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Modulation & Demodulation in Zigbee



This Model has covered most of the physical layer blocks which is used in Zigbee Protocol.

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In the transmitter, spreading is done using a PN Sequence at chip rate of 2 Mcps and then the spreaded bits are modulated using OQPSK modulator. In the receiver side, OQPSK demodulation is done first,then the spreaded bits are despreaded using the delayed version of PN chip sequence. The delay in transmitted and received bits is 4us.

Required Products Communications System Toolbox
MATLAB release MATLAB 7.12 (R2011a)
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Comments and Ratings (12)
01 Oct 2014 Lorik

Dear Jitesh,

In the receiver, can you please explain to me why you are delaying by 2 samples after the output buffer?

Thank you.

14 Apr 2014 Jitesh

@suryatapa Analag data cannot be given directly to this model. You have to sample it and give it in digital format as this model is working on baseband layer.

@Abiodun First the input data stream is scrambled using the PN sequence at 2Mcps. To scramble, I have converted the bits into bipolar format and then converted it back to unipolar as OQPSK modulator doesnt take bipolar bits as input.

The reverse will followed at receiver. To compare the sequence perfectly, I have added a transport delay block for PN sequence. This is only the physical layer mapping of Zigbee. Is there anything you didnt understand, tell me.

14 Apr 2014 Abiodun

@ Jitesh, nice work you'v done here. please can you offer a brief explanation of the work flow of the model. i will appreciate you.

@ suryatapa, i think one can make use of the -from file- tool box under 'sources' in simulink library.

10 Mar 2014 suryatapa

how to input some analog data instead of the random generator to the model?

09 Jan 2013 Mujahid

Good work...

08 Jan 2013 Jitesh

@Zeeshan & @Mujahid
The 'Assemble 4 bits' block is the same buffer block. I have renamed it in my model for understanding the flow of model. The model runs in R2011a version and higher versions. You can use a normal buffer block of MATLAB version you have instead of 'Assemble 4 bits' block if it isn't working. Just make the buffer output size 4 in the parameter block and rest as it is. I am sure it will work.

08 Jan 2013 Zeeshan

I am reeving this error while running the ZigBee module, please help.

Error in 'Zigbee/Transmitter/Assemble 4 bits': This proxy block was inserted in the model because a block of type 'Buffer' could not be located during model load. Updating or simulating a model containing such a proxy block is not permitted

05 Jan 2013 Mujahid

what is main purpose of Proxy block in receiver and how can we change it with other things?
same for Disassemble Packet in receiver?
Can you explain it Jitesh....
Thanks for support..

27 Nov 2012 Jitesh

You can double click the Zigbee Transmitter Block and receiver block to view the internal structure..

27 Nov 2012 Anisur

How the transmitter and receiver are designed ?
I can't find such block for this simulation.
Where it's located?

09 May 2012 Jitesh

The 'assemble 4 bits' block is same as buffer block in simulink library with output buffer size as 4 . There might be a change in your simulation settings.
This model works on MATLAB 7.12 .

09 May 2012 Francisco Paisana

I don't know why but the "assemble 4 bits" block in the transmitter and the dissamble packet in the reception isn't recognized.

Anyone knows how to solve this?

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