Maximizing data rate by adjusting codes and code rates
View Patent ↗The present invention provides for making code rate adjustments and modulation type adjustments in a pseudonoise (PN) encoded CDMA system. Coding rate adjustments may be made by changing the number of information bits per symbol, or Forward Error Code (FEC) coding rate. A forward error correction (FEC) block size is maintained at a constant amount. Therefore, as the number of information bits per symbol are increased, an integer multiple of bits per epoch is always maintained. The scheme permits for a greater flexibility and selection of effective data rates providing information bit rates ranging from, for example, approximately 50 kilobits per second to over 5 mega bits per second (Mbps) in one preferred embodiment.
1. A mobile unit for receiving variable data rate communications in a communication system, the mobile unit comprising:
a receiver configured to receive a modulated signal and to receive forward error correction (FEC) rate data;
a symbol demodulator configured to generate a plurality of demodulated symbols from the modulated signal;
a block assembler configured to group the plurality of demodulated symbols according to a predetermined FEC block size;
a protocol converter configured to apply an inverse FEC coding process to decode the bits of the blocks into a plurality of FEC decoded bits based on the received FEC rate data; and
a segment disassembler configured to format the plurality of FEC decoded bits into a plurality of formatted frames.
2. The mobile unit of claim 1 , wherein the receiver is further configured to receive the modulated signal over a plurality of allocated sub- channels.
3. The mobile unit claim 2 , further comprising:
a multiplexer configured to reconstruct the transmission received over a plurality of allocated sub-channels into a signal.
4. The mobile unit of claim 1 , wherein the symbol modulating is selected from a group consisting of Quadrature Phase Keyed (QPSK), eight level Phase Shift Key (PSK), sixteen level Quadrature Amplitude Modulation (16 QAM) and 64 QAM.
5. The mobile unit of claim 1 , wherein the number of FEC symbols per block is selected from the group consisting of 2, 3, 4, and 6 bits per symbol.
6. A method of receiving variable data rate communications in mobile unit, the method comprising:
receiving a modulated signal;
receiving forward error correction (FEC) rate data;
demodulating the modulated signal to generate a plurality of demodulated symbols;
grouping the plurality of demodulated symbols according to a predetermined FEC block size;
applying an inverse FEC coding process for decoding the bits of the blocks into a plurality of FEC decoded bits based on the received FEC rate data; and
formatting the plurality of FEC decoded bits into a plurality of formatted frames.
7. The method of claim 6 , further comprising receiving the modulated signal over a plurality of allocated sub-channels.
8. The method of claim 6 , further comprising reconstructing the transmission received over a plurality of allocated sub-channels into a signal.
9. The method of claim 6 , further comprising receiving a modulated symbol from a group consisting of Quadrature Phase Keyed (QPSK), eight level Phase Shift Key (PSK), sixteen level Quadrature Amplitude Modulation (16 QAM) and 64 QAM.
10. The method of claim 6 , further comprising receiving data with a number of FEC symbols per block from a group consisting of 2, 3, 4, and 6 bits per symbol.