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g process itself is optimized by the usage of MPRs, but as explained in section 3.4.3, the MPR technique introduces two link-state declaration optimizations as well. One should notice that more robust routing could be achieved by announcing more than the MPR selector set.

The MPR functionality introduces two optimizations to TC messaging:
Size optimization

The size of TC messages is reduced due to the fact that a node may only declare its MPR selectors in TC messages. The factor of this reduction is related to how dense the network topology is. In a topology as shown in figure 3-2b the TC message size of the center node would be reduced to half the size of a “classical” TC message (not including headers). When using IPv6, a simple example like this reduces a net-wide broadcast message with 64 bytes.
Sender optimization

Nodes that have no links to declare usually do not transmit TC messages. The exception here is nodes that just lost their MPR selectors. These nodes are to generate empty TC messages for a given interval to update the nodes in the MANET.

But except from this special case, if only declaring MPR selectors in TC messages, only nodes selected as MPRs will generate TC messages. Such a reduction in actual transmitted messages greatly reduces the overall overhead of control traffic.

3.7 Route Calculation:

The proposed heuristic for route calculation in RFC3626 is a relatively trivial shortest-path algorithm. It can be outlined as:

1. Add all one hop neighbors registered as symmetric to the routing table with a hop-count of 1.

2. For each symmetric one-hop neighbor, add all two hop neighbors registered on that neighbor that has:
Not already been added to the routing table.
A symmetric link to the neighbor.

These entries are added with a hop-count of two and next-hop as the current neighbor.

3. Then, for every added node N in the routing table with hop-count n = 2 add all entries from the TC set where:
The originator in the TC entry = N
The destination has not already been added to the routing table

New entries are added with a hop-count of n+1 and next-hop as the next-hop registered on N’s routing entry.

4. Increase n with one and do step 3 over until there are no entries in the routing-table with hop-count = n+1 [26].

5. For all entries E in the routing table the MID set is queried for address aliases. If such aliases exist an entry is added to the routing table with hop-count set to Es hop-count, and next-hop set to Es next-hop for every alias address.

Summary

We have seen that OLSR functionality can be divided into three main modules: Neighbor sensing, multipoint relaying and link-state flooding. We have also seen that most control traffic is generated based on the set of repositories maintained by OLSR. These data sets are also updated dynamically based on received control messages.

Figure 3-10 displays an overview of the information repositories in OLSR and their relations to message processing, message generation and route calculation. Received HELLO messages trigger updates in the link set which again triggers updates in the neighbor set, which then again triggers recalculation of the MPR set. The 2 hop neighbor set is also updat本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。