Presentation on theme: "IEEE-15-05-0002-00-004a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 1 Project: IEEE P802.15 Working Group for Wireless Personal."— Presentation transcript:
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 1 Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs) Submission Title: Chirp Spread Spectrum (CSS) PHY Presentation for a Date Submitted: January 04, 2005 Source: John Lampe Company: Nanotron Technologies Address: Alt-Moabit 61, Berlin, Germany Voice: , FAX: , Re: This is in response to the TG4a Call for Proposals, 04/0380r2 Abstract:The Nanotron Technologies Chirp Spread Spectrum 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 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 may be made publicly available by P
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 2 Chirp Spread Spectrum (CSS) PHY Presentation for a by John Lampe, Rainer Hach, & Lars Menzer Nanotron Technologies GmbH Berlin, Germany
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 3 General Properties of Chirp Signals Simplicity –Basically a 2 ary baseband transmission –The windowed chirp is a linear frequency sweep with a total duration of 1 us
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 4 Chirp Properties (cont.) Real part of a windowed up-chirp signal with a total duration of 1us
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 5 Chirp Properties (cont.) Figure shows the autocorrelation function (acf) and cross-correlation function (ccf) of the signal described above –Note that the ccf has a constant low value (compared to DS sequences).
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 6 Chirp Properties (cont.) This figure shows the PSD of the signal with a power of 10 dBm By padding the signal with zeros the frequency resolution has been set to 100 kHz so that the plot is similar to what a spectrum analyzer would measure. At 12 MHz offset from the center is below -30dBm (which is the ETSI requirement for out of band emissions)
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 7 Chirp Properties (cont.) Further processing of the signals Sig A and Sig B for symbol detection could be done in coherent (real part processing) or non coherent manner (envelope filtering). –Since the analytical results are well known for AWGN channels we will mention these –Simulations over other channels will all refer to the non coherent system as drawn below.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 8 Chirp Properties (cont.) This figure shows the analytical BER values for 2 ary orthogonal coherent and non coherent detection and the corresponding simulation results (1E5 symbols) for up down chirp (using the chirp signals defined above) The performance loss due to the non-orthogonality of up and down chirp is very small.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 9 Signal Robustness The proposed 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 receivers 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 b, g and even Bluetooth (v1.2 has adaptive hopping) via DFS CSS proposal utilizes CCA mechanisms of Energy Detection (ED) and Carrier Detection These CCA mechanisms are similar to those used in IEEE –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.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 10 Support for Interference Ingress Example (w/o FEC): –Bandwidth B of the chirp = 20 MHz –Duration time T of the chirp = 1 µs –Center frequency of the chirp (ISM band) = GHz –Processing gain, BT product of the chirp = 13 dB –Eb/N0 at detector input (BER=10-4) = 12 dB –In-band carrier to interferer ratio ( BER=10 -4 ) = = -1 dB –Implementation Loss = 2 dB
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 11 Support for Interference Egress Low interference egress IEEE b receiver –More than 30 dB of protection in an adjacent channel –Almost 60 dB in the alternate channel these numbers are similar for the g receiver
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 12 Regulatory Devices manufactured in compliance with the 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 CSS proposal would adhere to the following worldwide regulations: –United States Part or –Canada DOC RSS-210 –Europe ETS –Japan ARIB STD T-66
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 13 Scalability – Data Rate Mandatory rate = 1 Mb/s Optional rate = 267 Kb/s Other possible data rates include 2 Mb/s to allow better performance in a burst type, interference limited environment or a very low energy consumption application 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.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 14 Scalability – Frequency Bands The proposer is confident that the CSS proposal would also work well in other frequency bands –Including the 5975 to 7250 MHz band Mentioned in the new FCC operating rules SECOND REPORT AND ORDER AND SECOND MEMORANDUM OPINION AND ORDER released December 16, 2004
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 15 Scalability – Data Whitener Additionally, the group may consider the use of a data whitener, similar to those used by Bluetooth and IEEE to produce a more noise-like spectrum and allow better performance in synchronization and ranging.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 16 Scalability – Power Levels For extremely long ranges the transmit power may be allowed to rise to each countrys 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 requires significantly higher current it doesnt 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 In this manner the averaged transmitter current drain will be less than the averaged receiver current drain.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 17 Scalability – Backward Compatibility Due to some of the similarities with DSSS it is possible to implement this proposal in a manner that will allow backward compatibility with the GHz standard The transmitter changes are relatively straightforward Changes to the receiver would include either dual correlators or a superset of CSS and DSSS correlators It is anticipated that this backward compatibility could be achieved via mode switching versus a dynamic change on-the- fly technique –left up to the implementer This backward compatibility would be a significant advantage to the marketplace by allowing these devices to communicate with existing infrastructure and eliminating customer confusion
