#include <BasicSnrEval.h>
Inheritance diagram for BasicSnrEval:
The BasicSnrEval module provides functionality like en- and decapsulation of messages. If you use the standard message formats everythng should work fine. Before a packet is sent some information, e.g. transmission power, can be written to the AirFrame header. If you write your own snrEval, just subclass and redefine the handleUpperMsg function (see description of the function). After receiving a message it can be processed in handleLowerMsgStart. Then it is buffered for the time the transmission would last in reality, and then can be handled again. Again you can redefine the 1. handleLowerMsgStart and 2. handleLowerMsgEnd for your own needs (see description). So, the call of these functions represent the following events: 1. received a message (i.e. transmission startet) 2. message will be handed on to the upper layer (i.e. transmission time is over)
Protected Member Functions | |
virtual void | initialize (int) |
Initialization of the module and some variables. | |
void | handleMessage (cMessage *) |
Called every time a message arrives. | |
virtual double | calcDuration (cMessage *) |
This function calculates the duration of the AirFrame. | |
Handle Messages | |
Functions to redefine by the programmer | |
virtual void | handleUpperMsg (AirFrame *) |
Fill the header fields, redefine for your own needs... | |
virtual void | handleSelfMsg (cMessage *msg) |
Handle self messages such as timer... | |
virtual void | handleLowerMsgStart (AirFrame *) |
Calculate Snr Information before buffering. | |
virtual void | handleLowerMsgEnd (AirFrame *) |
Calculate SnrInfo after buffering and add the PhySnrList to the message. | |
Convenience Functions | |
Functions for convenience - NOT to be modified
These are functions taking care of message encapsulation and message sending. Normally you should not need to alter these but should use them to handle message encasulation and sending. They will wirte all necessary information into packet headers and add or strip the appropriate headers for each layer. | |
void | bufferMsg (AirFrame *frame) |
Buffers message for 'transmission time'. | |
AirFrame * | unbufferMsg (cMessage *msg) |
Unbuffers a message after 'transmission time'. | |
void | sendUp (AirFrame *, SnrList &) |
Sends a message to the upper layer. | |
void | sendDown (AirFrame *msg) |
Sends a message to the channel. | |
void | sendDelayedUp (AirFrame *, double, SnrList &) |
Sends a message to the upper layer; waits delay seconds before sending. | |
void | sendDelayedDown (AirFrame *msg, double) |
Sends a message to the channel; waits delay seconds before sending. | |
AirFrame * | encapsMsg (cMessage *msg) |
Encapsulates a MAC frame into an Air Frame. | |
Abstraction layer | |
Factory function to create AirFrame into which a MAC frame is encapsulated. SnrEval authors should be able to use their own SnrEval packets. The framework does not need to know about them, but must be able to produce new ones. Both goals can be reached by using a factory method.
Overwrite this function in derived classes to use your own AirFrames | |
virtual AirFrame * | createCapsulePkt () |
Create a new AirFrame. | |
Protected Attributes | |
double | bitrate |
a parameter that has to be read in from omnetpp.ini | |
int | headerLength |
double | transmitterPower |
power used to transmit messages | |
int | uppergateOut |
gate id | |
int | uppergateIn |
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Buffers message for 'transmission time'. The packet is put in a buffer for the time the transmission would last in reality. A timer indicates when the transmission is complete. So, look at unbufferMsg to see what happens when the transmission is complete.. 00114 { 00115 // set timer to indicate transmission is complete 00116 TransmComplete *timer = new TransmComplete(NULL); 00117 timer->setContextPointer(frame); 00118 scheduleAt(simTime() + (frame->getDuration()), timer); 00119 }
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This function calculates the duration of the AirFrame. Usually the duration is just the frame length divided by the bitrate. However there may be cases (like 802.11) where the header has a different modulation (and thus a different bitrate) than the rest of the message. Just redefine this function in such a case! Reimplemented in SnrEval80211. 00149 { 00150 double duration; 00151 duration = (double) af->length() / (double) bitrate; 00152 return duration; 00153 }
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Create a new AirFrame.
