# Presentation: 091666

## Performance Evaluation of Coded UWB-IR on Multipath Fading Channels

- Michal Pietrzyk
- Jos Weber

**  ****March 3, 2005**

- Wireless and Mobile Communications Group
- Delft University of Technology
- The Netherlands

## Overview of Presentation

- What is Ultra-wideband (UWB)?
- Regulatory Issues
- Unique Properties of UWB
- UWB vs. Other Technologies
- Potential Applications of UWB
- Research Challenges
- Research Problem
- General Coding-Modulation
- UWB-IR Receiver Model
- UWB Channel Model
- Performance Evaluation
- Summary

## What is Ultra-wideband (UWB) ?

- UWB technology is a generic term describing radio systems having very large bandwidth.
- Two definitions under consideration by the FCC:
- 	-  fractional bandwidth of a radio signal becomes 20% or more of the signal’s center frequency
-           is the upper 10 dB and      is the lower 10 dB cut-off frequency of the signal spectrum.
- 	-  RF bandwidth of the signal is greater than 0.5 GHz.

## Regulatory Issues

**Regulatory Issues**

**802.11b**
**Band**

**802.11a**
**Band**

- Emission limits for UWB indoor communication systems set by the FCC.

## Narrowband vs. Different UWB Approaches

- Narrowband Systems
- UWB
- UWB –IR
- UWB-FM
- UWB-OFDM

## Unique Properties of UWB

- High data rate capability for communications
- Fine range resolution capability
- Multipath immunity
- Extremely difficult to intercept (LPD/I)
- Suitable for ad hoc resource allocation/selection
- Common architecture for communications, radar and positioning (software re-definable)
- Low power consumption
- Low cost

## UWB vs. Other Technologies (1)

## UWB vs. Other Technologies (2)

## Potential Applications of UWB (1)

- Collision avoidance radars
- Tags (Intelligent Transportation Systems, electronic signs)
- Precision geolocation systems
- Surveillance systems
- Tactical handheld & network LPD/I radios
- Medical imaging
- High Speed WPANs and WLANs

- Example use of collision avoidance radar.

## Potential Applications of UWB (2)

- Broadband

**wired &**
**wireless**

**wired &**
**wireless**

**wired &**
**wireless**

**Long range delivery**
**wired & wireless**

**wired &**
**wireless**

**wired &**
**wireless**

** **

**Local high data rate delivery**

- Source: Communication and Interconnect Technology Lab., Intel Research and Development

## Research Challenges

- Interference issues pose restrictions on the maximum data rate that can be supported. One way to overcome the destructive effects of ISI and IFI and simultaneously maintaining a certain performance level is to apply _error correction coding_.
- An error correction coding scheme dedicated for UWB-IR communications should
- 	- be of low complexity
- 	- be scalable
- 	- provide reasonable BER performance
- 	- introduce small delay.
- Potential candidates include
- 	- superorthogonal convolutional (SOC) coding
- 	- turbo superorthogonal convolutional (TSOC) coding
- 	- TCH (Tomlinson, Cercas, and Hughes) coding.
- There are methods for further BER performance improvements like e.g.
- 	- proposed interleaved coding-modulation (ICM) technique
- 	- polarity randomization (PR).

## Research Problem

- The UWB-IR system model incorporates:
- 		- differential autocorrelation receiver
- 		- realistic channel model proposed by the IEEE (802.15.3a)
- 		- real antennas’ characteristics
- 		- distortions introduced by amplifiers, and filters	  	modeled by a Chebyshev filter
- 		- frame repetition or superorthogonal convolutional 	coding as methods of protection against transmission errors.

- What is the performance of a feasible UWB-IR system with _error correction coding_ in a severe multipath environment ?

## General Coding-Modulation Scheme

## UWB-IR Receiver Model

- Fig. 1.  The modeled UWB-IR receiver architecture.

- Fig. 2.  Superorthogonal convolutional encoder.

- Fig. 3.  The Gaussian monocycle and the received waveform.

## UWB Channel Model

- Fig. 4.  Channel impulse response for the case of LOS environment.

- Fig. 5.  Channel impulse response for the case of NLOS environment.

- Main parameters (LOS and NLOS):

- a) RMS delay spread:  9 and 15 ns
- b) *Np*_*10dB*: 7 and 35.

## UWB-IR System Parameters

## Performance Evaluation (1)

- The upper bound on the bit error probability of the UWB-IR system with the SOC code is given by

- For a Gaussian channel and a rectangular pulse shape we have

- and

- [M. Pausini ‘04]

- Processing gain is defined as

- Free distance of the SOC code is

- The lower bound on the bit error probability of the UWB-IR system with the SOC code is expressed as

- where

- Free distance of the FR scheme is

## Performance Evaluation (2)

- Fig. 6. BER performance of the UWB-IR systems with SOC coding and FR for *Nf* = 8, *Np* = 6, *K* = 5 in AWGN and LOS environments.

- Fig. 7. BER performance of the UWB-IR systems with SOC coding and FR for *Nf* = 8, *Np* = 6, *K* = 5 in AWGN and NLOS environments.

## Summary

- Performance investigated with the use of
- a realistic channel model
- real antennas’ characteristics.

- The BER performance evaluated by theoretical and numerical analyses.

- SOC coding constitutes a good alternative to frame repetition without costs in any additional bandwidth expansion.

- 3.   Complexity of a SOC decoder grows linearly with *K *making the SOC decoder feasible.

- 1.    Novel coding-modulation scheme.

**Thank you**