1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Januay 2005
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [DSSS UWB Radio System]
Date Submitted: [January 2005]
Source: [Saeid Safavi and Ismail Lakkis ]
Company [Wideband Access, Inc.]
Address [10225 Barnes Canyon Road, Suite A209, San Diego, CA]
Voice:[ ], FAX: [ ],
Re: [Response to Call for Proposals]
Abstract: [This document describes Wideband Access Inc.’s approach for the TG4a alternate PHY]
Purpose: [Preliminary Proposal for the IEEE a Standard]
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
Safavi & Lakkis, Wideband Access, Inc.
<author>, <company>

2. DSSS UWB Radio System Saeid Safavi & Ismail Lakkis
Januay 2005
Wideband Access, Inc. Preliminary Proposal for IEEE a Alternate PHY
DSSS UWB Radio System
Saeid Safavi
&
Ismail Lakkis
Safavi & Lakkis, Wideband Access, Inc.

3. Januay 2005
Proposal Summary
A robust direct sequence spread spectrum radio with large processing gains is proposed.
Despite its robustness the radio has a very simple and implementable architecture which is anticipated to support the size, cost and power consumption requirements of the altPHY.
Using DSSS, channel coding and a low receiver sensitivity, the system provides extended coverage beyond 30 m.
The radio design supports all of the technical requirements of TG4a.
Safavi & Lakkis, Wideband Access, Inc.

4. Advantages Simple Architecture: Low Power Consumption: Low Cost:
Januay 2005
Advantages
Simple Architecture:
Facilitates manufacturability and time to market
Low Power Consumption:
Low rate ADC
CMOS technology
Low Cost:
Single chip implementation
Small Size:
Compact architecture
Minimal usage of external components
Extended Range:
Large processing gain
Improved receiver sensitivity
FEC
Resistant to Interference, Multipath and Frequency Offsets
Proven Location Awareness Methodology
Safavi & Lakkis, Wideband Access, Inc.

5. System Block Diagram (Transmitter) * (Receiver) Januay 2005 Integrator
Information
Bits
4 Mcps
Radio Channel
BPSK Mod
&
Channel
Coding
Short Code
Spreading
BPF A
125 kbps – 2 Mbps
Modulated
Long Code
Generator
4 GHz
(50 ppm)
Integrator
(Short Code
Despreader)
Channel
Decoding
&
Data
Detection
Recovered
Bits
Integrator
(Long Code
Despreader)
BPF
ADC
LNA * Tb
Differential
Detector
(Receiver)
Modulated
Long Code
Generator
4 GHz
(50 ppm)
Safavi & Lakkis, Wideband Access, Inc.

6. Band Plan Januay 2005 1 2 3 4 5 6 7 8 9 10 Future Development
3 dB BW = 1GHz
Safavi & Lakkis, Wideband Access, Inc.

7. Distinctive Radio Features
Januay 2005
Distinctive Radio Features
Data Rates: Raw (125 kbps to 2 Mbps), Coded (250 kbps to 4 Mbps)
BW: 1.0 GHz (3.5 – 4.5 GHz)
Chip Rate: 1 Gcps
Local Oscillator Offset: 50 ppm
High Processing Gain: 4 Mb/s to kb/s
Link Margin: 6 dB gain over OOK
Extended Range: due to large processing gain, low sensitivity and FEC the range is larger than 30 m
Robust: robustness against noise and phase reversal errors, and high interference resistance due to large processing gain
Low Levels of Interference to other systems: due to the usage of DSSS with large processing gains
Single low-power CMOS chip
ADC operation at low rate (rather than chip rate) and Small Size ADC (1- 2 bit)
Simple and Cheap Implementation (no expensive components such as SAW filters, etc.)
Wide Dynamic Range
High Frequency Efficiency: due to efficient use of frequency within the band
Precise Ranging Procedure: based on TDOA
Simple, all digital Signal Acquisition and Synchronization
Support of large LO offsets: due to the differential detection Scheme
Support of Intra-cell mobility
Low Interchip Interference: an excellent code cross-correlation through usage of a subset of Kasami codes
Safavi & Lakkis, Wideband Access, Inc.

8. Properties of Kasami Sequences
Januay 2005
Properties of Kasami Sequences
The small set of Kasami sequences is an optimal set of binary sequences with respect to the Welch Bound.
Long Code Spreading:
Sequence length: 255
Number of possible sequences 16
Max. Autocorrelation SLL: 17
Max. Cross-correlation level: 17
For lower data rates, a 2nd level of spreading (short code spreading) is introduced using the same set of Kasami sequences (further increasing the processing gain).
If more codes are needed, the large set of Kasami codes can be used
Safavi & Lakkis, Wideband Access, Inc.

