Smart Phone and Next Generation Mobile Computing

386 Smart Phone and Next-Generation Mobile Computing

account both the link layer and network layer accordingly, assuming

the wireless physical layer is properly secured.

6.5.1 Link Layer

Ad Hoc Security

For a MANET application, end-to-end security service can be provided

by authentication and encryption, which in turn rely on lower layer

security protocols to function. IEEE 802.11 WEP is an example of a

link layer security mechanism that unfortunately fails to protect one-

hop communication between a mobile station and an access point.

As discussed earlier, 802.11i has been designed to address the prob-

lem of WEP. Specifically, in the distribution coordination function

(DCF) mode, when a node senses the channel and finds out it is used

by other transmission, ...