

Abstract: The invention provides both a fixed and a mobile data telecommunication service using a fixed code, direct sequence spread spectrum, connection-free data protocol as an overlay on cellular or PCS wireless services. A wide band connectionless data protocol is employed to transmit packetized digital data from a variety of home sources e.g. www inputs, e-mail, utility meter readings, security system data, to a local cellular or PCS communications hub station. From the hub station the cellular/PCS provider routes the packet data into packet networks for delivery to a variety of recipient parties designated by address within the packets themselves. The data capability is provided as a supplement to the existing communications capability of the cellular/PCS system and overlays, but does not destructively interfere with, the pre-existing voice connection oriented services.

Abstract: A SAMA QAM demodulator and packet detector receives SAMA transmissions from multiple transmitters. The received data packets have bits divided into chips in a first spreading sequence in the in phase branches of the transmitters, and a second spreading sequence in the quadrature branches of the transmitters. A demodulator at the hub station has a received signal splitter and an oscillator and phase shifter and multipliers for mixing the incoming signals with the oscillator output and with the phase shifted oscillator output on different branches. Low pass filters are connected to the mixers to remove the carrier signals and to leave chip signals with cosine and sine of phase offsets. The signal from each low pass filter is fed to an in phase matched filter and a quadrature matched filter, four matched filters in total, to produce despread signals from all of the active transmitters with phase relation and start offsets.

Abstract: Broadcasting of data packets from a hub station to many remote terminals in a two-way data network uses a spread spectrum time division multiplexed (TDM) channel. A channel in the other direction is a multiple access channel. To provide substantially equal energy per bit of the received signal at each of the remote terminals for maintaining reliability per bit at all terminals, the spreading factor of number of chips per bit is increased according to the distance of the remote terminal from the hub or the strength of the signal from the hub received by the remote terminal. The spreading factor or number of chips per bit may be changed according to the strength of the signal received by the hub from the remote terminal. Terminals positioned around the hub transmitter are located in regions arbitrarily determined by signal strengths, terrain, weather conditions or range.

Abstract: A simplified process of signal detection in a multiple access data communications uses a small number of different spreading signals rather than a single spreading signal such as used in a Spread ALOHA multiple access network. The process selects a spreading signal which depends upon a property of the signal being transmitted rather than upon the transmitter which is transmitting the signal as in Code Division Multiple Access (CDMA). Multiple transmitters can use pilot signals and transmit the multiple data signal with the selected spreading sequences. The hub station receives the multiple data signals and detects the multiple data signals with matched filters or correlators matched to the code spreading sequences. Outputs of the matched filters or correlators can create control signals for offsetting the transmitted data signals by advancing or retarding timing of the transmitting of the multiple data signals from the multiple transmitters.

Abstract: Multiple transmitters transmit data signals using identical spreading codes. A single matched filter of a receiver receives all the signals. A broadcast timing control signal retards or advances timings of individual transmitters to offset the interleaved signals. A subtracting circuit subtracts first and strongest signals until a single signal remains, and then reinserts the subtracted signals in the receiver. The identical code spreading sequence used in all the transmitters and in the matched filter is selected from a specific class of codes known as maximum length shift register sequences in a length equal to 2 .sup.n -1 for integer values of n. The method provides multiple access to a data communications channel without prearranging times or querying availability, and with automatic offsetting of the identical form signals.