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Mobile Communications

WMAN, WPANManuel P. Ricardo

Faculdade de Engenharia da Universidade do Porto

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Type of Wireless Networks

♦ WPAN - Wireless Personal Area Networks» short distances among a private group of devices

♦ WLAN - Wireless Local Area Networks» areas such as an home, office or group of buildings

♦ WMAN - Wireless Metropolitan Area Networks» from several blocks of buildings to entire cities

♦ PLMN - Public Land Mobile Networks» regions and countries

♦ Broadcast » single direction, audio and video

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Technologies Comparison

• U=bit/s/Hz/km2

– PLMN 10 to 40 U (based on UMTS)

– WMAN 25 to 50 U – WLAN 100 to 500 U

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IEEE 802.16

Wireless MAN

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Information

♦ Current Standard» Freely available at IEEE site

http://www.ieee.org publications & standards get IEEE standards

» IEEE 802.16-2009 - IEEE Standard for Local and metropolitan area networks Part 16: Air Interface for Broadband Wireless Access Systems

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IEEE 802.16 Terms

♦ MAN – Metropolitan Area Network♦ BS – Base Station♦ SS – Subscriber Station♦ DL – Downlink, from BS to SS ♦ UL – Uplink, from SS to BS♦ FDD – Frequency Division Duplex♦ TDD – Time Division Duplex♦ TDMA – Time Division Multiple Access♦ TDM – Time Division Multiplexing♦ OFDM – Orthogonal Frequency Division Multiplexing♦ OFDMA - Orthogonal Frequency Division Multiple Access♦ QoS – Quality of Service

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Topology

Source: Understanding WiMAX and 3G for Portable/Mobile Broadband Wireless, Technical White Paper, Intel.

Base Station

Subscriber StationsMobile Station

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Reference Models

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Standard Aggregates Multiple WiMAX Versions

OFDM

OFDMA

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Adaptive Burst Profiles

♦ Burst profile: Modulation and FEC

♦ On DL» multiple SSs can associate on the same DL burst

♦ On UL» SS transmits in an given time slot with a specific burst

♦ Dynamically assigned according to link conditions» Burst by burst» Trade-off capacity vs. robustness in real time

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OFDM PHY TDD Frame Structure

DL Subframe

Frame n-1

pre.

Time

Adaptive

Frame n Frame n+1

UL subframe

FCH DLburst 1

DLburst n

ULMAP

Broadcast Conrol msgs

... UL burst 1 UL burst m

DLMAP

DCDopt.

UCDopt.

...DLburst 2

UL TDMADL TDM

pre. pre.

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OFDM PHY FDD Frame Structure

DL Subframe

Frame n-1

pre.

Time

BroadcastControl Msgs

Frame n Frame n+1

UL subframe

FCH DLburst 1

DLburst k...

DL TDMA

UL burst 1 UL burst m

DLburst 2

DLburst n

DLburst k+1 ...

DL TDM

...

UL TDMA

DLMAP

ULMAP

DCDopt.

UCDopt.

pre.pre.

UL MAP for nextMAC frame UL

burstspre. pre.

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FDD MAPs Time Relevance

frame

Broadcast

Full Duplex Capable User

Half Duplex Terminal #1

Half Duplex Terminal #2

UPLINK

DOWNLINK

DL MAP

UL MAP

DL MAP

UL MAP

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OFDMA

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OFDMA

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OFDMA, TDD

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IEEE 802.16 MAC Addressing and Identifiers

♦ SS has 48-bit IEEE MAC address♦ BS has 48-bit base station ID

» Not a MAC address; 24-bit used for operator indicator

♦ 16-bit connection ID (CID)♦ 32-bit service flow ID (SFID)♦ 16-bit security association ID (SAID)

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Convergence Sub-Layer (CS)♦ ATM Convergence Sub-Layer

» Support for VP/VC connections» Support for end-to-end signaling of dynamically created connections » ATM header suppression; Full QoS support

♦ Packet Convergence Sub-Layer» Initial support for Ethernet, VLAN, IPv4, and IPv6» Payload header suppression; Full QoS support

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MAC – CPS – Data Packet Encapsulations

PHSI

MAC PDU

Ethernet Packet

Ethernet Packet

Packet PDU(e.g., Ethernet)

CS PDU(i.e., MAC SDU)

HT

FEC block 1

CRCMAC PDU Payload

OFDMsymbol

1

PHY Burst(e.g., TDMA burst)

PreambleOFDMsymbol

2

OFDMsymbol

n......

FEC FEC Block 2 FEC block m......FEC Block 3

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MAC – CPS – MAC PDU Transmission

♦ MAC PDUs are transmitted in PHY Bursts♦ The PHY burst can contain multiple FEC blocks♦ MAC PDUs may span FEC block boundaries ♦ Concatenation, Fragmentation

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MAC – CPS – MAC PDU Concatenation

MAC PDU 2

HT

FEC block 1

CRCMAC PDU Payload

OFDMsymbol

1

PHY Burst(e.g., TDMA burst)

PreambleOFDMsymbol

2

OFDMsymbol

n......

FEC FEC Block 2 FEC block m......FEC Block 3

MAC PDU 1

HT CRCMAC PDU Payload ......

MAC PDU k

HT CRCMAC PDUPayload

Multiple MAC PDUs are concatenated into the same PHY burst

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MAC – CPS – MAC PDU Fragmentation

FEC block1

OFDMsymbol

1

PHY Burst

Pre.

MAC SDU

OFDMsymbol

n1......

FEC FEC Blockm1

......