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 18 Mobility Values Communication –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 due to high relative speed vrel between two devices Such situations also occur when one device is mounted on a rotating machine The limits will be determined by other, general processing modules (AGC, symbol synchronization,...) 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 We assume that the longest time in this procedure is the turnaround time tturn between the two nodes which will be determined by the respective uC performance. During this time the change of distance should stay below the accuracy da required by the application. For d a =1m t turn =10 ms this yields v rel << 100m/s
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 19 MAC Enhancements and Modifications There are no 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 that are expected to be developed by the Ranging subcommittee.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 20 Channel Models Since this proposal refers to the 2.4GHz ISM band, only channel models with complete parameter set covering this frequency range can be considered –At the time being these are LOS Residential (CM1) and NLOS Residential (CM2). The 100 realizations for each channel model were bandpass filtered with +-15MHz around 2.437GHz which corresponds to the second of the three sub-bands proposed. The filtered impulse responses were down converted to complex baseband. The magnitudes over time are shown in the following plots Furthermore some graphs of the function H_tilde as described and required in the SCD are shown For now we assume that the neighbor sub-bands will not differ significantly from the center sub-band and that we restrict simulations on the center sub-band 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 more than 100 packets or bits. Since the delay spread and thus the time in which subsequent symbols can influence each other of all given channel impulse responses are well below the symbol duration of 1us suggested by this proposal we believe that we get the best results when we simulate a large number of independent transmissions of symbols. Assuming an equal probability of error for all bits of a packet we can give the relationship between the BER and PER by With N being the number of payload bits. Thus we can calculate the BER which is required for any PER: For PER=1% and N=256 we get BER=3.9258E-5
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 21 Channel Model 1
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 22 Channel Model 2
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 23 Size and Form Factor The implementation of the CSS proposal will be much less than SD Memory at the onset –following the form factors of Bluetooth and IEEE /ZigBee The implementation of this device into a single chip is relatively straightforward –As evidenced in the Unit Manufacturing Complexity slides
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 24 PHY SAP Payload Bit Rate & Data Throughput The PPDU is composed of several components as shown in the figure below The following figure shows in greater detail, the component parts of each PPDU. Octets: 411Variable (up to 256) PreambleSFDFrame length (8 bits)PHY payload SHRPHRPSDU
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 25 PHY SAP Payload Bit Rate & Data Throughput (cont) The SFD structure has different values for, and determines, the effective data rate for PHR and PSDU The Preamble is 32 bits in duration (a bit time is 1 us) In this proposal, the PHR field is used to describe the length of the PSDU that may be up to 256 octets in length In addition to the structure of each frame, the following shows the structure and values for frames including overhead not in the information carrying frame
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 26 PHY SAP Payload Bit Rate & Data Throughput (cont) The figures show the structure, as defined in the IEEE Standard and the SCD –cases of acknowledged transmissions as used in section values and for unacknowledged transmissions. For this proposal, the value of Tack and SIFS are retained from the IEEE Standard and are each 192 microseconds The value of LIFS is also shown as 192 microseconds. –Additional revisions of this proposal may show a different value as the authors discuss the need for longer LIFS values with members of TG4b –The values of SIFS and LIFS have a MAC dependency above the value of 192uS required for PHY turn around –SIFS has a value of 192us (12 symbols) in the current standard and LIFS has a value of 40 symbols.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 27 Simultaneous Operating Piconets Separating Piconets by frequency division –This CSS proposal includes a mechanism for FDMA by including the three frequency bands used by b, g and also It is believed that the use of these bands will provide sufficient orthogonality –The chirp signal defined earlier has a rolloff factor of 0.25 which in conjunction with the space between the adjacent frequency bands allows filtering out of band emissions easily and inexpensively.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 28 Signal Acquisition The signal acquisition is basically determined by the structure and duration of the preamble –In contrast to always on systems like DECT or GSM –Low duty rate systems must be able to acquire a signal without any prior knowledge about that signals level or timing –While the IEEE uses a preamble duration of 32 symbols (128 µs at 2.4 GHz) other commercially available transceiver chips (e.g. nanoNET TRX from Nanotron) use 30 symbols at 1MS/s (i.e. 30µs). For consistency with IEEE this CSS proposal is based upon a preamble of 32 symbols which at 1MS/s turns out as 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 be setup in such a time duration The probability of missing a packet is then simply determined by the probability that the SFD is received correctly As shown before, the BER required for a PER of 1%, is BER=3.9258E-5
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 29 Clear Channel Assessment A combination of symbol detection (SD) and energy detection (ED) has proven to be useful in practice. The duration of the preamble can be used as upper bound for the duration for both detection mechanism. By providing access to the threshold for ED the system allows the application to adjust its behavior (false alarm vs. miss probability) according to its needs.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 30 System Performance 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 displayed below. The parameter n=4.48 indicates a very high attenuation for higher ranges. The results were interpreted as BER and PER respectively and for convenience were plotted twice (linear and log y scale).
