Method of determining the capacity of each transmitter antenna in a multiple input/multiple output (MIMO) wireless system

US 7,154,960 B2
Filed: 12/31/2002
Issued: 12/26/2006
Est. Priority Date: 12/31/2002
Status: Expired due to Fees

First Claim

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1. In a multiple input/multiple output wireless system in which a plurality of transmitter antennas at a transmitter end of the system transmit a plurality of signals on separate channels to a plurality of receiver antennas at a receiver end of the system, a method comprising:

determining, at the receiver end, instantaneous channel coefficients of each of the separate channels between the plurality of transmitter antennas and the plurality of receiver antennas;

determining an average signal-to-noise ratio of the signals received by the receiver antennas;

calculating, using the determined instantaneous channel coefficients and the determined average signal-to-noise ratio, the individual capacities of the transmitter antennas wherein the capacity of the k-th transmitter antenna, for k between 1 and t, is determined from the k-th term in $\log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{1}^{+} (I + \frac{ρ}{t} \sum_{i = 2}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{1}) + \log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{2}^{+} (I + \frac{ρ}{t} \sum_{i = 3}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{2}) + \log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{3}^{+} (I + \frac{ρ}{t} \sum_{i = 4}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{3}) + \dots + \log_{2} (1 + \frac{ρ}{t} {\underline{h}}_{t}^{+} {\underline{h}}_{t})$ where t is the number of transmitter antennas, ρ

is the average signal-to-noise ratio of the received signals, I is an identity matrix, h_jis an i-th column for any i between 1 and t of a channel matrix containing the determined channel coefficients in which each coefficient h_ijis the determined channel coefficient between the i-th transmitter antenna and the j-th receiver antenna, and h_i⁺ is the Hermitian transpose of h_i; and

using the calculated individual capacities of the transmitter antennas, transmitting information back to the transmitter end so that when each transmitter antenna uses a determined data rate and modulation and coding scheme for each transmitter antenna, the calculated individual capacity of each transmitter antenna is not exceeded.

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Abstract

The per antenna capacity of each of the transmitter antennas in a MIMO system are individually determined from measurable information at the receiver end. Specifically, the channel capacity for each individual transmitter antenna is calculated at the receiver end as a function of measurable channel coefficients (also known as channel state information), the measurable average signal-to-noise ratio, and the number of transmitter antennas. Once the per antenna capacity of each transmitter antenna is individually determined at the receiver end, the maximum transmission rate for each data stream transmitted by each transmitter antenna is determined from that individual capacity either at the receiver end and fed back to the transmitter end, or is determined at the transmitter end from the individual transmitter antenna capacities that are fed back by the receiver end to the transmitter end. A modulation scheme that supports each maximum transmission rate is then determined based on some defined criteria.

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14 Claims

1. In a multiple input/multiple output wireless system in which a plurality of transmitter antennas at a transmitter end of the system transmit a plurality of signals on separate channels to a plurality of receiver antennas at a receiver end of the system, a method comprising:
- determining, at the receiver end, instantaneous channel coefficients of each of the separate channels between the plurality of transmitter antennas and the plurality of receiver antennas;
  
  determining an average signal-to-noise ratio of the signals received by the receiver antennas;
  
  calculating, using the determined instantaneous channel coefficients and the determined average signal-to-noise ratio, the individual capacities of the transmitter antennas wherein the capacity of the k-th transmitter antenna, for k between 1 and t, is determined from the k-th term in $\log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{1}^{+} (I + \frac{ρ}{t} \sum_{i = 2}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{1}) + \log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{2}^{+} (I + \frac{ρ}{t} \sum_{i = 3}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{2}) + \log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{3}^{+} (I + \frac{ρ}{t} \sum_{i = 4}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{3}) + \dots + \log_{2} (1 + \frac{ρ}{t} {\underline{h}}_{t}^{+} {\underline{h}}_{t})$ where t is the number of transmitter antennas, ρ
  
