WiMAX for Broadband Wireless Access By: Karim M. El Defrawy ICS UCI-2005
Outline <ul><li>What is WiMAX </li></ul><ul><li>802.16 Introduction </li></ul><ul><li>802.16 MAC Highlights </li></ul><ul>...
What is WiMAX? <ul><li>Worldwide Interoperability for Microwave Access (WiMAX) is the common name associated to the IEEE 8...
IEEE 802.16 -- Introduction <ul><li>IEEE 802.16 (2001) </li></ul><ul><ul><li>Air Interface for Fixed Broadband Wireless Ac...
IEEE 802.16 -- Introduction Coverage range up to 50km and speeds up to 70Mbps(shared among users).
IEEE 802.16 -- Introduction Source: WiMAX, making ubiquitous high-speed data services a reality, White Paper, Alcatel.
IEEE 802.16 MAC -- Highlights <ul><li>WirelessMAN: Point-to-Multipoint and optional mesh topology </li></ul><ul><li>Connec...
Reference Model
Adaptive PHY Source: Understanding WiMAX and 3G for Portable/Mobile Broadband Wireless, Technical White Paper, Intel.
Adaptive Burst Profiles <ul><li>Burst profile: Modulation and FEC </li></ul><ul><li>On DL, multiple SSs can associate the ...
Duplex Scheme Support <ul><li>The duplex scheme is Usually specified by regulatory bodies, e.g., FCC </li></ul><ul><li>Tim...
IEEE 802.16 MAC  –  OFDM PHY TDD   Frame Structure
IEEE 802.16 MAC  –  OFDM PHY FDD   Frame Structure
FDD MAPs Time Relevance frame Broadcast Full Duplex Capable User Half Duplex T erminal #1 Half Duplex T erminal #2 UPLINK ...
IEEE 802.16 MAC  addressing and Identifiers <ul><li>SS has 48-bit IEEE MAC address </li></ul><ul><li>BS has 48-bit base st...
IEEE 802.16 MAC  – Convergence Sub-Layer (CS) <ul><li>ATM Convergence Sub-Layer: </li></ul><ul><ul><li>Support for VP/VC s...
IEEE 802.16 MAC -- CS – Packet Convergence Sub-Layer <ul><li>Functions: </li></ul><ul><ul><li>Classification: mapping the ...
IEEE 802.16 MAC -- CPS – MAC PDU Format
IEEE 802.16 MAC  -- CPS -- Three Types of MAC PDUs <ul><li>Data MAC PDUs  </li></ul><ul><ul><li>HT = 0 </li></ul></ul><ul>...
IEEE 802.16 MAC -- CPS – Data Packet Encapsulations
IEEE 802.16 MAC – CPS --  MAC Management Connections <ul><li>Each SS has 3 management connections in each direction: </li>...
IEEE 802.16 MAC – CPS  – MAC Management Messages <ul><li>MAC mgmt message format: </li></ul><ul><li>MAC mgmt msg can be se...
IEEE 802.16 MAC – CPS  – MAC PDU Transmission <ul><li>MAC PDUs are transmitted in PHY Bursts </li></ul><ul><li>The PHY bur...
IEEE 802.16 MAC – CPS  – MAC PDU Concatenation
IEEE 802.16 MAC – CPS  – MAC PDU Fragmentation
IEEE 802.16 MAC – CPS  – MAC PDU Packing
IEEE 802.16 MAC – CPS  QoS <ul><li>Three components of 802.16 QoS  </li></ul><ul><ul><li>Service flow QoS scheduling </li>...
IEEE 802.16 MAC – CPS  – Uplink Service Classes <ul><li>UGS: Unsolicited Grant Services </li></ul><ul><li>rtPS: Real-time ...
IEEE 802.16 MAC – CPS  – Uplink Services: UGS <ul><li>UGS: Unsolicited Grant Services </li></ul><ul><ul><li>For CBR or CBR...
IEEE 802.16 MAC – CPS  – Uplink Services: rtPS <ul><li>rtPS: Real-time Polling Services </li></ul><ul><ul><li>For rt-VBR-l...
