Wireless home network supporting concurrent links to legacy devices
A wireless access point (WAP) including: a station grouping module, a transmit selector, a spatial mapper, an output injector, and an input injector. The station grouping module selects a group of station nodes for concurrent MIMO communications. The transmit selector determines whether all station nodes in the group support a multi-user (MU) protocol. The spatial mapper precodes concurrent transmissions to the group using a precode matrix “Q” which spatially separates the concurrent MIMO transmissions to each station node in the group. The output injector injects preambles for synchronizing timing of the MIMO transmissions at the output of the spatial mapper, responsive to an affirmative determination by the transmit selector. The input injector injects preambles before precoding in the spatial mapper, responsive to a negative determination by the transmit selector; whereby transmission preambles are precoded when at least one station node in the group doesn't support the MU protocol.
1. A wireless access point (WAP) apparatus having a plurality of antennas and supporting multiple-input multiple-output (MIMO) wireless communications with associated station nodes on a selected one of a plurality of orthogonal frequency division multiplexed (OFDM) communication channels; and the WAP apparatus comprising:
a station grouping module configured to select a group of at least two of the associated station nodes for concurrent MIMO communication links with the WAP;
a transmit selector configured to determine whether all station nodes in the group support a multi-user (MU) protocol;
a spatial mapper including an input and an output, configured to precode concurrent transmissions to the selected group at the input using a precode matrix “Q” which spatially separates the concurrent MIMO transmissions to each station node in the group at the output;
an output injector coupled to the output of the spatial mapper and configured to inject preambles for synchronizing timing of the MIMO transmissions at the output of the spatial mapper, responsive to an affirmative determination by the transmit selector; and
an input injector coupled to the input of the spatial mapper and configured to inject preambles before precoding in the spatial mapper, responsive to a negative determination by the transmit selector, whereby transmission preambles are precoded when at least one station node in the group does not support the MU protocol.
2. The WAP apparatus of claim 1 , further comprising:
the output injector further configured to inject a single MU compliant preamble for each concurrent set of communication packets sent to the station nodes in the group; and
the input injector further configured to inject into each concurrent set of communication packets a discrete preamble for each station node in the group that does not support the MU protocol.
3. The WAP apparatus of claim 1 , further comprising:
the output injector further configured to inject a single MU compliant preamble for each concurrent set of communication packets sent to the station nodes in the group; and
the input injector further configured to inject into each concurrent set of communication packets, a discrete preamble for each station node in the group that does not support the MU protocol, wherein the discrete preambles match the selected one of the IEEE 802.11a, b, g, n, and ac ‘Wave 1’ standards supported by each station node.
4. The WAP apparatus of claim 1 , further comprising:
the station grouping module further configured to select a group of at least three of the associated station nodes at least two of which support the MU protocol and at least one of which does not support the MU protocol; and
the input injector further configured to inject into each concurrent set of communication packets a single MU compliant preamble for the at least two of the station nodes in the group which support the MU protocol together with discrete preambles for remaining station nodes in the group.
5. The WAP apparatus of claim 1 , further comprising:
a channel probe configured to probe each station node in the group to determine the wireless channel information for each prospective link, including obtaining reverse channel estimates for stations that do not support explicit channel sounding.
6. The WAP apparatus of claim 1 , further comprising:
an evaluator configured to evaluate reliability of channel information between the WAP and station nodes that do not support explicit channel sounding, by comparing throughput to said station nodes with and without MIMO beamforming using a steering matrix derived from the channel information; whereby absent improvements in throughput resulting from MIMO beamforming the channel information is deemed unreliable.
7. The WAP apparatus of claim 1 , further comprising:
an evaluator configured to evaluate reliability of the precoding matrix “Q”, by scaling the relative power of one link relative to remaining links in the group; whereby an unreliable precoding matrix results in degradation in throughput to the remaining links during scaling of relative power to the one link.
