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doc.: IEEE /210r0 Submission May, 2003 C. Razzell, PhilipsSlide 3 Scope of the problem UWB channel models are highly dispersive relative to the pulse widths typically considered. A channel matched filter would require an average of 132 taps at 6GHz to collect 85% of the energy in CM4. Good performance requires that we don’t discard a significant proportion of the available energy. A balance between hardware complexity and energy collection/performance is sought.
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May, 2003
C. Razzell, PhilipsSlide 1
doc.: IEEE 802.15-03/210r0
Submission
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Mutlipath Energy Collection in Multi-Band UWB Receivers]Date Submitted: [ 8 May, 2003]Source: [Charles Razzell, Dagnachew Birru, Bill Redman-White] Company [Philips]Address [1109 McKay Drive, San Jose, 95131, California, USA]Voice:[+1 408-474-7243], FAX: [+1 408-474-5343], E-Mail:[[email protected]]Re: []
Abstract: [This document discusses and evaluates multipath energy collection in the context of multi-band receivers. Various options are considered related to PRF, modulation order and number of parallel receive paths.]
Purpose: [Consider this when comparing the relative merits of a multi-band PHY against other options.]Notice: This document has been prepared to assist the IEEE P802.15. 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 may be made publicly available by P802.15.
May, 2003
C. Razzell, PhilipsSlide 2
doc.: IEEE 802.15-03/210r0
Submission
Energy Collection in Multi-band UWB Receivers
A technical contribution to the multi-band discussion
May, 2003
C. Razzell, PhilipsSlide 3
doc.: IEEE 802.15-03/210r0
Submission
Scope of the problem• UWB channel models are highly dispersive
relative to the pulse widths typically considered.
• A channel matched filter would require an average of 132 taps at 6GHz to collect 85% of the energy in CM4.
• Good performance requires that we don’t discard a significant proportion of the available energy.
• A balance between hardware complexity and energy collection/performance is sought.
May, 2003
C. Razzell, PhilipsSlide 4
doc.: IEEE 802.15-03/210r0
Submission
How Many Taps are Needed?
CM1 CM2 CM3 CM4
NP85% (BW=6GHz) 28.2 44.5 73.2 132.4
NP85% (BW=264MHz) 1.24 1.96 3.22 5.8
NP85% Number of Paths needed for 85% energy
May, 2003
C. Razzell, PhilipsSlide 5
doc.: IEEE 802.15-03/210r0
Submission
Cumulative Distribution Function of # significant RAKE fingers (CM2)
1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.60
10
20
30
40
50
60
70
80
90
100
number of significant chips (3.79ns/chip)
Cum
ulat
ive
num
ber o
f cha
nnel
s
CM2: number of chips to capture 85% energy
90% of channels require less than 2.3 RAKE fingers
May, 2003
C. Razzell, PhilipsSlide 6
doc.: IEEE 802.15-03/210r0
Submission
Cumulative Distribution Function of # significant RAKE fingers (CM3)
1.5 2 2.5 3 3.5 4 4.5 5 5.50
10
20
30
40
50
60
70
80
90
100
Cum
ulat
ive
num
ber o
f cha
nnel
s
number of significant chips (3.79ns/chip)
CM3: number of chips to capture 85% energy
90% of channels require less than 4 RAKE fingers
May, 2003
C. Razzell, PhilipsSlide 7
doc.: IEEE 802.15-03/210r0
Submission
Cumulative Distribution Function of # significant RAKE fingers (CM4)
3.5 4 4.5 5 5.5 6 6.5 7 7.5 80
10
20
30
40
50
60
70
80
90
100
number of significant chips (3.79ns/chip)
Cum
ulat
ive
num
ber o
f cha
nnel
s
CM4: number of chips to capture 85% energy
90% of channels require less than 7 RAKE fingers
