Operation for backward-compatible transmission

Abstract

The disclosure relates to a transmitter in a transmission system operable to optimize estimates of a quantity at a receiver for improved operation. The transmission system includes a transmitting means connected to a number of antennas (Txm), and to control means. The control means controls the transmitting means to initially transmit an initial training/quantity estimation sequence during an initial training/quantity estimation phase and subsequently transmit a sequence of data symbols such that the information rate of the data symbols is progressively increased.

1 . A transmitter in a transmission system operable to facilitate optimization of estimates of a channel transfer functions at a receiver for improved operation for backward-compatible multiple input multiple output (MIMO) OFDM-based wireless LAN networks comprising m number of transmitting antennas (Txm) and n number of receiving antennas, wherein m and n are integers and m, n≧2, wherein the transmissions on each transmitting antenna (Txm) during an initial training/channel estimating phase are separated in frequency, so that a given transmitting antenna (Txm) is the only one transmitting on a given subcarrier at a given time, comprising:
 a transmitting device operably coupled to a plurality of antennas (Txm); and   a control device operably coupled to the transmitting device and operable to control the transmissions from the transmitter to the receiver in such a way that a different assignment of subcarriers to the transmitting antennas is made for later portions of a training/estimation sequence than for an initial portion of the training/estimation sequence containing a 11a/11g SIGNAL field therein.   
   
   
       2 . The transmitter of  claim 1 , wherein the control device controls the transmissions of the transmitting device in such a way that a mapping of subcarriers to the transmit antennas follows a predetermined sequence known at the receiver. 
   
   
       3 . The transmitter of  claim 1 , wherein the control device controls the transmissions of the transmitting device in such a way that a mapping of subcarriers to the transmit antennas (Txm) optimizes a possibility for the receiver to estimate the channel transfer functions. 
   
   
       4 . An optimization system operable to optimize estimates of a channel transfer function at a receiver for improved operation for backward-compatible multiple input multiple output (MIMO) OFDM-based wireless LAN networks comprising m number of transmitting antennas and n number of receiving antennas, wherein m and n are integers and m, n≧2, wherein the transmissions on each transmitting antenna during an initial training/channel estimating phase are separated in frequency, so that a given transmitting antenna is the only one transmitting on a given subcarrier at a given time, comprising:
 a receiving device operably coupled to the receiving antennas; and   a control device operably coupled to the receiving device and operable to adapt an estimate updating process to a different subcarrier for transmit antenna mapping during later portions of a training/estimation sequence than for an initial portion of the training/estimation sequence containing an 11a/11g SIGNAL field therein.   
   
   
       5 . The optimization system of  claim 4 , further comprising:
 a first estimating device operable to make an initial estimate of the channel transfer function, based on the received symbols during the initial training/channel estimation phase;   an estimate updating device operable to update the estimate of the channel transfer function during the initial training/channel estimation phase,   wherein the control device controls the estimate updating process in such a way that the mapping of subcarriers to the transmit antennas follows a predetermined sequence used at the transmitter.   
   
   
       6 . The optimization system of  claim 4 , wherein the control device controls the estimate updating process in such a way as to optimize the estimate of the channel transfer functions. 
   
   
       7 . A method for optimising estimates of channel transfer functions at a receiver for improved operation for backward-compatible multiple input multiple output (MIMO) OFDM-based wireless LAN networks, comprising m number of transmitting antennas and n number of receiving antennas, wherein m and n are integers and m, n≧2, comprising:
 receiving an initial portion of a training/estimation sequence containing a 11a/11g SIGNAL field;   obtaining an initial estimate of the channel transfer function during receipt of the initial portion of the training/estimation sequence containing the 11a/11g SIGNAL field;   receiving a subsequent portion of the training/estimation sequence where a mapping of subcarriers to the transmit antennae is changed; and   updating the initial estimate of the channel transfer function based on the subsequent portion of the training/estimation sequence.   
   
   
       8 . The method of  claim 7 , further comprising controlling the updating of the channel transfer function estimates based on a predetermined sequence of mappings of subcarriers to the transmit antennae known to be used at the transmitter. 
   
   
       9 . A receiver in a transmission system operable to optimize estimates of channel transfer functions at said receiver for improved operation for backward-compatible multiple input multiple output (MIMO) OFDM-based wireless LAN networks, comprising m number of transmitting antennas and n number of receiving antennas, wherein m and n are integers and m, n≧2, comprising:
 a first estimating device operable to make an initial estimate of the channel transfer function, based on the received symbols during an initial training/channel estimation phase; estimate updating device operable to update the estimate of the channel transfer function; and   a pilot measuring device and control device connected to the pilot measuring device and the estimate updating device, wherein the control device is operable to control the pilot measuring device such that the subcarriers used for a pilot tone reception is changed from symbol to symbol.   
   
   
       10 . The receiver of  claim 9 , wherein the control device is further operable to decide in advance a pattern of which subcarriers and/or transmitting antennas are used for pilot tones in each symbol.