Networks: A Survey of Architectures and Technologies

Carles Gomez and Josep Paradells

Presented by Deepen Solanki and Aishwarya Rao Table of Contents

1. Introduction to WHANs 2. Solutions for WHANs a. ZIGBEE b. Z - WAVE c. WAVENIS d. e. IP BASED 3. Discussion 4. Conclusion INTRODUCTION - WHANs WHAN

Connectivity

Monitoring Control

Sensors Actuators

● Remote Control of Devices - Appliances ● Remote Care - wearables, fall detection ● Smart Energy Monitoring - HVAC, usage patterns ● Security Systems - burglar alarm, smoke detection INTRODUCTION - WHANs

Characteristics

● High node density - (100s) ● Multipath environment - multiple reflective surfaces ● Interference - devices, microwave ovens ● Multihop communications - combating range ● Self-healing network - mobile devices ● Various traffic patterns - P2P, P2MP, MP2P ● Quick results - emergency situations ● connectivity - Remote monitoring ● Highly constrained nodes - memory, processing power SOLUTIONS FOR WHANs

● ZigBee ● Z-Wave ● INSTEON ● Wavenis ● IP Based Solutions ZIGBEE (2004)

● Low Data Rate - 20, 40, 250kbps ● Short Range - 10 to 100m ● Bands - 868MHz / 915MHZ / 2.4GHz ● DSSS

● Device types Coordinator

End device Router

Beacon ● Channel access ● Profiles Beaconless

● Tree, Mesh ZigBee Home Automation Public Application Profile ZigBee Smart Energy Profile Z-WAVE (1999)

● Reliable transmission of short messages from a control unit to one or more nodes in the network ● 868.42 MHz in Europe, 908.42 MHz in US, 2.4GHz* ● Low data rate - 9.6kb/s, 40kb/s, 200kb/s* ● MAC Layer - CSMA/CA ● Source-routed mesh network ● Range - 90m outdoor, 20m indoor

● Device types

Controller End device

● primary / secondary ● blindly execute commands ● initiations, retransmissions ● routing slaves and static tables ● routing tables ● exclusions, node IDs WAVENIS

● Low-power, long-distance wireless communications ● Data rates between 4.8kb/s and 100kb/s ● 433MHz, 868MHz, 915MHz, 2.4GHz

Synchronous CSMA/TDMA ● MAC Layer

Non - synchronous CSMA/CA

● Only one type of device, virtual tree hierarchy

New device → Broadcast request → QoS → Joined!

http://www-coronis-com.dyn.elster.com/downloads/Wavenis_Data_Sheet_A4_CS5.pdf INSTEON (2005)

● Dual mesh topology ● Links between devices can be either RF lines, power lines or both ● FSK, 904MHz, 38.4kb/s ● All devices are peers ● Not in range? → time-synchronized multihop ● Simulcast → devices within same range can transmit messages simultaneously IP-BASED SOLUTIONS

● IPSO Alliance ● IPv6 over Low power Wireless Personal Area Networks → 6LoWPAN ● Fragmentation, Header compression, address auto-configuration, neighbor discovery ● Organization ○ Edge router = the bridge ○ Mesh router ○ Nodes

http://www.ti.com/lit/wp/swry013/swry013.pdf IP-BASED SOLUTIONS

http://www.ti.com/lit/wp/swry013/swry013.pdf DISCUSSION

Physical Layer

Modulation and Spread-Spectrum Techniques

● FSK- easy to implement, used by Z-Wave and INSTEON ● GFSK- greater spectral efficiency than FSK, used by Wavenis ● PSK- More complex but better SNR, used by ZigBee ● Spread Spectrum techniques provide protection against multipath and narrowband interference- ZigBee and Wavenis DISCUSSION

Single Channel vs. Multichannel

● ZigBee coordinator can decide to re-form the whole network in a new channel if severe interference is detected by any node ● Single channel sub gigahertz operation exploits lower susceptibility to interference than 2.4GHz band to simplify hardware design DISCUSSION

Link Layer

Reliability:

● Z-wave and INSTEON use 8-bit checksum ● ZigBee and 6LoWPAN use 16-bit checksum ● Optional ACKs for reliable link transmission

Delay:

● For reliable mode, the roundtrip time including transmission of an ACK is provided ● 900 MHz channels DISCUSSION

Network Layer

Routing/Multihopping State

● Z-Wave- only the controller stores and maintains a routing table ● ZigBee- recommends the use of large routing tables due to high density expected in a residential scenario, which increases memory requirements on nodes ● Wavenis- each device only stores its own route to the root, root stores the routes to reach each node ● INSTEON- use simulcast instead of routing, avoids the need to store state for multihop communications DISCUSSION

Routing Metrics

● ZigBee and 6LoWPAN use link quality indicator (LQI) offered by IEEE 802.15.4 ● Wavenis uses a link quality estimator based on RSSI- may not be accurate due to interference and multipath

Route Change Latency

● INSTEON uses simulcast instead of routing so doesn't suffer from a connectivity gap ● Other solutions experience the latency for detecting the link failure and finding an alternative path ● 1s for Z-wave, 50-100ms for ZigBee DISCUSSION

End to End Reliability

● ZigBee filters duplicate packets ● In 6LoWPAN, use UDP augmented with sequence numbers, ACKs, and retries

Application Layer

● ZigBee, Z-Wave, and INSTEON - well defined commands and attributes for various WHAN applications DISCUSSION

Security

● ZigBee, Z-Wave 400 series, Wavenis and 6LoWPAN- 128-bit key Advanced Encryption Standard (AES) algorithm ● INSTEON offers various encryption methods but recommends the use of simple rolling-code encryption

Internet Connectivity

● 6LoWPAN is intrinsically interoperable with the Internet- avoids issues in terms of security, management, and consistency in QoS policies DISCUSSION

Implementation Size

● ZigBee, Z-Wave, and INSTEON implement protocol architectures up to application-layer functionality ● Zigbee requires largest footprint, INSTEON requires least memory ● Wavenis consumes a small amount of RAM but requires a medium flash memory size ● 6LoWPAN implementations require less ROM/flash than ZigBee, Z-Wave, and Wavenis

Standardization and Market Adoption

● 6LoWPAN unlike the others is open, and its implementation does not require a license ● ZigBee products in the market has been delayed in comparison with those based on other solutions ● Smart Energy Version 2 - providing end-to-end connectivity between energy providers and consumers CONCLUSION

● ZigBee and 6LoWPAN were designed for general purposes ● Other solutions were developed for specific application ● Trend in converging toward IP- future WHAN applications will benefit from enhanced quality, security, and interoperability.

Questions?