WARP APIs: rtsctsMac.c File Reference

#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include "xparameters.h"
#include "xutil.h"
#include "ofdm_pktdetector_mimo_regMacros.h"
#include "warp_timer_regMacros.h"
#include "ofdm_txrx_mimo_regMacros.h"
#include "warpmac.h"
#include "warpphy.h"
#include "rtsctsMac.h"
#include "rtsctsTest.h"
#include "ascii_characters.h"

Go to the source code of this file.


Enumerations
enum
	MAC/NAV states.
enum
	packet types and MAC states
enum
	packet counter array indices
Functions
void	unlockRXantenna ()
	enables antenna selection diversity after setting SISO antenna to A (to ensure that transmissions are initiated from antenna A)
void	lockRXantenna ()
	locks onto the last selected antenna disables antenna selection diversity and checks the gains assigned by the AGC to determine which antenna to use
void	loadCSI (unsigned char *newCSI)
	test function for loading CSI into CTS packet buffer 3 this will eventually be done by the PHY
void	updateTimer (unsigned char type, unsigned int newTime)
	timer management function Handles setting and updating the timers
int	rtsmac_timer_callback (unsigned char unused)
	Callback for the expiration of timers.
void	dropPacket ()
	Drops the ethernet packet waiting to be sent Reenables ethernet reception.
int	rtsmac_emacRx_callback (Xuint32 length, char *payload)
	Callback for the reception of Ethernet packets This function is called by the ethernet MAC drivers when a packet is available to send. If the packet is addressed to a specific IP address, this function translates that IP address into a MAC address using the routeTable, completes the headers of the RTS and data packets, and calls initTX. If the packet is to be broadcast, sendBCD is called.
void	initTX ()
	Initiate a packet exchange sequence The sequence begins with an RTS if the data packet length exceeds the RTS/CTS threshold or with the data packet if not. The packet is dropped if the maximum resend count has been reached. If a carrier is sensed, a backoff timer is set. Once the timer ends, the communication will be retried. After sending a packet, this function sets a timeout for receiving the response.
void	sendCTS (Macframe *packet)
	Send Clear To Send packet over the PHY checks NAV state to determine whether channel is reserved Channel state information should be in TxBuffer 3.
void	sendDAT ()
	Send a data packet over the PHY.
void	sendBCD ()
	Broadcast a data packet Verifies that the channel is not reserved or busy before transmitting.
int	rtsmac_phyRx_badHeader_callback ()
	Callback for the reception of bad wireless packets.
int	rtsmac_phyRx_goodHeader_callback (Macframe *packet)
	Callback for the reception of good wireless packet headers This interrupt service routine is called when a packet header is detected, allowing a reduction in the turn-around time of the response packet. This is accomplished by completing the response packet header and loading it into the PHY before the rest of the incoming packet is received, letting us send the response as soon as possible.
int	main ()
	Main function.
void	initFeedback ()
	Set up RTS/CTS MAC to send per subcarrier antenna selection feedback. Feedback is sent in the CTS packet payload and is used only in transmitting data packets.
void	initDelays ()
	Define transmit, inter-frame, and timeout times.
void	initAddresses ()
	Set up addresses and routing table.
void	initHeaders ()
	Set up headers for each packet type.
void	rtsmac_left ()
	Left push-button handler decrease transmitter gain.
void	rtsmac_middle ()
	Middle push-button handler print state variables.
void	rtsmac_right ()
	Right push-button handler increase transmitter gain.
void	rtsmac_up ()
	Up push-button handler toggle between RTS/CTS and ordinary CSMA/CA by moving the rtsThreshold.
void	printState ()
	display status of the node
void	clearPktCtr ()
	clear packet counter arrays
void	printStatistics ()
	display packet counts TX - transmitted packets RX_good - received good packet RX_unexp - good packet received when a different type of packet was expected RX_bad - received bad packet
Variables
struct {
Macframe rx
	received packet
Macframe rts
	Request To Send.
Macframe cts
	Clear To Send.
Macframe dat
	DATa.
Macframe ack
	ACKnowledgement.
Macframe bcd
	BroadCast Data.
}	pkt
	packet headers
struct {
unsigned short slot
	backoff time increments
unsigned short SIFS
	time between adjacent symbols within a packet exchange sequence, used only for timer calculations
unsigned short DIFS
	time the channel must be idle to begin a packet exchange
unsigned short EIFS
	time the channel must be idle to begin a packet exchange after receiving a bad packet
unsigned short header
	header transmission time
unsigned short transmit [5]
	transmission times for each of the packet types (not all are used)
unsigned short timeout [5]
	timeouts for receiving each of the packet types (not all are used)
}	delay
	inter-frame delays, packet transmission times, and packet timeouts
unsigned int	pktCtr [4][7]
	packet counters
struct {
unsigned char antA [8]
	set all subcarriers to antenna A
unsigned char antB [8]
	set all subcarriers to antenna B
unsigned char half [8]
	enable the first half of subcarriers on A and last half on B
unsigned char otherhalf [8]
	enable the first half of subcarriers on B and last half on A
unsigned char alternating [8]
	enable odd subcarriers on A, even on B
unsigned char * current
	pointer to currently used csi
}	csi
	channel state information
const unsigned char	modMasks [64]
	modulation masks for each subcarrier
const unsigned char	modFlags [64]
	flags indicating which subcarriers are used for data
struct {
unsigned short rtsThreshold
	packets with payload shorter than rtsThreshold are sent without RTS/CTS handshake
unsigned char feedback_en
	enable sending of CSI in the CTS packet
unsigned char mac
	MAC state; idle or indicates the type of packet that we expect to receive.
unsigned char chan
	wireless channel number (1-14)
unsigned char currentAnt
	current antenna; 0 - antenna A, 1 - antenna B
unsigned char myID
	index to the routing table that identifies this node
unsigned char GPIOval
	state of the general purpose IO pins (for debugging)
const unsigned char baseRate
	modulation for base rate symbols
const unsigned char fullRate
	modulation for full rate symbols
const unsigned char csiLength
	number of bits of CSI
struct {
unsigned short rts
	RTS packet resend limit.
unsigned short dat
	data packet resend limit
} maxResend
	resend limits
struct {
unsigned char my [6]
	MAC address of this node.
const unsigned char bc [6]
	broadcast MAC address
const unsigned char net [4]
	network IP address
} addr
	addresses
struct {
unsigned char addr [6]
} routeTable [16]
	Routing table with agreed-upon mapping between dip-switches and physical addresses.
}	state
	struct for RTS/CTS MAC state variables

