written 7.8 years ago by
teamques10
★ 64k
|
• modified 7.8 years ago |
Mumbai University > Computer Engineering > Sem6 > Mobile Communication and Computing
Marks: 5M
Year: Dec 2015
|
written 7.8 years ago by
teamques10
★ 64k
|
• modified 7.8 years ago |
| Infrastructure mode | Ad-hoc mode |
|---|---|
| What is it? | |
| In infrastructure mode, the communication occurs only between the wireless nodes and access points (AP) , but not directly between wireless nodes | In ad-hoc mode, each node communicates directly with other nodes, so no access point control is needed. |
| External Communication | |
| Access points acts as a bridge to other wireless/wired network | Nodes in Ad-hoc can communicate if they are within the same range. |
| Physical needs | |
| Physical infrastructure is needed | No physical infrastructure is needed. |
| Complexity | |
| Designing is simple as most of the network functionality lies within AP and client is just a simple machine. | As no central co-ordination exists, we need to use decentralized MAC protocols such as CSMA/CA, with all nodes having same functionality. This shoots up the complexity and cost. |
| When it can’t be used: | |
| It can’t be used in critical situations like disaster relief where no infrastructure is left. | It is not always fully connected as two mobile nodes may temporarily be out of range. |
| Applications | |
| IEEE 802.11 & HIPERLAN2 are based on infrastructure mode. | Bluetooth is a typical ad-hoc network. |
| Channel Access | |
| Most infrastructure based WLAN uses TDMA-based protocols | Most Ad-hoc based WLAN uses contention MAC protocols (e.g. CSMA) |
| Topology | |
| Based on topology, one main advantage is the ability of infrastructure WLANs to provide wired network applications and services | Ad-hoc WLANs are easier to set-up and require no infrastructure |
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