Tutorial 9 Solutions

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Tutorial 9 Solutions
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Exercises

• 1. Give the procedures for entering and
  registering for a new SS.
• 2. Suppose SSx has n service flow connections
  with BS. Total how many connections SSx got to
  BS?
• 3. Describe the meanings for DL-Map and UL-Map.
• 4. Describe the concepts of polling ranging
  (initial ranging).
• 5. Can you design the scheduling algorithms using
  Round Robin, Weighted Round Robin or Weighted
  Fair Queuing to schedule the services flows for a
  BS.

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1. Give the procedures for entering and
registering for a new SS.

• Systems must follow a list of procedures for
  entering and registering a new SS.
• A new node to the network. The network entry
  procedures apply only to the PMP topology.
• 1. Scan for a downlink channel and establish
  synchronisation with the BS.
• 2. Perform initial ranging.
• 3. Negotiate basic capabilities.
• 5. Authorise the SS and perform keys exchange.
• 6. Perform registration.
• 7. Establish IP connectivity
• 8. Establish the time of day.

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2. Suppose SSx has n service flow connections
with BS. Total how many connections SSx got to BS?

• Multiple connection can be established for
  multiple service flows
• Higher layer sessions can share the same
  connection
• Connections share the air link

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3. Describe the meanings for DL-Map and UL-Map.

• WiMAX has been called a Demand Assigned Multiple
  Access (DAMA) system.
• The following time instants are used as
  references for timing information for each of
  these two timings
• DL-MAP start of the first symbol (including the
  preamble if present) of the frame in which the
  message was transmitted
• UL-MAP start of the first symbol (including the
  preamble if present) of the frame in which the
  message was transmitted plus the value of the
  Allocation Start Time (whose value is given in
  the UL-MAP message, see below).

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TDD DL/UL-MAP
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FDD DL/UL-MAP
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4. Describe the concepts of polling ranging
(initial ranging).

• Polling BS periodically gives SSs a chance
  (bandwidth and/or time slots) to make bandwidth
  requests
• Ranging BS allocates the SSs time slots to make
  bandwidth requests
• Initial ranging when a node enters a network,
  initial ranging is performed
• Contention based ranging SSs contend random
  access through ranging slot

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5. Can you design the scheduling algorithms using
Round Robin, Weighted Round Robin or Weighted
Fair Queuing to schedule the services flows for a
BS.
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Weighted Fair Queuing

• A generalized Round Robin
• Each flow gets weighted amount of service in each
  cycle