초록 ▼

A technique for using energy received by subscriber units over multiple orthogonal channels within a spread spectrum communication system to acquire signal timing by controlling signal amplitude integration intervals used in detecting such timing. Received signals are despread and respective amplitu

A technique for using energy received by subscriber units over multiple orthogonal channels within a spread spectrum communication system to acquire signal timing by controlling signal amplitude integration intervals used in detecting such timing. Received signals are despread and respective amplitudes integrated over periods that are divisible by factors of 2 into the length of Walsh functions used to generate orthogonal signal channels. Non-coherent combinations of the results of this integration are subsequently formed over periods that commence and terminate on Walsh function boundaries, and used to determine when a correct time offset has been selected for despreading signals. Additional advantages are realized by assigning signals that consistently provide a higher energy content such as paging, synchronization, and most frequently assigned traffic channels to specific orthogonal channels within the communication system. In exemplary embodiments, Walsh functions of length 128 are used as channelizing codes and a pilot signal is assigned to channel 0. This results in traffic channels or paging and synchronization functions being assigned to channel 64 when the integration periods are 64 chips long, and to channels 32, 64, and 96 when the periods are 32 chips long. In this manner, additional energy is available during the integration process for use in determining when correct signal acquisition timing offsets have been selected, without the use of additional hardware.

대표청구항 ▼

A method of acquiring time synchronization with one or more orthogonal channel signals in a spread spectrum communication system in which one or more communication signals are received and demodulated by system subscribers, comprising the steps of: receiving one or more communication signals each co

A method of acquiring time synchronization with one or more orthogonal channel signals in a spread spectrum communication system in which one or more communication signals are received and demodulated by system subscribers, comprising the steps of: receiving one or more communication signals each comprising multiple channel signals which are orthogonally encoded using one of a preselected set of Walsh functions which are spread using at least one common pseudorandom noise (PN code) sequence applied at one of a plurality of timing offsets relative to each other within said system; selecting a PN code sequence time offset value to use in a receiving subscriber unit; despreading said communication signals by applying said PN code sequence at said selected time offset to produce encoded symbols; coherently accumulating amplitudes of encoded symbols over a predetermined time interval equivalent to a length of said Walsh functions divided by a factor of 2n, where n is a positive integer; squaring the results of said coherent accumulation; combining square products over an interval commencing and ending at Walsh function boundaries as selected by the receiving subscriber unit; comparing results of said combining to at least one threshold value; selecting said time offset chosen by said receiving subscriber unit as a time offset for a desired orthogonal channel signal when the combining results exceed said threshold; and altering said time offset value selection and repeating said despreading, accumulating, squaring, combining, and comparing steps in order until said threshold is exceeded.