Routing

Challenges and Requirements

Major challenges

  • Mobility – path breaks, packet collisions, transient loops.

  • Bandwidth constraint – channel shared by all nodes in the broadcast region.

  • Error-prone and shared channel – take into account the larger BERs in wireless ad-hoc.

  • Location-dependent contention – high when the number of nodes increases.

Major requirements

  • Minimum route acquisition delay.

  • Quick route reconfiguration (handle path breaks).

  • Loop-free routing (avoid waste of resources).

  • Distributed routing approach (reduce the bandwidth consumed).

  • Minimum control overhead (bandwidth, collisions).

  • Scalability (scale with a large network – minimize control overhead).

  • Provisioning of QoS (provide QoS levels) - support for time-sensitive traffic.

  • Security and privacy (resilient to threats and vulnerabilities).

Proactive and Reactive Protocols

Which approach achieves a better trade-off depends on the traffic and mobility patterns.

Proactive protocols

  • Always maintain routes.

  • Little or no delay for route determination.

  • Consume bandwidth to keep routes up-to-date.

  • Maintain routes that may never be used.

Reactive protocols

  • Lower overhead since routes are determined on demand.

  • Significant delay in route determination.

  • Employ flooding (global search).

  • Control traffic may be bursty.

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