region discription

1. REGION DESCRIPTION
B.KOHILA
M.SC INFORMATION TECHNOLOGY
NADAR SARASWATHI COLLEGE OF
ARTS&SCIENCE

2. 1. INTRODUCTION
• THE GREAT DEMANDS OF MOBILE SERVICES PROMOTE THE WIDESPREAD
GROWTH OF MOBILE NETWORKS. THESE MOBILE NETWORKS MAY HAVE WIRE
BACKBONE SUCH AS TRADITIONAL MOBILE IP (MIP) NETWORKS, OR WIRELESS
BACKBONE SUCH AS WIRELESS MESH NETWORKS (WMNS). NO MATTER WHICH
NETWORKS, WHEN A MOBILE NODE (MN) ROAMS AMONG DIFFERENT ACCESS
POINTS, THE NETWORK NEEDS TO FIND ITS EXACT LOCATION TO MAINTAIN
THE ONGOING COMMUNICATION(S), WHICH MAKES THE MOBILITY
MANAGEMENT (MM) OF NETWORKS MORE AND MORE IMPORTANT.

3. • MM CONSISTS OF TWO FUNCTIONS: LOCATION AND HANDOFF MANAGEMENT.
LOCATION MANAGEMENT MAINTAINS THE CURRENT LOCATION OF MNS WHILE
HANDOFF MANAGEMENT IS RESPONSIBLE FOR FORWARDING PACKETS TO
MNS AFTER HANDOFF.
• EXISTING MM SCHEMES CAN BE ROUGHLY DIVIDED INTO THREE
CATEGORIES 1: AD HOCROUTING PROTOCOL, THE CENTRALIZED‐DATABASE
MM PROTOCOL, AND MIP. THE FIRST CATEGORY ADOPTS AD HOC ROUTING
PROTOCOL TO RELAY PACKETS HOP BY HOP FROM SOURCES TO
DESTINATIONS.

4. • ON THE OTHER HAND, THE RAPID PROGRESS OF MOBILE NETWORK
CONVERSELY INTENSIFIES THE DEMAND OF MOBILE SERVICES, ESPECIALLY
THE MOBILE MULTICAST SERVICE BECAUSE IT OUTPERFORMS THE BASIC
BROADCAST STRATEGY BY SHARING RESOURCES ALONG COMMON LINKS,
WHILE SENDING MESSAGES TO A SET OF PREDEFINED DESTINATIONS

5. • 2. DUE TO ITS EFFICIENCY AND FLEXIBILITY, MOBILE MULTICAST GAINS A WIDE
SPECTRUM OF APPLICATIONS, SUCH AS VIDEO‐CONFERENCING,
VIDEO‐ON‐DEMAND, STOCK‐QUOTE DISTRIBUTION, AND SO ON. THESE WIDE
APPLICATIONS MAKE MOBILE MULTICAST OBTAIN SIGNIFICANT ATTENTION IN
RECENT YEARS.
• IN FACT, MOBILE MULTICAST IS A CHALLENGING TASK IN THAT IT MUST DEAL WITH
NOT ONLY DYNAMIC GROUP MEMBERSHIP, BUT ALSO DYNAMIC LOCATIONS OF
MEMBERS. TO PROVIDE MOBILE MULTICAST, MIP PROPOSES TWO BASIC SCHEMES:
REMOTE SUBSCRIPTION (RS) AND BI‐DIRECTIONAL TUNNELING (BT) SCHEMES

6. •
• RS REQUIRES AN MN TO RE‐SUBSCRIBE TO ITS DESIRED MULTICAST GROUPS
EVERY TIME IT ENTERS A NEW SUBNET. THEREFORE, RS ALWAYS TRANSFERS
MULTICAST PACKETS ON THE SHORTEST PATHS. HOWEVER, IT INCURS LONGER
MULTICAST SERVICE DISRUPTION TIME AND EXCESSIVE SIGNALING REDUNDANCY
BECAUSE THE FREQUENCY OF MULTICAST TREE RECONFIGURATION IS DIRECTLY
PROPORTIONAL TO THE USER HANDOFF FREQUENCY. THIS SITUATION IS WORSE IN
WMNS BECAUSE THE SCARCE AND POSSIBLY ASYMMETRICAL WIRELESS
BANDWIDTH REQUIRES THE AMOUNT OF CONTROL SIGNALING TO BE LIMITED.