IEEE 802.16 MAC – CPS  – Uplink Services: nrtPS <ul><li>nrtPS: non-real-time polling services </li></ul><ul><ul><li>For nr...
IEEE 802.16 MAC – CPS  – Uplink Services: BE <ul><li>BE: Best Effort </li></ul><ul><ul><li>For best-effort traffic, e.g., ...
IEEE 802.16 MAC – CPS  – Bandwidth Grant <ul><li>BW grants are per Subscriber Station: </li></ul><ul><ul><li>Allows real-t...
IEEE 802.16 MAC – CPS  – BW Request/Grant Mechanisms <ul><li>Implicit requests (UGS):  No actual requests </li></ul><ul><l...
IEEE 802.16 MAC – CPS  -- Contention UL Access <ul><li>Two types of Contention based UL slots </li></ul><ul><ul><li>Initia...
IEEE 802.16 MAC – CPS  UL Sub-Frame Structure Source: http://www.cygnuscom.com/pdf/WP_PN_Article.pdf
IEEE 802.16 MAC – CPS  – Ranging <ul><li>Ranging is a process of acquiring the correct timing offset, and PHY parameters, ...
IEEE 802.16 MAC – CPS  – Automatic Repeat reQuest (ARQ) <ul><li>A Layer-2 sliding-window based flow control  mechanism. </...
IEEE 802.16 MAC  – Privacy Sub-layer (PS) <ul><li>Two Major Functions: </li></ul><ul><ul><li>Secures over-the-air transmis...
IEEE 802.16 MAC – PS  -- Security Associations <ul><li>A set of privacy information, e.g., encryption keys, used encryptio...
IEEE 802.16 MAC – PS  --  Multi-level Keys and Their Usage <ul><li>Public Key </li></ul><ul><ul><li>Contained in X.509 dig...
IEEE 802.16 MAC – PS  -- Data Encryption <ul><li>Use DES (Data Encryption Standard) in CBC (Cipher Block Chaining) mode wi...
IEEE 802.16 MAC  – one big item is out of scope <ul><li>Scheduler </li></ul>
<ul><li>Questions ?? </li></ul>
References <ul><li>IEEE802.16-2004 </li></ul><ul><li>Alcatel White Paper: WiMAX, making ubiquitous high-speed data service...
IEEE 802.16 MAC – commonly used terms <ul><li>BS – Base Station </li></ul><ul><li>SS – Subscriber Station, (i.e., CPE) </l...
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Wi Max

  1. 1. WiMAX for Broadband Wireless Access By: Karim M. El Defrawy ICS UCI-2005
  2. 2. Outline <ul><li>What is WiMAX </li></ul><ul><li>802.16 Introduction </li></ul><ul><li>802.16 MAC Highlights </li></ul><ul><li>802.16 Reference Model </li></ul><ul><li>MAC Convergence Sub-Layer (CS) </li></ul><ul><li>MAC Common Part Sub-Layer (CPS) </li></ul><ul><li>MAC Privacy Sub-Layer (PS) </li></ul><ul><li>Questions </li></ul>
  3. 3. What is WiMAX? <ul><li>Worldwide Interoperability for Microwave Access (WiMAX) is the common name associated to the IEEE 802.16a/REVd/e standards. </li></ul><ul><li>These standards are issued by the IEEE 802.16 subgroup that originally covered the Wireless Local Loop technologies with radio spectrum from 10 to 66 GHz. </li></ul>
  4. 4. IEEE 802.16 -- Introduction <ul><li>IEEE 802.16 (2001) </li></ul><ul><ul><li>Air Interface for Fixed Broadband Wireless Access System MAC and PHY Specifications for 10 – 66 GHZ (LoS) </li></ul></ul><ul><ul><li>One PHY: Single Carrier </li></ul></ul><ul><ul><li>Connection-oriented, TDM/TDMA MAC, QoS, Privacy </li></ul></ul><ul><li>IEEE 802.16a (January 2003) </li></ul><ul><ul><li>Amendment to 802.16, MAC Modifications and Additional PHY Specifications for 2 – 11 GHz (NLoS) </li></ul></ul><ul><ul><li>Three PHYs: OFDM, OFDMA, Single Carrier </li></ul></ul><ul><ul><li>Additional MAC functions: OFDM and OFDMA PHY support, Mesh topology support, ARQ </li></ul></ul><ul><li>IEEE 802.16d (July 2004) </li></ul><ul><ul><li>Combines both IEEE 802.16 and 802.16a </li></ul></ul><ul><ul><li>Some modifications to the MAC and PHY </li></ul></ul><ul><li>IEEE 802.16e (2005?) </li></ul><ul><ul><li>Amendment to 802.16-2004 </li></ul></ul><ul><ul><li>MAC Modifications for limited mobility </li></ul></ul>
  5. 5. IEEE 802.16 -- Introduction Coverage range up to 50km and speeds up to 70Mbps(shared among users).
