Session Outline

1
Session Outline

• Challenges enabling technologies
• What ZigBee/15.4 Expects to Deliver
• What does 802.15.4 offer?
• What does ZigBee offer?
• Myths about 802.15.4 and ZigBee
• Session Summary

2
Challenges of Wireless Networking

• What problem solved?
• Cable replacement (point-to-point or multi-drop)
• Benefits of EM wave
• Broadcast
• Overcome obstacles
• Portable and Configurable
• What problem created?
• Administration (security, identity, control of
  information)
• Variations in environments
• Not necessarily cheap at the beginning

3
Enabling Technologies

• A good wireless networking solution requires
• Integrated circuits
• Microcontrollers
• Protocol engineering
• A cost-effective wireless solution requires
• Highly-integrated RF ASIC
• Low-cost microcontroller
• Simple yet extensible protocols
• Acceptable power consumption for its target apps

4
15.4/ZigBees Promises

• A Just-Right wireless networking technologies
  for device-to-device networking
• Data rate
• Range
• Flexibility
• Security features
• Goal Best-in-class mix of price and performance

5
802.15.4 Overview

• 802.15.4 provides a building block network
• Key services offered by 802.15.4
• Air Interface
• Regulated Access to Air Interface
• Network forming and identification
• Access schemes
• Transport services
• Information security, integrity, and authenticity
• On top of all, all these services must be
  delivered at very light-weight implementation

6
State of a 15.4 Device A Simplistic View

• A wireless device usually goes through these
  stages
• Looking for communication channel
• Looking for network-able peers
• Establish network membership
• Communicate
• Communicate securely
• Re-establish network in case of error conditions

7
802.15.4 Design Objectives

• Low latency
• Balanced messaging latency for all network sizes
• Low complexity
• Low data rate
• Message types
• Message overhead
• Low total system cost
• Low gate count (ICs)
• Low s/w footprint (microcontroller)
• Low power consumption (battery)

8
ZigBee Overview

• ZigBee to address
• Building a larger network
• Out-of-the-box Plug-and-Play
• Interoperable products from multiple vendors
• Extensible framework for building many many
  wireless products
• What 15.4 does not offer
• Locating and connecting a devices peer for real
  applications
• Maintaining such logical relationship under all
  conditions
• Secrecy
• Application Profile Description
• Negotiation of application profiles

9
ZigBee Networking

• A fundamental question
• Cascading two or more 15.4 networks together
• Possible topological arrangement
• Star
• Mesh
• Cluster-tree
• Routing
• Route establishment
• Route maintenance
• Route computation
• Unique address assignment across linked 15.4
  networks

10
ZigBee Security

• Security Key The Key to Wireless Security
• ZigBee Security Covers
• Key Establishment
• How does the key get into a ZigBee device?
• Key Exchange
• How do the device exchange keys over the air?
• Key Preservation
• How do the key information get preserved in face
  of battery outage, device swap?
• End-to-end Security services
• (encryption, authentication, and integrity) x N

11
ZigBee Application Sub-layer (APS)

• Devised mostly as an optional service layer
• Add-on services that might be needed by a certain
  applications
• Fragmentation
• Retransmission

12
ZigBee Profile

• A standard definition on application profile
• A profile is a common definition of device
  behaviors and capabilities
• ZigBee Profile Service also provide discovery and
  matching of profiles
• Compatible devices will understand each other.
• Profile can be extended
• Base Profile
• Extended Profile

13
Myths about 802.15.4/ZigBee

• 15.4/ZigBee is slow, so the technology is easy
• ZigBee is just like 802.11.x
• ZigBee Product Design is just like 802.11.x

14
Reality

• All the capabilities are familiar
• DSSS and MAC
• Ad hoc (or mesh)
• Encryption
• Interoperable profiles
• But squeezing them into a sub-5 module is not
  easy
• RF, microcontroller, protocol, and power
  consumption
• System-level design perspective is critical
• Unlikely TCP/IP
• Even one finishes the entire spec, the untold
  effort on
• Battery life optimization
• Multi-processor porting
• Networking diagnosis tool development
• Input/output limitation
• Proprietary technologies cannot not help reduce
  the cost

15
Summary

• Complementary services provided by 15.4 and
  ZigBee
• Key Features of 15.4
• Key Features of ZigBee
• Likely product design will adopt a toolbox
  approach
• Security
• APS
• Profiles