Operation for backward-compatible transmission

• US 20050220209A1
• Filed: 03/24/2005
• Published: 10/06/2005
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Lewis, Michael
• Granted Patent: US 8,958,493 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/022 of frequency response
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/025 using least-mean-square [LMS] method
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/1446 of transmission speed

Abstract

The present invention 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.

Claims

1. A transmission system including a transmitter operable to optimize estimates of a quantity at a receiver for improved operation, comprising:

a transmitting means operably coupled to a plurality of antennas (Txm); and

a control means operably coupled to the transmitting means, wherein the control means is configured to control the transmitting means to 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.

2. The transmission system of claim 1, wherein the transmission system comprises a multiple input multiple output (MIMO) transmission system comprising m number of transmitting antennae (Txm) and n number of receiving antennae (Rxn), wherein m and n are integers and m, n≧

2, and wherein the transmission means is operable to transmit an initial training/quantity estimation sequence on each transmitting antenna during an initial training/quantity estimation phase that are separated in frequency from one another, so that a given transmitting antenna is the only one transmitting on a given subcarrier at a given time.

3. An optimization system operable to generate estimates of a quantity at a receiver for improved operation in a communications system, comprising:

a receiving means operably coupled to a plurality of receiving antennas (Rxn) configured to receive transmissions thereat; and

a receiving means operably coupled to the receiving means and configured to control the receiving means to initially receive an initial training/quantity estimation sequence comprising training symbols during an initial training/quantity estimation phase and subsequently receive a sequence of data symbols such that the information rate of the data symbols is progressively increased.

4. The optimization system of claim 3, further comprising:

a first estimating means operable to make an initial estimate of the quantity, based on the received symbols during the initial training/quantity estimation phase;

estimate updating means operable to store a current estimate of the quantity from the first estimating means;

decoding means operable to decode the received symbols;

remodulating means operably coupled to the decoding means and the estimate updating means, and operable to duplicate a modulation function performed at a transmitter associated therewith to generate estimated transmitted symbols;

control means connected to the decoding means and the remodulating means, wherein the control means operable to compare the received symbols and the estimated transmitted symbols and to calculate an error vector, and wherein the estimate updating mean updates the estimate of the quantity based on the error vector.

5. The optimization system of claim 3, wherein the quantity comprises a channel transfer function from a transmitting antenna to a receiving antenna, a frequency offset, a timing offset, a sampling rate offset, or a spatial position of the transmitter.

6. The optimization system of claim 3, wherein the optimization system is implemented in a multiple input multiple output (MIMO) transmission system comprising m number of transmitting antennae and n number of receiving antennae, wherein m and n are integers and m, n≧

2, wherein the transmissions on each transmitting antenna during an initial training/quantity estimation phase are separated in frequency, so that a given transmitting antenna is the only one transmitting on a given subcarrier at a given time.

7. A method at a transmitter to facilitate an optimization of estimates of a quantity at a receiver in a communications system, comprising:

transmitting an initial training/quantity estimation sequence comprising training symbols to the receiver; and

transmitting a first few data symbols of a remainder of the transmission to the receiver at a low information rate and increasing the information rate progressively with time.

8. The method of claim 7, further comprising:

deciding upon in advance and signalling a manner in which the information rate is to be changed during the data symbol transmission, by using a predetermined encoding of symbols during the initial training/quantity estimation sequence transmission.

9. The method of claim 7, wherein the communications system comprises a backward-compatible multiple input multiple output (MIMO) transmission system comprising m number of transmitting antennas and n number of receiving antennas, wherein m and n are integers and m, n≧

2, that the transmissions on each transmitting antenna are separated in frequency during the initial training/quantity estimation phase, so that a given transmitting antenna is the only one transmitting on a given subcarrier at a given time.

10. A method for optimization of estimates of a quantity at a receiver in a communications system, comprising:

receiving an initial training/quantity estimation sequence comprising training symbols during an initial training/quantity estimation phase; and

adapting the receiver to an increasing information rate used at the transmitter after the training symbols during a transmission of data symbols.

