The PHICH generation is wrong.
HARQ process X is uplink scheduled at TTI n.
At TTI n+4 the eNB receives the data.
At TTI n+8 the eNB sends ACK/NACK on the PHICH.

The problem is that PHICH generation is done after scheduling.
And PHICH generation uses "first_rb" and "n_DMRS" to compute
"ngroup_PHICH" and "nseq_PHICH".

So at TTI n+8 if the eNB has reused the HARQ process X for
a new uplink scheduling the values "first_rb" and "n_DMRS"
may have changed.

We need to use the previous values.

One solution would have been to do PHICH generation before
scheduling. The problem is that "generate_phich_top" does more
than PHICH generation. It has to setup parameters to sort of
"emulate" a DCI0 in case of retransmission scheduled without
DCI0. So part of it has to be done after scheduling. We would
have to split the function.

The simple adopted fix is to store old values of "first_rb"
and "n_DMRS" and use those values in "generate_phich_top".

This fix has only been tested with FDD. TDD may miserably fail.

The case of a CRC == 0 is legal.

After discussion with Raymond, it is also possible to have all
bits at 0 (and so a CRC==0) if there is no transmission and thus
not much energy.

So this hotfix may introduce new problems (false decoding).

A future work is to handle this case properly by not calling the
turbo decoder if there is not enough energy received.

The problem might manifest itself more in the UE part, especially
when it tries to decode MIB and/or SIB (if I understood correctly).

Enhancement 64 phy test



See merge request !46

Conflicts:
	targets/ARCH/EXMIMO/USERSPACE/OCTAVE/txsig.m
	targets/RT/USER/lte-ue.c

- time_meas to measure time spent in scheduling
- timeplot to show nice histograms in realtim of above measurement

The VCD traces have changed. This commit gets in synch
with current status.

The RBs were not marked as used. A later UE downlink scheduling
could use those RBs, messing up everything.

Not sure this is the right place to mark them used. Maybe better
to do it in the "if (!CCE_allocation_infeasible" test.

This hack was probably put in place in an attempt to circumvent
problems solved by previous commits.

As far as I checked (with my knowledge of the day) we can't exhaust
uplink physical bits with ULSCH data bits when there is CQI reporting
at the same time.

To be refined if this idea is proved wrong.

RI bits are present only in some transmission modes.

For aperiodic reporting (the mode we do as of today),
36.213 7.2.1 (release 10) says:

    "RI is only reported for transmission modes 3 and 4,
    as well as transmission modes 8 and 9 with PMI/RI reporting"

This commit activates decoding of RI bits only for transmission
modes 3 and 4. 8 and 9 are not done today (as far as I know).

G was wrongly computed in some places, not taking into account
CQI and RI bits. This commit saves the correct value computed
in ulsch_decoding so we can reuse it in ulsch_decoding_data
(and the like).

Only the file openair1/PHY/LTE_TRANSPORT/ulsch_decoding.c has
been checked. If the computation is done somewhere else the
problem might still exist.