IEEE 802.15.4, ZigBee, WirelessHART, ISA SP-100, ROLLcarlofi/teaching/pwsn-2009/... · · 2013-12-31Fall 2009 Principles of Wireless Sensor Networks Carlo Fischione IEEE 802.15.4,

Fall 2009 Principles of Wireless Sensor Networks Carlo Fischione

IEEE 802.15.4, IEEE 802.15.4, ZigBeeZigBee, , WirelessHARTWirelessHART, ISA SP, ISA SP--100, ROLL100, ROLL

Lecture 6Principles of Wireless Sensor Networks

Carlo Fischione

Royal Institute of Technology - KTHStockholm, Swedene-mail: [email protected]


TodayToday’’s Lectures Lecture

IEEE 802.15.4

Overview of ZigBeeWirelessHARTISA SP-100 ROLL

Protocol stack

Phy

MAC

Routing

Transport

Session

Application

Itera

tive m

ethod

s:

Presentation


IEEE 802.15IEEE 802.15

The IEEE 802.15 working group is responsible to create Wireless Personal Area Networks (WPANs) standards.

IEEE 802.15 working group has defined three classes of WPANs that are differentiated by data rate, battery drain, and quality of service (QoS).

1. IEEE 802.15.3: high data rate WPAN for multi-media applications that require very high QoS.

2. IEEE 802.15.1/Blueetooth: Medium rate WPANs that will handle a variety of tasks ranging from cell phones to PDA communications and have voice QoS.

3. IEEE 802.15.4/LR-WPAN: The low rate WPAN for industrial, residential and medical applications with very low power consumption and cost requirement, low for data rate and QoS.

The reference standard for low data rate WSNs


IEEE 802.15.4IEEE 802.15.4

Characteristics: high network flexibility, low cost, very low power consumption, low data rate in an ad hoc self-organizing network among inexpensive fixed, portable and moving devices

IEEE 802.15.4 specifies two layersPhysical layer• 2.4Ghz global, 250Kbps • 915MHz America, 40Kbps• 868MHz Europe, 20Kbps

Medium Access Control (MAC) layerIEEE 802.15.5 does not specify the routing. Phy

MAC

Routing

Transport

Session

Application

Presentation


IEEE 802.15.4IEEE 802.15.4

Network topologyPhysical LayerMedium Access Control


IEEE 802.15.4 NetworksIEEE 802.15.4 Networks

An IEEE 802.15.4 network is composed of devices:full-function device (FFD) reduced-function device (RFD).

A network includes at least one FFD, operating as the PAN coordinator.The FFD can operate in three modes:

a personal area network (PAN) coordinator a coordinatoror a device

An FFD can talk to RFDs or FFDsRFD

simple applications for low amounts of data. can only talk to an FFD.


IEEE 802.15.4 Network IEEE 802.15.4 Network TopologiesTopologies

3 types of topologies star topology.peer-to-peer topology.cluster tree.


ClusterCluster--tree topologytree topology


Star TopologyStar Topology

The communication is established between devices and a single central controller (the PAN coordinator). The PAN coordinator may be mains powered. The devices are most likely battery powered.

Applications: Home automation, personal computer (PC) peripherals, toys and games.

After an FFD is activated for the first time, it may establish its own network and become the PAN coordinator.

Each star network chooses a PAN identifier that is not currentlyused by any other network within the radio sphere of influence.


PeerPeer--toto--peer topologypeer topology

There is one PAN coordinator.

Any device can communicate with any other device in the range.

It allows multiple hops to route messages from any device to anyother device in the network.

It can provide reliability by multipath routing.

Applications industrial control,monitoring, asset and inventory tracking.


ClusterCluster--tree Topologytree Topology

A special case of a peer-to-peer network Most devices are FFDsRFD may connect to a cluster-tree network as a leave node at the end of a branch. Any of the FFD can act as a coordinator and provide synchronization services to other devices and coordinators.

There is only a PAN coordinator:forms the first cluster by establishing itself as the cluster head (CLH) with a cluster identifier (CID) of zero, chooses an unused PAN identifier, and broadcasts beacon frames to neighboring devices.


ClusterCluster--tree Topologytree Topology

A candidate device receiving a beacon frame may request to join the network at the CLH. If the PAN coordinator permits the device to join, it will add this new device as a child device in its neighbor list. The newly joined device will add the CLH as its parent in its neighbor list and begin transmitting periodic beacons such that other candidate devices may then join the network at that device. Once application or network requirements are met, the PAN coordinator may instruct a device to become the CLH of a new cluster adjacent to the first one. The advantage of this clustered structure is the increased coverage area at the cost of increased message latency.


