Post by andito on Jan 28, 2009 10:58:33 GMT -5
To whom it may concern.
I believe this forum consists of different people form different expertise. But we have common interest, that is Telecommunication.
Back to the topic..right now i am making matlab simulation for OFDM based telecommunication standard, Mobile WiMAX, and now i am trying to simulate the effect of interference for the monitored-entity which is formulated in general by equation:
SINR = S/(N+I);
S = EIRP + Tx Antenna Gain + Rx Antenna Gain - System Loss - Pathloss - Noise Figure
I is interference power from other source which is using same frequency as the entity being monitored (in this case whether Base St. or Mobile St.). in general, the derivation of Interference calculation is the same as S but maybe the differ in the value of Pathloss as a result in different range to the entity being monitored.
N is the noise power which is AWGN.
You know, my question is kinda simple and i have no idea at all. Here we go:
1. N is formulated by:
N= (sigma)^2*(B/L)
that (sigma)^2 means power spectrum density of AWGN
B is the bandwidth of operation
L is the OFDM subcarriers being used that is related to B (defined by IEEE standard).
When it comes to direct calculation, what is the value of (sigma)^2?
I read the tutorial written by Charan Langton about link budget and it stated there that noise for No has the power of 2 watt. Is it an assumption or empirical value? Please provide me with the possible value of (sigma)^2 that occurs in cellular communication.
2. In OFDM theory, why does we use the term 'mapping' for modulating OFDM subcarrier with certain modulation like QPSK or QAM? please give me short answer.
Kindly regards,
andito
I believe this forum consists of different people form different expertise. But we have common interest, that is Telecommunication.
Back to the topic..right now i am making matlab simulation for OFDM based telecommunication standard, Mobile WiMAX, and now i am trying to simulate the effect of interference for the monitored-entity which is formulated in general by equation:
SINR = S/(N+I);
S = EIRP + Tx Antenna Gain + Rx Antenna Gain - System Loss - Pathloss - Noise Figure
I is interference power from other source which is using same frequency as the entity being monitored (in this case whether Base St. or Mobile St.). in general, the derivation of Interference calculation is the same as S but maybe the differ in the value of Pathloss as a result in different range to the entity being monitored.
N is the noise power which is AWGN.
You know, my question is kinda simple and i have no idea at all. Here we go:
1. N is formulated by:
N= (sigma)^2*(B/L)
that (sigma)^2 means power spectrum density of AWGN
B is the bandwidth of operation
L is the OFDM subcarriers being used that is related to B (defined by IEEE standard).
When it comes to direct calculation, what is the value of (sigma)^2?
I read the tutorial written by Charan Langton about link budget and it stated there that noise for No has the power of 2 watt. Is it an assumption or empirical value? Please provide me with the possible value of (sigma)^2 that occurs in cellular communication.
2. In OFDM theory, why does we use the term 'mapping' for modulating OFDM subcarrier with certain modulation like QPSK or QAM? please give me short answer.
Kindly regards,
andito