MAC SDUseg-1

HT CRCMAC PDU PayloadHT CRCMAC PDU

Payload

A MAC SDU can be fragmented into multiple segments, eachsegment is encapsulated into one MAC PDU

FEC block1

OFDMsymbol

1

PHY Burst

Pre.OFDMsymbol

n2......

FEC Blockm2

......

HT CRCMAC PDUPayload

MAC SDUseg-2

MAC SDUseg-3

FSH

FSH

FragmentationSub-Header

(8 bits)

FSH

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MAC – CPS QoS

♦ Three components of 802.16 QoS » Service flow QoS scheduling» Dynamic service establishment» Two-phase activation model (admit first, then activate)

♦ Service Flow » A unidirectional MAC-layer transport service characterized by a set of

QoS parameters (latency, jitter, throughput)» Identified by a 32-bit SFID (Service Flow ID)

♦ Three types of service flows» Provisioned: controlled by network management system » Admitted: the required resources reserved by BS, but not active» Active: the required resources committed by the BS

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MAC – CPS – Uplink Service Classes

♦ UGS: Unsolicited Grant Services♦ rtPS: Real-time Polling Services♦ nrtPS: Non-real-time Polling Services♦ BE: Best Effort

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MAC – CPS – Automatic Repeat reQuest (ARQ)

♦ A Layer-2 sliding-window based flow control mechanism♦ Per connection basis♦ Only effective to non-real-time applications♦ Uses a 11-bit sequence number field♦ Uses CRC-32 checksum of MAC PDU to check data errors♦ Maintain the same fragmentation structure for Retransmission♦ Optional

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IEEE 802.15.1

Wireless PAN (Bluetooth)

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Information

♦ Current Standard» Freely available at IEEE site

http://www.ieee.org publications & standards get IEEE standards

» IEEE 802.15.1-2005 IEEE Standard for Information technology--Telecommunications and information exchange between systems-- Local and metropolitan area networks--Specific requirements. Part 15.1: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Wireless Personal Area Networks

♦ Read : Section 5 - General Description

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♦ Overview» Wireless personal area networks (WPANs) are used to convey information

over short distances among a private, intimate group of participant devices. Unlike a wireless local area network (WLAN), a connection made through a WPAN involves little or no infrastructure or direct connectivity to the world outside the link. This allows small, power-efficient, inexpensive solutions to be implemented for a wide range of devices.

♦ Scope» This standard defines physical layer (PHY) and medium access control

(MAC) specifications for wireless connectivity with fixed, portable, and moving devices within or entering a personal operating space (POS). A POS is the space about a person or object that typically extends up to 10 m in all directions and envelops the person whether stationary or in motion. This standard is based upon technology originally developed by the Bluetooth Special Interest Group (SIG).

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Reference Model

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IEEE 802.15.4

Wireless PAN (Sensor Networks)

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Information

♦ Current Standard» Freely available at IEEE site

http://www.ieee.org publications & standards get IEEE standards

» IEEE 802.15.4-2006 IEEE Standard for Information technology--Telecommunications and information exchange between systems--Local and metropolitan area networks-- Specific requirements Part 15.4: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low Rate Wireless Personal Area Networks (LR-WPANs)

♦ Read : Section 5 - General Description

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Introduction♦ Low Rate WPAN (LR-WPAN )

» simple, low-cost communication network» wireless connectivity» applications with limited power and low throughput requirements

♦ Characteristics of an LR-WPAN» Over-the-air data rates of 250 kb/s, 100kb/s, 40 kb/s, 20 kb/s» 64-bit addresses or allocated 16-bit short addresses » Carrier sense multiple access with collision avoidance (CSMA-CA)» Low power consumption» Energy Detection (ED); Link quality indication (LQI)» Radio channels

– 16 channels in the 2450 MHz band– 30 channels in the 915 MHz band – 3 channels in the 868 MHz band

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Types of Devices

♦ Two types» FFD - full-function device

– Can operate in 3 modes: PAN coordinator, coordinator, device– FFD can talk to RFDs or other FFDs

» RFD - reduced-function device – intended for applications that are extremely simple

(light switch , passive infrared sensor)– RFD can talk only to an FFD

♦ WPAN shall include at least one FFDoperating as the PAN coordinator

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Topologies, Identifiers♦ Topologies

» star topology communication between devices and PAN coordinator» peer-to-peer topology devices may communicate directly; needs PAN coordinator

enables mesh networking - 802.15.5, IP (6lowPAN), Zigbee

♦ Identifiers» Each devices has a unique 64-bit address; short 16-bit addresses may be used» Each PAN has an identifier

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Cluster Tree Network

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Architecture

♦ Physical layer (PHY)» activation and deactivation of the radio transceiver» ED, LQI, channel selection, clear channel assessment» transmitting and receiving data» The radio operates at the following unlicensed bands

– 868–868.6 MHz (Europe)– 2400–2483.5 MHz (worldwide)

♦ MAC sublayer» beacon management» channel access» frame validation, frame acknowledged» association and disassociation» hooks for implementing application-appropriate security mechanisms

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Superframe Structure♦ Superframe format

» defined by the PAN coordinator » bounded by beacons» can have an active and an inactive portions

♦ Beacons used to » synchronize attached devices» identify the PAN» describe superframe structure

♦ Superframe may have 2 periods» Contention access period

– Devices use slotted CSMA-CA mechanism» Contention-free period (CFP)

– Guaranteed timeslots (GTS) for devices

♦ If coordinator desires no superframe it turns off beacon transmissions » Unslotted CSMA-CA is used

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Data Transfer to a Coordinator

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Data Transfer from a Coordinator

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Beacon Frame

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Data Frame

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Acknowledgment and Comand Frames

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ZigBee Stack Architecture

Slide 43 Joe Dvorak, Motorola 9/27/05