Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

July 2003

Lampe, Ianelli, Nanotron TechnologiesSlide 1

doc.: IEEE 802.15-15-03-0312-00-0040r0

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: The Principles and Benefits of CSSDate Submitted: 24 July, 2003Source: John Lampe, Zbigniew Ianelli, Nanotron TechnologiesAlt-Moabit 61, Berlin, 10555, GermanyVoice: +49 30 399 954-0, FAX: +49 30 399 954-288, E-Mail: [email protected]

Re: Discussion of possible PHY/MAC enhancement in response to CFP for 15.4 enhancements

Abstract: PHY enhancement

Purpose: Basis for formation of a Study Group to amend 15.4 to expand potential markets opened by an optional CSS 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.

July 2003


doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

Introduction

• Nanotron presented its technology to TG4 March 11, 2003 in Dallas (doc# 03/169).

• TG4 requested Nanotron to prepare a white paper and answer specific questions.– Doc# 15-03-0313-00-0040

• In March, we spoke about MDMA (Multi Dimensional Multiple Access) and CSS (Chirp Spread Spectrum).– We would like to clarify that CSS is the technology we

propose now.– MDMA is the next-generation extension of CSS.– CSS has a fixed symbol duration.

July 2003


doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

The Principles and Benefits of CSS

• CSS = Chirp Spread Spectrum• New modulation method using chirps• Very robust radio link• Highly resistant against interference and multipath fading• Extended range due to system gain• Extremely power efficient transmission technique• Simple circuitry for modulation / demodulation• No digital signal processing needed• Nearly-simultaneous sensing of multiple 15.4 channels is possible• Backwards-compatible to DSSS• Allows simple and accurate position calculation• Perfect for mission critical applications• Addresses new wireless applications where other technologies fail

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doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

New Applications / Markets

• Mission critical (e.g. industrial)• Longer battery life (shorter transmit durations,

reduced retransmits)• Low latency tolerance applications (e.g. control,

gaming, streaming)• Device sharing/participating among multiple networks

(multiple simultaneous channel sensing)• Longer-range applications at 2.4 GHz where

repeaters are not practical• Location-awareness: finding items, motion detection,

automatic network installation

July 2003


doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

Multi-Dimensional Adaptive Matched Filter System

The symbols are transformed into sinc pulses (sin x/x), the shortest pulses possible at given bandwidth with a duration time δ and a constant spectral power density exploitation of the bandwidth highest speed possible δ = 1/B.

All operations are performed on the time axis: symbol rate (frequency spreading) and sinc pulse generation with one exception to adjust the amplitude of the sinc pulses to determine the respective symbol energy. So these principles are not restricted to but can be ideally combined with TDMA, where different time slot lengths can be used to manage the total system capacity.

Noise and disturbances are suppressed by the system gain and/or are spread by the dispersive delay line in the receiver.

Chirp signals by their constant spectral density are ideal for precise channel measurement combined with the ability to improve the S/N despite channel limited power. This precision allows accurate compensation of multi path effects.

Spectralefficiency

Flexibility

Disturbances

Multi path

July 2003


doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

Constant Power Versus Frequency

t [s]

t [s]

U [V ]

U [V ]

Tim e dom ain Frequency dom ain

<< 1/B

Solution No. 2: sync pulse shaping

t [s]

U [V ] S IN C P u lse

s in xx

= 1 /B B /2

July 2003


doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

Constant Power Versus Time

t [s ]

U [V ]

S IN C P u lse

s in xx

B

fo

Transformation of AM into FM via a dispersive delay line

t [s ]

t [s ]

U 1 [V ]

U 1 [V ]

C hirp P ulse

s in xx

LFMPulse

t [s ]

U 2 [V ]

C hirp P ulse LFMPulse

t [s ]

U 2 [V ]

s in xx

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Submission

The Different BT Productsin the Channel and the Baseband

B = 1 B T >> 1

f1 f2

t1 t2

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doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

Coexistence

• CSS’s power spectral density is lower than 15.4’s O-QPSK for the same transmit power

• 802.15.4’s duty cycle is very low• CSS’s packet duration is shorter than

that of 15.4’s O-QPSK• Based on the above, we believe that

coexistence is not an issue

July 2003


doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

Regulatory

• Operates in the 2.40 – 2.483 GHz band

• This modulation technique is:– Allowable under ETSI 300-328 in Europe– Designed to meet US regulatory

requirements, currently seeking opinion– Designed to meet ARIB regulatory

requirements, have not sought opinion yet

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doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

Backward-Compatibility

• CSS is very similar to DSSS• Straightforward hardware modifications to a CSS-only solution

allow backward-compatibility• Nanotron has identified a method to sense all 15 of the current

802.15.4 DSSS channels at the “same” time.• Without backward-compatibility, a proposal would be more of a

revision than an amendment.• Backward compatibility:

– eliminates interoperability issues– eliminates IC vendor deployment issues (no waiting)– allows the users to select the methods that best suit their model

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doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

CSS Benefits

• HIGH…– Performance (high symbol rate)– Reliability (customer demand for predictable

minimum range, network planning)– Robustness against multipath fading– Robustness against interference

• The robustness of a frequency hopper hopping over the full band can be of value to users in select cases. CSS gives this same quality without the negative attributes of frequency hopping.

– Correlation gain (4dB more)• Location-awareness (wideband, chirps)

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doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

CSS Benefits

• The current range of the 2.4 GHz 15.4 is much less than that of the 900 MHz for 0 dBi antennae (1/4 for the specified sensitivity).

• CSS Range Measurements– Indoor (European office building) measurement results for a data

rate of 1 Mbps (over air interface) and BER = 0.001 are as follows:• Output power (EIRP) = -30 dBm (1 µW), distance = 5 m, 1 wall• Output power (EIRP) = -15 dBm (32 µW), distance = 23 m, 4 walls

– Outdoor measurement results for a data rate of 1 Mbps (over air interface) and BER = 0.001 are as follows:

• Output power (EIRP) = +7 dBm (5 mW), distance = 739 m (+/-10 m)– Both transceivers use equivalent isotropic antenna (gain = 0 dBi)

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doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

CSS Benefits

• LOW…– Transmit power– Energy per bit– Latency

• No synch chips• Reduced retransmits

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doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

Proposal for 15.4 Amendment

• MAC– Location-awareness

• Add primitives to expose the new service to upper layers• Define non-CSMA response mechanism – e.g. extra

“acknowledges” for distance measurement protocol

– Modify primitives for enhanced channel scanning

• PHY– Add CSS modulation section

July 2003


doc.: IEEE 802.15-15-03-0312-00-0040r0

Submission

Action Items

• Participated in Interest Group 4a

• Request the support of TG4

• Consolidate this proposal with additional complementary proposals

• Participate in the 4a Study Group to generate a new PAR and 5C

Documents

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)