chest=====Channel knowledge is necessary for the detection of symbols in a MIMOreceiver. Knowledge of channel is gained by sending a known trainingsequence. This traininig sequence satisfies certain desired propertiesas given by 1) Jaiganesh Balakrishnan, Markus Rupp, Harish Viswanthan'Optimal Training for Multiple Antenna Systems' 2)C.Fragouli, N. Al-Dhahir,W. Turin 'Training based channel estimation for Multiple Antenna BrodbandTransmissions'. Please refer to them for more technical details.dirac=====Output a single non-zero sample - used to debug a chain.Can set both the amplitude and the position of the sample.energy====== Sums up the square of the input-signal. It doesn't change the samples, so they are just passed along.mapper======This is a PSK and QAM mapper module which allows both to map and to decideon the mappings made. It uses hard decisions, but a nice extension would beto make a module with a soft-output...midamble======== One of the most important modules: in order to be able to decode areceived signal, one has to make an estimation of the channel which isthen used to 'correct' the signal. This module provides a 'midamble' tocreate a well-known series of symbols, and a 'matched_filter', whichtries to recognise the midamble part and correct for the wrongly receivedsignal.ofdm==== A module to compute the Fast Fourier Transform and its inverse, thus enablingOFDM transmission. As the scaling of the output of a OFDM is difficult, thereis a manual scaling-factor that can be chosen by the programmer.rrc=== This is a pulse-shaper, using a root-raised cosine with roll-off factor0.22. At the same time it converts the complex-signal to a real signaland upsamples by a factor of 2. So one complex signal is converted into4 samples. The main application is to prepare the signal for the STM-cards whichtake a real, pass-band signal.rrc_complex===========This module is used to interface the ICS-cards in a fast way. Theoperations done here should be put in the cards FPGA later. For the reception-part, two versions exist: one for an 'optimal'receiver (all samples aligned), another for the ICS-receiver, whichhas the samples all mangled up... There are different possible pulse-shape filters available. You canfind them in the file rrcs.[ch], where you can also add your ownfilters. The following points are important:- The peak has to be in the middle- The filter should cut half the spectrum- The filter should be short, for optimality...snr=== A module to test independently the SNR of the received slot. This is tocompare against the SNR calculated by the matchde_filter. The sending andreveiving module both need an input of the same random-bytes. SNR - measure the signal to noise ratio of a transmitted slot. In order to do this, we send a slot of known random data thatis measured on the other side.stfa==== The STFA implements a framed TDD-transmission. It is THE module in the software-radio. It is responsible for the interaction with the hardwareor the simulator, and allows to define the scheduling of the different slots. This module has x inputs and x outputs which are tied to one antenna.stfa_complex============ The STFA_complex implements a framed TDD-transmission. It is THE module in the software-radio. It is responsible for the interaction with the hardware or the simulator, and allows to define the scheduling of the different slots. This module has x inputs and x outputs which are tied to one antenna. It differs from STFA in that it has complex in- and outputsstfa_ics======== The STFA_ics implements a framed TDD-transmission. It is THE module in the software-radio. It is responsible for the interaction with the hardware or the simulator, and allows to define the scheduling of the different slots. This module has x inputs and x outputs which are tied to one antenna. It differs from STFA in that it has in- and outputs suited for theICS-cards.sic===Successive Interference Cancellation (SIC) :-)sum_symbol_complex================== Sums up complex-signal blocks to one block. For every module connectedit waits for available data, and only processes all data, once all moduleshave something to send.synch===== Before two mobiles can communicate together, they need to have a commontime. This is usually done with a synchronisation-signal sent by onemobile, that is picked up by another, which then synchronises on thissignal. In 3GPP, this is called 'primary synchronisation'. There is one synch_send, but one synch_rcv for each of:- STM-cards- complex-cards (which never existed)- ICS-cards This is due to the different data-structures from each of the cards, andthe fact that the synchronisation is best done on the raw signal...