00161 { 00162 return new AirFrame(); 00163 };
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Encapsulates a MAC frame into an Air Frame. This function encapsulates messages from the upper layer into an AirFrame, copies the type and channel fields, adds the headerLength, sets the pSend (transmitterPower) and returns the AirFrame. 00128 { 00129 AirFrame *frame = createCapsulePkt(); 00130 frame->setName(msg->name()); 00131 frame->setPSend(transmitterPower); 00132 frame->setLength(headerLength); 00133 //FIXME frame->setChannelId(((MacPkt*)msg)->getChannelId()); --MF generally lacks support for channels, that will have to be rectified 00134 frame->encapsulate(msg); 00135 frame->setDuration(calcDuration(frame)); 00136 frame->setSenderPos(myPosition()); 00137 return frame; 00138 }
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Calculate SnrInfo after buffering and add the PhySnrList to the message. Redefine this function if you want to process messages from the channel before they are forwarded to upper layers This function is called right before a packet is handed on to the upper layer, i.e. right after unbufferMsg. Again you can caluculate some more SNR information if you want. You have to copy / create the SnrList related to the message and pass it to sendUp() if you want to pass the message to the decider. Do not forget to send the message to the upper layer with sendUp() For a "real" implementaion take a look at SnrEval
Reimplemented in GilbertElliotSnr, and SnrEval. 00256 { 00257 coreEV << "in handleLowerMsgEnd\n"; 00258 00259 // We need to create a "dummy" snr list that we can pass together 00260 // with the message to the decider module so that also the 00261 // BasicSnrEval is able to work. 00262 SnrList snrList; 00263 00264 // However you can take this as a reference how to create your own 00265 // snr entries. 00266 00267 // Everytime you want to add something to the snr information list 00268 // it has to look like this: 00269 // 1. create a list entry and fill the fields 00270 SnrListEntry listEntry; 00271 listEntry.time = simTime(); 00272 listEntry.snr = 3; //just a senseless example 00273 00274 // 2. add an entry to the SnrList 00275 snrList.push_back(listEntry); 00276 00277 // 3. pass the message together with the list to the decider 00278 sendUp(frame, snrList); 00279 }
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Calculate Snr Information before buffering. Redefine this function if you want to process messages from the channel before they are forwarded to upper layers This function is called right after a message is received, i.e. right before it is buffered for 'transmission time'. Here you should decide whether the message is "really" received or whether it's receive power is so low that it is just treated as noise. If the energy of the message is high enough to really receive it you should create an snr list (SnrList) to be able to store sn(i)r information for that message. Every time a new message arrives you can add a new snr value together with a timestamp to that list. Make sure to store a pointer to the mesage together with the snr information to be able to retrieve it later. In this function also an initial SNR value can be calculated for this message. Please take a look at SnrEval to see a "real" example.
Reimplemented in GilbertElliotSnr, and SnrEval. 00307 { 00308 coreEV << "in handleLowerMsgStart, receiving frame " << frame->name() << endl; 00309 00310 //calculate the receive power 00311 00312 // calculate snr information, like snr=pSend/noise or whatever.... 00313 00314 // if receive power is actually high enough to be able to read the 00315 // message and no other message is currently being received, store 00316 // the snr information for the message someweher where you can find 00317 // it in handleLowerMsgEnd 00318 }
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Called every time a message arrives. The basic handle message function. Depending on the gate a message arrives handleMessage just calls different handle*Msg functions to further process the message. Messages from the channel are also buffered here in order to simulate a transmission delay You should not make any changes in this function but implement all your functionality into the handle*Msg functions called from here.
