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					P-MIP:Paging Extensions for
Mobile IP

1.   Introduction
2.   Related work
3.   P-MIP overview
4.   P-MIP design
5.   Performance evaluation
6.   Conclusion
    I .Introduction
   Cellular network
                         시스템 전반에 걸쳐
       Registration     상호보완적으로 작용
       Paging
          Minimize signalling overhead
           Optimize mobility management performance

   Cellular network 사용자의 경우와 같이 Mobile
    IP 사용자
    도 대부분의 경우 actively communicating 상태
    가 아님
     Idle 상태  actively communicating 상태와 Idle
    상태의 구분 필요
    I .Introduction
   What is Paging?
      Procedure that allows a wireless
     system to search for an idle mobile
     host when there is a message
     destined for it, such that mobile
     user does not need to register it’s
     precise location to the system
     whenever it moves
    I .Introduction
    Advantages of Paging
       Reduce signalling Overhead
           Registration, location system database update
       Reduce power consumption of MN
           Idle MN no longer have to register
       Paging은 registration delay를 줄이는 것이 아니
        라 registration
        의 숫자를 줄이는 것임
I .Introduction
   Disadvantages of Paging
       Uncertainty location of MN
           Additional delays with message delivery
       Additional signalling
          System의 성능을 극대화하기 위해 paging과
          registration의 균형을
            맞추는 것이 중요
II. Related work
 Paging area: base station의 group으로 구성
 MSC (Mobile switching center): control base
       Send paging message to all base station in
        same paging area
       Base station broadcasts the paging message
        in its own cell
       Receiving paging response message
       Determine mobile stations accurate location
II. Related work

   Mobile node state
    1.Active mode
      - when MN has recently sent or received IP data
      - Active timer (MN sent or received data에 포함)
    2. Idle mode
      - Active timer expires
    3. Data session
      - packet train안의 packet들이 충분히 가까운 위치
      에 있을 때 Active 상태 유지
III. P-MIP overview
   Extend Mobile IP agent advertisement
       “P bit” [Appendix 4]

   FA
       Set P bit in agent advertisement message
         FA가 paging을 support함
       Set P bit in registration request message
         MN이 paging을 support하는지 알아보기 위함
III. P-MIP overview
   Classification of registration
     MN changes its point of attachment
     registration
     Idle MN moves new paging area
     registration
     Moving within a paging area
     unnecessary of registration
Active MN Operation (a viewpoint of FA)

   MN로 전송되는 packet이 존재시
        HA에서 registered FA로 전송
        ① FA는 MN의 정보를 조사
        ② FA는 MN가 paging을 support 하는지 조사
        ③ FA는 MN의 operational state를 조사
        ④ MN이 active mode 일시 FA는 decapsulates
         packet 후 MN으로
           MN을 forward 함
        ⑤ MN가 idle mode 일시 FA는 paging request
         message를 같은 paging area 안의 모든 FA에 전
         송함과 동시에 자신의 cell 안에 paging request
         message를 broadcast 함
          – MN를 Active mode로 바꾸기 위함
Active MN Operation (a viewpoint of MN)

   ① MN receives paging request message
   ② register with its HA through current FA

   ③ MN receive registration reply message

   ④ MN send paging reply message to FA

    - previous FA에게 Current FA를 통해 자신의 위치 알림

   ⑤ Previous FA가 paging reply message 받으면
    buffered packet을 current FA를 통해 MN로 forward
Example P-MIP scenario
      (an Idle MN’s Movement)

                      Reg reply
        Reg request               MN

PA1                               PA2
          (Page an Idle MN)



(Transmissions from MNs )

PA1                           FA

                            Active MN

                            Idle MN
IV.P-MIP Design
   Paging area construction
   Movement detection
   Registration
   Paging
   Data handling
Paging area construction

   Paging area 구분: unique paging area

    ID (PID) 존재
       Manually by administers
       Or automatically by paging servers

   Two type of paging area
    ① non-overlapping
    ② overlapping paging area
Non-overlapping paging area
Non-overlapping paging area

 A network can only be associated
  with one paging area
 Each paging area has a unique PID
 PID로 page 의 공간을 조절
 FA maintains paging table
       Agent advertisement message에 포함
       주기적으로 broadcasting – PID도 같이
Overlapping paging area
 Overlapping paging area
 Entire list of FA IP addresses in the paging
  area – PID구성
 PID 는 주기적으로 broadcasting 할 필요 없
       PID는 Extended registration reply message를 통
        해 전송됨
   No specific PID value – paging table
       Non-overlapping paging area와의 차이점
Overlapping과 Non-overlapping의 비교
   Non-overlapping PA
       장점
         PID is much shorter
         BW and Power consumed more efficiently

       단점
           PA border 에서 registration traffic이 발생
   Overlapping PA
       장점
           PID가 주기적으로 broadcasting되지 않아 radio
            resource와 MN resource 의 충돌을 제한함
       단점
         PA에 많은 FA 존재시 PID값이 커짐
         모든 MN은 PA내의 모든 FA IP 주소를 알아야함
Movement detection

