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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Revised Frequency Plan and PRF Proposal for TG4a] Date Submitted: [27 April 2005] Source: [Ismail Lakkis & Saeid Safavi, Wideband Access Inc.] Contact: Saeid Safavi.

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slide1

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

Submission Title: [Revised Frequency Plan and PRF Proposal for TG4a]

Date Submitted: [27 April 2005]

Source: [Ismail Lakkis & Saeid Safavi, Wideband Access Inc.]

Contact: Saeid Safavi.

Voice:[+1 858 642 9114, E-Mail: [email protected]]

Abstract: [Ban Plan, PRF, Preamble & Modulation]

Purpose: [Clarification of relationship between minimum PRF and maximum allowed voltage level in UWB IR]

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.

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

agenda
Agenda
  • Proposed system features
  • Frequency Plan / PRF
  • Preamble
  • Modulation

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

frequency plan prf
Frequency Plan / PRF

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

proposed system features
Proposed System Features
  • Meets requirements for TG4a baseline draft
  • Frequency plan with simple PLL structure and safe margins to 3.1GHz and 4.9 GHz
  • Support of a range of PRFs (low and high)
  • Impulse-radio system
  • Common preamble structure for different classes of nodes/receivers type ( coh./noncoh.) & ranging
  • Flexible adaptive data rate
  • Robustness against SOP interference through frequency and code division
  • Robustness against other in-band interference
  • Scalability to trade-off complexity/performance

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

frequency plan requirements
Frequency Plan Requirements
  • Requirements
    • Sub-banding (Three bands) with mandatory center band of ~500MHz and an optional wider co-centric band of ~1.5GHz
    • Mandatory: FCC spectral mask @ 3.1GHz  at least 10 dB attenuation constraint on filtering
    • Desirable: co-existence with WLAN @ 4.9GHz
  • Implications
    • A safe margin to 3.1GHz to meet FCC requirement
    • For IR system using a pulser (no mixer), the BPF is responsible for the 3.1GHz corner filtering
    • A safe margin to 4.9GHz to coexist with WLAN
    • Different frequencies should be easily generated from the system PLL with first divisions in powers of 2

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

prf requirements
PRF Requirements
  • Requirements
    • Support of multiple (at least 2) PRF in band
    • Limit on lowest possible PRF due to CMOS 90 nm technology
    • Limit on highest possible PRF due to inter-frame interference for a non-coherent receiver
  • Implications
    • Supported PRFs should be easily derived from the PLL through simple divisions
    • Low PRF as base PRF
    • High PRF as second PRF
    • PRF should be high enough to take advantage of FCC rules

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

relationship between prf peak power

PRI

VPeak

TC

Relationship between PRF & Peak Power

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

minimum prf vs peak power cmos 90nm
Minimum PRF vs Peak Power (CMOS 90nm)

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

low prf vs high prf
Low PRF vs High PRF
  • A low PRF system has a lower implementation cost when compared to high PRF system
  • RF radio overall gain is lower for a low PRF system. A 12 MHz PRF system , for example, would reduce the receiver dynamic range by 7 dB when compared to a 60 MHz PRF system
  • The ADC would run at 12 MHz instead of 60 MHz in the above example and the entire digital processor would run at a lower clock reducing the power by a factor of 5 in CMOS
  • Easier acquisition with lower PRF due to a smaller sync matched filter size
  • Since energy per pulse is higher (7 dB in the above example), a non-coherent receiver would perform better
  • Better acquisition and tracking performance since a 60 MHz PRF system needs to integrate perfectly 5 pulses to perform equivalently to a 12 MHz PRF system

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

proposed frequency plan
Proposed Frequency Plan

Band No. 4

111

MHz

207

MHz

1

2

3

3

4

5

GHz

3.25

3.5

3.75

4.25

4.5

4.75

Note: This plan has almost double margin to 4.9 GHz as compared to 3.1 GHz

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

frequency plan details
Frequency Plan Details

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

proposed prfs
Proposed PRFs
  • A wide range of PRFs (total of 3) are supported which are compliant with the harmonic chip rate requirements
  • The base recommended PRF is 15.4375 MHz: it has an 8 dB peak power margin for a 500MHz BW
  • PRFs of 30.875MHz and 61.75MHz are also supported (margin > 4.5 dB)
  • The proposed PRFs can be easily generated from the center frequencies of the supported bands (next slide)

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

prf generation
PRF Generation
  • All High frequency divisions are in powers of 2, while the low frequency divisions are only by 3 and 7

Center Freq.

(MHz)

PRF1

(MHz)

PRF2

(MHz)

PRF3

(MHz)

Harmonic Ratio

3952

61.75

30.875

15.4375

64

2

2

3458

61.75

30.875

15.4375

8x7

2

2

4446

61.75

30.875

15.4375

8x3x3

2

2

Prime Factors: 7, 3

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

pll reference diagram
PLL Reference Diagram

FX

FComp

Oscillator

Reference

Divider

(R)

XTAL

Phase Det.