  6. 6. IEEE 802.16 -- Introduction Source: WiMAX, making ubiquitous high-speed data services a reality, White Paper, Alcatel.
  7. 7. IEEE 802.16 MAC -- Highlights <ul><li>WirelessMAN: Point-to-Multipoint and optional mesh topology </li></ul><ul><li>Connection-oriented </li></ul><ul><li>Multiple Access: DL TDM & TDMA, UL TDMA;UL OFDMA & TDMA, DL OFDMA & TDMA (Optional) </li></ul><ul><li>PHY considerations that affect the MAC </li></ul><ul><ul><li>Duplex: TDD, FDD, FDX FDD BS and SS, HDX FDD SS </li></ul></ul><ul><ul><li>Adaptive burst profiles (Modulation and FEC) on both DL and UL </li></ul></ul><ul><li>Protocol-independent core (ATM, IP, Ethernet) </li></ul><ul><li>Flexible QoS offering (CBR, rt-VBR, nrt-VBR, BE) </li></ul><ul><li>Strong security support </li></ul>
  8. 8. Reference Model
  9. 9. Adaptive PHY Source: Understanding WiMAX and 3G for Portable/Mobile Broadband Wireless, Technical White Paper, Intel.
  10. 10. Adaptive Burst Profiles <ul><li>Burst profile: Modulation and FEC </li></ul><ul><li>On DL, multiple SSs can associate the same DL burst </li></ul><ul><li>On UL, SS transmits in an given time slot with a specific burst </li></ul><ul><li>Dynamically assigned according to link conditions </li></ul><ul><ul><li>Burst by burst </li></ul></ul><ul><ul><li>Trade-off capacity vs. robustness in real time </li></ul></ul>
  11. 11. Duplex Scheme Support <ul><li>The duplex scheme is Usually specified by regulatory bodies, e.g., FCC </li></ul><ul><li>Time-Division Duplex (TDD) </li></ul><ul><ul><li>Downlink & Uplink time share the same RF channel </li></ul></ul><ul><ul><li>Dynamic asymmetry </li></ul></ul><ul><ul><li>does not transmit & receive simultaneously (low cost) </li></ul></ul><ul><li>Frequency-Division Duplex (FDD) </li></ul><ul><ul><li>Downlink & Uplink on separate RF channels </li></ul></ul><ul><ul><li>Full Duplexing (FDX): can Tx and Rx simultaneously; </li></ul></ul><ul><ul><li>Half-duplexing (HDX) SSs supported (low cost) </li></ul></ul>
  12. 12. IEEE 802.16 MAC – OFDM PHY TDD Frame Structure
  13. 13. IEEE 802.16 MAC – OFDM PHY FDD Frame Structure
  14. 14. FDD MAPs Time Relevance frame Broadcast Full Duplex Capable User Half Duplex T erminal #1 Half Duplex T erminal #2 UPLINK DOWNLINK DL MAP UL MAP DL MAP UL MAP
  15. 15. IEEE 802.16 MAC addressing and Identifiers <ul><li>SS has 48-bit IEEE MAC address </li></ul><ul><li>BS has 48-bit base station ID </li></ul><ul><ul><li>Not a MAC address </li></ul></ul><ul><ul><li>24-bit operator indicator </li></ul></ul><ul><li>16-bit connection ID (CID) </li></ul><ul><li>32-bit service flow ID (SFID) </li></ul><ul><li>16-bit security association ID (SAID) </li></ul>
  16. 16. IEEE 802.16 MAC – Convergence Sub-Layer (CS) <ul><li>ATM Convergence Sub-Layer: </li></ul><ul><ul><li>Support for VP/VC switched connections </li></ul></ul><ul><ul><li>Support for end-to-end signaling of dynamically created connections </li></ul></ul><ul><ul><li>ATM header suppression </li></ul></ul><ul><ul><li>Full QoS support </li></ul></ul><ul><li>Packet Convergence Sub-Layer: </li></ul><ul><ul><li>Initial support for Ethernet, VLAN, IPv4, and IPv6 </li></ul></ul><ul><ul><li>Payload header suppression </li></ul></ul><ul><ul><li>Full QoS support </li></ul></ul>
