wlan_inoise.ps.c

calculate the noise in th wireless

/* wlan_inoise.ps.c */                                                       
/* WLAN interference noise model for radio link Transceiver Pipeline */

/****************************************/
/*		  Copyright (c) 2007		*/
/*		by OPNET Technologies, Inc.		*/
/*		(A Delaware Corporation)		*/
/*	7255 Woodmont Av., Suite 250  		*/
/*     Bethesda, MD 20814, U.S.A.       */
/*			All Rights Reserved.		*/
/****************************************/

#include "opnet.h"
#include "jammers.h"

#if defined (__cplusplus)
extern "C"
#endif
void
wlan_inoise_mt (OP_SIM_CONTEXT_ARG_OPT_COMMA Packet * pkptr_prev, Packet * pkptr_arriv)
	{
	int			arriv_match, prev_match;
	double		prev_rcvd_power, arriv_rcvd_power;
	
	
	/** Evaluate a collision due to arrival of 'pkptr_arriv'	**/
	/** where 'pkptr_prev' is the packet that is currently		**/
	/** being received.											**/
	FIN_MT (wlan_inoise (pkptr_prev, pkptr_arriv));

	/* If the previous packet ends just as the new one begins, this is not	*/
	/* a collision (just a near miss, or perhaps back-to-back packets).		*/ 
	if (op_td_get_dbl (pkptr_prev, OPC_TDA_RA_END_RX) != op_sim_time ())
		{
		/* Increment the number of collisions in previous packet. */
		op_td_increment_int (pkptr_prev, OPC_TDA_RA_NUM_COLLS, 1);

		/* Increment number of collisions in arriving packet. */
		op_td_increment_int (pkptr_arriv, OPC_TDA_RA_NUM_COLLS, 1);

		/* Determine if previous packet is valid or noise. */
		prev_match = op_td_get_int (pkptr_prev, OPC_TDA_RA_MATCH_STATUS);
		
		/* Determine if arriving packet is valid or noise. */
		arriv_match = op_td_get_int (pkptr_arriv, OPC_TDA_RA_MATCH_STATUS);
	
		
		/* if the current packet is a WLAN and we already marked a jammer packet */
		/* as valid, then mark the previous jammer packet as noise				 */
		if ((op_pk_encap_flag_is_set (pkptr_prev, OMSC_JAMMER_ENCAP_FLAG_INDEX) == OPC_TRUE)
			&& prev_match == OPC_TDA_RA_MATCH_VALID && arriv_match == OPC_TDA_RA_MATCH_VALID)	
			{
			/* The previous packet (jammer)  will be dropped in wlan_ecc;  */
			/* Indicate previous match is noise to prevent unnecessary	   */
			/* computation below										   */
			prev_match = OPC_TDA_RA_MATCH_NOISE;
			
			/* use a special TDA to indicate this jammer packet should be  */
			/* dropped in wlan_ecc stage								   */
			op_td_set_int (pkptr_prev, OPC_TDA_RA_MAX_INDEX + 1, OPC_TRUE); 			
			}

		/* If the arriving packet is valid, calculate		*/
		/* interference of previous packet on arriving one.	*/
		if (arriv_match == OPC_TDA_RA_MATCH_VALID)
			{
			prev_rcvd_power   = op_td_get_dbl (pkptr_prev, OPC_TDA_RA_RCVD_POWER);
			op_td_increment_dbl (pkptr_arriv, OPC_TDA_RA_NOISE_ACCUM, prev_rcvd_power);
			}

		/* And vice-versa. */
		if (prev_match == OPC_TDA_RA_MATCH_VALID)
			{
			arriv_rcvd_power = op_td_get_dbl (pkptr_arriv, OPC_TDA_RA_RCVD_POWER);
			op_td_increment_dbl (pkptr_prev, OPC_TDA_RA_NOISE_ACCUM, arriv_rcvd_power);
			}
		}

	FOUT;
	}