USF coding
Systems and methods are provided for transmitting and receiving an uplink state flag (USF) in a cellular network. A base station may transmit the USF to plurality of mobile stations that share the same frequency channel, and each mobile station can use the USF to determine whether that mobile station can transmit data in an upcoming uplink time period. The base station can encode the USF bits into a plurality of encoded USF symbols, where the encoded USF symbols may be selected from corner signal points in a QAM signal constellation set or from signal points adjacent to the corners of a QAM signal constellation set. The base station can interleave the encoded USF symbols and modulate the encoded USF symbols for transmission using the signal constellation set. A mobile station that can communication with the base station can include a corresponding receiver, de-interleaver, and decoder.
1. A mobile station for use on a cellular network, comprising:
a receiver configured to:
receive from the cellular network transmitted signals that include an encoded uplink state flag (USF);
process the received signals to generate estimated symbol values corresponding to the received signals, wherein the estimated symbol values can correspond to any of the symbol values in a quadrature amplitude modulation (QAM) constellation set;
a USF decoder employing a USF codebook having codewords that are defined by a subset of the symbol values in the QAM constellation set, the subset being selected from among symbol values that each correspond to a signal point located at or adjacent to a corner of the QAM constellation set, the USF decoder being configured to generate an estimated USF from the estimated symbol values based on a correspondence between the estimated symbol values and the codewords; and
computational logic circuitry configured to determine whether to transmit data in a next uplink time period based on the estimated USF.
2. The mobile station of claim 1 , wherein the QAM constellation set is a 16QAM constellation set that includes 16 signal points.
3. The mobile station of claim 1 , wherein the QAM constellation set is a 32QAM constellation set that includes 32 signal points.
4. The mobile station of claim 1 , wherein the transmitted signals correspond to interleaved symbols that are interleaved among a plurality of bursts, the mobile station further comprising:
a de-interleaver configured to de-interleave the received interleaved symbols from among the plurality of bursts to produce de-interleaved symbols.
5. The mobile station of claim 4 , wherein the USF decoder is configured to compute the estimate of the USF from the de-interleaved symbols.
6. The mobile station of claim 1 , wherein the subset of symbol values corresponds to a pair of symbol values that are associated with signal points located at antipodal locations in the QAM constellation set.
7. The mobile station of claim 1 , wherein the computational logic comprises at least one of hardware, software, and firmware logic.
8. The mobile station of claim 1 , wherein the estimate of the USF is one of a predetermined number of possible USF values.
9. The mobile station of claim 8 , wherein the predetermined number is eight, and wherein the USF decoder is configured to output one of the eight possible USF estimates.
10. A method for using uplink state flag (USF) information on a cellular network, the method comprising:
receiving from the cellular network transmitted signals that include an encoded USF;
processing the received signals to generate estimated symbol values corresponding to the received signals, wherein the estimated symbol values can correspond to any of the symbol values in a quadrature amplitude modulation (QAM) constellation set;
generating an estimated USF from the estimated symbol values based on a correspondence between the estimated symbol values and codewords in a USF codebook, wherein the codewords are defined by a subset of the symbol values in the QAM constellation set, the subset being selected from among symbol values that each correspond to a signal point located at or adjacent to a corner of the QAM constellation set; and
determining whether to transmit data in a next uplink time period based on the estimated USF.
11. The method of claim 10 , wherein the processing comprises processing the received signals to generate estimated symbol values that can correspond to any of the symbol values in a 16QAM constellation set that includes 16 signal points, and wherein the generating comprises generating an estimated USF based on codewords defined by a subset of the symbol values in the 16QAM constellation set.
12. The method of claim 10 , wherein the processing comprises processing the received signals to generate estimated symbol values that can correspond to any of the symbol values in a 32QAM constellation set that includes 32 signal points, and wherein the generating comprises generating an estimated USF based on codewords defined by a subset of the symbol values in the 32QAM constellation set.
13. The method of claim 10 , wherein the transmitted signals correspond to interleaved symbols that are interleaved among a plurality of bursts, the method further comprising:
de-interleaving the received interleaved symbols from among the plurality of bursts to produce de-interleaved symbols.
14. The method of claim 13 further comprising computing the estimate of the USF from the de-interleaved symbols.
15. The method of claim 10 , wherein the generating comprises generating an estimated USF based on codewords defined by a pair of symbol values associated with signal points located at antipodal locations in the QAM constellation set.
16. The method of claim 10 , wherein the generating comprises generating an estimated USF corresponding to one of a predetermined number of possible USF values.
17. The method of claim 10 , wherein the generating comprises generating an estimated USF corresponding to one of eight possible USF values.