Legacy cyclic shift delay (CSD) for orthogonal frequency division multiplexing (OFDM) signaling within multiple user, multiple access, and/or MIMO wireless communications
View Patent ↗Legacy cyclic shift delay (CSD) for use within multiple user, multiple access, and/or MIMO wireless communications. Appropriately designed CSD is applied to communications in wireless communication systems thereby ensuring a minimized power error difference between respective portions of a packet transmitted therein. Such respective portions of the packet may be portions of the packet's preamble. For example, the first and second portions may be a legacy short training field (L-STF) and a very high throughput short training field (VHT-STF). By applying such appropriately designed CSD to a packet, a wireless communication device receiving a signal corresponding to that packet need not perform extra or very significant backoff (e.g., with respect to a signal subsequent to automatic gain control (AGC) processing) thereby simplifying signal processing and potentially also reducing a total number of effective analog to digital converter (ADC) bits needed to represent a digitally sampled version of that signal.
1. A method for operating a wireless communication device, the method comprising:
generating a multi-user packet including a first portion being compliant with a first communication protocol and a second portion being compliant with a second communication protocol in accordance with a plurality of Cyclic Shift Delays (CSDs), each of the plurality of CSDs being a respective integer multiple of a time period, for minimizing difference between a first transmit power associated with the first portion and a second transmit power associated with the second portion; and
via a plurality of antennae, transmitting a signal including the multi-user packet to a plurality of wireless communication devices such that each of the plurality of antennae transmitting at a respective time in accordance with a respective one of the plurality of CSDs.
2. The method of claim 1 , wherein:
the plurality of CSDs also minimizing difference between the first transmit power associated with the first portion and a third transmit power associated with a third portion of the multi-user packet being compliant in accordance with the first communication protocol.
3. The method of claim 2 , wherein:
the first portion corresponding to a legacy short training field (L-STF); and
the third portion corresponding to a legacy long training field (L-LTF), a legacy signal field (L-SIG), and a very high throughput signal field (VHT-SIGA).
4. The method of claim 1 , wherein:
the first portion of the multi-user packet being intended for a first of the plurality of wireless communication devices; and
the second portion of the multi-user packet being intended for a second of the plurality of wireless communication devices.
5. The method of claim 1 , wherein:
the second communication protocol being a legacy communication protocol relative to the first communication protocol;
a first subset of the plurality of CSDs corresponding to the first communication protocol; and
a second subset of the plurality of CSDs corresponding to the second communication protocol.
6. The method of claim 1 , further comprising:
generating the multi-user packet in accordance with a first subset of the plurality of CSDs when the plurality of antennae transmitting the signal using a first subset of the plurality of antennae; and
generating the multi-user packet in accordance with a second subset of the plurality of CSDs when the plurality of antennae transmitting the signal using a second subset of the plurality of antennae.
7. The method of claim 1 , wherein:
the first portion being a legacy short training field (L-STF); and
the second portion being a very high throughput short training field (VHT-STF).
8. The method of claim 1 , wherein:
the time period being 25 nano-seconds; and
each of plurality of CSDs being in a range of 0 nano-seconds to 200 nano-seconds, inclusive.
9. The method of claim 1 , wherein:
the plurality of antennae including even numbered antennae and odd numbered antennae; and further comprising:
phase shifting transmissions from the even numbered antennae by 180 degrees with respect to transmissions from the odd numbered antennae.
10. The method of claim 1 , wherein:
the wireless communication device being an access point (AP); and
the plurality of wireless communication devices being a plurality of wireless stations (STAs).
11. An apparatus, comprising:
a baseband processing module to generate a multi-user packet including a first portion being compliant with a first communication protocol and a second portion being compliant in accordance with a second communication protocol in accordance with a plurality of Cyclic Shift Delays (CSDs) for minimizing difference between a first transmit power associated with the first portion and a second transmit power associated with the second portion; and
a plurality of antennae to transmit a signal including the multi-user packet to a plurality of wireless communication devices; and wherein:
each of the plurality of CSDs being a respective integer multiple of a time period; and
each of the plurality of antennae to transmit at a respective time in accordance a respective one of the plurality of CSDs.