  is the average signal-to-noise ratio of the received signals, I is an identity matrix, h_jis an i-th column for any i between 1 and t of a channel matrix containing the determined channel coefficients in which each coefficient h_ijis the determined channel coefficient between the i-th transmitter antenna and the j-th receiver antenna, and h_i⁺ is the Hermitian transpose of h_i; and
  
  using the calculated individual capacities of the transmitter antennas, transmitting information back to the transmitter end so that when each transmitter antenna uses a determined data rate and modulation and coding scheme for each transmitter antenna, the calculated individual capacity of each transmitter antenna is not exceeded.
- View Dependent Claims (2, 3, 4, 5, 6)
- - 2. The method of claim 1 wherein the information transmitted back to the transmitter end comprises the calculated individual capacities of the transmitter antennas, whereby the transmitter end determines the data rate and modulation and coding scheme for each transmitter antenna so that the calculated individual capacity of each transmitter antenna is not exceeded.
  - 3. The method of claim 1 wherein the receiver end:
    - determines the data rate and modulation and coding scheme for each transmitter antenna so that the calculated capacity of each individual transmitter antenna is not exceeded, andthe information transmitted back to the transmitter end comprises the determined data rate and modulation and coding scheme for each transmitter antenna.
  - 4. The method of claim 1 wherein the transmitter end is a base station and the receiver end is a wireless unit.
  - 5. The method of claim 1 wherein the transmitter end is a wireless unit and the receiver end is a base station.
  - 6. The method of claim 1 wherein the capacities of the transmitter antennas are calculated every n-th frame, where n is 1 or more.

7. In a multiple input/multiple output wireless system in which a plurality of transmitter antennas at a transmitter end of the system transmit a plurality of signals on separate channels to a plurality of receiver antennas at a receiver end, a method comprising:
- determining, at the receiver end, the individual capacity of each of the transmitter antennas from instantaneous channel coefficients of the separate channels and a measured average signal-to-noise ratio of the transmitted signals received at the receiver end wherein the capacity of the k-th transmitter antenna, for k between 1 and t, is determined from the k-th term in $\log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{1}^{+} (I + \frac{ρ}{t} \sum_{i = 2}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{1}) + \log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{2}^{+} (I + \frac{ρ}{t} \sum_{i = 3}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{2}) + \log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{3}^{+} (I + \frac{ρ}{t} \sum_{i = 4}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{3}) + \dots + \log_{2} (1 + \frac{ρ}{t} {\underline{h}}_{t}^{+} {\underline{h}}_{t})$ where t is the number of transmitter antennas, ρ
  
  is the average signal-to-noise ratio of the received signals, I is an identity matrix, h_iis an i-th column for any i between 1 and t of a channel matrix containing the determined channel coefficients in which each coefficient h_ijis the determined channel coefficient between the i-th transmitter antenna and the j-th receiver antenna, and h_i⁺ is the Hermitian transpose of h_i; and
  
  using the determined individual capacity of each of the transmitter antennas, transmitting information back to the transmitter end so that when each transmitter antenna uses a determined data rate and modulation and coding scheme for each transmitter antenna, the calculated individual capacity of each transmitter antenna is not exceeded.
- View Dependent Claims (8, 9)
- - 8. The method of claim 7 wherein the information transmitted back to the transmitter end comprises the calculated individual capacity of each of the transmitter antennas, whereby the transmitter end determines the data rate and modulation and coding scheme for each transmitter antenna so that the calculated individual capacity of each transmitter antenna is not exceeded.
  - 9. The method of claim 7 wherein the receiver end:
    - determines the data rate and modulation and coding scheme for each transmitter antenna so that the calculated capacity of each individual transmitter antenna is not exceeded, andthe information transmitted back to the transmitter end comprises the determined data rate and the modulation and coding scheme for each transmitter antenna.