  17. 17. IEEE 802.16 MAC -- CS – Packet Convergence Sub-Layer <ul><li>Functions: </li></ul><ul><ul><li>Classification: mapping the higher layer PDUs (Protocol Data Units) into appropriate MAC connections </li></ul></ul><ul><ul><li>Payload header suppression (optional) </li></ul></ul><ul><ul><li>MAC SDU (Service Data Unit), i.e, CS PDU, formatting </li></ul></ul>
  18. 18. IEEE 802.16 MAC -- CPS – MAC PDU Format
  19. 19. IEEE 802.16 MAC -- CPS -- Three Types of MAC PDUs <ul><li>Data MAC PDUs </li></ul><ul><ul><li>HT = 0 </li></ul></ul><ul><ul><li>Payloads are MAC SDUs/segments, i.e., data from upper layer (CS PDUs) </li></ul></ul><ul><ul><li>Transmitted on data connections </li></ul></ul><ul><li>Management MAC PDUs </li></ul><ul><ul><li>HT =0 </li></ul></ul><ul><ul><li>Payloads are MAC management messages or IP packets encapsulated in MAC CS PDUs </li></ul></ul><ul><ul><li>Transmitted on management connections </li></ul></ul><ul><li>BW Req. MAC PDUs </li></ul><ul><ul><li>HT =1; and no payload, i.e., just a Header </li></ul></ul>
  20. 20. IEEE 802.16 MAC -- CPS – Data Packet Encapsulations
  21. 21. IEEE 802.16 MAC – CPS -- MAC Management Connections <ul><li>Each SS has 3 management connections in each direction: </li></ul><ul><ul><li>Basic Connection : </li></ul></ul><ul><ul><ul><li>short and time-urgent MAC management messages </li></ul></ul></ul><ul><ul><ul><li>MAC mgmt messages as MAC PDU payloads </li></ul></ul></ul><ul><ul><li>Primary Management connection : </li></ul></ul><ul><ul><ul><li>longer and more delay tolerant MAC mgmt messages </li></ul></ul></ul><ul><ul><ul><li>MAC mgmt messages as MAC PDU payloads </li></ul></ul></ul><ul><ul><li>Secondary Management Connection: </li></ul></ul><ul><ul><ul><li>Standard based mgmt messages, e.g., DHCP, SNMP, …etc </li></ul></ul></ul><ul><ul><ul><li>IP packets based CS PDU as MAC PDU payload </li></ul></ul></ul>
  22. 22. IEEE 802.16 MAC – CPS – MAC Management Messages <ul><li>MAC mgmt message format: </li></ul><ul><li>MAC mgmt msg can be sent on: Basic connections; Primary mgmt connection; Broadcast connection; and initial ranging connections </li></ul><ul><li>41 MAC mgmt msgs specified in 802.16 </li></ul><ul><li>The TLV (type/length/value) encoding scheme is used in MAC mgmt msg, e.g., in UCD msg for UL burst profiles, </li></ul><ul><ul><li>(type=1, length=1, value=1)  QPSK modulation </li></ul></ul><ul><ul><li>(type=1, length=1, value=2)  16QAM modulation </li></ul></ul><ul><ul><li>(type=1, length=1, value=3)  64QAM modulation </li></ul></ul>
  23. 23. IEEE 802.16 MAC – CPS – MAC PDU Transmission <ul><li>MAC PDUs are transmitted in PHY Bursts </li></ul><ul><li>The PHY burst can contain multiple FEC blocks </li></ul><ul><li>MAC PDUs may span FEC block boundaries </li></ul><ul><li>Concatenation </li></ul><ul><li>Packing </li></ul><ul><li>Segmentation </li></ul><ul><li>Sub-headers </li></ul>
  24. 24. IEEE 802.16 MAC – CPS – MAC PDU Concatenation
  25. 25. IEEE 802.16 MAC – CPS – MAC PDU Fragmentation
