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US 7,352,718 B1Granted
Spatial division multiple access for wireless networks
AssigneeCisco Technology, Inc.
InventorsEldad Perahia, Bretton Douglas, David Pignatelli, David Stephenson
Life of this patent
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Abstract
Multiple Input Multiple Output (MIMO) technology in conjunction with the IEEE 802.11 standard enables simultaneous communication of data packets to or from multiple users in the same frequency. Spatial divisional multiple access (SDMA) is thus provided. In this way, system capacity can be increased to an extent that depends on available antenna resources and the multipath characteristics of the communication channel. Doubling or quadrupling of network throughput can be achieved.
Claims16
A method for operating an access point in a MIMO wireless communication system, said method comprising:
- inserting a first preamble into a first packet and a second preamble into a second packet, at least one of said first and second preambles comprising symbols for use in synchronization and both of said first and second preambles comprising symbols for use in channel estimation, wherein said first and second preambles are each configured with a quiet period to allow transmission of one of said symbols in said other packet;
- sending said first packet to a first subscriber unit via a first spatial subchannel;
- and
- sending said second packet to a second subscriber unit via a second spatial subchannel, said first spatial subchannel and said second spatial subchannel occupying the same bandwidth;
- wherein said second packet has greater data length than said first packet;
- and
- wherein sending said first packet and sending said second packet begin and end substantially simultaneously.
4 more elements
A method for operating an access point in a MIMO wireless communication system, said method comprising:
- for a plurality of subscriber units of said access point, identifying ranges of said subscriber units from said access point;
- assigning a first group of said subscriber units to transmit simultaneously during a first upstream transmission slot;
- and
- assigning a second group of said subscriber units to transmit simultaneously during a second upstream transmission slot;
- and
- wherein subscriber units of said first group are chosen to have substantially similar ranges to one another and subscriber units of said second group are chosen to have substantially similar ranges to one another.
3 more elements
A method for operating an access point in a MIMO communication system, said method comprising:
- receiving a first packet from a first subscriber unit within a first spatial subchannel wherein a second packet has commenced transmission substantially simultaneously with said first packet, said second packet being transmitted within a second spatial subchannel sharing bandwidth with said first spatial subchannel, wherein said second packet is longer than said first packet;
- and
- transmitting an acknowledgement of said first packet to said first subscriber unit only after completing reception of said second packet;
- wherein said first packet comprises a first preamble and said second packet comprises a second preamble, at least one of said first and second preambles comprising symbols for use in synchronization and both of said first and second preambles comprising symbols for use in channel estimation, wherein said first and second preambles are each configured with a quiet period to allow transmission of one of said symbols in said other packet.
1 more element
Apparatus for operating an access point in a MIMO wireless communication system, said apparatus comprising:
- an insertion block configured to insert a first preamble into a first packet and a second preamble into a second packet, at least one of said first and second preambles comprising symbols for use in synchronization and both of said first and second preambles comprising symbols for use in channel estimation, wherein said first and second preambles are each configured with a quiet period to allow transmission of one of said symbols in said other packet;
- a first transmitter block that sends said first packet to a first subscriber unit via a first spatial subchannel;
- and
- a second transmitter block that sends said second packet to a second subscriber unit via a second spatial subchannel, said first spatial subchannel and said second spatial subchannel occupying the same bandwidth;
- wherein said second packet has greater data length than said first packet;
- and
- wherein sending said first packet and sending said second packet begin and end substantially simultaneously.
4 more elements
Apparatus for operating an access point in a MIMO wireless communication system, said apparatus comprising:
- a MAC layer processor that, for a plurality of subscriber units of said access point, identifies ranges of said subscriber units from said access point, assigns a first group of said subscriber units to transmit simultaneously during a first upstream transmission slot, and assigns a second group of said subscriber units to transmit simultaneously during a second upstream transmission slot;
- and
- wherein subscriber units of said first group are chosen to have substantially similar ranges to one another and subscriber units of said second group are chosen to have substantially similar ranges to one another.
Apparatus for operating an access point in a MIMO communication system, said apparatus comprising:
- a receiver system that receives a first packet from a first subscriber unit within a first spatial subchannel wherein a second packet has commenced transmission substantially simultaneously with said first packet, said second packet being transmitted within a second spatial subchannel sharing bandwidth with said first spatial subchannel, wherein said second packet is longer than said first packet;
- and
- a transmitter system that transmits an acknowledgement of said first packet to said first subscriber unit only after completing reception of said second packet;
- wherein said first packet comprises a first preamble and said second packet comprises a second preamble, at least one of said first and second preambles comprising symbols for use in synchronization and both of said first and second preambles comprising symbols for use in channel estimation, wherein said first and second preambles are each configured with a quiet period to allow transmission of one of said symbols in said other packet.
1 more element
Dependencies are inferred from the claim text.