10. Apparatus at a receiver end of a multiple input/multiple output wireless system in which a plurality of transmitter antennas at a transmitter end of a wireless system transmit a plurality of signals on separate channels to a plurality of receiver antennas at the receiver end of the system, the apparatus comprising:
- means for determining instantaneous channel coefficients of the each of the separate channels between the transmitter antennas and receiver antennas;
  
  means for determining an average signal-to-noise ratio of the signals received by the receiver antenna;
  
  means for calculating, using the determined instantaneous channel coefficients and the determined average signal-to-noise ratio, the individual capacities of each of the transmitter antennas wherein the capacity of the k-th transmitter antenna, for k between 1 and t, is determined from the k-th term in $\log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{1}^{+} (I + \frac{ρ}{t} \sum_{i = 2}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{1}) + \log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{2}^{+} (I + \frac{ρ}{t} \sum_{i = 3}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{2}) + \log_{2} (1 + \frac{ρ}{t} {{\underline{h}}_{3}^{+} (I + \frac{ρ}{t} \sum_{i = 4}^{t} {\underline{h}}_{i} {\underline{h}}_{i}^{+})}^{- 1} {\underline{h}}_{3}) + \dots + \log_{2} (1 + \frac{ρ}{t} {\underline{h}}_{t}^{+} {\underline{h}}_{t})$ where t is the number of transmitter antennas, ρ
  
  is the average signal-to-noise ratio of the received signals, I is an identity matrix, h_iis an i-th column for any i between 1 and t of a channel matrix containing the determined channel coefficients in which each coefficient h_ijis the determined channel coefficient between the i-th transmitter antenna and the j-th receiver antenna, and h_i⁺ is the Hermitian transpose of h_i; and
  
  means for transmitting information back to the transmitter end that uses the individual capacities of each of the transmitter antennas calculated by the calculating means so that when each transmitter antenna uses a determined data rate and modulation and coding scheme for each transmitter antenna, the calculated individual capacity of each transmitter antenna is not exceeded.
- View Dependent Claims (11, 12, 13, 14)
- - 11. The apparatus of claim 10 wherein the information transmitted back to the transmitter end by the transmitting means comprises the calculated individual capacities of the transmitter antennas, whereby the transmitter end determines the data rate and modulation and coding scheme for each transmitter antenna so that the calculated individual capacity of each transmitter antenna is not exceeded.
  - 12. The apparatus of claim 10 further comprising:
    - means for determining the data rate and modulation and coding scheme for each transmitter antenna so that the calculated capacity of each individual transmitter antenna is not exceeded, andthe information transmitted by the transmitting means back to the transmitter end comprises the determined data rate and modulation and coding scheme for each transmitter antenna.
  - 13. The apparatus of claim 10 wherein the transmitter end is a base station and the receiver end is a wireless unit.
  - 14. The apparatus of claim 10 wherein the transmitter end is a wireless unit and the receiver end is a wireless unit.

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Current Assignee
WSOU Investments, LLC (WSOU Holdings, LLC)
Original Assignee
Lucent Technologies, Inc. (Nokia Corporation)
Inventors
Rudrapatna, Ashok N., Liu, Jung-Tao
Primary Examiner(s)
Bocure, Tesfaldet
Assistant Examiner(s)
PANWALKAR, VINEETA S

Application Number

US10/334,314
Publication Number

US 20040125900A1
Time in Patent Office

1,456 Days
Field of Search

375/130, 375/140, 375/141, 375/146, 375/147, 375/358, 375/354, 375/295, 375/316, 375/259, 375/260, 375/267, 375/347, 455/91, 455/101, 455/103, 455/272, 455/269, 455/130, 370/277, 370/278, 370/282, 370/464
US Class Current

375/267
CPC Class Codes

H04B 7/04   using two or more spaced in...

H04B 7/061   using feedback from receivi...

H04B 7/0619   using feedback from receivi...

H04L 1/0003   by switching between differ...

H04L 1/0013   Rate matching, e.g. punctur...

H04L 1/0068   by puncturing

H04L 1/08   by repeating transmission, ...

Method of determining the capacity of each transmitter antenna in a multiple input/multiple output (MIMO) wireless system

First Claim

5 Assignments

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Abstract

105 Citations

14 Claims

Specification

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Method of determining the capacity of each transmitter antenna in a multiple input/multiple output (MIMO) wireless system

First Claim

5 Assignments

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0 Petitions

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Accused Products

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Abstract

105 Citations

14 Claims

Specification

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Solutions

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