May, 2003
C. Razzell, PhilipsSlide 8
doc.: IEEE 802.15-03/210r0
Submission
Local Oscillator Requirements (1)
• Oscillator must switch frequency in time slot << 3.8ns
• Multi-frequency generator is a feasible approach
3.79ns 3.79ns 3.79ns 3.79ns 3.79ns 3.79ns 3.79nsTime
Single Local Oscillator SignalRequired
3.79ns 3.79ns 3.79ns 3.79ns 3.79ns 3.79ns 3.79nsTime
Ideal Transmitted Signal
26.53ns
May, 2003
C. Razzell, PhilipsSlide 9
doc.: IEEE 802.15-03/210r0
Submission
Local Oscillator Requirements (2)
3.79ns 3.79ns 3.79ns 3.79ns 3.79ns 3.79ns 3.79nsTime
Signal Component Amplitude
Frequency Band Received
Signal Pulses With Echo Outside Time Slots
Local Oscillator Signals Needed 2 at a Time
3.79ns
May, 2003
C. Razzell, PhilipsSlide 10
doc.: IEEE 802.15-03/210r0
Submission
LNA
RAKE RECEIVER QPSK DEMOD
LOW PASS BAND FILTERS & VARIABLE GAIN AMP
NDA
NDA
/ 2
LOW PASS BAND FILTERS & VARIABLE GAIN AMP
NDA
NDA
/ 2
FREQUENCY GENERATION
• Implementation choice, for higher performance, employs 2 receiver paths
• 2 oscillator frequencies needed at same time
Parallel Receiver Architecture
Estimated RF Area ~ 2.5mm2 in 0.25m SiGe BiCMOS
Estimated Digital Area ~ 7mm2 in 0.12m CMOS
May, 2003
C. Razzell, PhilipsSlide 11
doc.: IEEE 802.15-03/210r0
Submission
Number of feasible RAKE fingers
Fully Serial Rx
Parallel (2) Rx(see previous slide)
Parallel (3) Rx (extension of previous slide)
Half PRF(110Mbps)
2 4 6
Full PRF(200Mbps)
1 2 3
May, 2003
C. Razzell, PhilipsSlide 12
doc.: IEEE 802.15-03/210r0
Submission
Simulation Results
• Evaluate the need for energy collection– Serial and parallel receivers and multiple RAKE
fingers• Parameters:
– 132 MHz PRF for QPSK (“half PRF”)– 264 MHz PRF for BPSK (“full PRF”)– Rate ½ convolutional code– 7 Bands spaced at 440 MHz– Interleaver after convolutional encoder to further
spread the information bits across multiple bands
May, 2003
C. Razzell, PhilipsSlide 13
doc.: IEEE 802.15-03/210r0
Submission
BER for CM4, one finger, one path
The multipath curves are the average of the best 45 from 50 channel realizations.
Eb is energy per uncoded bit-2 0 2 4 6 8 10 12 14 16 1810-4
10-3
10-2
10-1
100
Eb/No [dB]
BER
CM4: QPSK 1 RAKE finger, one receive path
AWGNuncoded QPSKcoded QPSK
May, 2003
C. Razzell, PhilipsSlide 14
doc.: IEEE 802.15-03/210r0
Submission
BER for CM4, two fingers, one path
The multipath curves are the average of the best 45 from 50 channel realizations.
Eb is energy per uncoded bit-2 0 2 4 6 8 10 12 14 16 1810-4
10-3
10-2
10-1
100
Eb/No [dB]
BER
CM4: QPSK 2 RAKE fingers, one receive path
AWGNuncoded QPSKcoded QPSK
May, 2003
C. Razzell, PhilipsSlide 15
doc.: IEEE 802.15-03/210r0
Submission
BER for CM4, two fingers per path, parallel receiver paths
The multipath curves are the average of the best 45 from 50 channel realizations.
Eb is energy per uncoded bit-2 0 2 4 6 8 10 12 14 16 1810-4
10-3
10-2
10-1
100
Eb/No [dB]
BER
CM4: QPSK 2 RAKE fingers, multiple receive paths
AWGNuncoded QPSKcoded QPSK
May, 2003
C. Razzell, PhilipsSlide 16
doc.: IEEE 802.15-03/210r0
Submission
BER for CM4, four fingers per path, parallel receiver paths
The multipath curves are the average of the best 45 from 50 channel realizations.
Eb is energy per uncoded bit-2 0 2 4 6 8 10 12 14 16 1810-4
10-3
10-2
10-1
100
Eb/No [dB]
BER
CM4: QPSK 4 RAKE fingers, multiple receive paths
AWGNuncoded QPSKcoded QPSK
May, 2003
C. Razzell, PhilipsSlide 17
doc.: IEEE 802.15-03/210r0
Submission
BPSK BER for CM4, one finger, one path
The multipath curves are the average of the best 45 from 50 channel realizations.
