initial ns-3 lr-wpan module

This is being submitted for potential inclusion to ns-3.18 release cycle.  

This is not a full 802.15.4 model but covers these items for now:

- APIs for PD, PLME, MCPS, MLME, and classes implementing Mac and Phy based on the spectrum architecture
- 802.15.4 header/trailer, and PPDU formats
- CSMA/CA state machine for unslotted operation
- initial phy, error rate, and loss models for 2.4 GHz OQPSK

[Sascha Jopen, 2013-11-05 14:50:04]

Hi,

i started using the lr-wpan code and found that it is missing acknowledgements.
While i am trying to implement this feature, i found some lines of code which i
either do not fully understand, or which are not correct. Because the lr-wpan
module is not part of ns-3-dev, i used this code review to drop my comments.

I'm willing to contribute my future implementation of the ACK feature to this
module.

Regards,
Sascha

https://codereview.appspot.com/8339045/diff/1/src/lr-wpan/model/lr-wpan-mac.cc
File src/lr-wpan/model/lr-wpan-mac.cc (right):

https://codereview.appspot.com/8339045/diff/1/src/lr-wpan/model/lr-wpan-mac.c...
src/lr-wpan/model/lr-wpan-mac.cc:223: //extract the last 3 bits in TxOptions and
map to macHdr
Maybe the "bits" should have symbolic names from an enum like
int b0 = params.m_txOptions & TX_OPTION_ACK;
int b1 = params.m_txOptions & TX_OPTION_GTS;
int b2 = params.m_txOptions & TX_OPTION_INDIRECT;

https://codereview.appspot.com/8339045/diff/1/src/lr-wpan/model/lr-wpan-mac.c...
src/lr-wpan/model/lr-wpan-mac.cc:310: m_mcpsDataConfirmCallback (confirmParams);
MCPS_DATA.confirm with status SUCCESS should be called after successfull
transmission by the PHY, including the acknowlegment, if requested, see Figure
84, page 223 IEEE 802.15.4-2009.

https://codereview.appspot.com/8339045/diff/1/src/lr-wpan/model/lr-wpan-mac.c...
src/lr-wpan/model/lr-wpan-mac.cc:316: if (m_txQueue.empty ())
I think there should be no queuing involved in packet transmission. Only if this
is a PAN coordinator and we received a packet for indirect transmission, the
packet should be put into a transaction queue. Queuing should be done by the
NetDevice if appropriate.

https://codereview.appspot.com/8339045/diff/1/src/lr-wpan/model/lr-wpan-mac.c...
src/lr-wpan/model/lr-wpan-mac.cc:321: Simulator::ScheduleNow
(&LrWpanCsmaCa::Start, m_csmaCa);
Shouldn't we do a PLME-SET-TRX-STATE.request(RX_ON) before starting the CCA?