无线Mesh网络路由度量性能分析（AODV/OLSR）及NS2实现咨询

Great question! Let’s tackle your two main concerns one by one to get your wireless Mesh performance analysis up and running.

Absolutely! This combination is not only feasible but also a common approach for evaluating link-quality-aware routing in Mesh networks. Here’s why and how:

• AODV’s Fit for Mesh: As a reactive on-demand routing protocol, AODV works well in dynamic Mesh environments where routes are established only when needed, reducing unnecessary overhead.
• ETX as a Metric: Unlike the default hop-count metric in AODV, ETX (Expected Transmission Count) quantifies the expected number of transmissions needed to send a packet across a link, accounting for both forward and reverse link loss rates. This makes it far more accurate for measuring real-world link quality.

To implement this in NS2:

• Locate the AODV source files (typically in ns-2.x/aodv/, e.g., aodv_rtable.cc, aodv_rqueue.cc, and aodv.cc).
• Modify the route selection and update logic to replace hop-count with ETX:
  • Add code to track MAC-layer ACKs and calculate link loss rates for each neighbor.
  • Compute ETX as 1 / (forward_success_prob * reverse_success_prob) (where success probability = 1 - loss rate).
  • Update the routing table to prioritize paths with lower ETX values instead of fewer hops.
• Use NS2’s built-in tracing tools (like nam or trace file parsing scripts) to analyze key performance metrics: throughput, end-to-end delay, routing overhead, and packet delivery ratio.

It sounds like you’re working with an older or partially incomplete OLSR patch for NS2. Here’s how to resolve this:

• Check the Patch File Structure: First, double-check the downloaded OLSR package—sometimes olsr_parameter.h might be nested in a subdirectory (like olsr/) or renamed (e.g., olsr_params.h). Use find . -name "olsr*.h" in the patch directory to locate it.
• Create the File Manually: If the file truly doesn’t exist, you can create it yourself with standard OLSR protocol parameters. Example content:

#ifndef OLSR_PARAMETER_H
#define OLSR_PARAMETER_H

// Core OLSR timing parameters
#define OLSR_HELLO_INTERVAL 2.0          // Hello message interval (seconds)
#define OLSR_TC_INTERVAL 5.0             // Topology Control message interval (seconds)
#define OLSR_NEIGHBOR_HOLD_TIME (3 * OLSR_HELLO_INTERVAL)  // Neighbor timeout
#define OLSR_TOP_HOLD_TIME (3 * OLSR_TC_INTERVAL)          // Topology entry timeout

// Optional parameters
#define OLSR_WILLINGNESS 3               // Default node willingness (0-7)
#define OLSR_HELLO_WINDOW 0.5            // Hello message jitter window

#endif

• Update Source Code References: Open the OLSR source files (e.g., olsr.cc) and ensure they include your new olsr_parameter.h with #include "olsr_parameter.h". If existing code has hardcoded parameters, move them into this header file for consistency.
• Adjust Makefile Paths: If the compiler still can’t find the header, add its directory to the INCLUDES line in your NS2 Makefile (e.g., -I./olsr if the file is in an olsr subfolder).
• Use a Modern Patch: If possible, switch to an NS2-compatible OLSR patch maintained for your specific NS2 version (e.g., NS2.35 or later)—community-updated patches often fix missing file issues and compatibility gaps.

Hope these steps help you get your experiments up and running smoothly!

内容的提问来源于stack exchange，提问作者Akash Malla