Eb is energy per uncoded bit-2 0 2 4 6 8 10 12 14 16 1810-4
10-3
10-2
10-1
100
Eb/No [dB]
BER
CM4: BPSK 1 RAKE finger, 1 receive path
AWGNuncoded BPSKcoded BPSK
May, 2003
C. Razzell, PhilipsSlide 18
doc.: IEEE 802.15-03/210r0
Submission
BPSK BER for CM4, one finger per path, parallel receiver paths
The multipath curves are the average of the best 45 from 50 channel realizations.
Eb is energy per uncoded bit-2 0 2 4 6 8 10 12 14 16 1810-4
10-3
10-2
10-1
100
Eb/No [dB]
BER
CM4: BPSK 1 RAKE finger, multiple receive paths
AWGNuncoded BPSKcoded BPSK
May, 2003
C. Razzell, PhilipsSlide 19
doc.: IEEE 802.15-03/210r0
Submission
BPSK BER for CM4, two fingers per path, parallel receiver paths
The multipath curves are the average of the best 45 from 50 channel realizations.
Eb is energy per uncoded bit-2 0 2 4 6 8 10 12 14 16 1810-4
10-3
10-2
10-1
100
Eb/No [dB]
BER
CM4: BPSK 2 RAKE fingers, multiple receive paths
AWGNuncoded BPSKcoded BPSK
May, 2003
C. Razzell, PhilipsSlide 20
doc.: IEEE 802.15-03/210r0
Submission
BPSK BER for CM4, four fingers per path, parallel receiver paths
The multipath curves are the average of the best 45 from 50 channel realizations.
Eb is energy per uncoded bit-2 0 2 4 6 8 10 12 14 16 1810-4
10-3
10-2
10-1
100
Eb/No [dB]
BER
CM4: BPSK 4 RAKE fingers, multiple receive paths
AWGNuncoded BPSKcoded BPSK
May, 2003
C. Razzell, PhilipsSlide 21
doc.: IEEE 802.15-03/210r0
Submission
Modulation Schemes and PRF
• Options to use BPSK and QPSK• Which modulation is the best?
Two Repetitions at Full PRF
One Repetition at Half PRF
26.5 ns
53 ns
1
0
-1
1.41
0
-1.41
BPSK
QPSK
May, 2003
C. Razzell, PhilipsSlide 22
doc.: IEEE 802.15-03/210r0
Submission
Modulation Schemes and PRF (cnt’d)
• QPSK lowers PRF– Improved multipath performance via
• Energy collection• Reducing ISI
– Improved piconet performance– But requires more accurate phase reference
• BPSK increases PRF– Lower multipath performance
• ISI performance could be improved via equalization• Efficient energy collection is impossible at 110MB/s
without using parallel receivers (or reducing data rate) – But can tolerate less accurate phase reference
For identical data rates
May, 2003
C. Razzell, PhilipsSlide 23
doc.: IEEE 802.15-03/210r0
Submission
-2 0 2 4 6 8 10 12 14 16 1810-4
10-3
10-2
10-1
100
Eb/No [dB]
BER
CM4: QPSK/BPSK various numbers of RAKE fingers
BPSK 1 finger, serialBPSK, 1 finger, parallelBPSK 2 fingers, parallelBPSK, 4 fingers, parallelQPSK, 1 finger, serialQPSK, 2 finger, serialQSPK, 2 fingers, parallelQPSK, 4 fingers, parallel
Modulation Schemes and PRF (cnt’d)
Can achieve this with serial Rx at 110Mbps
May, 2003
C. Razzell, PhilipsSlide 24
doc.: IEEE 802.15-03/210r0
Submission
Discussion
• Simulations have shown that at least 2 RAKE fingers are needed to obtain a reasonable link budget in CM4.
• This is compatible with a fully serial receiver implementation at 110Mbps (half PRF, QPSK).
• The number of receiver branches can be an implementation choice, depending on the robustness and data rates targeted.
• Further results need to be collected to find the optimum balance of complexity vs. performance.
