Method and apparatus for constant envelope modulation
Certain aspects of the present disclosure relate to a method for modulating single carrier signals using constant envelope 2-CPM modulation and quasi-constant envelope filtered continuously rotated pseudo-PSK modulation in a wireless communication system.
1. A method for communication, comprising:
encoding a binary data stream using continuously rotated differential pseudo BPSK (πh 2 -DPBPSK) encoding, wherein the πh 2 -DPBPSK encoding comprises mapping each binary bit of the data stream into one of two constant-amplitude constellation points, differentially encoding the mapped data stream, and continuously rotating the differentially encoded and mapped data stream by a constant phase of πh 2 , wherein π is Pi, and h 2 is a modulation index; and
filtering the encoded binary data stream to produce a quasi-constant envelope modulated signal.
2. The method of claim 1 , wherein the πh 2 -DPBPSK encoding comprises chip-level continuous rotation, wherein each n th chip is rotated by nπh 2 , where n is an integer-valued index.
3. The method of claim 1 , wherein the mapping is BPSK mapping, and wherein the modulation index h 2 =½.
4. A method for communication, comprising:
encoding a binary data stream using continuously rotated generalized differential pseudo QPSK (πh 4 -GDPQPSK) encoding, wherein the πh 4 -GDPQPSK encoding comprises generating even complex chips and odd complex chips, wherein generating the even complex chips comprises mapping bit pairs of the data stream into a constellation of four constant-amplitude points, differentially encoding the mapped data stream, continuously rotating the differentially encoded and mapped data stream by a constant phase of πh 4 , wherein π is Pi, and h 4 is a modulation index, and wherein the odd chips are generated by modifying the even chips using a correction term computed from the bit pairs and the modulation index h 4 ; and
filtering the encoded binary data stream to produce a quasi-constant envelope modulated signal.
5. The method of claim 4 wherein the πh 4 -GDPQPSK encoding employs chip-level continuous rotation, wherein each n th chip is rotated by πh 4 , where n is an integer-valued index.
6. The method of claim 4 wherein the mapping is a QPSK mapping and wherein the modulation index h 4 =¼.
7. A method for communication, comprising:
encoding a binary data stream using continuously rotated differential pseudo BPSK (πh 2 -DPBPSK) encoding and continuously rotated generalized differential pseudo QPSK (πh 4 -GDPQPSK) encoding; and
filtering the encoded binary data stream to produce a quasi-constant envelope modulated signal,
wherein the data stream comprises a preamble, a header, and a payload.
8. The method of claim 7 wherein the preamble of the data stream is encoded using continuously rotated differential pseudo-BPSK encoding.
9. The method of claim 7 wherein the data stream further comprises a training sequence.
10. The method of claim 9 wherein the preamble and header are encoded using continuously rotated differential pseudo-BPSK encoding, and the training sequence and payload are encoded using continuously rotated generalized differential pseudo QPSK encoding.
11. The method of claim 7 wherein the encoding employs πh 2 -DPBPSK encoding or πh 4 -GDPQPSK encoding in the payload depending on signaling in the header.
12. An apparatus for communication, comprising:
an encoder configured for encoding a binary data stream using continuously rotated differential pseudo BPSK (πh 2 -DPBPSK) encoding, the encoder comprising a mapper for mapping each binary bit of the data stream into one of two constant-amplitude constellation points, a differential encoder for differentially encoding the mapped data stream, and a rotator for continuously rotating the differentially encoded and mapped data stream by a constant phase of πh 2 , wherein π is Pi, and h 2 is a modulation index;
a filter for filtering the encoded binary data stream to produce a quasi-constant envelope modulated signal; and
a transmitter for transmitting the quasi-constant envelope modulated signal.
13. The apparatus of claim 12 , wherein the rotator is configured for performing chip-level continuous rotation, wherein an n th chip is rotated by nπh 2 , where n is an integer-valued index.
14. The apparatus of claim 12 , wherein the mapper is a BPSK mapper, and wherein the modulation index h 2 =½.
15. An apparatus for communication, comprising:
an encoder configured for encoding a binary data stream using continuously rotated generalized differential pseudo QPSK (πh 4 -GDPQPSK) encoding, the encoder comprising a first generator for generating even complex chips and a second generator for generating odd complex chips, the first generator comprising a mapper for mapping bit pairs of data stream into a constellation of four constant-amplitude points, a differential encoder for differentially encoding the mapped data stream, and a rotator for continuously rotating the differentially encoded and mapped data stream by a constant phase of πh 4 , wherein π is Pi, and h 4 is a modulation index, and the second generator configured for modifying the even complex chips using a correction term computed from data bit pairs and the modulation index h 4 ;
a filter for filtering the encoded binary data stream to produce a quasi-constant envelope modulated signal; and
a transmitter for transmitting the quasi-constant envelope modulated signal.
16. The apparatus of claim 15 , wherein the rotator employs chip-level continuous rotation to rotate each n th chip by nπh 4 , where n is an integer-valued index.
17. The apparatus of claim 15 , wherein the mapper is a QPSK mapper, and the modulation index h 4 =¼.
18. An apparatus for communication, comprising:
an encoder for encoding a binary data stream using continuously rotated differential pseudo BPSK (πh 2 -DPBPSK) encoding and continuously rotated generalized differential pseudo QPSK (πh 4 -GDPQPSK) encoding;
a filter for filtering the encoded binary data stream to produce a quasi-constant envelope modulated signal; and
a transmitter for transmitting the quasi-constant envelope modulated signal,
wherein the data stream comprises a preamble, a header, and a payload.
19. The apparatus of claim 18 , wherein the preamble is encoded using πh 2 -DPBPSK.
20. The apparatus of claim 18 , wherein the data stream further comprises a training sequence.
21. The apparatus of claim 20 , wherein the encoder is configured to encode the preamble and header using πh 2 -DPBPSK, and encode the training sequence and payload using πh 4 -GDPQPSK.
22. The apparatus of claim 18 , wherein the encoder is configured to encode the payload is encoded using πh 2 -DPBPSK encoding or πh 4 -GDPQPSK encoding depending on signaling in the header.