High speed overlay mode for burst data and real time streaming (audio) applications
In a wireless 802.15.4 communication system ( 300 ), a high-speed data frame structure ( 340 ) is provided which uses the 802.15.4 SHR structure that is spread modulated to obtain the synchronization benefits of the 802.15.4 protocol, but which uses a modified data frame structure for the payload portion without using spreading to thereby improve its transmission efficiency. The transmission efficiency can be further increased by increasing the size of the data payload (and correspondingly, the frame length size).
1. A data transfer method in a wireless device having a short range communication link with a receiving device, comprising:
modulating a first data packet in accordance with a predetermined transmission protocol by spreading all data bits in the first data packet, thereby transferring data at a first data rate during a standard transmit mode; and
modulating a second data packet by spreading only a synchronization header portion in the second data packet and separately processing at least a data payload portion so that the data payload portion is not spread, thereby transferring data at a second higher data rate during a high-speed overlay mode.
2. The data transfer method of claim 1 , where modulating the first data packet comprises modulating the first data packet in accordance with IEEE 802.15.4 protocol requirements.
3. The data transfer method of claim 1 , where modulating the second data packet comprises spreading only the synchronization header portion of the second data packet so that a frame length and data payload portion of the second data packet are not spread modulated.
4. The data transfer method of claim 1 , where modulating the second data packet comprises spreading only the synchronization header portion of the second data packet and performing offset quadrature phase-shift keying (O-QPSK} modulation on at least the data payload portion without spreading.
5. The data transfer method of claim 1 , where the second higher data rate is approximately of 2 Mbps.
6. The data transfer method of claim 1 , further comprising applying data whitening to the data payload portion prior to processing the data payload portion.
7. The data transfer method of claim 1 , where modulating the first and second data packets each comprise modulating a shared preamble sequence by spreading all data bits in the shared preamble sequence.
8. A wireless communication device for transferring data over a short range communication link to a receiving device, comprising:
a transmitter packet processor for processing outbound data to produce digital packet data in accordance with a predetermined transmission protocol; and
a digital modem for modulating the digital packet data in accordance with the predetermined transmission protocol by spreading all data bits in the digital packet data for transferring data at a first data rate during a standard transmit mode, and for modulating the digital packet data by spreading only a synchronization header portion in the digital packet data and separately processing at least a data payload portion so that the data payload portion is not spread, thereby transferring data at a second higher data rate during a high-speed overlay mode.
9. The wireless communication device of claim 8 , where the digital modem modulates the digital packet data in accordance with the IEEE 802.15.4 protocol requirements during the standard transmit mode.
10. The wireless communication device of claim 8 , where the digital modem modulates the digital packet data by spreading only a synchronization header portion of the digital packet data during the high-speed overlay mode.
11. The wireless communication device of claim 8 , where the digital modem modulates the digital packet data by spreading a synchronization header portion of the digital packet data and performing offset quadrature phase-shift keying (O-QPSK) modulation on at least the data payload portion without spreading during the high-speed overlay mode during which a frame length and data payload portion of the digital data packet are not spread modulated.
12. The wireless communication device of claim 8 , where the second higher data rate is approximately of 2 Mbps during the high-speed overlay mode.
13. The wireless communication device of claim 8 , where the transmitter packet processor applies data whitening to the data payload portion prior to processing the data payload portion.
14. The wireless communication device of claim 8 , where the digital modem modulates the digital packet data by generating a predetermined synchronization header (SHR) structure in which spreading code modulation is applied to only an IEEE 802.15.4 preamble sequence during the high-speed overlay mode.