Hi Bernard-
Thanks again for another textbook response.
More questions:
<..a fixed amount of bandwidth to each point to point link, independently of the amount of traffic on this link. Point to multipoint transmission has the ability to allocate bandwidth based on the actual demand, so that it increases capacity...>
Is the P-MP bandwidth allocation then more like ethernet, or does it have some QoS capabilities like VBR and CBR?
And does P-P in general have the capability to accomodate bursts, or is it just that WCII may have chosen to limit the P-P bandwidth?
And I'm pretty elementary in my understanding of the P-P/P-MP distinctions, but I have seen reference to P-MP being "digital" relative to P-P. Is P-P analog? Is the main benefit of P-MP that a receiver can retransmit the signal to another non-LOS receiver? Rouhana made the point that P-MP will increase their potential plant by 15-20x, which I uderstood was a function of this non-LOS P-MP capability, presumably sectorized.
<..one for each of the orthogonally phase-shifted modulating waveforms..>
I have understood that using "polarization" techniques (which I'm not sure if this is simple 2D phase shifting or an orthogonal phase shift or something completely different), FDM and WDM systems can double their bandwidth. I know Lucent applies some form of this in their DWDM, and that it is theoretically possible for wireless. Just don't know any specifics.
<..discrete multitone (DMT) and discrete wavelet multitone schemes for ADSL/VDSL are extremely interesting since they come very close to achieving the theoretical capacity of a communication channel...>
My understanding from some DSL engineers is as you suggest, ADSL (both DMT and CAP) pretty closely approach the Shannon channel capacity. With hardware (both ASICs and DSP) implementation soon available for ADSL, is it a short or long wait for adaptation to wireless. And do you see this as a likely R&D direction? And who would be working on stuff like this? MOT? ROK? PCMS?
<..Wireless ATM is one implementation of bandwidth management. However, I am not sure that any standard has yet been put in place..>
Did you see that the radios that LU is fronting to ARTT will use (YURI based, LU OEM'ed) ATM switching?
Thanks again and have a great one Bernard!
Steve |
