Method and apparatus for multi-stream transmission with time and frequency diversity in an orthogonal frequency division multiplexing (OFDM) communication system
View Patent ↗A method and apparatus increase the time and frequency diversity of a multi-stream signal in a DAB system. A plurality of audio streams are divided into four (4) digital sub-streams, C 00 , C 01 , C 10 , and C 11 . Each sub-stream C 00 , C 01 , C 10 , and C 11 is assigned a unique frequency band, and time slot. A first core sub-stream C 10 is mapped to one frequency partition and a second core sub-stream C 00 is mapped to another frequency partition and delayed relative to the first core sub-stream. Similarly, two enhancement sub-streams C 11 and C 01 are mapped to different frequency partitions and are time delayed relative to each other and the core sub-streams. The two core sub-streams C 00 and C 10 can have a maximum separation across both the time and frequency axes.
1. A method of transmitting a plurality of sub-streams in a multi-stream digital audio broadcasting system, said method comprising the steps of:
allocating a unique frequency partition to each of said sub-streams for a plurality of consecutive time slots;
allocating a unique time slot to each of said plurality of sub-streams; and
transmitting said sub-streams to a receiver.
2. The method of claim 1 , wherein said sub-streams include at least two core streams and at least two enhancement streams.
3. The method of claim 2 , wherein said core sub-streams have a maximum separation in the time domain.
4. The method of claim 2 , wherein said multi-stream digital audio broadcasting system is an all-digital IBOC (In-Band-On-Channel) system and said core sub-streams have a maximum separation in the frequency domain.
5. The method of claim 2 , wherein said multi-stream digital audio broadcasting system is a hybrid IBOC (In-Band-On-Channel) system and said core sub-streams are transmitted in the frequency domain in the innermost side bands.
6. The method of claim 2 , wherein said multi-stream digital audio broadcasting system is an all-digital IBOC (In-Band-On-Channel) system and each of said core sub-streams has a maximum separation from one of said enhancement sub-streams in the frequency domain and a maximum separation from the other enhancement sub-stream in the time domain.
7. The method of claim 2 , wherein said multi-stream digital audio broadcasting system is an all-digital IBOC (In-Band-On-Channel) system and said core sub-streams are separated by a data stream.
8. The method of claim 1 , wherein no two sub-streams associated with the same audio segment are transmitted in the same time slot.
9. The method of claim 1 , wherein a unique time slot is allocated to each of said sub-streams by introducing a delay between each of said sub-streams.
10. A transmitter in a multi-stream digital audio broadcasting system, comprising:
a modulator for allocating a unique frequency partition to each of two or more sub-streams for a plurality of consecutive time slots;
a delay circuit for allocating a unique time slot to each of said two or more sub-streams; and
a transmitter for transmitting said two or more sub-streams to a receiver.
11. The transmitter of claim 10 , wherein said two or more sub-streams include at least two core streams and at least two enhancement streams.
12. The transmitter of claim 11 , wherein said core sub-streams have a maximum separation in the time domain.
13. The transmitter of claim 11 , wherein said multi-stream digital audio broadcasting system is an all-digital IBOC (In-Band-On-Channel) system and said modulator provides a maximum separation of said core sub-streams in the frequency domain.
14. The transmitter of claim 11 , wherein said multi-stream digital audio broadcasting system is a hybrid IBOC (In-Band-On-Channel) system and said modulator allocates said core sub-streams in the frequency domain to the innermost side bands.
15. The transmitter of claim 11 , wherein said multi-stream digital audio broadcasting system is an all-digital IBOC (In-Band-On-Channel) system and each of said core sub-streams has a maximum separation from one of said enhancement sub-streams in the frequency domain and a maximum separation from the other enhancement sub-stream in the time domain.
16. The transmitter of claim 11 , wherein said multi-stream digital audio broadcasting system is an all-digital IBOC (In-Band-On-Channel) system and said core sub-streams are separated by a data stream.
17. The transmitter of claim 10 , wherein no two sub-streams associated with the same audio segment are transmitted in the same time slot.
18. The transmitter of claim 10 , wherein a unique time slot is allocated to each of said two or more sub-streams by introducing a delay between each of said two or more sub-streams.