1. Month Year
doc.: IEEE /0xxxxr0
Sep 2008
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: study of UWB interference issues
Date Submitted: September 7th, 2008
Source: Kiran Bynam, Giriraj Goyal , Ranjeet Kumar Patro, Arun Naniyat, EunTae Won
Contact: Kiran Bynam, Samsung Electronics
Voice: ,
Re: []
Abstract: brief study on Interference and co-existence in BAN Networks in UWB
Purpose: To discuss the Interference and co-existence problems in BAN
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual's) or organization's). The material in this document is subject to change in form and content after further study. The contributor's) reserve's) the right to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and in March’08 it would be made publicly available by P
Slide 1
Slide 1
Kiran Bynam, Samsung 1
Kiran Bynam, Samsung

2. Outline Problems with interference
Sep 2008
Outline
Problems with interference
Overview of Interference of UWB to NB systems
Interference problems to the UWB networks
Future work

3. Interference aspects Effects of interference Types of interference
Sep 2008
Interference aspects
Effects of interference
Loss of performance
Reduction in range
Link unavailability
Types of interference
UWB interference on narrow band
Narrow band interference on UWB
UWB to UWB

4. Interference scenario and implications
Sep 2008
Interference scenario and implications
BAN TRx
NB TRx
BAN Receiver node is receiving the Narrow band interference signals coming from N different sources
Performance of BAN network is limited by the N narrow band interference powers and their power levels

5. Interference from NB to UWB systems
Sep 2008
Interference from NB to UWB systems
The signal at the BAN receiver can be defined as
Y(n) = α * s(t) + hUWB (t) * a(t) + nUWB(t)
Where s(t) is the UWB transmit signal
a(t) is the Narrow band signal
nUWB(t) is the noise generated in the UWB receiver
The signal to noise density ratio at UWB receiver can be given as
(C/N)density = PUWB/(NUWB + IUWB /BUWB)
PUWB is the power of the UWB band signal at the input of narrow band receiver
NUWB is the power density of the noise generated in the UWB receiver
IUWB is the power of the other NB interferers in the band of UWB

6. Lower bounds on UWB power due to NB interference
Sep 2008
Lower bounds on UWB power due to NB interference
Prx/D > (Nu+ Iu/Buwb) (Eb/No)min
Where D is the date rate required
(Eb/No)min is the minimum Eb/No required for satisfactory operation
Example in a BAN scenario
At typical interference power of -80 dBm
Minimum Eb/No of 10 dB
Data rate of 10 Mbps
The received power should more than approximately dBm

7. Sep 2008
NB to UWB interference
Even at very close range, the transmit power should be higher in case of strong interference
The continuous interferer signal transmission scenario may be avoided using energy detection at the time of network initialization
What is the criteria for meeting performance requirements in the interference conditions? Needs to be verified.

8. Interference from UWB to NB systems
Sep 2008
Interference from UWB to NB systems
The signal at the Narrow band receiver can be defined as
Y(n) = α * sNB(t) + hNB (t) * a(t) + nNB(t)
Where sNB(t) is the narrow band transmit signal
a(t) is the UWB band signal
nNB(t) is the noise generated in the UWB receiver
The signal to noise density ratio at NB receiver can be given as
(C/N)density = PNB/(NNB + INB / BNB)
PNB is the power of the narrow band signal at the input of narrow band receiver
NNB is the power density of the noise generated in the narrow band receiver
INB is the power of the UWB interferers in the band of narrow band signal

9. Effects of UWB Interference on NB
Sep 2008
Effects of UWB Interference on NB
Typical Narrow band signal bandwidth is assumed to be 10 M Hz
The UWB signal in the NB receiver bandwidth will be processed at receiver after getting filtered at the BPF of the receiver
For a typical case when the NB node is at 1 m distance from UWB transmitter
UWB power in 10 MHz band is dBm ( assuming a path loss of 40 dB at 1m)
This power is not at all negligible as some of the narrow band receiver sensitivities will be typically below -70 dBm
Results in huge loss of performance or power consumption

10. UWB Interference on Narrow band
Sep 2008
UWB Interference on Narrow band
The UWB is typically viewed as the modulation of narrow pulses
Accumulation of more power in the active region of pulses
Leads to higher instantaneous interference to narrow band systems
Is there any restrictions posed by any regulatory body for the UWB devices co-existing with Narrow band devices?

11. Sep 2008
Conclusion
Need to have a Threshold for channel migration so that we can change the channel without spending more power to counter the interference and not sacrificing the performance at low received energy levels.
Is there any thing defined by regulatory?
Should work on power control algorithm so that we radiate only required power and reduce the interference to narrow band systems.

12. References UWBRadio deployment challenges – R.A.Scholtz et. al
Sep 2008
References
UWBRadio deployment challenges – R.A.Scholtz et. al

13. Sep 2008
Thank You