Design of A QoS Guaranteed Power Saving Schedule Algorithm in IEEE 802.16e WMANs

1
Design of A QoS Guaranteed Power Saving Schedule
Algorithm in IEEE 802.16e WMANs
2
Procedure Flow
MSS side
1. Generate and Overlap PSCs
4. Resource Reservation
2. Update QoS Parameters
5. Power Saving Classes De-multiplexing
3. Send MOB-SLP-REQ
6. Reply MOB-SLP-RSP
BS side
3
Generate and Overlap PSCs for Real-Time
Connections

• Generate a Power Saving Class (PSC) for each
  Real-Time service flow
• Assume the bandwidth of each frame is unlimited
• For a connection Fi, define its PSC Ci to be
  Ci.TL1, Ci.TS (unsolicited Grant Interval or
  Polling Interval)/ (frame length) 1 (This
  unsolicited grant interval or polling interval
  come from PI or frame rate)
• If a connection Fj is a rtPS connection, its PSC
  Cj parameters Cj.TL should be 2 because the 1st
  listening frame is for bandwidth request.
• Re-arrange PSCs to increase the whole overlap
• Find the PSC Cn , Cn minCi.TLCi.TS, Ci is
  all PSCs
• For all PSCs Cm, m!n, generate another PSC Cm
  for it (Cns Cn is the same as Cn)

4
Update QoS Parameters to the Serving BS

• If Ci ! Ci, then do following
• Real-time constant bit rate
• Voice with fixed size data traffic (UGS) - min
  reserved traffic rate (MRTR) (original MRTR) x
  (Cm.TLCm.TS)/ (Cm.TLCm.TS) - Unsolicited
  Grant Interval (Cm.TLCm.TS) x (frame length)
  (uplink only)
• E1/T1 application (UGS) (uplink only) - only
  update Unsolicited Grant Interval
  (Cm.TLCm.TS) x (frame length)
• Voice with silence suppression (ertPS)- max
  sustained traffic rate (max voice packet size) x
  1000(ms) / (frame length) /(Cm.TLCm.TS) -
  Unsolicited Grant Interval (Cm.TLCm.TS) x
  (frame length) (uplink only)
• Video (rtPS) (uplink only)- Unsolicited Polling
  Interval (Cm.TLCm.TS) x (frame length)
• Send message to update QoS parameters if needed.

5
Resource Reservation in BS Side

• Resource Reservation for Uplink and Downlink are
  separated
• BS stacks all received PSCs up (each PSC Ci
  starts its listen interval at the 1st frame, then
  sleeps for Ci.TS frames, and then listens again
  starting at the (Ci.TLCi.TS)th frame, .
• Then, estimate the wireless resource and decide a
  Threshold TU (TD) in a frame for the MSS. For
  eg., see the figure below.
• For downlink connections, though a real-time
  connection may declare that it requires more
  resource than it truly requires, BS will not give
  the connection more than what it needs, because
  BS allocates space to the connection when there
  is data for it in the BS-side.

6
Power Saving Classes De-multiplexing

• After step 5, we can get a curve representing the
  wake-up and sleep pattern of the MSS, for
  e.g.,We call it target waveform (Wtarget), which
  is a periodic wave and the cycle
  Tlcm(Ci.TLCi.TS)
• Next, we will divide the curve into several Type
  II PSC curve. The procedure is called Power
  Saving Classes De-multiplexing.

7
Definition Common Multiple Set

• A set of numbers Ss common multiple set C is
  composed of all lcms (lest common multiples) of
  any one or multiple number(s) in S.
• e.g., S1,2,5,7, C1,2,5,7,10,14,35,70

8

• Find the common multiple set C of
  SxxCi.TLCi.TS,i? all indices of input PSCs
  of the MSS and sort C in an increasing order.
• For all xix1, , xS, do
• Divide the target waveform into pieces, the unit
  is xi
• And these pieces and then get the result wi.
  Generate a new PSC CBSi, CBSi.TLCBSi.TSxi,
  CBSi.TLthe number of continuous 1 in the front
  of wi.
• WcurrentWold or CBSi. If WcurrentWold, discard
  CBSi else WoldWcurrent.
• If WcurrentWtarget, return
• If Wcurrent ! Wtarget, W Wtarget- (Wcurrent and
  Wtarget). For each pulse in W, generate a new PSC
  for it.

9
Power Saving Classes De-multiplexing
10
Power Saving Classes De-multiplexing
11

• Exploiting max. delay, arriving packets can be
  accumulated and be transferred at a time before
  the max. delay expires.Thus, the wireless
  interface can sleep longer and has fewer switches
  between ON/OFF.
• To do this, the MSS will adjust each PSC Cms
  parameters (TL and TS) (this modification is
  before step 1).