Signal detection method and receiving apparatus in MIMO system

• US 8,098,777 B2
• Filed: 10/30/2007
• Issued: 01/17/2012
• Est. Priority Date: 12/06/2006
• Status: Active Grant

• Current Assignee: Electronics and Telecommunications Research Institute, Samsung Electronics Co. Ltd.
• Original Assignee: Electronics and Telecommunications Research Institute, Samsung Electronics Co. Ltd.
• Inventors: Bahng, Seung-Jae, Bang, Young-Jo, Park, Youn-Ok
• Primary Examiner(s): Corrielus, Jean B
• Application Number:
  US11/930,047
• Publication Number:
  US 20080137782A1
• Time in Patent Office: 1,540 Days
• Field of Search: 375/260, 375/267, 375/285, 375/340, 375/341, 375346-347
• US Class Current: 375/346
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0246 with factorisation

Abstract

The present invention relates to a signal detection method and a receiving apparatus in a multiple input multiple output (MIMO) system. More particularly, the present invention relates to a signal detection device in a MIMO system using a spatial multiplexing (SM) method. In the signal detection method, a channel is estimated and layers are rearranged according to a predetermined layer arrangement rule. QR-decomposition is performed by using a rearranged system model, all constellation points in a symbol of a layer having the lowest reliability are considered, and symbols are detected by using a sequential interference elimination method.

Claims

1. A receiving apparatus of a multiple input multiple output (MIMO) system, the receiving apparatus comprising:

a layer arrangement unit for rearranging channel estimated layers for a received signal based on reliability of the each of the layers, wherein the reliability of each of the layers is determined based on a reception quality of each of the layers; and

a symbol detection unit for detecting a transmission symbol vector according to the layers that are rearranged by the layer arrangement unit, wherein the symbol detection unit detects the transmission symbol vector according to the layers rearranged by the layer arrangement unit by;

QR-decomposing a channel matrix H rearranged after the layer arrangement unit rearranges the channel estimated layers for the received signal, based on the reliability of the each of the layers;

considering all constellation points for a symbol of a layer having a lowest reliability among the layers rearranged after the layer arrangement unit rearranges the channel estimated layers for the received signal based on the reliability of the each of the layers, based on signals obtained by applying a matrix QH to the received signal; and

detecting the symbol by performing sequential interference elimination.

2. The receiving apparatus of claim 1, wherein the reception quality of each of the layers is determined based on a signal-to-noise ratio (SNR) of each of the layers when the layer arrangement unit rearranges the layers.

3. The receiving apparatus of claim 1, wherein the layer arrangement unit arranges the layer having the lowest reliability as a last layer, and remaining layers are arranged in order of a layer having a second lowest reliability to a layer having a highest reliability.

4. The receiving apparatus of claim 3, wherein the symbol detection unit detects a symbol by performing sequential symbol elimination for the remaining layers.

5. A receiving method of a multiple input multiple output (MIMO) system, the receiving method comprising:

a) rearranging channel estimated layers for a received signal based on reliability of the each of the layers, wherein the reliability of each of the layers is determined based on a reception quality of each of the layers; and

b) detecting a transmission symbol vector according to the layers rearranged by a layer arrangement unit, wherein the detecting of the transmission symbol vector according to the layers rearranged by the layer arrangement unit comprises;

b-1) QR-decomposing a channel matrix H rearranged after a); and

b-2) considering all constellation points for a symbol of a layer having a lowest reliability among the layers rearranged after a) based on signals obtained by applying a matrix QH to the received signal, and detecting the symbol by performing sequential interference elimination.

6. The receiving method of claim 5, wherein, in a), a channel estimation unit estimates and compensates a signal distortion caused by multipath fading of a transmission channel with respect to the received signal.

7. The receiving method of claim 5, wherein, in a), the layer having the lowest reliability is arranged as a last layer, and remaining layers are arranged in order from a layer having a second lowest reliability to a layer having a highest reliability.

8. The receiving method of claim 7, wherein a) comprises:

a-1) calculating an inverse matrix G to represent a channel characteristic of the received signal by using an equation;

G={tilde over (H)}<sup>−

1</sup>,

where {tilde over (H)} denotes a MIMO channel before rearrangement.

9. The receiving method of claim 8, wherein a) further comprises:

a-2) arranging and considering all constellation points of the layer having the lowest reliability by using an equation;

{tilde over (y)}=Hx+ñ

,

where {tilde over (y)}=[{tilde over (y)}₁ {tilde over (y)}₂ {tilde over (y)}₃ {tilde over (y)}₄]^T denotes a received signal, x=[x₁ x₂ x₃ x₄]^T denotes a rearranged transmission signal, ñ

=[ñ

₁ ñ

₂ ñ

₃ ñ

₄]^T denotes noise, and H=[h₁ h₂ h₃ h₄]^T denotes a 4×

4 estimated channel matrix after the rearrangement,

wherein the rearranged signals are arranged in order of x₄, a symbol of the layer having the lowest reliability, x₃, a symbol of the layer having the highest reliability, x₂, a symbol of the layer having the second highest reliability, and x₁, a symbol of the layer having the third highest reliability, based on a signal-to-noise ratio (SNR).

10. The receiving method of claim 5, wherein, in b-1), the rearranged channel matrix H is QR-decomposed by using an equation:

11. The receiving method of claim 10, wherein, in b-2), when performing sequential interference elimination, symbols are sequentially detected by using characteristics of an R matrix with respect to the symbol of the layer having the lowest reliability.

12. The receiving method of claim 11, wherein, when x=[x₁ x₂ x₃ x₄]^T denotes a rearranged signal received from the layer arrangement unit, a mapping to closest constellation points is determined, with respect to a symbol x₄ of the layer having the lowest reliability, by using equations:

13. The receiving method of claim 10, wherein a symbol vector having a least maximum likelihood (ML) metric is detected as a final transmission vector from symbol vectors corresponding to the number of constellation points by using an equation:

arg min∥

y−

Rx∥

²,

wherein y is a received signal, R is an upper triangular matrix and x is a rearranged transmission signal.