LR WPAN OVERVIEW

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					                      LR WPAN OVERVIEW

                                    Ivan Howitt
                                  ECE Department
                                   UNC Charlotte
                                     8/27/2006




                                                      8/28/2006- 1




            Why 2.4 GHz ISM Band?


            2.4 GHz UL Band               0            MH
                                                         z
                                                                                                                                                               .5      MH
                                                                                                                                                                         z
                                      240                                                                                                          2       483
                                                                                     2446.6




                                                                                                                                                  2483.5
                                                                                                                                   2475




              No license fee
                                   2400




                                                                                                                            2471




                                                                                                                                                                2497
                                                                                2445




                                                                     USA and Europe*
              No service charge                                           83.5 MHz
                                                                                              * Spain and France Excluded




              World Wide                Unlicensed
                                                                                                                                           Japan
                                                                                                                                             26 MHz




              Availability          2.4 GHz Spectrum
                                        Worldwide                                                   Spain
                                                                                                      30 MHz




            Other UL Bands                                                                                 France
                                                                                                               36.9 MHz




                                                                                                                                          4 MHz


              5 GHz                                                                                         36.9 MHz




                                                                                                                                                              MHz


              900 MHz
                                          JAG/0199 Ver 1




                                                      8/28/2006- 2




8/28/2006                                                                                                                                                                    1
                                                                                                                                                                                 1
            2.4 GHz ISM Band Wireless Services


                                            802.11g
             Data rate
             (Mbps)
               10
                 8
                 6
                         802.11b
                 4
                 2
                                        802.11                    Range
                 0
                                                                  (meters)
                     0    10       30         60            100
                               Bluetooth    HomeRF
                               (802.15.1)
                 LR-WPAN
                 (802.15.4)                  8/28/2006- 3




            What is IEEE 802.15.4?


               Part of the IEEE 802.15
               Working Group
               Dedicated to low rate/low
               power WPANs
               Low Complexity and
               cheap




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8/28/2006                                                                    2
                                                                                 2
            Motivation IEEE 802.15.4


              Ultra Low
                 Complexity
                 Cost
                 Power Consumption                            802.11b WLAN    802.15.1 WPAN   802.15.4 LR-WPAN

              Trade-Off                 Range                       ~100 m     ~10 - 100 m          10 m
                 Range
                                     Raw Data Rate                  11 Mbps      1 Mbps         <= 0.25 Mbps
                 Data Rate
              Applications         Power Consumption                medium         low            ultra low




                                                     8/28/2006- 5




            Architecture


              Zigbee Stack

              Joint Effort
                 IEEE
                 Zigbee Alliance




                                                     8/28/2006- 6




8/28/2006                                                                                                        3
                                                                                                                     3
                                 MAC LAYER




                                              8/28/2006- 7




            IEEE 802.15.4 MAC

                                                                            RFD or
              Star & Peer to Peer                                           FFD
              Topologies
                 Master/Slave, Point to any                             FFD
                 Point, Cluster Tree, etc.                              (PAN Coordinator)
                 16 bit or 64 bit addresses                    Star
              CSMA-CA &
              Slotted CSMA-CA
              Optional Network beacons
              Optional Super-frame
              Optional time slot
              reservation (low latency
              transfer)                                      Cluster Tree

                                              8/28/2006- 8




8/28/2006                                                                                   4
                                                                                                4
            IEEE 802.15.4 MAC: Node Types


              PAN Coordinator (Distribution Node)
                FFD – Full function device
                Controls network topology
                Coordinates or Mediates Node Traffic
                Stores Routing Information
                Talks to other Coordinator or Slave Nodes
              Slave Node
                RFD (Reduced FD) or FFD
                Talks only to PAN Coordinator
                Simple Device


                                      8/28/2006- 9




            IEEE 802.15.4 MAC: Super Frame Structure


              Beacons                         Superframe Beacons
                Synchronize
                Nodes
                                                               CFP
                Network Info
                Pending
                                                        …




                Messages                              CAP
              16 Time Slots
              CAP – Contention Access Period



                                      8/28/2006- 10




8/28/2006                                                            5
                                                                         5
            IEEE 802.15.4 MAC: Super Frame Structure


              Beacons                        Superframe Beacons
                Synchronize
                Nodes
                Network Info                                  CFP

                Pending
                Messages




                                                       …
              16 Time Slots              CAP                 CFP
              CAP – Contention Access Period
              CFP – Contention Free Period
              PAN Coordinator Provides Guaranteed
              Time Slots (GTS)

                                     8/28/2006- 11




            Data Transfer


              Coordinator to Network Device (Standard PG 19)
                Beacon-enabled network
                Non-beacon-enabled network
              Network Device to Coordinator
                Beacon-enabled network
                Non-beacon-enabled network
              Peer-to-Peer




                                     8/28/2006- 12




8/28/2006                                                           6
                                                                        6
            Frame Structure




                                 8/28/2006- 13




                              PHY LAYER




                                 8/28/2006- 14




8/28/2006                                        7
                                                     7
              ChipCon CC2420




            15.4
            Transceiver
                                     8/28/2006- 15




              IEEE 802.15.4 PHY – High Band


                 16 Freq Channels @ 2.4 GHz
                 DS/SS with 2MHz chip rate
                 O-QPSK
                 Receiver Sensitivity < -85 dBm
                 5 MHz Channel Separation
                 250 kb/s data rates
                 Range 1m to 10m (~100m with trade-offs)
                 Tx Power 1mW (capability)
                 Supports 915 MHz & 866 MHz operation

                                     8/28/2006- 16




8/28/2006                                                  8
                                                               8
            PHY Variation vs ISM Frequency Bands




                                        8/28/2006- 17




            Modulation and Spreading (2.4GHz)



              Half-Sine Shaped O-QPSK
                 Peak to average ratio of 1


              Direct Sequence Spread Spectrum

              16 pseudo-random (32 chip) PN sequences
              ChipCon PG 22



                                        8/28/2006- 18




8/28/2006                                               9
                                                            9
            Measured Power Spectrum – Tx Power -10dBm


                              0

                             -10
                                                                          Center 2.45GHz
                             -20
                                                                          2MHz/div
               Power (dBm)




                             -30

                             -40

                             -50

                             -60

                             -70
                                   2.42   2.436   2.44            2.444     2.448

                                             Frequency (GHz)


                                                  8/28/2006- 19




            ChipCon CC2420 LR-WPAN Implementation


              Operational Specification (PG 8-13)
              Block Diagram (PG 16)
              Demodulator (PG 34)
              RSSI & LQI (PG 47 & 48)
              LR-WPAN as a State Machine (PG 43)




                                                  8/28/2006- 20




8/28/2006                                                                                  10
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Description: WPAN ( Wireless Personal Area Network Communication Technologies ) is a wireless connection to the personal area network. It is used in such as the telephone, computer, ancillary equipment and a small range ( personal area network working range is generally within 10 meters ) within the digital assistant communication between devices. Support wireless personal area network technologies include: Bluetooth, ZigBee, OC band ( UWB ), IrDA, HomeRF, the Bluetooth technology in the wireless personal area network used in most widely. Each technology has only been used for specific uses, applications or fields to play to the best effect. In addition, although in some respects, some techniques are considered in the wireless personal area network space in competition with each other, but they often each other is complementary.