9. Scalability RRaw RCoded 5.8 dB 23.49 m 33.22 m 46.98 m 66.43 m 93.95 m
Januay 2005
Scalability
RRaw
2 Mbps
1 Mbps
500 kbps
250 kbps
125 kbps
RCoded
4 Mbps
Spreading Factors
256
256 & 2
256 & 4
256 & 8
256 & 16
Total Processing Gain
24 dB
27 dB
30 dB
33 dB
36 dB
Total Gain
(FER + Spreading)
39 dB
Required Eb/No
for PER of 1%
5.8 dB
Max. Range
23.49 m
33.22 m
46.98 m
66.43 m
93.95 m
Safavi & Lakkis, Wideband Access, Inc.

10. Link Budget Parameter Januay 2005 Data Rates
Peak payload bit rate (Rb)
250 kbps
4 Mbps
Average Tx power (Pt)
dBm
Tx antenna gain (Gt)
0 dBi
Geometric center frequency of waveform (fc)
3.944 GHz
Path loss at 1 meter (L1)
44.36 dB
Path loss at d m (Ld)
29.54 dB at
d = 30 m
20.00 dB at
d = 10 m
Rx antenna gain (Gr)
Rx power (Pr)
dBm
dBm
Average noise power per bit: ( )
dBm
dBm
Rx Noise Figure ( )
7 dB
Average noise power per bit ( )
dBm
dBm
Minimum Eb/N0 (S)
8 dB
Implementation Loss ( I )
3 dB
Link Margin
17.92 dB
15.42 dB
Proposed Min. Rx Sensitivity Level
dBm
dBm
Safavi & Lakkis, Wideband Access, Inc.

11. Simultaneously Operating Piconets
Januay 2005
Simultaneously Operating Piconets
More channel can be identified with quasi-orthogonal spreading codes.
There are two levels of spreading which provide an extra degree of flexibility when defining system parameters for co-located piconets.
Kasami codes provide excellent cross-correlation properties which allows coexistence with other devices.
Safavi & Lakkis, Wideband Access, Inc.

12. Coexistence and Interference Susceptibility
Januay 2005
Coexistence and Interference Susceptibility
Due to the usage of a simple DSSS scheme with no frequency or time hopping, the interference to the neighboring systems is minimal (resulting in low levels of both instantaneous as well as average interference), satisfying the TG4a’s coexistence requirements
DSSS with large processing gain would also ensures robustness against interfering devices, hence a high interference susceptibility.
Safavi & Lakkis, Wideband Access, Inc.

13. Januay 2005
Location Strategy
The location strategy is based on Time Difference of Arrival (TDOA) using one-way ranging (OWR). This method involves measuring the time of arrival of a known signal from the mobile device at three or more reference (fixed) nodes. The location estimate is derived from the value of the Geometric Time Difference (GTD) between the time of arrivals at each node and a known time reference.
The server or controller node periodically broadcasts synchronization packets to the reference nodes. Each reference node captures the message packet it has received to a specific time resolution. The signals received at each fixed node is transmitted back to the controller node to give the time difference of arrival. Each of the time differences represent a location hyperbola that the mobile node can reside on (based on its TDOA). The intersection of two such hyperbolas are used to locate the position of the mobile in a 2D space.
Therefore, the position is calculated at the controller node location (based on hyperbolic trilateration).
Safavi & Lakkis, Wideband Access, Inc.

14. Location Strategy (TDOA) A dC – dB = dCB dA , tA C dC , tC dB , tB
Januay 2005
Location Strategy
Fixed Node
dC – dA = dCA A
dC – dB = dCB
dA , tA C
dC , tC
Fixed Node
Station of Interest
(to be located) M
dB , tB
(TDOA) B
Fixed Node
Safavi & Lakkis, Wideband Access, Inc.

15. Januay 2005
Conclusions
The DSSS system proposed herein is a simple and implementable radio that through its counter measures against fading, noise and interference can provide the robustness and extended range (well above 30 m) required by TG4a.
The location awareness methodology based on TDOA provides a precision ranging capability.
This system can be integrated in a compact CMOS chip with minimal external components and hence is a small-size, low-cost device. This combined with the radio robustness and location accuracy can support various a applications.
The simplicity and the proven modulation techniques used ensures feasibility and scalability of the radio.
FFD’s and RFD’s for different applications can be supported due to the scalability provided by a large set of spreading codes.
Safavi & Lakkis, Wideband Access, Inc.