  26. 26. IEEE 802.16 MAC – CPS – MAC PDU Packing
  27. 27. IEEE 802.16 MAC – CPS QoS <ul><li>Three components of 802.16 QoS </li></ul><ul><ul><li>Service flow QoS scheduling </li></ul></ul><ul><ul><li>Dynamic service establishment </li></ul></ul><ul><ul><li>Two-phase activation model (admit first, then activate) </li></ul></ul><ul><li>Service Flow </li></ul><ul><ul><li>A unidirectional MAC-layer transport service characterized by a set of QoS parameters, e.g., latency, jitter, and throughput assurances </li></ul></ul><ul><ul><li>Identified by a 32-bit SFID (Service Flow ID) </li></ul></ul><ul><li>Three types of service flows </li></ul><ul><ul><li>Provisioned: controlled by network management system </li></ul></ul><ul><ul><li>Admitted: the required resources reserved by BS, but not active </li></ul></ul><ul><ul><li>Active: the required resources committed by the BS </li></ul></ul>
  28. 28. IEEE 802.16 MAC – CPS – Uplink Service Classes <ul><li>UGS: Unsolicited Grant Services </li></ul><ul><li>rtPS: Real-time Polling Services </li></ul><ul><li>nrtPS: Non-real-time Polling Services </li></ul><ul><li>BE: Best Effort </li></ul>
  29. 29. IEEE 802.16 MAC – CPS – Uplink Services: UGS <ul><li>UGS: Unsolicited Grant Services </li></ul><ul><ul><li>For CBR or CBR-like services, e.g., T1/E1. </li></ul></ul><ul><ul><li>The BS scheduler offers fixed size UL BW grants on a real-time periodic basis. </li></ul></ul><ul><ul><li>The SS does not need to send any explicit UL BW req. </li></ul></ul>
  30. 30. IEEE 802.16 MAC – CPS – Uplink Services: rtPS <ul><li>rtPS: Real-time Polling Services </li></ul><ul><ul><li>For rt-VBR-like services, e.g., MPEG video. </li></ul></ul><ul><ul><li>The BS scheduler offers real-time, periodic, UL BW request opportunities. </li></ul></ul><ul><ul><li>The SS uses the offered UL BW req. opportunity to specify the desired UL BW grant. </li></ul></ul><ul><ul><li>The SS cannot use contention-based BW req. </li></ul></ul>
  31. 31. IEEE 802.16 MAC – CPS – Uplink Services: nrtPS <ul><li>nrtPS: non-real-time polling services </li></ul><ul><ul><li>For nrt-VBR-like services, such as, bandwidth-intensive file transfer. </li></ul></ul><ul><ul><li>The BS scheduler shall provide timely (on a order of a second or less) UL BW request opportunities. </li></ul></ul><ul><ul><li>The SS can use contention-based BW req. opportunities to send BW req. </li></ul></ul>
  32. 32. IEEE 802.16 MAC – CPS – Uplink Services: BE <ul><li>BE: Best Effort </li></ul><ul><ul><li>For best-effort traffic, e.g., HTTP, SMTP. </li></ul></ul><ul><ul><li>The SS uses the contention-based BW request opportunities. </li></ul></ul>
  33. 33. IEEE 802.16 MAC – CPS – Bandwidth Grant <ul><li>BW grants are per Subscriber Station: </li></ul><ul><ul><li>Allows real-time reaction to QoS need, i.e., SS may re-distribute bandwidth among its connections, maintaining QoS and service-level agreements </li></ul></ul><ul><ul><li>Lower overhead, i.e., less UL-MAP entries compare to grant per connection </li></ul></ul><ul><ul><li>Off- loading base station’s work </li></ul></ul><ul><ul><li>Requires intelligent subscriber station to redistribute the allocated BW among connections </li></ul></ul>
