March 2005 Lampe, Hach, Menzer, Nanotron; Lee, Orthotron Slide 1 IEEE-15-05-0126-00-004a Submiss ion Project: IEEE P802.15 Working Group for Wireless Personal Area Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Networks (WPANs) Submission Title: DBO-CSS PHY Presentation for 802.15.4a Date Submitted: March 07, 2005 Source: [(1) John Lampe, et al, (2) Kyung-Kuk Lee, et al] Company: [(1) Nanotron Technologies, (2) Orthotron Co., Ltd.] Address: [(1) Alt-Moabit 61, 10555 Berlin, Germany, (2) 709 Kranz Techono, 5442-1 Sangdaewon-dong, Jungwon-gu, Sungnam-si, Kyungki-do, Korea 462-120] Voice: [(1) +49 30 399 954 135, (2) 82-31-777-8198 ], E-Mail: [(1) [email protected], (2) [email protected]] Re: This is in response to the TG4a Call for Proposals, 04/0380r2 Abstract: The Nanotron - Orthotron DBO-CSS is described and the detailed response to the Selection Criteria document is provided Purpose: Submitted as the candidate proposal for TG4a Alt-PHY 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
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IEEE-15-05-0126-00-004a Submission March 2005 Lampe, Hach, Menzer, Nanotron; Lee, OrthotronSlide 1 Project: IEEE P802.15 Working Group for Wireless Personal.
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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Re: This is in response to the TG4a Call for Proposals, 04/0380r2
Abstract: The Nanotron - Orthotron DBO-CSS is described and the detailed response to the Selection Criteria document is provided
Purpose: Submitted as the candidate proposal for TG4a Alt-PHY
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.
■ Band in Use■ Signal Robustness interference mitigation techniques. Interference Susceptibility Coexistence
■ Technical Feasibility Manufacturability Time to Market Regulatory Impact Backward Compatibility
■ Scalability■ Mobility ■ MAC Protocol Supplement■ PHY Layer Criteria Unit Manufacturing Cost/Complexity (UMC) Size and Form Factor Payload Bit Rate and Data Throughput
■ Simultaneously Operating Piconets■ Signal Acquisition■ Clear Channel Assessment■ System Performance Error rate Receiver sensitivity
■ Ranging■ Link Budget■ Power Management Modes■ Power Consumption■ Antenna Practicality
Selection Criteria Document TopicSignal Robustness: Signal Robustness: Interference Mitigation Techniques The proposed DBO-CSS PHY is designed to operate in a hostile
environment – Multipath– Narrow and broadband intentional and unintentional interferers
Since a chirp transverses a relatively wide bandwidth it has an inherent immunity to narrow band interferers
Multipath is mitigated with the natural frequency diversity of the waveform Broadband interferer effects are reduced by the receiver’s correlator Forward Error Correction (FEC) can further reduce interference and
multipath effects. Three non-overlapping frequency channels in the 2.4 GHz ISM band
– This channelization allows this proposal to coexist with other wireless systems such as 802.11 b, g and even Bluetooth (v1.2 has adaptive hopping) via DFS
DBO-CSS proposal utilizes CCA mechanisms of Energy Detection (ED) and Carrier Detection
These CCA mechanisms are similar to those used in IEEE 802.15.4-2003– In addition to the low duty cycle for the applications served by this standard
sufficient arguments were made to convince the IEEE 802 sponsor ballot community that coexistence was not an issue.
Selection Criteria Document TopicTechnical Feasibility: Technical Feasibility: Time to Market
No regulatory hurdles DBO-CSS based chips are available on the market No research barriers – no unknown blocks Normal design and product cycles will apply Can be manufactured in all CMOS
Devices manufactured in compliance with the DBO-CSS proposal can be operated under existing regulations in all significant regions of the world- Including but not limited to North and South America, Europe, Japan,
China, Korea, and most other areas- There are no known limitation to this proposal as to indoors or
outdoors The DBO-CSS proposal would adhere to the following
worldwide regulations:- United States Part 15.247 or 15.249- Canada DOC RSS-210- Europe ETS 300-328- Japan ARIB STD T-66
Due to the similarities with DSSS it is possible to implement this proposal in a manner that will allow backward-compatibility with the 802.15.4 2.4 GHz standard.