00078 { 00079 if (msg->arrivalGateId() == uppergateIn) 00080 { 00081 AirFrame *frame = encapsMsg(msg); 00082 handleUpperMsg(frame); 00083 } 00084 else if (msg->isSelfMessage()) 00085 { 00086 if (dynamic_cast<TransmComplete *>(msg) != 0) 00087 { 00088 coreEV << "frame is completely received now\n"; 00089 00090 // unbuffer the message 00091 AirFrame *frame = unbufferMsg(msg); 00092 00093 handleLowerMsgEnd(frame); 00094 } 00095 else 00096 handleSelfMsg(msg); 00097 } 00098 else 00099 { 00100 // msg must come from channel 00101 AirFrame *frame = (AirFrame *) msg; 00102 handleLowerMsgStart(frame); 00103 bufferMsg(frame); 00104 } 00105 }
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Handle self messages such as timer... Define this function if you want to process timer or other kinds of self messages Reimplemented in GilbertElliotSnr, and SnrEval. 00094 {delete msg;};
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Fill the header fields, redefine for your own needs... Redefine this function if you want to process messages from upper layers before they are send to the channel. The MAC frame is already encapsulated in an AirFrame and all standard header fields are set. To forward the message to lower layers after processing it please use sendDown. It will take care of decapsulation and anything else needed Reimplemented in SnrEval. 00234 { 00235 sendDown(frame); 00236 }
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Initialization of the module and some variables. First we have to initialize the module from which we derived ours, in this case ChannelAccess. Then we have to intialize the gates and - if necessary - some own variables. If you want to use your own AirFrames you have to redefine createCapsulePkt function. Reimplemented from ChannelAccess. Reimplemented in GilbertElliotSnr, SnrEval, and SnrEval80211. 00041 { 00042 ChannelAccess::initialize(stage); 00043 00044 coreEV << "Initializing BasiSnrEval, stage=" << stage << endl; 00045 00046 if (stage == 0) 00047 { 00048 uppergateIn = findGate("uppergateIn"); 00049 uppergateOut = findGate("uppergateOut"); 00050 00051 headerLength = par("headerLength"); 00052 bitrate = par("bitrate"); 00053 00054 transmitterPower = par("transmitterPower"); 00055 00056 // transmitter power CANNOT be greater than in ChannelControl 00057 if (transmitterPower > (double) (cc->par("pMax"))) 00058 error("tranmitterPower cannot be bigger than pMax in ChannelControl!"); 00059 } 00060 }
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Sends a message to the channel; waits delay seconds before sending. Just calls sentToChannel from ChannelAccess.
00183 { 00184 sendToChannel((cMessage *) msg, delay); 00185 }
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Sends a message to the upper layer; waits delay seconds before sending. Attach control info to the message and send message to the upper layer. Wait delay seconds before sending.
00198 { 00199 // create ControlInfo 00200 SnrControlInfo *cInfo = new SnrControlInfo; 00201 // attach the list to cInfo 00202 cInfo->setSnrList(list); 00203 // attach the cInfo to the AirFrame 00204 msg->setControlInfo(cInfo); 00205 00206 sendDelayed((cMessage *) msg, delay, uppergateOut); 00207 }
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Sends a message to the channel. Convenience function which calls sendToChannel with delay set to 0.0.
00173 { 00174 sendToChannel((cMessage *) msg, 0.0); 00175 }
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Sends a message to the upper layer. Convenience function which calls sendDelayedUp with delay set to 0.0.
00162 { 00163 sendDelayedUp(msg, 0.0, list); 00164 }
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Unbuffers a message after 'transmission time'. Get the context pointer to the now completely received AirFrame and delete the self message 00214 { 00215 AirFrame *frame = (AirFrame *) msg->contextPointer(); 00216 //delete the self message 00217 delete msg; 00218 00219 return frame; 00220 }
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a parameter that has to be read in from omnetpp.ini
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brief a parameter that has to be read in from omnetpp.ini |
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power used to transmit messages
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gate id
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