12. The apparatus of claim 11 , wherein:
the plurality of CSDs also to minimize difference between the first transmit power associated with the first portion and a third transmit power associated with a third portion of the multi-user packet being compliant in accordance with the first communication protocol.
13. The apparatus of claim 12 , wherein:
the first portion corresponding to a legacy short training field (L-STF); and
the third portion corresponding to a legacy long training field (L-LTF), a legacy signal field (L-SIG), and a very high throughput signal field (VHT-SIGA).
14. The apparatus of claim 11 , wherein:
the first portion of the multi-user packet being intended for a first of the plurality of wireless communication devices; and
the second portion of the multi-user packet being intended for a second of the plurality of wireless communication devices.
15. The apparatus of claim 11 , wherein:
the second communication protocol being a legacy communication protocol relative to the first communication protocol;
a first subset of the plurality of CSDs corresponding to the first communication protocol; and
a second subset of the plurality of CSDs corresponding to the second communication protocol.
16. The apparatus of claim 11 , wherein:
the baseband processing module to generate the multi-user packet in accordance with a first subset of the plurality of CSDs when the plurality of antennae transmitting the signal using a first subset of the plurality of antennae; and
the baseband processing module to generate the multi-user packet in accordance with a second subset of the plurality of CSDs when the plurality of antennae transmitting the signal using a second subset of the plurality of antennae.
17. The apparatus of claim 11 , wherein:
the first portion being a legacy short training field (L-STF); and
the second portion being a very high throughput short training field (VHT-STF).
18. The apparatus of claim 11 , wherein:
the time period being 25 nano-seconds; and
each of plurality of CSDs being in a range of 0 nano-seconds to 200 nano-seconds, inclusive.
19. The apparatus of claim 11 , wherein:
the plurality of antennae including even numbered antennae and odd numbered antennae; and
transmissions from the even numbered antennae being phase shifted by 180 degrees with respect to transmissions from the odd numbered antennae.
20. The apparatus of claim 11 , wherein:
the apparatus being an access point (AP); and
the plurality of wireless communication devices being a plurality of wireless stations (STAs).
21. An apparatus, comprising:
a baseband processing module to generate a multi-user packet including a legacy short training field (L-STF) being compliant in accordance with a first communication protocol and a very high throughput short training field (VHT-STF) being compliant in accordance with a second communication protocol in accordance with a plurality of Cyclic Shift Delays (CSDs) for minimizing difference between a first transmit power associated with the L-STF and the VHT-STF associated with the second portion and also for minimizing difference between the first transmit power associated with the L-STF and a second transmit power associated with a legacy long training field (L-LTF), a legacy signal field (L-SIG), and a very high throughput signal field (VHT-SIGA); and
a plurality of antennae to transmit a signal including the multi-user packet to a plurality of wireless communication devices; and wherein:
each of the plurality of CSDs being a respective integer multiple of 25 nano-seconds;
each of the plurality of antennae to transmit at a respective time in accordance a respective one of the plurality of CSDs; and
each of plurality of CSDs being in a range of 0 nano-seconds to 200 nano-seconds, inclusive.
22. The apparatus of claim 21 , wherein:
the second communication protocol being a legacy communication protocol relative to the first communication protocol;
a first subset of the plurality of CSDs corresponding to the first communication protocol; and
a second subset of the plurality of CSDs corresponding to the second communication protocol.
23. The apparatus of claim 21 , wherein:
the baseband processing module generating the multi-user packet in accordance with a first subset of the plurality of CSDs when the plurality of antennae transmitting the signal using a first subset of the plurality of antennae; and
the baseband processing module generating the multi-user packet in accordance with a second subset of the plurality of CSDs when the plurality of antennae transmitting the signal using a second subset of the plurality of antennae.
24. The apparatus of claim 21 , wherein:
the apparatus being an access point (AP); and
the plurality of wireless communication devices being a plurality of wireless stations (STAs).