8. The WAP apparatus of claim 1 , further comprising:
the transmit selector further configured to determine whether all station nodes in the group support the multi-user (MU) protocol specified in IEEE 802.11ac ‘Wave 2’.
9. A method for operating a wireless access point (WAP) apparatus having a plurality of antennas and supporting a multiple-input multiple-output (MIMO) wireless local area network (WLAN) with associated station nodes on a selected one of a plurality of orthogonal frequency division multiplexed (OFDM) communication channels; and the method comprising the acts of:
selecting a group of at least two of the station nodes for concurrent wireless MIMO communication links with the WAP;
determining whether all station nodes in the selected group support a multi-user (MU) protocol;
inserting a single MU compliant preamble for a set of concurrent communication packets transmitted to the station nodes in the selected group, responsive to a determination that all station nodes in the group support the MU protocol; and
inserting into the set of concurrent communication packets transmitted to station nodes in the selected group, a discrete preamble for the communication packet to each station node in the selected group that does not support the MU protocol, responsive to a determination that a station node in the group does not support the MU protocol;
determining a precode matrix “Q” for precoding transmissions over the plurality of antenna which spatially separates the concurrent MIMO transmissions to each station node in the group;
spatially mapping concurrent transmissions to the selected group using the precode matrix “Q” to precode the set of concurrent communication packets except for the single MU compliant preamble thereof, responsive to the determination that all station nodes in the selected group support the MU protocol, whereby the MU compliant preamble is ‘heard’ by all station nodes in the selected group; and
spatially mapping concurrent transmissions to the selected group using the precode matrix “Q” to precode the set of concurrent communication packets including the discrete preambles thereof, responsive to the determination that a station node in the group does not support the MU protocol; thereby transforming the discrete preambles into spatially separate transmissions which avoid interference with one another.
10. The method for operating a WAP of claim 9 , wherein the discrete preambles match a corresponding one of the IEEE 802.11a,b,g,n, and ac ‘Wave 1’ standards supported by each station node.
11. The method for operating a WAP of claim 9 , further comprising:
selecting, in the selecting act, a group of at least three of the station nodes at least two of which support the MU protocol and at least one of which does not support the MU protocol; and
inserting, into the set of communication packets a single MU compliant preamble for the communication packets to the at least two of the station nodes in the group which support the MU protocol together with the discrete preamble for the communication packet to the at least one station node in the group that does not support the MU protocol.
12. The method for operating a WAP of claim 9 , further comprising:
probing each station node in the group to determine the wireless channel information for each prospective link, including obtaining reverse channel estimates for station nodes that do not support explicit channel sounding; and
determining the precode matrix “Q” based on the wireless channel information for each prospective link obtained in the probing act.
13. The method for operating a WAP of claim 9 , further comprising:
evaluating reliability of channel information between the WAP and station nodes that do not support explicit channel sounding, by comparing throughput to said station nodes with and without MIMO beamforming using a steering matrix derived from the channel information; whereby absent improvements in throughput resulting from MIMO beamforming the channel information is deemed unreliable.
14. The method for operating a WAP of claim 9 , further comprising:
evaluating reliability of the precoding matrix “Q”, by scaling the relative power of one link relative to remaining links in the group; whereby an unreliable precoding matrix results in degradation in throughput to the remaining links during scaling of relative power to the one link.
15. The method for operating a WAP of claim 9 , wherein the determining act further comprises:
determining whether all station nodes in the group support the MU protocol specified in IEEE 802.11ac ‘Wave 2’.
16. The method for operating a WAP of claim 9 , further comprising:
transmitting a “CTS-to-SELF” packet prior to transmission of the set of concurrent communication packets where the selected group includes at least one station node that does not support the MU protocol, thereby controlling access by the station nodes to the selected one of the plurality of communication channels.
17. The method for operating a WAP of claim 9 , further comprising:
varying a communication bandwidth of each communication racket in a set of concurrent communication packets, where the selected group includes at least one station node that does not support the MU protocol, thereby matching bandwidth with each station node's capabilities.