Wimax standards and Security The Wimax

Step b: Similarly, ∆d_i2(∆t₂) of MSS_i can be calculated. Thus the movement distance between them is ∆d_i2 − ∆d_i1, and the time

between them is ∆t₂ − ∆t₁ = 10 s.
−−−−−−→

• 
  Step c: The MSS_i drives in the direction of ∆d_i1∆d_i2. Following this direction, the SBS can decide a unique TBS for MSS_i to handover. Details can be found in Ref. 7.
  
• 
  Step d: According to the velocity equation, distance divided by time, we have
  

∆d_i2 − ∆d_{i1 = V}MSS

(7.20)

∆t₂ − ∆t_{1 i}
The average time of velocity MSS_iv(AV) will be

^V¯MSS_i
= ^{VMSSi1 + VMSSi2 + ··· + VMSSix} , x ∈ 1, 2, 3, ... (7.21)

x
By using Equation 7.5 and SBS, we can predict T_HO of MSS_i, denoted as

⁼ i^THO
^{dcell − ∆di2} MSS (7.22)
^V¯MSS_i

• 
  
  ≥ ÷ × −
  Step e: When MSS_i approaches ∆d_HO d_cell h (h 1), SBS requests precoordination to TBS for handover and HO_ID by MOB_BSHO-REQ message, which includes channel quality infor- mation channel identifier (CQICH_ID) assigned to the MSS_i as identification. The ∆d_HO is the boundary h of a macrocell.
  
• 
  Steps f and g: If the resource of TBS is available, TBS will allocate a noncontention-based initial ranging opportunity to the MSS_i. Synchronously, TBS puts fast ranging information element (fast_ranging_IE message) in UL-MAP and responds agreement to SBS by handover (HO) respond (MOB_BSHO-RSP) message, which
  

allocates BSID, physical frequency, DCD, and UCD of TBS. For this precoordination, TBS will hold the request service for 10 s.

• 
  Step h: SBS will prepare precoordination handover message of boundary MSS every 10 s. When MSS requests HO, SBS broadcasts responded agreement message from TBS to MSS_i by the neighbor advertisement (MOB_NBR-ADV) message, which includes BSID, physical frequency, DCD, and UCD of TBS.
  
• 
  Step i: When MSS_i receives the TBS message, MSS_i will immediately send an HO indication (MOB_HO-IND) message, which includes BSID, physical frequency, DCD, UCD, and fast_ranging_IE message of TBS for HO with TBS. If the TBS is available for MSS_i, MSS_i can quickly enter TBS without preceding CDMA-based initial raging by a nonzero value of fast_ranging_IE parameter at MSS_iT_HO in approaching d_cell. The MSS_i will migrate to a new channel in A_TBS.
  

In view of the centralized control handover processes of PHS as shown in Figure 7.4, we can get the service DT for PHS (DT_PHS) during the handover process by
^DTPHS ^{= T}SBS→MSS ^{+ T}SYN ^(7.23)

4.