Method and apparatus for using empty time slots for spread spectrum encoding
Communication circuitry uses a combination of Pseudo-Noise (PN) coded and non-PN coded transmission periods to represent different data values. In one embodiment, a number of data values are encoded into a smaller second number of encoded ternary values. The Pseudo-Noise (PN) codes are transmitted representing some of the encoded ternary values and no transmitted PN codes represent other encoded ternary values. The throughput of spread spectrum radio systems is increased by representing data values in fewer spread spectrum time slots.
1. A wireless communication device, comprising:
an encoder configured to combine Pseudo-Noise (PN) coded and non-PN coded data values into a same packet;
a transmitter configured to wirelessly transmit the packet containing the combined PN coded data values and non-PN coded values;
a first register configured to store a first set of PN encoded data values and a second set of non-PN encoded data values; and
a second register configured to identify the PN encoded data values and non-PN encoded data values.
2. The wireless communication device according to claim 1 wherein the encoder enables a PN encoder during PN coded transmission periods and disables the PN encoder during non-PN coded transmission periods.
3. The wireless communication device according to claim 1 wherein the encoder further comprises:
a first stage configured to encode a first set of binary data bits into the first set of PN encoded data values in the packet; and
a second state configured to combine the second set of non-PN encoded data values with the first set of PN encoded data values in the same packet.
4. The wireless communication device according to claim 3 wherein the transmitter is prevented from transmitting PN codes during time periods associated with the second set of non-PN encoded data values.
5. The wireless communication device according to claim 3 wherein the first and second stage of the encoder attach the PN encoded data values and non-PN encoded data values back to back wherein the second set of non-PN encoded data values are sandwiched between the first set of PN encoded data values and a third set of PN-encoded data values.
6. The wireless communication device according to claim 1 wherein the transmitter is a Direct Sequence Spread Spectrum (DSSS) transmitter that transmits spread spectrum signals that contain the PN encoded data values.
7. The wireless communication device according to claim 1 including:
a first serial register configured to generate PN codes;
a second serial register configured to select groups of data bits for PN encoding; and
a spread spectrum encoder that encodes the selected groups of data bits with the PN codes and does not encode other non-selected data bits with the PN codes.
8. An apparatus, comprising:
a correlator identifying Pseudo Noise (PN) encoded portions and non-PN encoded portions of a received packet;
a first decoder configured to convert each of the PN encoded portions of the packet into a first set of decoded data values corresponding with PN codes, and treat each of the non-PN encoded portions of the packet as an additional second set of data values that are not PN encoded;
a second decoder configured to convert a sequence of the first set of decoded data values corresponding with the PN codes and the second set of decoded data values not corresponding with the non-PN codes into the same packet radio circuitry configured to receive spread spectrum signals that include the PN encoded portions of the packet; and
wherein the first decoder identifies the PN-encoded portions of the packet when the spread spectrum signal is within a first upper threshold number of matching PN chips, and identifies the non-PN encoded portions of the packet when the spread spectrum signal is not within the first upper threshold number of matching PN chips.
9. The apparatus according to claim 8 wherein the second decoder formats the first set of decoded data values and the second set of data values into a sequence of binary bit values for the same packet.
10. The apparatus according to claim 8 wherein the receiver is a Universal Serial Bus (USB) device that converts at least a portion of the received data packet into USB signals.
11. A method of transmitting data, comprising:
encoding a first set of data values into Pseudo-Noise (PN) encoded data values;
combining the first set of PN encoded data values with a second set of data values that are not PN encoded into a same packet;
storing in a first register the first set of PN encoded data values and the second set of data values that are not PN encoded;
identifying with a second register the first set of PN encoded data values and the second set of data values that are not PN encoded; and
transmitting the packet that includes the first set of PN encoded data values and the second set of data values that are not PN encoded.
12. The method according to claim 11 including disabling a PN transmission during periods when the second set of data values are being transmitted.
13. The method according to claim 11 including encoding the first set of PN encoded data values back to back with the second set of data values.
14. The method according to claim 11 including sandwiching the second set of non-PN encoded data values between the first set of PN encoded data values and a third set of PN encoded data values.
15. The method according to claim 11 including:
receiving a sequence of binary data bits;
encoding a first set of the binary data bits with PN codes and transmitting the first set of PN encoded binary data bits;
not encoding the PN codes with a second set of binary data bits and transmitting the second set of binary data bits immediately after transmitting the first set of PN encoded binary data bits.