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The Secret of Multipoint Relay: Why OLSR Can Optimize Your Mobile Network?
In today's digital era, the demand for mobile networks has increased dramatically with the popularity of smart devices. Optimized Link State Routing Protocol (OLSR), as a proactive routing protocol, is specially designed for mobile ad hoc networks and provides an efficient data transmission solution. OLSR is not only suitable for mobile ad hoc networks, but can also be adapted to other wireless ad hoc networks. This article will explore the working principle, characteristics and application of OLSR in modern networks.
How OLSR works
The OLSR protocol uses "Hello" and topology control (TC) messages to discover and disseminate link status information, allowing each node to obtain routing information from all other nodes in the network. Each node uses this topology information to calculate the next hop destination and forward data with the shortest number of hops.
"The operation of OLSR relies on multi-point relay (MPR) technology, which gives it unique advantages in wireless ad hoc networks."
Features of OLSR
Unlike other link state routing protocols (such as OSPF and IS-IS), OLSR optimizes the dissemination process of topology information in wireless ad hoc networks. OLSR discovers 2-hop neighbor information through the Hello messages of each node, and then distributes the selected multi-point relay (MPR) nodes to forward the message. The selection of MPR nodes ensures that every 2-hop neighbor has a reachable path.
"OLSR has made compromises in improving reliability and efficiency, but this is its major advantage in a wireless environment."
Advantages of OLSR
Because OLSR is a proactive protocol, the paths to all destinations are known before use, avoiding the delay problem of route discovery. This is quite convenient for some systems and network applications. Even though routing overhead is relatively large, its overhead does not increase significantly as more routes are created. In addition, through HNA messages, OLSR's network routes can also be easily injected into the system, which is difficult to achieve with other reactive protocols.
Challenges of OLSR
Although OLSR excels in many aspects, it also faces some criticism. One of them is the shortcomings of OLSR in link quality perception. The original definition of OLSR assumes that the link is either normal or failed, which is not completely true in real wireless networks. To make up for this shortcoming, the open source OLSRd implementation has begun to include link quality monitoring.
"OLSR requires relatively large bandwidth and computing resources, which does not cause problems in small-scale wired networks."
Message passing of OLSR
OLSR finds one-hop and two-hop neighbors through "Hello" messages and selects their MPRs based on the optimal path. These MPR nodes further use Topology Control (TC) messages to communicate neighbor information. In this way, OLSR ensures that each node in the network can obtain its surrounding topology information in real time.
The future of OLSR and other solutions
In the ever-changing wireless network environment, OLSR is not the only solution. Many researchers are exploring whether a completely new protocol is needed, or whether the existing OSPF can be extended to support wireless interfaces. Although OLSR has advantages in efficiency, keeping the network silent seems more attractive in bandwidth- and energy-constrained environments.
OLSR version 2
In April 2014, the IETF released OLSR version 2, a standards tracking protocol that maintains the multipoint relay selection and information dissemination features of the original version. Its main changes are flexibility and modular design, providing common components for the next generation IETF MANET protocol.
Experimentation and implementation
Implementations of OLSR are available on a variety of platforms, including Linux, Windows, and Mac OS X, and there are multiple open source projects dedicated to its continuous improvement and application. Whether in academia or industry, OLSR has demonstrated its application potential in wireless ad hoc networks.
Ultimately, whether OLSR can truly become a mainstream solution for future wireless networks depends on its performance in different environments?