  34. 34. IEEE 802.16 MAC – CPS – BW Request/Grant Mechanisms <ul><li>Implicit requests (UGS): No actual requests </li></ul><ul><li>BW request messages, i.e., BW req. header </li></ul><ul><ul><li>Sends in either a contention-based BW req. slot or a regular UL allocation for the SS; he special B </li></ul></ul><ul><ul><li>Requests up to 32 KB with a single message Request </li></ul></ul><ul><ul><li>Incremental or aggregate, as indicated by MAC header – </li></ul></ul><ul><li>Piggybacked request (for non-UGS services only) </li></ul><ul><ul><li>Presented in Grant Management (GM) sub-header in a data MAC PDU of the same UL connection </li></ul></ul><ul><ul><li>is always incremental </li></ul></ul><ul><ul><li>Up to 32 KB per request for the CID </li></ul></ul><ul><li>Poll-Me bit </li></ul><ul><ul><li>Presented in the GM sub-header on a UGS connection </li></ul></ul><ul><ul><li>request a bandwidth req. opportunity for non-UGS services </li></ul></ul>
  35. 35. IEEE 802.16 MAC – CPS -- Contention UL Access <ul><li>Two types of Contention based UL slots </li></ul><ul><ul><li>Initial Ranging </li></ul></ul><ul><ul><ul><li>Used for new SS to join the system </li></ul></ul></ul><ul><ul><ul><li>Requires a long preamble </li></ul></ul></ul><ul><ul><li>BW Request </li></ul></ul><ul><ul><ul><li>Used for sending BW req </li></ul></ul></ul><ul><ul><ul><li>Short preamble </li></ul></ul></ul><ul><li>Collision Detection and Resolution </li></ul><ul><ul><li>Detection: SS does not get the expected response in a given time </li></ul></ul><ul><ul><li>Resolution: a truncated binary exponential backoff window </li></ul></ul>
  36. 36. IEEE 802.16 MAC – CPS UL Sub-Frame Structure Source: http://www.cygnuscom.com/pdf/WP_PN_Article.pdf
  37. 37. IEEE 802.16 MAC – CPS – Ranging <ul><li>Ranging is a process of acquiring the correct timing offset, and PHY parameters, such as, Tx power level, frequency offset, etc. so that the SS can communicate with the BS correctly. </li></ul><ul><li>BS performs measurements and feedback. </li></ul><ul><li>SS performs necessary adjustments. </li></ul><ul><li>Two types of Ranging: </li></ul><ul><ul><li>Initial ranging: for a new SS to join the system </li></ul></ul><ul><ul><li>Periodic ranging (also called maintenance ranging): dynamically maintain a good RF link. </li></ul></ul>
  38. 38. IEEE 802.16 MAC – CPS – Automatic Repeat reQuest (ARQ) <ul><li>A Layer-2 sliding-window based flow control mechanism. </li></ul><ul><li>Per connection basis. </li></ul><ul><li>Only effective to non-real-time applications. </li></ul><ul><li>Uses a 11-bit sequence number field. </li></ul><ul><li>Uses CRC-32 checksum of MAC PDU to check data errors. </li></ul><ul><li>Maintain the same fragmentation structure for Retransmission. </li></ul><ul><li>Optional. </li></ul>
  39. 39. IEEE 802.16 MAC – Privacy Sub-layer (PS) <ul><li>Two Major Functions: </li></ul><ul><ul><li>Secures over-the-air transmissions </li></ul></ul><ul><ul><li>Protects from theft of service </li></ul></ul><ul><li>Two component protocols: </li></ul><ul><ul><li>Data encryption protocol </li></ul></ul><ul><ul><li>A client/server model based Key management protocol (Privacy Key Management, or PKM) </li></ul></ul>