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 31 System Performance
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 32 System Performance
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 33 System Performance
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 34 TOA Estimation for Ranging Noise and Jitter of Band-Limited Pulse Given a band-limited pulse with noise σ u we want to estimate how the jitter (timing error) σ t with which the passing of the rising edge of the pulse through a given threshold can be detected is effected by the bandwidth B. Since the power σ 2 of band-filtered AWGN is proportional to the bandwidth we know that: We approximate the impact of σ u by the simple formula: The assume the rising speed of a the signal being proportional to the signal bandwidth: Which leads to:
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 35 Symmetrical Double-Sided Two-Way Ranging (SDS TWR) T round... round trip time T reply... reply time T prpp... propagation of pulse Double-Sided: Each node executes a round trip measurement. Symmetrical: Reply Times of both nodes are identical ( T replyA = T replyB ). Results of both round trip measurements are used to calculate the distance. T roundA T prop T replyA t T prop t T roundB T replyB Node A Node B T prop
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 36 Ranging - Effect of Time Base Offset Errors Assuming offset errors e A, e B of the timebases of node A and B we get: On the condition that the two nodes have almost equal behavior, we can assume: This has the effect that timebase offsets are canceled out: final measurement error Calculations show that for 40ppm crystals and 20 us max difference between T roundA and T roundB and between T replyA and T replyB an accuracy below 1 ns can easily be reached!
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 37 Example System EtA = ±40 ppm, EtB = ± 40 ppm (worst case combination selected): Influence of Symmetry Error: Calculation of an SDS TWR Example System d d (ΔTreply = 20 ns) d (ΔTreply = 200 ns) d (ΔTreply = 2 µs) d (ΔTreply = 20 µs) d (ΔTreply = 200 µs) 10 cm± cm± 0.12 cm± 1.2 cm± 12 cm± 120 cm 1 m± cm± 0.12 cm± 1.2 cm± 12 cm± 120 cm 10 m± 0.05 cm± 0.12 cm± 1.2 cm± 12 cm± 120 cm 100 m± 0.4 cm ± 1.2 cm± 12 cm± 120 cm 1 km± 4 cm ± 12 cm± 120 cm 10 km± 40 cm ± 120 cm Conclusion: Even 20 µs Symmetry Error allows excellent accuracy of distance ! Symmetry Error below 2 µs can be guaranteed in real implementations !