7. • RS REQUIRES AN MN TO RE‐SUBSCRIBE TO ITS DESIRED MULTICAST GROUPS
EVERY TIME IT ENTERS A NEW SUBNET. THEREFORE, RS ALWAYS TRANSFERS
MULTICAST PACKETS ON THE SHORTEST PATHS. HOWEVER, IT INCURS
LONGER MULTICAST SERVICE DISRUPTION TIME AND EXCESSIVE SIGNALING
REDUNDANCY BECAUSE THE FREQUENCY OF MULTICAST TREE
RECONFIGURATION IS DIRECTLY PROPORTIONAL TO THE USER HANDOFF
FREQUENCY. THIS SITUATION IS WORSE IN WMNS BECAUSE THE SCARCE AND
POSSIBLY ASYMMETRICAL WIRELESS BANDWIDTH REQUIRES THE AMOUNT OF
CONTROL SIGNALING TO BE LIMITED.

8. • IN BT, ALL MULTICAST PACKETS AND SIGNALS ARE SENT OR RECEIVED
THROUGH THE TUNNEL BETWEEN THE HOME AGENT (HA) AND THE FOREIGN
AGENT (FA) SERVING FOR MNS. SINCE THIS SCHEME HIDES A USER'S MOBILITY
FROM OTHER MEMBERS OF THE GROUP 5, NO MULTICAST TREE NEEDS TO BE
UPDATED AFTER THE USER HANDOFF. HOWEVER, BT INTRODUCES THE
TRIANGLE ROUTING PROBLEM. THIS CAUSES THE MULTICAST PACKET
DELIVERY PATH TO BE FAR FROM OPTIMAL. THE LONGER THE PACKET
DELIVERY PATH, THE WORSE QUALITY OF SERVICE AN MN RECEIVES
ESPECIALLY IN THE MULTI‐HOP WIRELESS SCENARIO.

9. • IN THESE SCHEMES, THE WHOLE NETWORK IS DIVIDED INTO MULTIPLE
REGIONS. WITHIN EACH REGION, A MOBILE MULTICAST AGENT (MMA) (NOTE:
MMA HAS DIFFERENT NAMES IN DIFFERENT SCHEMES) IS DEPLOYED TO
MANAGE THE MOBILE MULTICAST SERVICES. LIKEWISE, AN MMA ONLY SERVES
THE USERS WITHIN ITS REGION.

10. • IF THE SERVICE RANGE IS SHORTER, THE MULTICAST PACKETS MAY BE
DELIVERED ON A SHORTER PATH. HOWEVER, AS SHOWN IN FIGURE 1 (B), THE
SHORTER SERVICE RANGE, THE SMALLER MHA REGION, AND THUS THE MORE
FREQUENT MHA HANDOFF WOULD HAPPEN, WHICH LEADS TO THE FREQUENT
MULTICAST TREE RECONFIGURATION AND SERVICE DISRUPTIONS.
•

11. • IN ADDITION, ARBMOM CAN ONLY CALCULATE AN APPROXIMATE OPTIMAL
SERVICE RANGE FOR INDIVIDUAL USERS BECAUSE ITS CALCULATION IS
BASED ON THE MOBILITY AND SERVICE CHARACTERISTICS OF AGGREGATE
USERS. HOWEVER, IF AN MN HAS ENOUGH CAPACITY (INCLUDING ELECTRONIC
POWER AND COMPUTATION CAPACITY), IT CAN COMPUTE ACCURATE OPTIMAL
SERVICE RANGE FOR ITSELF ACCORDING TO ITS MOBILITY AND SERVICE
CHARACTERISTICS, THUS OBTAINING EFFICIENT MULTICAST WITH FINER
GRANULARITY.

12. 2. RELATED WORK
• DUE TO THE SHORTCOMINGS OF THE TWO BASIC METHODS—RS AND BT—
MANY EXISTING MOBILE MULTICASTING SCHEMES INTENDED TO IMPROVE THE
SYSTEM PERFORMANCE OF RS AND BT. IN RS, AN MN NEEDS TO
RE‐SUBSCRIBE TO THE FA WHENEVER HANDOFF OCCURS. IN THIS SCENARIO,
THE PACKET LOSS RATE MIGHT BE VARIABLE BETWEEN 1–30% 11. TO REDUCE
THE PACKET LOSS, LITERATURE 12 PROPOSES A MECHANISM PERMITTING AN
OLD AGENT TO DELIVER THE PACKETS THAT AN MN RECEIVED DURING
HANDOFF TO A NEW ONE. A SIMILAR METHOD IS PROPOSED IN REFERENCE 13,
WHICH MAKES THE MN RECEIVE THE MULTICAST PACKETS SOON AFTER
HANDOFF THROUGH THE TUNNEL BETWEEN THE NEW FA AND THE OLD ONE.

