Calculate the WiMAX mesh throughput of NCTUns @ All By Myself

Provided by NCTUns user: janice

The NCTUns simulator adopted a simpler but fairer scheduling design whereby during each bandwidth request (three-way handshake), the node requests for a fixed number of mini-slots. The default setting is 20 mini-slots and is specified in the source file ( ../wimax/mac/mesh/sch/data/scheduler.h, the parameter: REQUEST_SIZE).

Therefore, you can easily calculate the utilized channel bandwidth based on the 1) requested mini-slots size, 2) modulation scheme and 3) the symbol time. Herewith, I present a simple calculation for your reference:

Default Settings in the simulator are the followings:

1) Request_size = 20 mini-slots

2) Modulation scheme = QAM 64, coded at 3/4 coding rate

3) Total mini-slots per frame = 221 mini-slots

4) the Symbol time = 13.8875 us

5) Number of coded bits per symbol time = 1152 (../wimax/phy/channel_coding.cc, the parameter: Ncbps)

For QAM 64 , the raw channel capacity is calculated as :

Raw channel capacity = 1152 bits/symbol time / 13.8875us = 82.952 Mbps

For QAM 64 encoded at 3/4, the raw channel capacity = 82.952 Mbps * 3/4 = 62.214 Mbps.

For QAM 64 encoded at 3/4, 20 mini-slots will utilize a total raw channel capacity of

= (62.241 Mbps/ 221) * 20 = 5.63 Mbps.

The calculated 5.63 Mbps includes the overhead of both the physical layer and MAC layer. As such, the data throughput will be definitely slightly lower than the raw channel capacity.

In order to increase the overall data throughput, you can modify the relevant network parameters as mentioned above.