Advantage of Multi Antenna Technique

Only available on StudyMode
  • Topic: MIMO, Radio resource management, Antenna diversity
  • Pages : 8 (1099 words )
  • Download(s) : 461
  • Published : August 9, 2010
Open Document
Text Preview
Tutorial ─ MIMO Communications with Applications to (B)3G and 4G Systems

Introduction
Juha Ylitalo

Tutorial #2: MIMO Communications with Applications to (B)3G and 4G Systems ─ Introduction

© J. Ylitalo & M. Juntti, University of Oulu, Dept. Electrical and Inform. Eng., Centre for Wireless Communications (CWC) 1

Introduction
• Short historical note • Advantages of multi-antenna techniques • Adaptive antennas – - Beamforming: spatial focusing of correlated signals – - Rx/Tx diversity: combining of decorrelated signals – - MIMO: increasing spectral efficiency/ data rates

• Simple example: SINR improvement • Definition of MIMO • Spatial correlation matrix • Example: Diversity & MIMO in WCDMA

Tutorial #2: MIMO Communications with Applications to (B)3G and 4G Systems ─ Introduction

© J. Ylitalo & M. Juntti, University of Oulu, Dept. Electrical and Inform. Eng., Centre for Wireless Communications (CWC) 2

Historical Note
• Multiple antenna transmission used by Marconi in 1901
– Four 61m high tower antennas (circular array) – Morse signal for "S" from England to Signal Hill, St. John, Newfoundland, distance 3425km

• • • •

Submarine sonar during 1910's Acoustic sensor arrays 1910's RF radars 1940's Ultrasonic scanners from 1960's

Tutorial #2: MIMO Communications with Applications to (B)3G and 4G Systems ─ Introduction

© J. Ylitalo & M. Juntti, University of Oulu, Dept. Electrical and Inform. Eng., Centre for Wireless Communications (CWC) 3

Advantages of Multiple Antenna Techniques
• • • • • • • Resistivity to fading (quality) Increased coverage Demonstration by Lucent Increased capacity with 8 Tx /12 Rx antennas: Increased data rate 1.2 Mbit/s in 30kHz Improved spectral efficiency Reduced power consumption Reduced cost of wireless network Some challenges: - RF: Linear power amplifiers, calibration - Complex algorithms: DSP requirements, cost - Network planning & optimisation Tutorial #2: MIMO Communications with Applications to (B)3G and 4G Systems ─ Introduction © J. Ylitalo & M. Juntti, University of Oulu, Dept. Electrical and Inform. Eng., Centre for Wireless Communications (CWC) 4

Adaptive Antennas
• An adaptive antenna system consists of several antenna elements, whose signals are processed adaptively in order to exploit the spatial dimension of the mobile radio channel. Weight Adaptation

RF

IF

RF

IF

+

RF

IF

Baseband processing

Tutorial #2: MIMO Communications with Applications to (B)3G and 4G Systems ─ Introduction

© J. Ylitalo & M. Juntti, University of Oulu, Dept. Electrical and Inform. Eng., Centre for Wireless Communications (CWC) 5

Adaptive Antenna Operation
• Conventional BTS:
– radiation pattern covers the whole cell area

• “Smart” Antenna BTS:
– adaptive radiation pattern, "spatial filter" – transmission/reception only to/from the desired user direction – minimise antenna gain to direction of other users

Conventional BTS radiation pattern
Tutorial #2: MIMO Communications with Applications to (B)3G and 4G Systems ─ Introduction

Smart Antenna BTS
© J. Ylitalo & M. Juntti, University of Oulu, Dept. Electrical and Inform. Eng., Centre for Wireless Communications (CWC) 6

Beamforming (beam steering)
• Beamforming = phasing the antenna array elements • Only Direction-of-Arrival (DOA) parameter needed in both TX and RX: simple and robust • Suits especially well to FDD systems 0 -5 -10 -15 -20 -25 -30 DOA = 0 deg. 1 DOA = 30 deg.

2

M=8

Array Gain [dB]

-50

0 Azimuth [deg]

50

Tutorial #2: MIMO Communications with Applications to (B)3G and 4G Systems ─ Introduction

© J. Ylitalo & M. Juntti, University of Oulu, Dept. Electrical and Inform. Eng., Centre for Wireless Communications (CWC) 7

RX Diversity
• De-correlated (statistically independent) signals received • spatial and polarisation diversity arrangements • combining of fading signals: – Maximum Ratio Combining (MRC) – Interference Rejection...
tracking img