MIMO-OFDM Communication System Learning notes (i)

"Note one: Single-carrier and Multicarrier transmission"

MIMO-OFDM technology is the key technology of 3g-lte,wimax communication system and WLAN such as ieee802.11a,ieee802.11n and so on, as a communication dog, these should be knowledge that must be mastered. However, the undergraduate communication course is boring and disconnected from the actual system, in class, the teacher always lists a lot of professional terminology, what is said, but the contact and details of the processing is difficult to speak clearly, coupled with itself as a college slag often skipped classes, so the communication base is obviously not very reliable, Good recently boss in a related course for undergraduates, let me help to write some of the small program to demonstrate in class, take advantage of this opportunity, make up a communication base is also good, the recent intermittent study notes posted here.

I. Single-Carrier transmission

For a typical single-carrier transmission communication system. Consider the channel of bandwidth (w\) \ (h (t) \), through the transmitter and emission filter \ (G_TX (t) \), the transmission symbol \ ({a_n}\) pulse molding, the signal is received, respectively, through the receiver side of the receiver filter, equalizer and detector processing. Order \ (G_{tx} (t) \), \ (G_{rx} (t) \), \ (H^{-1} (t) \) respectively represent the impulse response of the transmit filter, the impulse response of the receiving filter, and the impulse response of the equalizer. The output of the equalizer can be expressed as: \[y (t) =\sum_{m=-\infty}^{\infty}a_mg (T-MT) +z (t) \]
where \ (z (t) \) is additive noise, \ (g (t) \) is the overall impulse response of the system: \[g (t) =g_{tx} (t) *h (t) *g_{rx} (t) *h^{-1} (t) \]
To support the rate of transmit \ (r_s\) symbols per second, the minimum transmission bandwidth required is the Nyquist bandwidth, which is \ (\frac{r_s}{2}\). means that in a single-carrier transmission system, greater transmission bandwidth is required to support higher data rates. Assuming that the equalizer can perfectly compensate for the impact of the channel, and then the signal bandwidth increases with the symbol rate increases, when the signal bandwidth Daewoo wireless channel coherent bandwidth, the link will be affected by multipath fading, resulting in ISI, in general, the use of adaptive equalizer can be processed by the time-varying multipath fading channel caused by the ISI, in addition, As the data rate increases, the complexity of the equalizer increases.
Two. Multi-carrier transmission
In order to overcome the influence of wideband channel frequency selectivity on single carrier transmission, high data rate transmission can be realized by using Multicarrier.
A block diagram of the transmitter and receiver for the OFDM system:

MIMO-OFDM Communication System Learning notes (i)