LRLR--WPAN Device ArchitectureWPAN Device Architecture

LLC (logical link control) can access the MAC sublayers through the SSCS (service-specific convergence sublayer)


IEEE 802.15.4IEEE 802.15.4



IEEE 802.15.4 physical layerIEEE 802.15.4 physical layer

Frequency bands:• 2.4 - 2.4835GHz Ghz, global, 16 channels, 250Kbps • 902.0 - 928.0MHz, America, 10 channels, 40Kbps• 868 - 868.6MHz, Europe, 1 channel, 20Kbps

Features of the PHY layeractivation and deactivation of the radio transceiver, energy detection (ED), link quality indication (LQI), clear channel assessment (CCA), transmitting and receiving packets across the wireless channel,channel selection: the standard allows a dynamic channel selection by a scan function that steps through a list of channels in search of beacon, ED, LQI, and channel switching.


IEEE 802.15.4 physical layerIEEE 802.15.4 physical layer


Physical Layer data unitPhysical Layer data unit

The SFD indicates the end of the SHR and the start of the packet data.PHR: PHY headerPHY payload < 128 byte


IEEE 802.15.4IEEE 802.15.4



IEEE 802.15.4 MACIEEE 802.15.4 MAC

The MAC provides two services: the MAC data service the MAC management service

The MAC data service enables the transmission and reception of MAC protocol data units (MPDU) across the PHY data service.MAC features: beacon management, channel access, GTS management, frame validation, acknowledged frame delivery, association and disassociation.


SuperframesSuperframes

LR-WPAN allows the optional use of a superframe structure:format defined by the PAN coordinator.bounded by network beacons. divided into 16 equally sized slots.

Beacons packets are used to synchronize the attached devices, to identify the PAN and to describe the structure of superframes.a beacon is sent in the first slot of each superframe.if a coordinator does not use the superframe structure, it may turn off the beacon transmissions.

The superframe can have an active and an inactive portion. During the inactive portion, a node does not interact with its PAN and may enter a low-power mode. The active portion consists of contention access period (CAP) and contention free period (CFP). Any device wishing to communicate during the CAP shall compete with other devices using a slotted CSMA/CA mechanism. The CFP contains guaranteed time slots (GTSs).


IEEE 802.15.4 CSMAIEEE 802.15.4 CSMA--CACA

A Carrier Sense Multiple Access/ Collision Avoidance (CSMA/CA) algorithm is implemented at the MAC layer.If a superframe structure is used in the PAN, then slotted CSMA-CA is used.

CSMA/CA is used in the CAP period

If beacons are not used in the PAN or a beacon cannot be located in a beacon-enabled network, unslottedCSMA-CA algorithm is used.


CSMACSMA--CACA

Each device has 3 variables: NB, CW and BE.

NB: number of times the CSMA/CA algorithm was required to backoff while attempting the current transmission.

It is initialized to 0 before every new transmission.

BE: backoff exponenthow many backoff periods a device shall wait before attempting to assess the channel.

CW: contention window length (used for slotted CSMA-CA),Is the number of backoff periods that need to be clear of activity before the transmission can start. It is initialized to 2 before each transmission attempt and reset to 2 each time the channel is assessed to be busy.


CSMA/CACSMA/CA

Flow diagram to Transmit a packet with CSMA/CA inSlotted and Unslotted modalities


Guarantee Time Slot (GTS) Guarantee Time Slot (GTS) AllocationAllocation

The GTSs always appears at the end of the active superframe starting at a slot boundary immediately following the CAP. The PAN coordinator may allocate up to seven GTSs. A GTS can occupy more than one slot period.

SO <15. If SO=15, the superframe will not be active anymore after the beaconBO < 15. If BO=15, the superframe is ignored


GTS Allocation and ManagementGTS Allocation and Management

A GTS allows a device to operate on the channel within a portionof the superframe that is dedicated exclusively to that device. A device attempts to allocate and use a GTS only if it is currently tracking the beacons. GTS allocation:

The management of the GTSs is undertaken by the PAN coordinator only.A GTS is allocated only by the PAN coordinator and it is used only for communications between the PAN coordinator and a device. The GTS direction is specified as either transmit or receive.A single GTS can extend over one or more superframe slots.


The PAN coordinator may allocate up to seven GTSs at the same time, provided there is sufficient capacity in the superframe.A GTS is allocated before use, with the PAN coordinator decidingwhether to allocate a GTS based on the requirements of the GTS request and the current available capacity in the superframe. GTS is allocated on a first-come-first-serve basis and all GTSs are placed contiguously at the end of the superframe and after the CAP. Each GTS shall be deallocated when it is no longer required, and a GTS can be deallocated at any time at the discretion of the PAN coordinator or by the device that originally requested the GTSs. A device that has been allocated GTS may also operate in the CAP.For each GTS, the PAN coordinator stores its starting slot, length, direction and associated device address.

A GTS analysis: P. Park, P. Di Marco, C. Fischione, K. H. Johansson,”Performance Analysis of GTS Allocation in Beacon Enabled IEEE 802.15.4”, in Proc. of Sixth Annual IEEE Communications Society Conference on Sensor, Mesh and Ad Hoc Communications and Networks (IEEE SECON 09), Rome, Italy, June 2009.