The transmitter changes are relatively straightforward. Changes to the receiver would include either dual
correlators or a superset of DBO-CSS and DSSS correlators.
Optional methods for backward-compatibility could be left up to the implementer - mode switching - dynamic change (on-the-fly) technique
This backward-compatibility would be a significant advantage in the marketplace by allowing these devices to communicate with existing deployed 802.15.4 infrastructure and eliminating customer confusion.
Mandatory rate = 1 Mb/s Optional rates = 500 Kb/s, 250 Kb/s Lower data rates achieved by using interleaved FEC Lower chirp rates would yield better performance
- longer range, less retries, etc. in an AWGN environment or a multipath limited environment
It should be noted that these data rates are only discussed here to show scalability, if these rates are to be included in the draft standard the group must revisit the PHY header such as the SFD.
For extremely long ranges the transmit power may be raised to each country’s regulatory limit, for example:– The US would allow 30 dBm of output power with up to a 6 dB gain
antenna
– The European ETS limits would specify 20 dBm of output power with a 0 dB gain antenna
Note that even though higher transmit power requires significantly higher current it doesn’t significantly degrade battery life since the transmitter has a much lower duty cycle than the receiver, typically 10% or less of the receive duty cycle.
Selection Criteria Document TopicScalability: Scalability: Power LevelsPower Levels
– No system inherent restrictions are seen for this proposal• The processing gain of chirp signals is extremely robust against frequency offsets
such as those caused by the Doppler effect when there is a high relative speed vrel between two devices.
• The Doppler effect must also be considered when one device is mounted on a rotating machine, wheel, etc.
• The limits will be determined by other, general (implementation-dependent) processing modules (AGC, symbol synchronization, etc.).
• Ranging– The ranging scheme proposed in this document relies on the exchange of
two hardware acknowledged data packets• One for each direction between two nodes
– The total time for single-shot (2 data, 2 Ack) ranging procedure between the two nodes is the time tranging which, depending on the implementation, might be impacted by the uC performance. During this time the change of distance should stay below the accuracy da required by the application. The worst case is:
• For da = 1m• tranging = 2 ms this yields • vrel << 1000 m/sranging
There are very minimal anticipated changes to the 15.4 MAC to support the proposed Alt-PHY. – Three channels are called for with this proposal and it is
recommended that the mechanism of channel bands from the proposed methods of TG4b be used to support the new channels.
– There will be an addition to the PHY-SAP primitive to include the choice of data rate to be used for the next packet. This is a new field.
Ranging calls for new PHY-PIB primitives are expected to be developed by the Ranging subcommittee.
Selection Criteria Document TopicPHY Layer Criteria: PHY Layer Criteria: Size and Form Factor
The implementation of the DBO-CSS proposal will be much less than SD Memory at the onset– Following the form factors of Bluetooth and IEEE 802.15.4 / ZigBee
The implementation of this device into a single chip is relatively straightforward– As evidenced in the “Unit Manufacturing Complexity” slides
SOP: Assigning Different Time-Gap between the Chirp-Shift-Keying Signal Minimize ISI for CM8 NLOS: Assign the Time-Gap between symbol more then 200nsec
Although DBO-CSS could use a shorter preamble, for consistency with IEEE 802.15.4-2003 this DBO-CSS proposal is based upon a preamble of 32 symbols which at 1MS/s is 32 µs
Existing implementations demonstrate that modules, which might be required to be adjusted for reception (gain control, frequency control, peak value estimation, etc.), can settle in this time
Since this proposal refers to the 2.4GHz ISM band, only channel models with complete parameter sets covering this frequency range can be considered:– These are LOS Residential (CM1) and NLOS Residential (CM2).
The SCD requirements on the payload size to be simulated seem to be somewhat inconsistent. At some point 10 packets with 32 bytes are mentioned which would be a total of 2560 bits. On the other hand a PER of 1% is required which mean simulating much more than 100 packets or 25600 bits.
Accurate results are obtained when large number of independent transmissions of symbols are simulated.
