Routing Metrics

The routing metrics for wired networks are

i. Hop-Count- It is related to the total number of hops between two nodes.

ii. Queuing delay- This corresponds to the load of the link ie. the traffic going on in the line.

For wireless networks the metrics are

i. Hop-Count

ii. RTT(Round Trip Time)

iii. Packet Pair

iv. ETx(Expected Transmission Count)

Hop-Count:

Advantages –

o Easy to evaluate

o Simple

o Little Overhead

Performance characteristics of GSM

GSM

 formerly: Groupe Spéciale Mobile (founded 1982)

 now: Global System for Mobile Communication

 Pan-European standard (ETSI, European Telecommunications Standardisation Institute)
 simultaneous introduction of essential services in three phases

(1991, 1994, 1996) by the European telecommunication administrations (Germany: D1 and D2)

 seamless roaming within Europe possible

 today many providers all over the world use GSM (more than 200  countries in Asia, Africa, Europe, Australia, America)

 more than 1.2 billion subscribers in more than 630 networks

 more than 75% of all digital mobile phones use GSM (74% total)

 over 200 million SMS per month in Germany, > 550 billion/year  worldwide

(> 10% of the revenues for many operators)

Performance characteristics of GSM

1. Communication

2. Total mobility

3. Worldwide connectivity

4. High capacity

5. High transmission quality

6. Security functions

-mobile, wireless communication; support for voice and data services

-international access, chip-card enables use of access points of  different providers

-one number, the network handles localization

-better frequency efficiency, smaller cells, more customers per cell

-high audio quality and reliability for wireless, uninterrupted phone calls at higher speeds (e.g., from cars, trains)

-access control, authentication via chip-card and PIN