  40. 40. IEEE 802.16 MAC – PS -- Security Associations <ul><li>A set of privacy information, e.g., encryption keys, used encryption algorithm </li></ul><ul><li>Three types of Security Associations (SAs) </li></ul><ul><ul><li>Primary SA: established during initial registration </li></ul></ul><ul><ul><li>Static SA: provisioned within the BS </li></ul></ul><ul><ul><li>Dynamic SA: dynamically created on the fly </li></ul></ul><ul><li>Identified by a 16-bit SAID </li></ul><ul><li>Connections are mapped to SAs </li></ul>
  41. 41. IEEE 802.16 MAC – PS -- Multi-level Keys and Their Usage <ul><li>Public Key </li></ul><ul><ul><li>Contained in X.509 digital certificate </li></ul></ul><ul><ul><li>Issued by SS manufacturers </li></ul></ul><ul><ul><li>Used to encrypt AK </li></ul></ul><ul><li>Authorization Key (AK) </li></ul><ul><ul><li>Provided by BS to SS at authorization </li></ul></ul><ul><ul><li>Used to derive KEK </li></ul></ul><ul><li>Key Encryption Key (KEK) </li></ul><ul><ul><li>Derived from AK </li></ul></ul><ul><ul><li>Used to encrypt TEK </li></ul></ul><ul><li>Traffic Encryption Key (TEK) </li></ul><ul><ul><li>Provided by BS to SS at key exchange </li></ul></ul><ul><ul><li>Used to encrypt traffic data payload </li></ul></ul>
  42. 42. IEEE 802.16 MAC – PS -- Data Encryption <ul><li>Use DES (Data Encryption Standard) in CBC (Cipher Block Chaining) mode with IV (Initialization Vector). </li></ul><ul><li>CBC IV is calculated from </li></ul><ul><ul><li>IV parameter in TEK keying info; and </li></ul></ul><ul><ul><li>PHY synchronization field in DL-MAP. </li></ul></ul><ul><li>Only MAC PDU payload (including sub-headers) is encrypted. </li></ul><ul><li>MAC PDU headers are unencrypted. </li></ul><ul><li>Management messages are unencrypted. </li></ul>
  43. 43. IEEE 802.16 MAC – one big item is out of scope <ul><li>Scheduler </li></ul>
  44. 44. <ul><li>Questions ?? </li></ul>
  45. 45. References <ul><li>IEEE802.16-2004 </li></ul><ul><li>Alcatel White Paper: WiMAX, making ubiquitous high-speed data services a reality </li></ul><ul><li>Intel White Paper: Understanding WiMAX and 3G for Portable/Mobile Broadband Wireless </li></ul><ul><li>WiMAX Forum: www.wimaxforum.com </li></ul><ul><li>http://en.wikipedia.org/wiki/WiMax </li></ul>
  46. 46. IEEE 802.16 MAC – commonly used terms <ul><li>BS – Base Station </li></ul><ul><li>SS – Subscriber Station, (i.e., CPE) </li></ul><ul><li>DL – Downlink, i.e. from BS to SS </li></ul><ul><li>UL – Uplink, i.e. from SS to BS </li></ul><ul><li>FDD – Frequency Division Duplex </li></ul><ul><li>TDD – Time Division Duplex </li></ul><ul><li>TDMA – Time Division Multiple Access </li></ul><ul><li>TDM – Time Division Multiplexing </li></ul><ul><li>OFDM – Orthogonal Frequency Division Multiplexing </li></ul><ul><li>OFDMA - Orthogonal Frequency Division Multiple Access </li></ul><ul><li>QoS – Quality of Service </li></ul>

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