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 38 Dithering: Principle of Dithering and Averaging Averaging:
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 39 Simulation of a SDS TWR System Example system: Simulates SDS TWR + Dithering & Averaging Crystal Errors ±40 ppm Single shot 1 MBit/s data rate (DATA-ACK) Transmit Jitter = ± 4 ns (systematic/pseudo RN-Sequence) Pulse detection resolution = 4 ns Pulses averaged per packet = 32 Symmetry error = 4 µs (average) Distance = 100 m Results of Distance Error d: |d WC | < 50 cm |d RMS | < 20 cm (ideal channel without noise)
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 40 Link Budget footnotes  Rx noise figure: in addition the proposer can select other values for special purpose (e.g. 15 dB for lower cost lower performance system)  The minimum Rx sensitivity level is defined as the minimum required average Rx power for a received symbol in AWGN, and should include effects of code rate and modulation.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 41 Sensitivity The sensitivity to which this CSS proposal refers is based upon non-coherent detection –It is understood that coherent detection will allow dB better sensitivity but at the cost of higher complexity (higher cost?) and poorer performance in some multipath limited environments The sensitivity for the 1 Mb/s mandatory data rate is -92 dBm for a 1% PER in an AWGN environment with a front end NF of 7 dB The sensitivity for the optional 267 kb/s data rate is -97 dBm for a 1% PER in an AWGN environment with a front end NF of 7 dB
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 42 Power Management Modes Power management aspects of this proposal are consistent with the modes identified in the IEEE : 2003 standard There are no modes lacking nor added Once again, attention is called to the 1 Mbit/s basic rate of this proposal and resulting shorter on times for operation
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 43 Power Consumption The typical DSSS receivers, used by , are very similar to the envisioned CSS receiver The two major differences are the modulator and demodulator –The modulator of the CSS is much simpler than the DSSS however since the major power consumption is the transmitter and the difference is negligible –The power consumption for a 10 dBm transmitter should be 198 mW or less The receiver for the CSS is remarkably similar to that of the DSSS with the major difference being the correlator –The correlator for the CSS uses a frequency dispersive mechanism while the DSSS uses a chip additive 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 The power consumed during the CCA is basically similar to the receiver power consumption –All of the receiver circuits are being used during the CCA (correlator is used for the carrier detect function)
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 44 Power Consumption (cont.) Power save mode is used most of the time for this device and has the lowest power consumption –Typical power consumptions for 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 40 nJ As an example, the energy consumed during an exchange of a 32 octet PDU between two devices (including the transmission of the PDU, the t ack, and the ack) would be 70.6 µJ for the sender device while the receiving device consumed 33.2 µJ –As a reference point it should be noted that according to the Duracell web site, a Duracell AA alkaline cell contains more than 12,000 Joules of energy.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 45 Antenna Practicality The antenna for this CSS proposal is a standard 2.4 GHz antenna such as widely used for b,g devices and Bluetooth devices. These antennas are very well characterized, widely available, and extremely low cost. Additionally there are a multitude of antennas appropriate for widely different applications. The size for these antennae is consistent with the SCD requirement.
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 46 Time To Market No regulatory hurdles No research barriers – no unknown blocks, CSS chips are available in the market Normal design and product cycles will apply Can be manufactured in CMOS
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 47 Unit Manufacturing Complexity Target process: RF-CMOS, 0.18 µm feature size Pos.Block descriptionEstimated AreaUnit 1Receiver with high-end LNA2.00mm² 2Transmitter, Pout = + 10 dBm1.85mm² 3Digitally Controlled Oscillator + miscellaneous blocks0.62mm² 4Digital and MAC support0.60mm² 5Digital Dispersive Delay Line (DDDL) for selected maximum chirp duration 0.32mm² 6Chirp generator for selected maximum chirp duration0.08mm² 7Occupied chip area for all major blocks required to build complete transceiver chip utilizing CSS technology 5.47mm²
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 48 Unit Manufacturing Complexity Target process: RF-CMOS, 0.13 µm feature size Pos.Block descriptionEstimated AreaUnit 1Receiver with high-end LNA1.90mm² 2Transmitter, Pout = + 10 dBm1.71mm² 3Digitally Controlled Oscillator + miscellaneous blocks0.59mm² 4Digital and MAC support0.38mm² 5Digital Dispersive Delay Line (DDDL) for selected maximum chirp duration0.21mm² 6Chirp generator for selected maximum chirp duration0.06mm² 7Occupied chip area for all major blocks required to build complete transceiver chip utilizing CSS technology 4.85mm²
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 49 Summary Chirp Spread Spectrum (CSS) is simple, elegant, efficient Combines DSSS and UWB strengths Adds precise location-awareness Robustness – multipath, interferers, correlation, FEC, 3 channels, CCA Can be implemented with todays technologies –Low-complexity –Low-cost –Low power consumption Globally certifiable Scalability with many options for the future Backward compatible with Mobility enhanced No MAC changes (minimal for ranging) Size and Form Factor – meets or exceeds requirements Excellent throughput SOPs – FD channels Signal Acquisition – excellent Link Budget and Sensitivity – excellent Power Management and Consumption - meets or exceeds requirements Antenna – many good choices
IEEE a Submission January 2005 J. Lampe, R. Hach, L. Menzer, NanotronSlide 50 Summary Chirp Spread Spectrum (CSS) Proposal Meets the PAR and 5C: Precision ranging capability accurate to one meter or better Extended range over Enhanced robustness over Enhanced mobility over International standard Ultra low complexity (comparable to the goals for ) Ultra low cost (comparable to the goals for ) Ultra low power consumption (comparable to the goals for ) Support coexisting networks of sensors, controllers, logistic and peripheral devices in multiple compliant co-located systems.