System topologies for optimum capacity transmission over wireless local area networks

Abstract

An inventive method provides optimum topology for a multi-antenna system dedicated to higher throughput/capacity by bundling the Point Coordination Function (PCF) operation in infrastructure mode of the current and/or enhanced IEEE MAC with PHY specifications that employ some form of coherent weighting based on CSI at the transmitter in conjunction with the corresponding optimum receiver detection based on CSI. Specifically, CSI is measured from a control message, so data messages and control messages are separated. In the contention period of IEEE 802.11, the RTS/CTS exchange is used for CSI and the data message is sent following the CTS message. In the contention free period, a poll by the PC is separated from a data frame, which gives the polled station the first opportunity to send a data message. This change in topology results in various changes to the frame exchange format in the CFP for various scenarios of data and control messages to be exchanged.

1 - 24 . (canceled)  
   
   
       25 . In a wireless local area network wherein a first network entity transmits to a second network entity a packet having a guard interval preceding one of a data signal and a training sequence, the improvement comprising: 
 the first network entity measuring channel state information CSI for the channel between the first and second network entity;    the first network entity selecting a length of the guard interval based on the CSI; and    the first network entity sending the packet with the guard interval of length selected based on CSI.    
   
   
       26 . In the wireless local area network of  claim 25 , wherein the first network entity encodes the packet using a capacity enhancing code, the improvement comprising: 
 the first network appending to a tail end of the packet an iterative decoding signal extension.    
   
   
       27 . In the wireless local area network of  claim 26 , wherein the capacity enhancing code is at least one of a low density parity check code and a turbo code.  
   
   
       28 . A method for transmitting a packet in a wireless local area network WLAN, comprising: 
 determining, at a first network entity, channel state information CSI for a channel between the first and a second network entity in a WLAN;    selecting, at the first network entity, a guard interval length from among at least two lengths based on the determined CSI; and    sending a packet with the guard interval of the selected length from the first network entity over the WLAN.    
   
   
       29 . The method of  claim 28 , further comprising: 
 encoding the packet with a capacity enhancing code, and including in the packet an iterative decoding signal extension disposed at a tail end of said packet.    
   
   
       30 . The method of  claim 29 , wherein the capacity enhancing code comprises one of a low density parity check code and a turbo code.  
   
   
       31 . The method of  claim 28 , wherein determining CSI comprises measuring CSI from a poll message.  
   
   
       32 . The method of  claim 28  in two iterations, wherein for a first iteration a first packet comprises a cyclic prefix of a first length and a guard interval of the second length, and for a second iteration a second packet comprises a cyclic prefix of a length different from the first length and a guard interval of a length different from the second length, wherein the first and second iterations of the method are for the same first network entity and the same channel.  
   
   
       33 . The method of  claim 28 , wherein selecting a guard interval length comprises selecting from among lengths that are integer multiples of 0.4 microseconds.  
   
   
       34 . The method of  claim 28 , wherein selecting a guard interval length comprises selecting from among a first and second length, wherein the second length is twice the first length.  
   
   
       35 . A network entity for communicating over a wireless local area network WLAN comprising: 
 a receiver for receiving a message from an entity of a wireless local area network WLAN;    a memory for storing at least two different guard interval lengths, each associated with a different channel state information CSI;    a processor, coupled to the receiver and the memory, for determining CSI from the received message, and for selecting from the memory one guard interval length associated with the determined CSI;    a transmitter having an input coupled to an output of the processor, and an output for coupling to an antenna, said transmitter output for outputting a packet comprising a guard interval of the selected length.    
   
   
       36 . The network entity of  claim 35 , wherein the transmitter comprises an encoder for encoding the packet with a capacity enhancing code, further wherein the packet further comprises an iterative decoding signal extension disposed at a tail end of said packet.  
   
   
       37 . The network entity of  claim 36 , wherein the capacity enhancing code comprises one of a low density parity check code and a turbo code.  
   
   
       38 . The network entity of  claim 35 , wherein the message is a poll message and determining CSI comprises measuring CSI from the poll message.  
   
   
       39 . The network entity of  claim 35 , wherein the processor varies a cyclic prefix of a packet to be transmitted according to the selected guard interval length for that packet.  
   
   
       40 . The network entity of  claim 35  wherein the at least two different lengths are each multiples of 0.4 microseconds.  
   
   
       41 . The network entity of  claim 35  wherein the at least two different lengths comprise a first and second length, wherein the second length is twice the first length.  
   
   
       42 . The network entity of  claim 35 , wherein the network entity comprises a mobile station.  
   
   
       43 . A device for communicating over a wireless local area network WLAN comprising: 
 a receiver for receiving a message from a node of a WLAN;    means for determining channel state information CSI from the received message;    means for determining a guard interval length from at least two lengths based on the determined CSI; and    means for transmitting a packet comprising a guard interval of the selected length.    
   
   
       44 . The device of  claim 43 , wherein the means for determining a guard interval length comprise a processor couple to a memory, wherein said memory is for storing at least two guard interval lengths and at least two values of CSI, each value of CSI associated with one of the guard interval lengths.  
   
   
       45 . The device of  claim 43 , wherein the means for transmitting comprises a transmitter coupled to at least one antenna.  
   
   
       46 . The device of  claim 43  wherein the received message comprises a poll message, and wherein the means for determining CSI from the received message comprises a processor coupled to the receiver for measuring CSI from the poll message.