Wireless Technologies and WSA Overview Kevin Gifford, John Saiz - - PowerPoint PPT Presentation

Wireless Technologies and WSA Overview

Kevin Gifford, John Saiz April 13, 2005

Presentation Outline

! Wireless Technologies

Overview

! WSA Overview

Wireless Technologies Overview

! Advantages of wireless networks ! Applicable wireless standards ! Wireless device classes/capabilities ! RF multipath and RF coexistence ! RF vs. Optical wireless systems

Wireless System Architecture (WSA)

! Goal ! High-level support for end-users ! Overview/Review/Progress in Phase I ! Future Work (Phase II) ! Summary

Topological considerations

Primary Habitat

NAG HAB

Wired network

APP APP

1 2 3 4 5

Habitat 1

HAB

1 2 3 4 5

Habitat 2

HAB

1 2 3 4 5

Wired network

Advantages of wireless networks

! Flexibility:

! Communicate without restriction (outside of s/c as well) ! RF radio waves can penetrate walls ! Untethered mobility for users and devices ! Eliminate the need to run cabling

! Mass and volume reduction ! Harness complexity reduction/elimination

! Retro-fit existing infrastructure

! Ad-hoc networking ! Small form factor ! Robustness

Disadvantages of wireless networks

! Quality/reliability of service ! Cost ! Proprietary solutions, heterogenous

devices (WSA to the rescue…)

! Transmission restrictions ! Security (more later)

Applicable wireless standards

! IEEE 802.11 (WiFi) ! IEEE 802.15.1 (Bluetooth) ! IEEE 802.15.4 LR-WPAN with Zigbee ! IEEE 802.15.3 HR-WPAN ! IEEE 1073 Medical devices ! IEEE 1451 Transducer (sensors) ! IrDA (Optical)

Important characteristics of IEEE wireless standards

250 kbps 19.8 Mbps 12.4 Mbps 5.8 Mbps 0.72 Mbps Max through-put at 100 ft Very low High High High Medium Power required Low High High High High System complexity Ad hoc, star, mesh Point-to- multipoint Point-to- multipoint Point-to- multipoint Ad hoc piconets Network Topologies 0.1 – 10 mW 100 mW 100 mW 100 mW I mW Typical TX power DSSS OFDM OFDM DSSS FHSS Modulation technique 2.4 - 2.497 GHz 2.4 - 2.497 GHz 5.425 - 5.875 GHz 2.4 - 2.497 GHz 2.4 - 2.497 GHz Radio frequencies Up to 250 kbps Up to 54 Mbps Up to 54 Mbps Up to 11 Mbps 0.72 Mbps Maximum data rate Zigbee (802.15.4) 802.11g 802.11a WiFi 802.11b Bluetooth (802.15.1) Wireless Standard

Multipath fading considerations

Direct Diffracted Reflected Scattered Wall Wall

Reflected waves are the source of multipath fading RF transmission wave path classes

Multipath: random phase and amplitude fluctuations

! If signal fading depends

upon position of receiver in room fading is a function of space

! When motion is involved

fading is a function of time

! If signal amplitude and

phase changes is a function of frequency

Peak Null

RF standing wave pattern from a reflecting wall

Multipath mitigation techniques

! Spatial diversity (multiple antennas) ! Temporal diversity ! Spectral diversity ! Alternative modulation techniques ! Feedback equalization ! Automatic Repeat Requests (ARQ) ! Forward Error Correction

RF interference/fading

! Fading is an “inward” type of

interference

! Outward interference occurs when

WLAN signals interfere with adjacent electronics

! In practice however, the use of spread

spectrum signaling (DSSS and FHSS) eliminates this concern

RF Coexistence

! WiFi, Bluetooth, and 801.15.4 / Zigbee all

transmit in the 2.4 GHz ISM band

! These transmissions all have the potential for

collision with the result a dramatically reduced throughput

! Several mechanisms are available to minimize

interference and maximize interoperability

RF Coexistence: signaling

! 802.11b, 802.15.4 are DSSS which

• perate over a wide amount of

bandwidth

! Narrowband interference affects only part

• f the signal

! Wideband interference has disastrous

effects on any type of radio transmission

! 802.15.1 is a FHSS transmission

RF co-existence

RF coesistence

RF Coexistence – mitigation mechanisms

! Engineer proper access point spacing ! TDMA ! CSMA ! DTPA: Dynamic TxPower Adjustment ! Implement collaborative mechanisms ! Engineer clear channel techniques ! Engineer frequency domain: s/w radios

