Optimized companding for communication over cellular systems
AssigneeSierra Wireless, Inc.
InventorMarek Karol Dutkiewicz
Life of this patent
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Abstract
An integrated cellular switched modem for enhanced cellular data communication by implementing in DSP or Software all baseband processing normally carried out in a cellular radio transceiver within the processor of the single integrated wireless modem. Adjustments are made to EIA/TIA standards for pre-emphasis, de-emphasis, and companding functions implemented by DSP in order to optimize communication for data.
Claims6
An integrated cellular switched modem for enhanced data communication comprising:
- data source;
- a receiver for receiving incoming data;
- a programmed digital processor reading signals from the data source and the receiver for baseband processing of said signals;
- and
- a transmitter for transmitting said processed baseband signals, wherein said baseband processing implements a companding function on said data signal, wherein said companding function includes an expandor, whereby a variable gain proportional to the average input signal power is applied to the input signal and the expandor implements the following algorithm:
- (a) sig.sub.-- out(n)=gain(n)*sig.sub.-- in(n)
- (b) sig.sub.-- avg(n+1)=k*abs(sig.sub.-- in(n))+(1-k)*sig.sub.-- avg(n)
- (c) gain(n+1)=sig.sub.-- avg(n+1)/sig.sub.-- ref . . . sig.sub.-- ref
- where k is an averaging constant and sig-ref is the reference signal amplitude.
An integrated cellular switched modem for enhanced data communication comprising:
- a data source;
- a receiver for receiving incoming data;
- a programmed digital processor reading signals from the data source and the receiver for baseband processing of said signals;
- and
- a transmitter for transmitting said processed baseband signals, wherein said baseband processing implements a companding function on said data signal, wherein said companding function includes a compressor whereby a variable gain proportional to the inverse average output signal strength is applied to the input signal and the compressor implements the following algorithm:
- (d) sig.sub.-- out(n)=sig.sub.-- in(n)/gain(n)
- (e) sig.sub.-- avg(n+1)=k*abs(sig.sub.-- out(n))+(1-k)*sig.sub.-- avg(n)
- (f) gain(n+1)=sig.sub.-- avg(n+1)/sig.sub.-- ref
- k is averaging constant and sig.sub.-- ref is the reference signal amplitude.
A method for enhanced data communications in a cellular wireless modem comprising the steps of:
- inputting data signals from a data source;
- receiving incoming data;
- performing baseband processing by implementing a companding function on the data signals and incoming data by said modem;
- and
- transmitting said processed data signals, wherein the step of processing further comprises the step of:
- expanding the data signals, wherein a variable gain proportional to the average input signal power is applied to the input signal and the step of expanding is implemented by the algorithm:
- (a) sig.sub.-- out(n)=gain(n)*sig.sub.-- in(n)
- (b) sig.sub.-- avg(n+1)=k*abs(sig.sub.-- in(n))+(1-k)*sig.sub.-- avg(n)
- (c) gain(n+1)=sig.sub.-- avg(n+1)/sig.sub.-- ref . . . sig.sub.-- ref
- where k is an averaging constant and sig-ref is the reference signal amplitude.
A method for enhanced data communications in a cellular wireless modem comprising the steps of:
- inputting data signals from a data source;
- receiving incoming data;
- performing baseband processing by implementing a companding function on the data signals and incoming data by said modem;
- and
- transmitting said processed data signals, wherein the step of processing further comprises the step of:
- compressing the data signals, wherein a variable gain proportional to the inverse average output signal strength is applied to the input signal and the step of compressing is implemented by the algorithm:
- (d) sig.sub.-- out(n)=sig.sub.-- in(n)/gain(n)
- (e) sig.sub.-- avg(n+1)=k*abs(sig.sub.-- out(n))+(1-k)*sig.sub.-- avg(n)
- (f) gain(n+1)=sig.sub.-- avg(n+1)/sig.sub.-- ref
- k is averaging constant and sig.sub.-- ref is the reference signal amplitude.
Dependencies are inferred from the claim text.