CS3260 Tutorial 6    -    (week Sep 29 – Oct 3)

6A. Suppose the Kranji turf club is considering three betting systems: 1. A Smart terminal that allows users to dial (through wired telephone lines) into Kranji's server and place bets directly without going through an operator; 2. A telebet system where users place bets by talking to operators through telephone calls; 3. A wireless betting system where users place bets directly into Kranji’s server using mobile phones with WAP or GPRS.

a) Compare the benefits of the three alternatives.  

b) From the turf club's point of view, which system has a higher scalability?  Why?

c) Suppose the turf club wants to let customers place bets when they are overseas. Which system is more feasible? Explain your answer.

6B. On September 11, 2002, a typhoon, named Hagupit, struck Hong Kong, and the Hong Kong Observatory hoist the typhoon signal number 8. Under this signal, all students and employees are advised to go home as soon as possible, and public transportations would remain in service for only a limited period. Because most people wanted to make calls to family members/friends/colleagues about the latest typhoon development, the surge in demand for phone calls caused a severe disruption of both fixed and cellular phone services. Read http://www.thestandard.com.hk/thestandard/news_detail_frame.cfm?articleid=34521&intcatid=1 and http://www.thestandard.com.hk/thestandard/news_detail_frame.cfm?articleid=34546&intcatid=1.

a) Why are fixed and cellular phone service quality/connectivity dependent on demand? Given fixed network capacity, how could the telcos prevent such a disruption of service from happening? Suggest a few possible means and explain your answer.

b) Can a packet-switched network alleviate the demand in such a situation? Explain your answer.