IEEE 1451 Sensors

! Address heterogeneous naming and

service identification issues

! 1451 uses a TEDS to specify naming

and services

! No legacy installation bases ! Wireless devices have req’d CPU/EEPROM ! Desire for plug and play

RF vs Optical

106 105 107 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021

Radio Waves Infrared Microwaves

Visible light

Ultraviolet X-Rays Gamma Rays

Frequency, Hz

IR (850 – 900 nm) uses diffuse light reflected at walls, furniture, etc., or a directed line of sight exists between the sender and the receiver

Advantages of Optical

!

Simple and very cheap senders and receivers which are integrated into most mobile devices today. PDAs, laptops, notebooks, mobile phones, etc., have an infrared data association (IrDA) interface

!

Version 1.0 of the IrDA standard implements data rates of up to 115 kbit/sec, while IrDA 1.1 defines higher data rates of 1.152 and 4 (maybe 16) Mbit/sec

!

No licenses are needed for infrared transmission

!

Shielding is very simple with IR devices – due to their limited range shielding is much less of an issue than with RF devices

!

Electrical devices do not interfere with infrared transmission.

Disadvantages of Optical

! Low bandwidth compared to other LAN

technologies

! Infrared is quite easily shielded. Infrared

transmission cannot penetrate walls or other

• bstacles, and for good transmission quality

and high data rates typically a direct line-of- sight is required

! Much less flexibility for mobility as compared

to RF

Advantages of RF

! Long term experiences made with radio transmission

for wide area networks (e.g., microwave links) and mobile cellular telephones

! Radio transmission can cover larger areas and can

penetrate (thinner) walls, furniture, plants, etc

! RF does not require direct line of sight for reliable

communication transmission

! Current RF-based products offer higher transmission

rates (e.g., 10 Mbit/sec) than infrared.

Disadvantages of RF

! Long term experiences made with radio transmission

for wide area networks (e.g., microwave links) and mobile cellular telephones

! Radio transmission can cover larger areas and can

penetrate (thinner) walls, furniture, plants, etc

! RF does not require direct line of sight for reliable

communication transmission

! Current RF-based products offer higher transmission

rates (e.g., 10 Mbit/sec) than infrared

! Most WLAN technologies rely on RF instead of optical

Wireless System Architecture (WSA)

! Goal ! High-level support for end-users ! Overview/Review/Progress in Phase I ! Future Work (Phase II) ! Summary

WSA Goal

! To provide the required architectural

infrastructure to support heterogeneous wireless devices in a single unified system

! System evolution

! Ground system ! ISS as a testbed ! Support Exploration effort

WSA Objectives

! Hide complexity of implementation ! Easy to integrate disparate devices ! Easy to compose data manipulation

applications

! Support applicable standards

! IEEE 802.11, 802.15.1, 802.15.4 ! IEEE 1451, 1073, and IrDA

WSA Middleware emphasis

IP Layer Transport Presentation and Application layers Data Link Physical Middleware: session and presentation Network /Transport Application Data Link / Physical WWW network emphasis Wireless distributed system emphasis

Middleware services

! Integrate heterogeneous devices ! Wireless device network management ! Time synchronization ! Device and Service discovery ! Security ! Grouping ! Database management

HAB – NAG specifics

Bluetooth Net Layer TCP/IP Custom Net Layer

Application Layer

Bluetooth 802.15.1 Custom PHYS WSN - tdma/csma

• r Zigbee

WSN - custom or 802.15.4

T E S T H A B L O C A T E W I S

• C

O 2 M e d I c a l E m b e r T I n y

• s

T e l

• s

UWB Net Layer UWB PHYS Eth LAN Eth WLAN Power Monitor Event Monitor RT Data Display Device Command Data Visualize

Data Link / PHYS Transport / Network Network Aggregator (nag) Hardware Abstractors (habs) (in kernel) (hardware)

M a n t I s

Custom Apps

Middleware

WSA-standard application interface to the nag WSA-standard hab-nag interface Device specific interface

Deployment Scenario

Primary Habitat

NAG HAB

Wired network

APP APP

Habitat 1

HAB

Habitat 2

HAB

Wired network

Naming

nag Mantis hab “Destiny” Host 0 Mantis hab “Russian” Host 0

Wired network

Mantis node ID 0 Mantis node ID 0

HAB Development Kit

App

Network Aggregator (nag) Hardware Abstractors (habs) (in kernel) (hardware)

WSA-standard application interface to the nag WSA-standard hab-nag interface Device specific interface Develoment Kit for HAB with published APIs.