Detailed Description

The RTS/CTS MAC is able to look at IP addresses in the ethernet packets that it receives and address those packets to a corresponding MAC address. Ethernet packets that are sent to broadcast addresses or that are unrecognized are sent directly over the PHY with no RTS, CTS, or ACK.

The RTS, CTS, and data packets carry information about how long the current exchange will take to finish, so that other nodes hearing any of those packets can defer until the end of the exchange, preventing them from interfering with the exchange. This is accomplished by setting a network allocation vector (NAV) timer.

Setup: The each node must have an IP address whose first three bytes match the net address (state.addr.net) and last byte matches the node ID (setting of the dip switches). (Since the last number of the IP address cannot be 0, the node ID cannot be 0 either). Each node's mac address must also match the routeTable entry corresponding to its node ID (routeTable[myID].addr[]).

Function Documentation

void loadCSI ( unsigned char * newCSI )

test function for loading CSI into CTS packet buffer 3 this will eventually be done by the PHY

Parameters:

newCSI

Pointer to array of channel state information

Definition at line 311 of file rtsctsMac.c.

References controlStruct, NUM_HEADER_BYTES, state, and warpphy_getBuffAddr.

Referenced by sendCTS().

int main ( )

Main function.

This function configures MAC parameters, enables the underlying frameworks, and then loops forever.

Definition at line 703 of file rtsctsMac.c.

References BACKOFF, clearPktCtr(), csi, GHZ_2, initAddresses(), initDelays(), initHeaders(), NAV, pkt, rtsmac_emacRx_callback(), rtsmac_left(), rtsmac_middle(), rtsmac_phyRx_badHeader_callback(), rtsmac_phyRx_goodHeader_callback(), rtsmac_right(), rtsmac_timer_callback(), rtsmac_up(), state, TIMEOUT, warp_timer_setMode(), warpmac_enableCSMA(), warpmac_enableEthernet(), warpmac_init(), warpmac_leftHex(), warpmac_pollEthernet(), warpmac_setBadHeaderCallback(), warpmac_setBaseRate(), warpmac_setEmacCallback(), warpmac_setGoodHeaderCallback(), warpmac_setLeftButtonCallback(), warpmac_setMiddleButtonCallback(), warpmac_setRightButtonCallback(), warpmac_setRxBuffer(), warpmac_setTimerCallback(), warpmac_setTxBuffer(), warpmac_setUpButtonCallback(), and warpphy_setChannel().

int rtsmac_emacRx_callback	(	Xuint32	length,
		char *	payload
	)

Callback for the reception of Ethernet packets This function is called by the ethernet MAC drivers when a packet is available to send. If the packet is addressed to a specific IP address, this function translates that IP address into a MAC address using the routeTable, completes the headers of the RTS and data packets, and calls initTX. If the packet is to be broadcast, sendBCD is called.

Parameters:

	length	Length, in bytes, of received Ethernet frame
	payload	Pointer to Ethernet payload.

Definition at line 423 of file rtsctsMac.c.

References delay, initTX(), pkt, pktCtr, sendBCD(), state, UTime::uint16, UTime::uint8, warpmac_disableEthernet(), and warpmac_prepPhyForXmit().

Referenced by main().

int rtsmac_phyRx_goodHeader_callback ( Macframe * packet )

Callback for the reception of good wireless packet headers This interrupt service routine is called when a packet header is detected, allowing a reduction in the turn-around time of the response packet. This is accomplished by completing the response packet header and loading it into the PHY before the rest of the incoming packet is received, letting us send the response as soon as possible.

Parameters:

packet

Pointer to received header

Definition at line 600 of file rtsctsMac.c.

References BACKOFF, BADPACKET, controlStruct, Maccontrol::currBackoff, GOODPACKET, Macframe::header, INCOMPLETE, NAV, pkt, pktCtr, phyHeader::pktType, phyHeader::reserved1, phyHeader::reserved2, phyHeader::reserved4, rtsmac_phyRx_badHeader_callback(), sendCTS(), sendDAT(), phyHeader::srcAddr, state, TIMEOUT, UTime::uint16, UTime::uint8, unlockRXantenna(), updateTimer(), warp_timer_isActive(), warp_timer_stop(), warpmac_addressedToMe(), warpmac_enableEthernet(), warpmac_finishPhyXmit(), warpmac_incrementLEDHigh(), warpmac_prepEmacForXmit(), warpmac_prepPhyForXmit(), warpmac_startEmacXmit(), warpmac_startPhyXmit(), and warpphy_pollRxStatus().