System and method for generating signal waveforms in a CDMA cellular telephone system
First Claim
1. A spread spectrum modulator for modulating variable rate input digital data for transmission, said input digital data being provided in data frames of a predetermined time duration with each frame of input digital data having a number of data bits corresponding to one of several predetermined frame bit counts, said modulator comprising:
- a convolutional encoder having an input receiving said frames of input digital data and an output;
a data interleaver having an input coupled to said convolutional encoder output and an output;
a Walsh function encoder having an input coupled to said interleaver output and an output;
a first pseudorandom noise (PN) code generator having an output;
a first exclusive-OR gate having a pair of inputs and an output, one of said first exclusive-OR gate inputs coupled to said first PN code generator output and another of said first exclusive-OR gate inputs coupled to said Walsh encoder output;
a second PN code generator having an output;
a third PN code generator having an output;
a second exclusive-OR gate having a pair of inputs and an output, one of said second exclusive-OR gate inputs coupled to said second PN code generator output and another of said second exclusive-OR gate inputs coupled to said first exclusive-OR gate output; and
a third exclusive-OR gate having a pair of inputs and an output, one of said third exclusive-OR gate inputs coupled to said third PN code generator output and another of said third exclusive-OR gate inputs coupled to said first exclusive-OR gate output.
0 Assignments
0 Petitions
Accused Products
Abstract
A system and method for communicating information signals using spread spectrum communication techniques. PN sequences are constructed that provide orthogonality between the users so that mutual interference will be reduced, allowing higher capacity and better link performance. With orthogonal PN codes, the cross-correlation is zero over a predetermined time interval, resulting in no interference between the orthogonal codes, provided only that the code time frames are time aligned with each other. In an exemplary embodiment, signals are communicated between a cell-site and mobile units using direct sequence spread spectrum communication signals. In the cell-to-mobile link, pilot, sync, paging and voice channels are defined. Information communicated on the cell-to-mobile link channels are, in general, encoded, interleaved, hi-phase shift key (BPSK) modulated with orthogonal covering of each BPSK symbol along with quadrature phase shift key (QPSK) spreading of the covered symbols. In the mobile-to-cell link, access and voice channels are defined. Information communicated on the mobile-to-cell link channels are, in general, encoded, interleaved, orthogonal signalling along with QPSK spreading.
-
Citations
36 Claims
-
1. A spread spectrum modulator for modulating variable rate input digital data for transmission, said input digital data being provided in data frames of a predetermined time duration with each frame of input digital data having a number of data bits corresponding to one of several predetermined frame bit counts, said modulator comprising:
-
a convolutional encoder having an input receiving said frames of input digital data and an output; a data interleaver having an input coupled to said convolutional encoder output and an output; a Walsh function encoder having an input coupled to said interleaver output and an output; a first pseudorandom noise (PN) code generator having an output; a first exclusive-OR gate having a pair of inputs and an output, one of said first exclusive-OR gate inputs coupled to said first PN code generator output and another of said first exclusive-OR gate inputs coupled to said Walsh encoder output; a second PN code generator having an output; a third PN code generator having an output; a second exclusive-OR gate having a pair of inputs and an output, one of said second exclusive-OR gate inputs coupled to said second PN code generator output and another of said second exclusive-OR gate inputs coupled to said first exclusive-OR gate output; and a third exclusive-OR gate having a pair of inputs and an output, one of said third exclusive-OR gate inputs coupled to said third PN code generator output and another of said third exclusive-OR gate inputs coupled to said first exclusive-OR gate output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. A method for spread spectrum modulating a data signal comprising the steps of:
-
converting sequential portions of a digitized data signal into respective orthogonal function signal portions wherein each orthogonal function signal portion is representative of an orthogonal function selected from a plurality of orthogonal functions according to a value of a respective portion of said sequential portions; generating a pseudorandom noise (PN) code; and combining said orthogonal function signal portions with said PN code to produce a PN spread signal. - View Dependent Claims (10, 11, 12, 13, 14)
-
-
15. A method for spread spectrum modulating digital data for transmission, comprising:
-
convolutional encoding digital data to produce symbol data in a first ordered sequence; reordering said symbol data of said first ordered sequence to a second ordered sequence; grouping symbols of said second ordered sequence of symbol data into corresponding symbol groups; determining from a binary value formed by said symbol data in each symbol group a respective Walsh function symbol of a plurality of Walsh function symbols; generating a first pseudorandom noise (PN) code; and combining said Walsh function symbols with said first PN code to produce first PN spread data. - View Dependent Claims (16, 17, 18, 19)
-
-
20. A system for modulating an information signal in a spread spectrum communication system comprising:
-
orthogonal function encoder means for receiving a digitized information signal and converting sequential portions of said digitized information signal into respective orthogonal function signals; and spreading means connected to said orthogonal function encoder means for generating a pseudorandom noise (PN) code and combining said orthogonal function signals with said PN code to produce a PN spread signal. - View Dependent Claims (21, 22, 23, 24, 25)
-
-
26. A modulator for spread spectrum modulating digital data for transmission, comprising:
-
convolutional encoder means for receiving and convolutional encoding digital data to produce symbol data in a first ordered sequence; interleaver means for reordering said symbol data in a second ordered sequence; orthogonal function encoder means for encoding said second ordered sequence symbol data into orthogonal function symbol data; first generator means for generating a first pseudorandom noise (PN) code; first combining means for combining said orthogonal function symbol data and said first PN code to produce a first PN spread data signal. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
-
Specification