Example Application: Bedrest Study

! Issue: Subjects may move excessively on the

bed, or they could leave the bed and fall

! Goal: Record the subject’s activity over the

duration of the study to ensure study protocol compliance and to account for possible deviations between subjects. To ensure a subject’s safety the nursing staff will be alerted when the bedridden subject is standing or walking

Math Processor Loop (e.g. 15 to 30 seconds) Inclination in xy- and yz-axes Activity Intensity (RMS – Average) Temperature Logic Processor Standing or Walking? Reading a book (bent knees)? Exercise: Activity above threshold? Data Storage Inclination, activity, and temperature data Inclination Event Log (duration, avg) Is Monitor on (Temperature below threshold)? Activity Event Log (duration, avg) Battery Voltage Is Battery Low (Voltage below threshold)? Event Log & Alarm Inclination Log & Alarm State Inclination Log Event Log Alarm State Alarm State

PC-104 based enclosure

Deployment Scenario

Primary Habitat

NAG HAB

Wired network

APP APP

1 2 3 4 5

Habitat 1

HAB

1 2 3 4 5

Habitat 2

HAB

1 2 3 4 5

Wired network

Future Work

! Application development

! Advanced environmental (in-situ, atmospheric particulates)

monitoring

! Advanced physiological monitoring ! EVA suit monitoring ! Radiation dosimetry monitoring ! Network power monitoring, optimization, and maintenance

prediction

! Advanced communication statistics ! Operations command and control display definition and

development

! PDA-specific display development ! Management, measurement, monitoring applications

Future Work

! Advanced visualization

! Custom user display development ! 2D, 3D gradient maps

! Integrate with ISHM ! Expert system development

! Visualization ! Diagnosis ! Prognosis

Future Work

! Database

! Database design and implementation ! Flight side design and replication to ground side ! Groundside distribution services (secure) ! Historical data

! Payload Data Historian integration ! Webplots integration

! Data snapshotting for redundancy and recovery

Future Work

! Architecture enhanced capabilities

! Time synchronization ! Advanced environmental (atmospheric, in-situ water)

monitoring

! Multi-hop routing with Zigbee ! UWB integration ! Enhanced alarming capabilities ! Web distribution/repository for WSA-BioNet binaries, maybe

• pen source, application DevKit and a hardware DevKit

! Improved fault tolerance

! Relay node failure ! NAG as single point interface (need redundancy)

Future Work

! Low power optimizations to increase

network lifetime and decrease required network maintenance

! Dynamic reprogramming of deployed

node set

! Install upgraded or completely different

program image

Future Work

! Full protocol implementation and support

! IEEE 802.11b, 802.15.1, are in Linux Kernel ! IEEE 802.15.4 is a PHY layer RF signaling protocol ! Zigbee: Strategy is that expect 802.15.4 / Zigbee to become

an integrated chipset with Linux device driver support in the future

! IEEE 1451: This will need to be developed in-house unless

there’s some Open Source development project ongoing that we could contribute to

! IEEE 802.15.3: Hi-Rate WPAN; expect more compliant

devices, then expect Linux device support

Future Work

! IEEE 1073: Same as 1451, this would

probably be an in-house development project

! IrDA: This would be a straightforward

implementation if there are suitable devices of interest

Future Work

! Security design and implementation

! Design the system is the first step ! Define threat model ! Authentication and authorization ! Compression ! Encryption for data privacy

! Wireless transmissions ! On-disk storage ! ISS-to-groundside ! Groundside access and data distribution

! MACing for data integrity

Future Work

! Ground System development

! System development and test

infrastructure

! Workload characterization ! Reliability analysis ! Performance monitoring