GTS Allocation and ManagementGTS Allocation and Management


BeaconBeacon--enabled, and nonenabled, and non--beaconbeacon--enabled communicationenabled communication

Communication to a coordinator in Communication to a coordinator in a beacona beacon--enabled networkenabled network

Communication to a coordinator in Communication to a coordinator in nonnon--beaconbeacon--enabled networkenabled network


Communication from a coordinator in a beacon-enabled PAN

Communication from a coordinator in a nonbeacon-enabled PAN

BeaconBeacon--enabled, and nonenabled, and non--beaconbeacon--enabled communicationenabled communication


TodayToday’’s Lectures Lecture

IEEE 802.15.4

Overview of ZigBeeWirelessHARTISA SP-100 ROLL


ZigBeeZigBee

http://www.zigbee.org/ZigBee covers the networking and application layers on top of IEEE 802.15.4Nodes:

IEEE 802.15.4 nodesZigBee coordinator: starts the networkZigBee router: needed for routing

Networks:Star networkTree networkMesh network

RoutingNo transport protocol for end-to-end reliability (only hop-by-hop).Tree routing: packets are sent to the coordinator, and then to the destination.Mesh routing: AODV protocol for route discovery (see Lecture 5).

http://www.zigbee.org/


ISA SPISA SP--100100

http://www.isa.orgStandard for non critical process applications tolerating delays up to 100ms. It is based on IEEE 802.15.4 plus a new data link layer and adaptation layer between MAC and data link

Frequency hopping

http://www.isa.org/


WirelessHARTWirelessHART

http://www.hartcomm.org/Released in September 2007 as part of HART 7 specifications.An open communication standard designed for process measurements and control applications.

strict timing requirements security concerns


WirelessHARTWirelessHART networknetwork

Field device, attached to the plant processHandheld, a portable computer to configure devices, run diagnostic and perform calibrationsGateway, that connect host applications to field devicesNetwork manager, responsible for configuring the network, scheduling and managing communication


WirelessHARTWirelessHART networknetwork

TopologyStarClusterMesh

Central network manager: maintains up-to-date routes and communication schedules for the networkBasic functionalities:

TimerNetwork wide synchronizationCommunication securityReliable mesh networkingCentral network management


A Five Layers ArchitectureA Five Layers Architecture


LayersLayers

Physical layer: similar to IEEE 802.15.42.4-2.4835 GHz, 26 channels, 250 Kbps per channel

Data link layer: Network wide synchronization (a fundamental functionality)TDMA with strict 10ms time slotsPeriodical superfamesChannel blacklisting: the network administrator removes the channels with high interference. Pseudorandom change of the channel for robustness to fadingTDMA security: industry-standard AES-128 ciphers and keys


WirelessHARTWirelessHART MACMAC


WirelessHARTWirelessHART RoutingRouting

Graph Routing: A graph is a collection of paths that connect network nodes. The paths in each graph is created by the network manager and downloaded to each individual network device. To send a packet, the source device writes a specific graph ID (determined by the destination) in the network header.All network devices on the way to the destination must be pre-configured with graph information that specifies the neighbors to which the packets may be forwarded.

Source Routing: is a supplement of the graph routing aiming at network diagnostics. To send a packet to its destination, the source device includes in the header an ordered list of devices through which the packet must travel. As the packet is routed, each routing device utilizes the next network device address in the list to determine the next hop until the destination device is reached.


ROLL: ROLL: RutingRuting over Low Power over Low Power LossyLossy NetworksNetworks

http://www.ietf.org/dyn/wg/charter/roll-charter.html

ROLL is a Working Group of the Internet Engineering Task Force.ROLL is specifying the routing protocols for low power and lossy networks (LLNs) for

Indusrial and home automationHealthcareSmart grid

Low power and Lossy networks are made up of many embedded devices with limited power, memory, and processing resources. LLNs are interconnected by a variety of links, such as EEE 802.15.4, Bluetooth, Low Power WiFi, wired or other low power PLC (Powerline Communication) links. LLNs are transitioning to an end-to-end IP-based solution to avoid the problem of on-interoperable networks interconnected by protocol translation gateways and proxies.

A proposed standard is going to be submitted in February 2010.

http://www.ietf.org/dyn/wg/charter/roll-charter.html


SummarySummary

We have seen the most popular solutions for commercial WSNsIEEE 802.15.4 is expected to be the reference standard for most of the low data-rate low power WSNs (Zigbee, WirelessHART, ISA-SP 100, ROLL).

Physical layerMAC layer

There is not any widely accepted routing protocol for WSNs

IETF is working to define the ROLL standard based on IEEE 802.15.4.


Next LectureNext Lecture

Anna Scaglione from University of California Davis gives an invited lecture about “Network coordination inspired by biological clocks”

The seminar starts at 10.00 sharp.

Documents

IEEE 802.15.4, ZigBee, WirelessHART, ISA SP-100, ROLLcarlofi/teaching/pwsn-2009/... · · 2013-12-31Fall 2009 Principles of Wireless Sensor Networks Carlo Fischione IEEE 802.15.4,