didac
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There's a million ways to see the things in life
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manresa,spain
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Hi Vivek, I've worked a little bit with UWB-Impulse Radio systems(using Time-Hopping for multiple access) so maybe I can help a little bit(although maybe you are not in UWB field). The problem you are describing it's more from architectural level than circuit level, detection of pulses it's "the easy part"(although timing synchronization in the matched filter can be quite difficult if you want something more than the detection of a pulse, i.e. maximum energy it's obtained only when the local generated template pulse an the receiver pulse are perfectly synchronized) the problem is the ability to discriminate between desired pulses and "interferences", I think that several approaches are valid: 1)Use an scheme like CSMA(but in this case without carrier):the transceiver don't transmit always, they listen the channel if free they sent,the others listen that somebody it's transmitting and then wait a predefined amount of time(duration of pulse + margin for the echo), it's similar to CSMA-CD in Ethernet wired systems but have the problem of the hidden terminal like in WLAN systems. The approach of WLAN it's CSMA-CA but needs a device that acts as "acces point" and a sequence of RTS/CTS(Request To Sent/Clear to Sent) but it avoids hidden terminal problem. 2)Using a topology Master/Slave where one device controls the others and authorizes for transmission, then the device has a temporal window for sending the train of pulses and listening, after that the master allows the following terminal. 3)Use of CDMA to code the train of pulses, each transceiver will have it's own pseudo-orthogonal sequence(I think Gold sequences are the ones used in 3G systems), this approach complicates the receiver since it's necessary to perform correlation of the whole received sequence and needs a perfect alignment of the the template with the received train end but in theory it's feasible to implement using Pulse-Position Modulation(PPM) where the code it's applied as a variable delay to the position of the pulse inside the chain(0 no delay,1 delay).
As you can see 1) & 2) fall inside what it would be TDMA techniques,3) it's CDMA one.
And I don't know, I will try to scratch my head a little bit more, Hope it helps,
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