11. The method of claim 10, further comprising:

making an initial estimate of the quantity, based on the received training symbols during the initial training/quantity estimating phase;

storing a current estimate of the quantity;

decoding the current estimate of the quantity;

receiving a data symbol and decoding the data symbol;

comparing the decoded data symbols and the decoded quantity estimates;

calculating an error vector based on the comparison; and

updating the quantity estimate based on the error vector.

12. The method of claim 10, further comprising using a predetermined encoding of the training symbols received during the initial training/quantity estimation sequence tranmission to determine a manner in which the receiver is to be adapted to a changing information rate during the subsequent data symbol transmission.

13. The method of claim 10, wherein the quantity comprises a channel transfer function from a transmitting antenna to a receiving antenna, a frequency offset, a timing offset, a sampling rate offset, or a spatial position of a transmitter.

14. The method of claim 10, wherein the communications system comprises a backward-compatible multiple input multiple output (MIMO) transmission systems comprising m number of transmitting antennas and n number of receiving antennas, wherein m and n are integers and m, n≧

2, that the transmissions on each transmitting antenna are separated in frequency during the initial training/quantity estimation phase, so that a given transmitting antenna is the only one transmitting on a given subcarrier at a given time.

15. 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 means operably coupled to a plurality of antenna means (Txm); and

control means operably coupled to the transmitting means 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.

16. The transmitter of claim 15, wherein the control means controls the transmissions of the transmitting means in such a way that a mapping of subcarriers to the transmit antennas follows a predetermined sequence known at the receiver.

17. The transmitter of claim 15, wherein the control means controls the transmissions of the transmitting means 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.

18. 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 means operably coupled to the receiving antennas; and

control means operably coupled to the receiving means 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.

19. The optimization system of claim 18, further comprising:

a first estimating means operable to make an initial estimate of the channel transfer function, based on the received symbols during the initial training/channel estimation phase;

estimate updating means operable to update the estimate of the channel transfer function during the initial training/channel estimation phase,

wherein the control means 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.

20. The optimization system of claim 18, wherein the control means controls the estimate updating process in such a way as to optimize the estimate of the channel transfer functions.

21. A method at a transmitter 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;

separating transmissions on each transmitting antenna in frequency during an initial training/channel estimation phase in which an initial training/channel estimation sequence is transmitted, so that a given transmitting antenna is the only one transmitting on a given subcarrier at a time; and

applying a different assignment of subcarriers to the transmitting antennas for later portions of the training/channel estimation sequence than for the initial portion containing an 11a/11g SIGNAL field.

22. The method of claim 21, further comprising controlling the transmissions in such a way that the mapping of subcarriers to the transmit antennas follows a predetermined sequence known at the receiver.

23. The method of claim 21, further comprising controlling the transmissions in such a way that the mapping of subcarriers to the transmit antennas optimizes the possibility for the receiver to estimate the channel transfer functions.

24. 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.

25. The method of claim 24, 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.

26. A transmitter in a transmission system operable to optimize 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 (Txm) and n number of receiving antennas, wherein m and n are integers and m, n≧

2, comprising;

a transmission means operable to transmit on a number of antennae (Txm); and

control means operably coupled to the transmission means and operable to control transmissions of the transmission means in such a way that the subcarriers used for a pilot tone transmission are changed from symbol to symbol.

27. The transmitter of claim 26, wherein the control means is further operable to decide in advance a pattern of which subcarriers and/or transmitting antennas are used for pilot tones in each symbol.

28. The transmitter of claim 26, wherein the control means is further operable to transmit known pilot tones on combinations of the transmitting antenna (Txm) and on subcarriers that have not been used during the initial training/channel estimating phase.

29. 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 means 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 means operable to update the estimate of the channel transfer function; and

pilot measuring means and control means connected to the pilot measuring means and the estimate updating means, wherein the control means is operable to control the pilot measuring means such that the subcarriers used for a pilot tone reception is changed from symbol to symbol.

30. The receiver of claim 29, wherein the control means is further operable to decide in advance a pattern of which subcarriers and/or transmitting antennas are used for pilot tones in each symbol.