July 2004
doc.: IEEE 802.15-04/341r0
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Extended Common Signaling Mode]
Date Submitted: [July 15, 2004]
Source: [Matt Welborn] Company [Freescale Semi, Inc]
Address [8133 Leesburg Pike]
Voice:[703-269-3000], FAX: [703-249-3092]
Re: []
Abstract: [This document provides an overview some possible extensions for the proposed Common
Signaling Mode that would allow the inter-operation or MB-OFDM and DS-UWB devices at data rates as
high as 110 Mbps.]
Purpose: [Promote further discussion and compromise activities to advance the development of the TG3a
Higher rate PHY standard.]
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.
Submission
Slide 1
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
Background
• Initial TG3a discussions on a “Common Signaling
Mode” (CSM) began some months ago
– A few ad hoc meetings during January TG3a Interim
– Ad hoc meeting in February
– Several presentations in March Plenary
• Other attempts at compromise to allow forward
progress in TG3a not successful
– ~50/50 split in TG3a voter support for two PHY proposals
– Little support for two optional independent PHYs
• Can we re-examine some of the ideas for a single
multi-mode UWB PHY as a path for progress?
Submission
Slide 2
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
The CSM Vision
• A single PHY with multiple modes to provide a
complete solution for TG3a
– Base mode that is required in all devices, used for control
signaling: “CSM” for beacons and control signaling
– Higher rate modes also required to support 110+ Mbps
– Compliant device can implement either DS-UWB or MBOFDM (or both)
– Interoperability between all compliant devices at high rates
• All devices work through the same 802.15.3 MAC
– User/device only sees common MAC interface
– Hides the actual PHY waveform in use
– Effectively only one PHY – with multiple modes
Submission
Slide 3
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
Talking with each other:
Basic Requirements
• Each class of UWB devices (MB-OFDM or DS-UWB)
needs a way to send control/data to the other type
– MB-OFDM  DS-UWB
– DS-UWB  MB-OFDM
• Goal: Minimize additional complexity for each type of
device while enabling this extra form of
communications
– Use existing RF components & DSP blocks to transmit
message to “other-class” devices
– Also need to enable low-complexity receivers
– Data rates need to support full piconet operation without
impacting throughput/capacity or robustness
Submission
Slide 4
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
UWB Consumer Electronics
Applications
Home Entertainment
Computing
Submission
Mobile Devices
Slide 5
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
Interoperation with a Common Signaling Mode
Images from
camera to
storage/network
Print from
handheld
Exchange your
music & data
Stream
presentation
from laptop/
PDA to
projector
Submission
Stream DV or
MPEG to display
MP3 titles to
music player
Slide 6
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
No Interoperation: Tragedy of the Commons
Images from
camera to
storage/network
Print from
handheld
Stream
presentation
from laptop/
PDA to
projector
Submission
Stream DV or
MPEG to display
MP3 titles to
music player
Slide 7
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
Interoperability Signal Generation
• One waveform possible for either class of device is a BPSK signal
centered in the middle of the “low band” at ~ 4GHz
• Such a signal could be generated by both MB-OFDM and DS-UWB
devices using existing RF and digital blocks
• MB-OFDM device contains a DAC nominally operating at 528 MHz
– A 528 MHz BSPK (3 dB BW) signal is too wide for MB-OFDM band
filters
– DAC an be driven at slightly lower clock rate to produce a BPSK signal
that will fit the MB-OFDM Tx filter
– Result: 500 MHz BPSK signal that DS-UWB device can receive &
demodulate
• DS-UWB device contains a pulse generator
– Use this to generate a 500 MHz BPSK signal at lower chip rate
– This signal would fit MB-OFDM baseband Rx filter and could be
demodulated by the MB-OFDM receiver
Submission
Slide 8
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
Issues & Solutions for CSM
• Common frequency band
– Solution: Use MB-OFDM Band #2
– Passed by MB-OFDM FE with hopping stopped
• Common FEC
– Solution: Each receiver uses native FEC (e.g. k=6/7 Viterbi)
– Every transmitter can encode for both codes – low complexity
• Common clock frequency (“chip rate”)
– Close, but final resolution still TBD
• Initial CSM rates were too low for some applications
– Add extensions to higher rates (at slightly reduced ranges)
– As high as 110-220 Mbps for interoperability, depending on
desired level of receiver complexity
Submission
Slide 9
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
MB-OFDM & DS-UWB Signal Spectrum with CSM
Compromise Solution
Relative
PSD (dB)
Proposed Common
Signaling Mode Band
(500 MHz bandwidth)
MB-OFDM (3-band)
Theoretical Spectrum
DS-UWB Low Band
Pulse Shape (RRC)
0
-3
-20
3432
3960
3100
4488
5100
Frequency (MHz)
FCC Mask
Submission
Slide 10
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
Interoperability Signal Overview