   Two algorithms
     Agent advertisement message와
      advertisement lifetime을 이용
      - MN가 advertisement lifetime이 expire하기
      전에 새로운 advertisement message를 받지
      못하면 MN는 새 network으로 이동한것을 인지
     Network prefix를 이용
      - MN가새로 받은 agent advertisement
      message의 network prefix를 비교하여 현재
      의 COA와 다를 경우 이동을 감지
Movement detection
-Non overlapping PA case

 MN 가 advertisement life time 이내에 같은
  agent로 부터 새로운 advertisement를 못받은
 Lifetime이 expire되기 전에 새로운 FA로부터
  advertisement를 받은경우
       현재의 PID와 비교하여 같을 경우 – Do nothing
       현재의 PID와 다른경우
        – Idle MN는 immediately register with new FA
       MN는 advertisement message를 받는 즉시 PID를
        - PID가 다를 경우 movement detection
Movement detection
-   overlapping PA case

    MN 가 advertisement life time 이내에 같은
     agent로 부터 새로운 advertisement를 못받은 경
    Lifetime이 expire되기 전에 새로운 FA로부터
     advertisement를 받은경우
        MN checks the source IP address of the new FA
         - PA FA list 와 비교
            New FA주소가 list에 없는 경우 – registration
    MN은 advertisement message를 받는 즉시 new
     FA의 IP address를 체크해야함
        현재의 FA list에 없는경우 새로운 PA로 이동한 것임
   MIP registration
     A MN changes its point of attachment
     A MN registration lifetime is about to expire
     A MN detects current FA has rebooted
   P-MIP registration
       A MN detects it has moved a new paging area
       A MN registration lifetime is about to expire
       A MN detects current FA has rebooted
       A MN is paged and is not on the same network as
        the paging FA
       An idle MN is about to transmit data

   Idle MN는 같은 PA내에서 이동시 registration을
    하지 않으므로 MIP에 비해 signalling을 줄일 수
Performance evaluation

   MIP성능과 P-MIP성능의 비교평가
   Consider only non-overlapping PA
   Signalling cost
       product of the weighted distance the signalling
        message travels and signalling rate
   Unit of cost : weighted hots·pkt/s
   P-MIP is implemented as extentions to the
     ns simulator Mobile IP code
   P-MIP ns source code is available on the Web
 Mobility models

   Assume PA and Cells are square-
   n cells in a PA

 MN picks random location
 MN moves at a speed between 0 and
  max speed
 MN reaches a destination point
 Stops for pause time
 Picks another location and moves again
Analysis Result
   Assume Cellular macro system
     Average perimeter cell size = 4000m
     Maximum MN velocity = 100mph (44.5m/s)
     User density = 200users/km2 (200 users/cell)
   Assume Cellular micro system
     Average perimeter cell size = 400m
     Maximum MN velocity = 20mph (8.9m/s)
     User density = 20 users/cell
   Assume Pico-cellular system
     Average perimeter cell size = 40m
     Maximum MN velocity = 5mph (2.2m/s)
     User density = 2 users/cell
Paging area size
Paging area size
   Benefit of paging is limited
       Small number of cells in PA
   Large number of unnecessary registration
    caused by boundary crossing
   Typical figure for the maximum number of cells
    in PA
    = 50 cells
   49cells 일때 400 weighted hops·pkt/s 에서
    100 weighted hops·pkt/s 으로 감소
Hop weight ratio(Rw)
Mobile node speed
Simulation enviroment
   Using NS simulation
   CBR(Constant Bit Rate) used as traffic source
   Active MN percentage is 5%
   Duration of simulation is 240s
   PA is square-shaped
   One base station supports a FA in each cell
   The number of cells in a PA
     4, 9, 16, 25, 36, 49
   The number of total base station
     8, 18, 32, 50, 72, 98
   Diameter of each cell : distance between two cells
     1000m : 1000m – macro
     100m : 100m – micro
     10m : 10m – pico cellular
Simulation enviroment
   Maximum velocity
       100mph-macro ,20mph-micro, 5mph-pico
   All MN have same HA
   MN position and movement are
    generated randomly
       More than two MNs are in the same cell at
        the same time
       Signalling message may collide
       High signalling cause
       Still comparable with MIP
Simulation results
   PA size – pause time 0
       Fluid flow model과 비슷한 경우
 MNs are confined within two PA
 PA size – pause time 60 = discrete
       MN move less, longer MN remains in the
        same cell
       Fewer cell boundary crossing and
       Less need for paging
Effect of PA size – macro case
Effect of PA size – micro case
Effect of PA size with 60s pase
 – macro case
Effect of data session rate
 P-MIP is backward compatible with MIP
 Inter net service provider have the
  freedom to configure P-MIP
 By carefully selecting suitable system
  (eg. PA, active timer, etc) improve
  system performance
 P-MIP also designed to provide power
  saving at MN