F123,c

LPF

VCO

Divider, M

÷8

÷ 7,8 or 9

PRF

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

band plan prf summary
Band Plan / PRF Summary
  • Enough margin to 3.1GHz (111 MHz) and 4.9GHz (207 MHz) to meet FCC requirements and to coexist with WLAN ( avoids expensive sharp roll-off filtering)
  • Support of a wide range of XTALs (9.6,19.2,13,26,12,24)
  • Center frequencies and PRFs can be generated from a single PLL with first divisions in power of 2 and low frequency division by 3 or 7
  • Support of a wide range of PRFs. The proposed PRFs have a peak power margin of 4.5-8 dB to accommodate implementation losses and take advantage of FCC rules

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

acquisition preamble structure
Acquisition Preamble Structure

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

ber of bpsk on off keying
BER of BPSK & ON-OFF Keying

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

ber requirements
BER Requirements
  • The requirement of PER < 1% for a 32 octets packet translates into a BER < 3.926e-5
  • EbN0 requirements for uncoded BPSK and ON-OFF keying systems:
    • g (BPSK) = 8.9dB
    • g (ON-OFF) = 15.45dB
  • EbN0 requirements for coded BPSK and ON-OFF keying systems (assuming a coding gain of 4dB and receiver implementation losses of 1.5 dB):
    • g (BPSK) = 6.4 dB
    • g (ON-OFF) = 13 dB

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

snr loss in square law detectors
SNR Loss in Square Law Detectors

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

bpsk detection false alarm probabilities
BPSK: Detection & False Alarm Probabilities
  • PRF = 16 MHz
  • AWGN Channel
  • 2 dB margin to account for timing/frequency errors & other factors
  • PD = 95% & PF = 5%

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

bpsk detection false alarm probabilities1
BPSK: Detection & False Alarm Probabilities
  • PRF = 16 MHz
  • Multipath Channel assuming we capture 25% of the energy
  • 2 dB margin to account for timing/frequency errors & other factors
  • PD = 95% & PF = 5%

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

bpsk detection false alarm probabilities2
BPSK: Detection & False Alarm Probabilities

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

bpsk detection false alarm probabilities3
BPSK: Detection & False Alarm Probabilities

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

on off detection false alarm probabilities
ON-OFF Detection & False Alarm Probabilities
  • PRF = 16 MHz
  • AWGN Channel
  • 2 dB margin to account for timing/frequency errors & other factors
  • PD = 95% & PF = 5%

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

spreading codes objectives
Spreading Codes: Objectives
  • Design a set of sequences with good autocorrelation (ACF) and cross correlation (CCF) properties that support
    • Coherent receivers
    • Differentially coherent receivers
    • Noncoherent receivers
  • The sequence set should be as large as possible to support multiple piconets per frequency band and to mitigate co-channel interference (in-band interference)

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

spreading codes desirable characteristics
Spreading Codes Desirable Characteristics
  • The autocorrelation function of a sequence can be characterized by the following parameters:
    • PAR of the PSD (back-off factor): a b PAR is desirable otherwise reduction in Tx power is required
    • Zero correlation zone (ZCZ) : for improved ranging, synchronization, channel estimation, and Pd vs Pf
    • Merit Factor (MF) of a binary sequence of length N: The MF measures the interference due to the sidelobe energies in the zone under interest (say 1μs)
    • Sequence length: this determines the coherent processing gain during acquisition ( a short spreading sequence  system is acquisition limited rather than PER limited)

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

barker code 11 m sequence 31
Barker code 11 & m-sequence 31

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

freescale zcz sequences
Freescale & ZCZ sequences

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

single spreading code system
Single Spreading Code System ?
  • A single spreading code common to the preamble and frame body is not recommended as all good sequences have bad PSD which results in a large Tx power reduction (Back-off)

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

hierarchical preamble code structure
Hierarchical Preamble code structure
  • Let Z be the ZCZ sequence of length 3
  • Create hierarchical code using zero-correlation Walsh sequences 1,2,3 and 5
  • For ternary –Z corresponds to an inverted sequence
  • There are at least 32 ZCZ, this gives 128 SOPs

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

modulation
modulation

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

modulation1
Modulation
  • Spreading via random scrambling
  • Use a single scrambler of length (ex: 32768) and assign a different offset (of 16 or 32) to different nodes
  • For ternary modulation invert sequence when transmitting a 0
  • Number of users supported is 1024
  • Perfect co-channel interference rejection
  • Support virtually any data rate from 16MHz to 32 Kbps for a PRF of 16MHz
  • Spectrum is virtually flat (no back-off)

Ismail Lakkis & Saeid Safavi

Wideband Access, Inc.

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