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802.11 WLAN Data Throughput and Security Overheads

Index

1. Abstract
2. Purpose
3. Theoretical Part
4. Experimental Section
5. Results
6. Discussion
7. Conclusion
8. References
9. Appendix A
10. Appendix B

Abstract

The contents of this report are based upon the structure of the referral assignment in which the network speed and performance testing needs to be performed and executed. As per the provided assignment guidelines the assignment is based upon the theory of the networking and the recent protocols and methodologies. The assignment is divided into two parts, firstly the theoretical part of the assignment is explained where the idea of the referral assignment is explained as how the testing is designed as how it needs to be executed. The section of the purpose elaborates and explains the procedure of the assignment by taking into account the most basic criteria, on which the testing is based, the pictorial representation of the basic model works as add-on feature of the assignment. Next, the principle moves forward to the execution part and the application of what we have learnt has been done. The methodology is modelled in the form of the timing and the delay parameters which has been divided into the different procedure of the tasks. The same principle has been used here which was explained in the previous section. Moreover, the implementation is also supported by the use of certain tools which can be programmed easily and provide the results by performing the test in the way which we have modelled them with the certain block sizes as per the 802.11 protocols. The further depth is explained now.

 The assignment begins with the network explanation and the system testing introduction, where the contents are made by referring the weekly lecture of the wireless network and security. The further part of the assignment explanations about the planning, methodology followed and the practical application of the test procedure, the observations and the outcomes, the final conclusion is the completing parts followed by the references and the data extracted in the appendix.

II. Purpose

Wireless Data Communication Technology

Wireless data communication is a technology which is a part of the communication systems in which the communication between two machines, devices and even robots is done through the wireless system of transmission of the EM waves, called as wireless signals. The network is designed in such a way that the propagation channel is kept wireless in nature, and free from any wires, and thus establishes the communication through the propagation (transmission) of the data in the form of packets of determined sizes (See Ref. 1 & 2).

As communication system is a very broad term which incorporates several entities such as router, Wi-Fi server etc. it is quite a job to cover them all. But on the ground note, the communication system we have implemented is the following mentioned model.

Following the above mentioned communication system where we will be implementing the wireless technique in our work and the execution is done in two phases: 1.) With Security 2.) Without Security. The WLAN system of 802.11a is used for our purpose of this experiment. Also known as the Wi-Fi channel in laymen terms will implement the above shown method of the communication via the different layers of communication.

For the developed system, the system has protocols defined via the IEEE 802.11 standards, which have different parameters, for the above systems as selected by the system protocol, we will take up the bit rates sizes defined as per the model testing tool such as Iperf and Jperf for transmission.

III. Theoretical Part

The theatrical procedure of the testing is taken from the conceptual method of the timing based and the delay of the packet receiving and the transmission of the test. For the easy understanding of the formulation and to avoid confusion, the conventional notations have been replaced with alphabets so that the reader will not get confused.  The procedure is explained as per the concept information and elaborative implementation as explained as follows (See Appendix B).

As per the PPDU frame system of the 802.11a, the protocol has two parts, the PLCP Header, OFDM code, signal and the Data. So as per the working formulation of the network, the average Back off time CW  

(K_.*N)/2

For the transmission delay T _{D_DATA­}, the ACK transmission delay, T_{D_ACK} and the MT are expressed as follows:

T_{D_DATA ­}= T_P +I + T_{H_DATA}

T_{D_ACK} = T_p+I+G

MT = (8*L_DATA)/(T_{D_DATA}+ T_{D_ACK} + 2C + L + M +).

T_DATA is the only useful transmission time in the equations above. Packet delay is defined as the time lapsed between the transmission of a packet and its successful reception. The MD is given by:

                        MD= T_{D_DATA}+ C +T_DIFS +

For the purpose to meet the IEEE standards, we have made the transmission time equals to the ratio of the packet size and the transmission rate:

MD = T_P + I +( 8*H + 8*L_DATA)/(100000*B).

T_{D_ACK} = T_P + I +( 8*L_ACK)/(100000*B).

T_D-DATA = T_P+I+D                                                        *Ceiling = ((16+6+8*H+8L_DATA)/N_DBPS) 

T_{D_ACK} = T_P+I+D                                                                                       *Ceiling = ((16+6+8L_ACK)/N_DBPS)

 

As per the data fixed limit of the packages, the network mathematically exhibits the functions which are increasing and the decreasing function of the data rate. So as per the limiting theorem, which states that:

For a basic access mechanism, the TUL and the DLL exist, independent of the data rate, even when the data rate goes to the level of infinite high, sets fixed for a given payload size and a given set of overhead parameters.

As per the given method:

TUL = (8*L_DATA ) / {2T_P+ 2I +2C +(2*T_DIFS)+(M)+((K*N )/2)}

DLL = T_P+ I+C+ T_DIFS + (K*N )/2)

IV. Experimental Section

According to the described testing procedure, the theoretical approach and perform the testing, we will take up the process in to the two steps as discussed:

1. With Security functionality
2. Without security functionality.

Using the equations of DUL and TTL and substituting the values in them, we have: –

N = 9µsec

M = 16 µsec.

L = 34 µsec.

K=15.

T_P=16 µsec.

I=4 µsec.

T_P=16 µsec.

D=4 µsec.

T= 1 µsec.

Steps of Execution

1. Perform the Iperf testing for the network by establishing the IP network system.
2. Using the command prompt, carry out the testing of the network of the system.
3. Record the data and keep for the observation.
4. Next, perform the testing via the Omni Peek and the Channelizer Spectrum analyser.
5. Record the observations for the above method.
6. Repeat from step 1 the testing by shutting down the 802.11a security protocol in the firewall.

