View source for Aqua-Sim-NG multichannel MAC implementation

== Multichannel MAC implementation ==

* new <code>aqua-sim-mac-multichannel</code> module:

Modified <code>TxProcess</code> and <code>RecvProcess</code> methods of the <code>AquaSimMac</code> base class. Added channel division on N number of subchannels, depending on given bandwidth. By default, the following bandwidth is used and the following subchannels are created:

* bandwidth: 10 - 40 kHz
* step frequency: 3 kHz
* N of subchannels: 10

The following <code>channel_id:frequency</code> map is generated:

&lt;channel_1 : 10 kHz&gt;, &lt;channel_2 : 13 kHz&gt;, …, &lt;channel_10 : 37 kHz&gt;

* modified <code>aqua-sim-phy-cmn</code> module:

Modified <code>recv()</code> method of <code>AquaSimPhyCmn</code> class, which is used for both transmission and reception of the scheduled packet. The modified <code>recv()</code> method has a new argument - frequency, and is executed by upper multichannel-mac module, depending on the selected channel_id.

* modified <code>aqua-sim-channel</code> module:

Modified <code>SendUp()</code> method of <code>AquaSimChannel</code> class. Now this method gets a frequency value of the incoming packet, using <code>AquaSimPacketStamp</code> class and inserts it into the <code>::Recv()</code> method of the <code>AquaSimPhyCmn</code> upon execution in the Scheduler.

== Initial tests ==

For the initial tests the following simulation scenario was used:

“node_1 (sender)” &lt;— 10m distance —&gt; “node_2 (sink)”

The following stack was used on both nodes: - OnOffApplication — OffTime: 0, OnTime: 1 - Routing — Dummy (for MAC layer testing) - MultichannelMac — default bandwidth (10 - 40 kHz), 10 subchannels, 3kHz frequency step - PhyCmn — modified PhyCmn module

Some other parameters: - Simulation time: 10 seconds - Transmission range: 100 meters (for Phy module) - Distance: 10 meters (Mobility model)

In all tests a throughput was measured by defining an application data rate, higher than possible capacity of the given channel:

'''80 kbps''' <code>dataRate</code> parameter of <code>OnOffApplication</code>. Thus, the throughput was measured by counting a total amount of received packets:

throughput = total_received_packets * packet_size * 8 / 10, [bps]

where: 10 - simulation time, seconds.

=== 1-st test ===

A single channel was used during entire simulation. - channel_id: 1, frequency: 10 kHz.

The throughput was measured, depending on varying packet length. The result is plotted on Fig.1.

[[File:throughput_1_channel.png]] Fig.1

Corresponding sent/received packet count is illustrated on Fig.2.

[[File:packet_count_1_channel.png]] Fig.2


=== 2-nd test ===

During the simulation, various channels were used in the following “round-robin” way:

* 1_packet: channel_1 (10kHz)
* 2_packet: channel_2 (13kHz)
* 3_packet: channel_3 (16kHz)
* 4_packet: channel_4 (19kHz)
* 5_packet: channel_5 (22kHz)
* 6_packet: channel_6 (25kHz)
* 7_packet: channel_7 (28kHz)
* 8_packet: channel_8 (31kHz)
* 9_packet: channel_9 (34kHz)
* 10_packet: channel_11 (37kHz)
* 11_packet: channel_1 (10kHz)
* …. etc.

The throughput is plotted on Fig.3.

[[File:throughput_n_channels.png]] Fig.3

Corresponding sent/received packet count is illustrated on Fig.4.

[[File:packet_count_n_channels.png]] Fig.4

Code of simulation script can be found here:

[https://github.com/dugdmitry/aqua-sim-ng/blob/master/examples/multichannel_mac_example.cc multichannel_mac_example.cc]