• MB-OFDM band 2 center frequency for common signaling band
– Centered at 3960 MHz with approximately 500 MHz bandwidth
– BPSK chip rate easily derived from carrier: chip = carrier frequency / 9
– Frequency synthesis circuitry already present in MB-OFDM radio
• 500 MHz BPSK is similar to original “pulsed-multiband” signals
– Proposed by several companies in response to TG3a CFP
– Better energy collection (fewer rake fingers) than wideband DS-UWB
– More moderate fading effects than for MB-OFDM (needs less margin)
• Relatively long symbol intervals (10-55 ns) avoids/minimizes ISI
– Equalization is relatively simple in multipath channels
– Not necessary for lowest (default) CSM control/beacon rates
• Use different CSM spreading codes for each piconet
– Each DEV can differentiate beacons of different piconets
– Provides processing gain for robust performance: signal BW is much
greater than data rate
Submission
Slide 11
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
Packets For Two-FEC Support
CSM PHY Preamble
Headers
FEC 1 Payload
FEC 2 Payload
• FEC used in CSM modes to increase robustness
– Each device can use native FEC decoder (e.g k=7 or 6)
• For multi-recipient packets (beacons, command frames)
– Packets are short, duplicate payload for two FEC types adds little
overhead to piconet
• For directed packets (capabilities of other DEV known)
– Packets only contain single payload with appropriate FEC
• FEC type(s) & data rate for each field indicated in header
fields
Submission
Slide 12
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
Data Rates Possible for CSM
CSM Mode
MB-OFDM to
DS-UWB
DS-UWB to
MB-OFDM
Submission
Data Rate
FEC Rate Code Length Symbol Time
Link Margin
9.2 Mbps
½
24
55 ns
9.3 dB at 10 m
27 Mbps
½
8
18 ns
6.5 dB at 10 m
55 Mbps
½
4
9 ns
3.5 dB at 10 m
110 Mbps
½
2
5 ns
0.4 dB at 10 m
220 Mbps
1
2
5 ns
0.8 dB at 4 m
6.3 Mbps
11/32
24
55 ns
12 dB at 10 m
19 Mbps
11/32
8
18 ns
9.1 dB at 10 m
68 Mbps
5/8
4
9 ns
2.8 dB at 10 m
137 Mbps
5/8
2
5 ns
-0.2 dB at 10 m
220 Mbps
1
2
5 ns
0.8 dB at 4 m
Slide 13
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
Implementation
• Mandatory/optional modes determined by TG to meet
performance & complexity goals for applications
• Implementations do not need “optimal” receivers
– Sufficient margins for moderate range interoperability
• Shorter codes for higher rates can be based on “sparse” codes
(e.g. “1-0-0-0”)
– Eliminate need for transmit power back-off
– Peak-to-average still supports low-voltage implementation
• Equalizers desirable at higher CSM rates (>20 Mbps?)
– Complexity is very low (a few K-gates), and works great
• Other transceiver blocks (Analog FE, ADC/DAC, Viterbi decoder,
digital correlators, etc.) already in radio
Submission
Slide 14
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
CSM Link Budgets with DS-UWB FEC
FEC Rate
Code Length
Data Rate (Mbps)
Theoretical Tx Power
Transmit Power (dBm)
Total Path Loss (dB)
Received Power
Noise Power per Bit
Noise Figure
Total Noise Power
Code Gain
Required Eb/No
Implementation Loss
Link Margin (at ref range)
Sensitivity
Reference Range
AWGN Range
Submission
CSM
Coded
0.50
24.0
9.2
-14.8
-16.7
64.2
-80.9
-104.4
6.6
-97.8
4.6
5.0
2.5
9.3
-90.3
10
29.3
0.50
8.0
27.5
-14.8
-14.8
64.2
-79.0
-99.6
6.6
-93.0
4.6
5.0
2.5
6.5
-85.5
10
21.1
Slide 15
0.50
4.0
55.0
-14.8
-14.8
64.2
-79.0
-96.6
6.6
-90.0
4.6
5.0
2.5
3.5
-82.5
10
14.9
0.50
2.0
110.0
-14.8
-14.8
64.2
-79.0
-93.6
6.6
-87.0
4.6
5.0
2.5
0.4
-79.5
10
10.5
CSM
Uncoded
1.00
2.0
220.0
-14.8
-14.8
56.3
-71.1
-90.6
6.6
-84.0
0.0
9.6
2.5
0.8
-71.9
4
4.4
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
CSM Link Budgets with MB-OFDM FEC
FEC Rate
Code Length
Data Rate (Mbps)
Theoretical Tx Power
Transmit Power (dBm)
Total Path Loss (dB)
Received Power
Noise Power per Bit
Noise Figure
Total Noise Power
Code Gain
Required Eb/No
Implementation Loss
Link Margin (at ref range)
Sensitivity
Reference Range
AWGN Range
Submission
CSM
Coded
0.34
0.34
0.63
24.0
6.3
-14.8
-16.7
64.2
-80.9
-106.0
6.6
-99.4
5.6
4.0
2.5
12.0
-92.9
10
39.7
8.0
18.9
-14.8
-14.8
64.2
-79.0
-101.2
6.6
-94.6
5.6
4.0
2.5
9.1
-88.1
10
28.5
4.0
68.8
-14.8
-14.8
64.2
-79.0
-95.6
6.6
-89.0
4.9
4.7
2.5
2.8
-81.8
10
13.8
Slide 16
CSM
Uncoded
0.63
1.00
2.0
137.5
-14.8
-14.8
64.2
-79.0
-92.6
6.6
-86.0
4.9
4.7
2.5
-0.2
-78.8
10
9.8
2.0
220.0
-14.8
-14.8
56.3
-71.1
-90.6
6.6
-84.0
0.0
9.6
2.5
0.8
-71.9
4
4.4
Welborn, Freescale Semi
July 2004
doc.: IEEE 802.15-04/341r0
Concerns
• A “two PHY” solution will confuse the market
– PHY waveform is transparent to application
– This “multi-mode PHY” solution allows interoperability with high
functionality and prevents interference/QoS breakdown
– Even a “single PHY” solution will have multiple modes & allows
devices with different capability levels
– CSM interoperability data rates can be high enough to meet PAR (110
Mbps) -- even between dissimilar device classes
• Complexity: CSM additional complexity can be very low and
doesn’t require optimal receivers
– Higher rates benefit from simple equalizers and/or digital rake
• “I would really like to continue attending TG3a meetings
indefinitely!”
– Are you crazy?
Submission
Slide 17
Welborn, Freescale Semi