The recording the above mentioned observations perform the theoretical analysis and the data interpretation via the analysis and the graphical methodology.

V. Results

Based upon the experimentation and the testing of the 802.11a based network and the test spectrum analysis data we received, we have the following outputs:

Fig. (Bandwidth Plot)

Fig. (Bandwidth Plot with Security & Spectral analysis of the system)

 

 

Fig. (Speed Testing)

VI. Discussion

So, based upon the above test procedure, the results and the spectrum report of the internet networking which includes the curve of the system are presented. From the above graph outputs, we can see that in the network, the bitrate of security enables system is having a bandwidth of 8110 Mbps at the sender and the 8101 Mbps at the receiver.

Also for the security disabled system, the overall bandwidth observed is 9650 Mbps at the sender and 9711 Mbps at the receiver. The packages size of the transmission maintained were 6.25 Mbps, at the start, and afterwards it was consequently made constant up to 1.12Gbps.the same trend is maintained for the security enabled as well as the security disabled system. The Testing of the system is done by taking into account the network which follows 802.11a protocols. The subsequent Protocols initiated were as per the protocol regulations and as can be observed in the curve as the linearity based curve is established. For the network part of testing the operation is done at particular time slots of 1 second which on subsequent successions has completed a testing time period of 10 seconds. As seen the graph of the upload and download the average value maintained is shown as 1.23Mbps for the network (for upload) and 1.20 Mbps for the other (for download). The power to frequency graph also shows the network response with respect the package input.

As a whole the network has exhibited the theoretical established formula and the expected response of the system network.

VII. Conclusion

So as per the above observations and the methodology, we arrived at the conclusion is that the security enabling feature has a slower speed as the 80.211 security protocol feature has been enabled and various testing algorithms were performed. But as the security functionality is removed, the speed and performance increases which proves the principle of delay, but the security and protection is comprised.

IX. Appendix A

As per the testing performed the data values are mentioned as follows for the security enabled part and the security disabled part. For the above mentioned system testing the values are:

INTERVAL	TRANSFER	BANDWIDTH	RETRY	CWND
0.00-1.00	4.90 MBytes	41.6 Mbits/sec	0	984 KBytes
1.00-2.00	330 MBytes	2779 Mbits/sec	0	65.4 MBytes
2.00-3.00	1.12 GBytes	9639 Mbits/sec	0	72.1 MBytes
0.00-1.00	1.12 GBytes	9655 Mbits/sec	0	72.1 MBytes
1.00-2.00	1.12 GBytes	9655 Mbits/sec	0	72.1 MBytes
2.00-3.00	1.12 GBytes	9655 Mbits/sec	0	72.1 MBytes
3.00-4.00	1.12 GBytes	9655 Mbits/sec	0	72.1 MBytes
4.00-5.00	1.12 GBytes	9655 Mbits/sec	0	72.1 MBytes
5.00-6.00	1.12 GBytes	9655 Mbits/sec	0	72.1 MBytes
6.00-7.00	1.13 GBytes	9646 Mbits/sec	0	72.1 MBytes
7.00-8.00	1.12 GBytes	9648 Mbits/sec	0	72.1 MBytes
8.00-9.00	1.12 GBytes	9650 Mbits/sec	0	72.1 MBytes
9.00-10.00	1.12 GBytes	9640 Mbits/sec	0	72.1 MBytes

 

INTERVAL	TRANSFER	BANDWIDTH	RETRY	CWND
0.00-1.00	4.93 MBytes	41.6 Mbits/sec	0	987 KBytes
1.00-2.00	332 MBytes	2780 Mbits/sec	0	65.2 MBytes
2.00-3.00	1.12 GBytes	9630 Mbits/sec	0	72.1 MBytes
0.00-1.00	1.12 GBytes	9627 Mbits/sec	0	72.1 MBytes
1.00-2.00	1.12 GBytes	9627 Mbits/sec	0	72.1 MBytes
2.00-3.00	1.12 GBytes	9627 Mbits/sec	0	72.1 MBytes
3.00-4.00	1.12 GBytes	9627  Mbits/sec	0	72.1 MBytes
4.00-5.00	1.12 GBytes	9627 Mbits/sec	0	72.1 MBytes
5.00-6.00	1.12 GBytes	9627 Mbits/sec	0	72.1 MBytes
6.00-7.00	1.13 GBytes	9629 Mbits/sec	0	72.1 MBytes
7.00-8.00	1.12 GBytes	9627 Mbits/sec	0	72.1 MBytes
8.00-9.00	1.12 GBytes	9627 Mbits/sec	0	72.1 MBytes
9.00-10.00	1.12 GBytes	9633 Mbits/sec	0	72.1 MBytes

 

X. Appendix B

S. No	Parameter	Formula Notation	Simplified Representation
1.	Control Rate	RACK	A
2.	Data Rate	RDATA	B
3.	Propagation Delay	T	C
4.	transmission time for the Symbol	D	D
5.	Transmission time for the payload	Tp	E
6.	Payload size in bytes	LP	F
7.	ACK Transmission Time	TACK­	G
8.	MAC overhead in bytes	LH_DATA	H
9.	Transmission time of Physical Header	TPHY	I
10.	Transmission time of the Preamble	TP	J
11.	Minimum back off window size	CWmin	K
12.	DIFS time	T DIFS	L
13.	SIFS time	T SIFS	M
14.	A slot time	TSLOT	N

 

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