13. • BT HAS THE TUNNEL CONVERGENCE PROBLEM. THAT IS, MULTIPLE HAS ALL
HAPPEN TO HAVE MNS BELONGING TO THE SAME MULTICAST GROUP AT THE
SAME FA. THUS ONE COPY OF EACH MULTICAST PACKET WOULD BE
DELIVERED TO THE FA FROM EACH HA, LEADING TO SIGNIFICANT
TRANSMISSION REDUNDANCY. TO SOLVE THE ABOVE PROBLEM,
LITERATURE 18 USES THE CONCEPT OF DESIGNATED MULTICAST SERVICE
PROVIDER (DMSP).

14. 3. OVERVIEW OF DRBMOM
• 3.1. BASIC TERMS
• DRBMOM USES THE CONCEPT OF MHA INTRODUCED IN RBMOM. THE
DIFFERENCE BETWEEN HA AND MHA MAINLY LIES IN TWO‐FOLD: THE FIRST IS
THAT THE FORMER IS NEVER CHANGED FOR A CERTAIN MN, WHILE THE
LATTER IS DYNAMICALLY CHANGED ACCORDING TO THE MN'S LOCATION. THE
SECOND IS THAT THE FORMER IS RESPONSIBLE FOR UNICAST SERVICES
WHILE THE LATTER FOR MULTICAST SERVICES.

15. • DEFINITION 1: OPTIMAL SERVICE RANGE, DENOTED AS KOPT, IS DEFINED AS
THE TUNNEL DISTANCE BETWEEN AN MHA AND AN FA THAT MINIMIZES THE
AVERAGE MULTICAST TREE RECONFIGURATION COST AND THE AVERAGE
MULTICAST PACKET DELIVERY COST. KOPT IS GIVEN BY:(1)
• WHERE K IS THE TUNNEL DISTANCE BETWEEN THE MHA AND THE FA, AND THE
DEFINITION OF IS DEFINED AS FOLLOW:

16. • DEFINITION 2: COST FUNCTION, DENOTED AS , IS DEFINED AS THE SUM OF
AVERAGE MULTICAST TREE CONFIGURATION COST () AND AVERAGE
MULTICAST PACKET DELIVERY COST (). IT IS A FUNCTION OF K:(2)
• THE TERM ‘OPTIMAL SERVICE RANGE’ BRINGS THE FOLLOWING DEFINITION:

17. • 3.2. TWO VERSIONS
• DRBMOM PROVIDES TWO VERSIONS: (I) THE PER‐USER VERSION, NAMED
DRBMOM‐U, AND (II) THE AGGREGATE‐USERS VERSION, NAMED DRBMOM‐A.
THE MOBILITY AND SERVICE CHARACTERISTICS OF AN INDIVIDUAL USER ARE
THE INPUTS IN DRBMOM‐U, WHILE THOSE OF THE AGGREGATE USERS ARE
THE INPUTS IN DRBMOM‐A.

18. 3.3. DATA INFORMATION
• THE DATA INFORMATION OF DRBMOM IS SHOWN IN FIGURE 3, WHICH IS
CREATED REFERRING TO MOM 18 AND RBMOM 5. EACH MHA MANAGES
A MULTICAST GROUP TABLE, AND EVERY MULTICAST GROUP ITEM INVOLVES
THREE LISTS: A MEMBER LIST, AN FA LIST, AND A DMSP LIST. THE MEMBER LIST
RECORDS THE MNS WHO ARE BEING SERVED. THE FA LIST KEEPS TRACK OF
WHERE THE MNS RESIDE. AS RBMOM, DRBMOM ALSO FACES THE TUNNEL
CONVERGENCE PROBLEM.

19. 4. OPTIMAL MHA REGION
• 4.1. COST FUNCTION
• THOUGH HAVING DIFFERENT DATA INFORMATION AND OPERATIONS, TWO
VERSIONS HAVE THE SAME METHOD FOR FINDING THE OPTIMAL MHA REGION,
WHICH IS DETERMINED BY KOPT. TO COMPUTE KOPT, WE MUST
DERIVE BEFOREHAND. IN LIGHT OF FORMULA (2), IS A FUNCTION OF K. IN THE
FOLLOWING, WE FIRST ASSUME THAT THE MHA REGION IS CONFINED BY K,
AND THEN WE WILL FIND THE K THAT MINIMIZES TO OBTAIN KOPT.

20. THANK YOU