BER is , with N = number bits.– For example, with PER=1% and N=256 (32 octets) we get
Simulation over 100 channel impulse responses (as required in the SCD) were performed for channel model 1 and channel model 2.
No bit errors could be observed on channel model 1 (simulated range was 10 to 2000m). This is not really surprising because this model has a very moderate increase of attenuation over range (n=1.79)
The results for channel model 2 are presented. The parameter n=4.48 indicates a very high attenuation for higher ranges. The results were interpreted as PER respectively and for convenience were plotted twice (linear and log y scale).
This figure shows the analytical BER values for 2-ary orthogonal coherent and non coherent detection and the corresponding simulation results (1E7 symbols) for up down chirp (using the chirp signals defined above)
The performance loss due to the non-orthogonality of up and down chirps is very small.
Given a band-limited pulse with noise σu we want to estimate how the jitter (timing error) σt, is affected by the bandwidth B. Jitter can be represented as a variation in the rising edge of a pulse through a given threshold,
Since the power σ2 of band-filtered AWGN is proportional to the bandwidth we know that:
t
urv
BB
B
vr
ut
1~
σu threshold
σt t
u Signal with rising speed vr
noise bar
Approximate the impact of σu by:
Bt
uv
rise
peakr ~
Assume the rising speed of the signal is proportional to the signal bandwidth:
Which leads to:
BNBu ~
Selection Criteria Document TopicRanging: Ranging: TOA Estimation for RangingTOA Estimation for Ranging
■ Coarse Timing Detection - Peak of Differential Detection (Averaging over 4 or more Symbols)
■ Fine Timing Detection - Cross-Correlation of Sampled Input Signal - Fine Timing by Interpolation (Fraction of Sampling-Clock Resolution < 1nsec) - Averaging over 4 or more Symbols - Less than 1m Ranging Resolution @ Eb/No >= 24dB
Arbitrary Sampling Instant
Detected TimingDetected TimingPeak
Edge
Selection Criteria Document TopicRanging: Ranging: TOA Estimation Using Chirp SignalsTOA Estimation Using Chirp Signals
The typical DSSS receivers, used by 802.15.4, are very similar to the envisioned DBO-CSS receiver
The two major differences are the modulator and demodulator– The power consumption for a 10 dBm transmitter should be 198 mW or less
The receiver for the DBO-CSS is remarkably similar to that of the DSSS with the major difference being the correlator
– The difference in power consumptions between these correlators is negligible so the power consumption for a 6 dB NF receiver should be 40 mW or less
Power save mode is used most of the time for this device and has the lowest power consumption
– Typical power consumptions for 802.15.4 devices are 3 µW or less Energy per bit is the power consumption divided by the bit rate
– The energy per bit for the 10 dBm transmitter is less than 0.2 µJ– The energy per bit for the receiver is 60 nJ
As an example, the energy consumed during an exchange of a 32 octet PDU between two devices would be 70.6 µJ for the sender and 33.2 µJ for the receiver
Requirements ChecklistDBO-CSS Proposal Meets the PAR and 5C: Precision ranging capability accurate to one meter or better Extended range over 802.15.4-2003 Enhanced robustness over 802.15.4-2003 Enhanced mobility over 802.15.4-2003 International standard Ultra low complexity (comparable to the goals for 802.15.4-2003) Ultra low cost (comparable to the goals for 802.15.4-2003) Ultra low power consumption (comparable to the goals for 802.15.4-2003) Support coexisting networks of sensors, controllers, logistic and peripheral devices in multiple compliant co-located systems.
SummaryDBO-CSS is simple, elegant, efficient: Combines DSSS and UWB strengths Precise location-awareness Robustness – multipath, interferers, correlation, FEC, 3 channels, CCA Mobility enhanced Optional backward compatibility with 802.15.4-2003 Excellent throughput SOPs – FD channels Signal Acquisition – excellent Link Budget and Sensitivity – excellent Very minimal MAC changes, CCA supported Power Management and Consumption - meets or exceeds requirements Antenna – many good choices Can be implemented with today’s technologies
• Low-complexity, low-cost• Size and Form Factor – meets or exceeds requirements• Low power consumption
Globally certifiable Scalability with many options for the future Meets all PAR and 5C requirements