 Healthcare is pleased to be furthering the mission of Colorado Dept. of Health Care...
Orchestrate Healthcare is working on the URMC Epic Inpatient implementation and is handling all of...I just responded to a pats fan asking for "concrete proof" that Brady cheated.  I deleted the comment before it was read because I didn't feel like dealing with the shitshow.  The point is concrete proof isn't the standard.

This is different from all the ideal gas law explains everything posts that I have seen.  This is a demand for a level of proof the NFL doesn't need.  This in the thread about how certain teams are pushing for brady's suspension.  No proof at all of that, but everyone there is sure that the Rooneys are part of it.

But this guy who was asking for concrete proof clearly isn't considering the legal standards that the NFL needs to meet.﻿namespace LibraProgramming.BlazEdit.Core.Extensions
{
    internal static class SelectionEventExtensions
    {
        
    }
}1 to control or adjust (the amount of available heat, sound, etc).
2 to control or adjust (a machine) so that it functions correctly.
3 to control or direct (a person, thing, etc) according to a rule or rules.
4 intr to make regulations.
1 the act of regulating or state of being regulated.
2 a rule or instruction.
3 law a form of legislation used to bring the provisions of an act of Parliament into force.
b normal; usual.
regulative or regulatory adjective.
regulatively adverb.
1 someone or something that regulates.
2 a controlling device, especially one that controls the speed of a clock or watch.Ethiopia unrest and the troop withdrawals have come as a opportune boost for al-Shabab as they seize more territory in Somalia.
By Hamza Mohamed (Al Jazeera) |
MO.
Totaling.
Continue reading this story on Al Jazeera
——
See also:
- Ethiopia Successful in Preventing Al-Shabab’s Attacks
- Ethiopia Claims Army Killed 101 Jihadists in Somali Raid
- Ban Condemns Attack on Ethiopian Troops at Mission Base
- Al-Shabaab ‘Takes Somali Town’ after Ethiopian Troops PulloutIn spectrum sensing, there is a tradeoff between the probability of missed detection and the probability of a false alarm according to the value of the sensing threshold. Therefore, it is important to determine the sensing threshold suitable to the environment of cognitive radio networks. In this study, we consider a cognitive radio-based ad hoc network where secondary users directly communicate by using the same frequency band as the primary system and control their transmit power on the basis of the distance between them. First, we investigate a condition in which the primary and the secondary users can share the same frequency band without harmful interference from each other, and then, propose an algorithm that controls the sensing threshold dynamically on the basis of the transmit power of the secondary user. The analysis and simulation results show that the proposed sensing threshold control algorithm has low probabilities of both missed detection and a false alarm and thus, enables optimized spectrum sharing between the primary and the secondary systems.
Cognitive radio is a paradigm for wireless communication in which either a network or a wireless node changes its transmission or reception parameters to communicate efficiently by avoiding interference with licensed or unlicensed users. This alteration of parameters is based on the active monitoring of several factors in the external and the internal radio environment, such as the radio frequency spectrum, user behavior, and network state. As a key technology enabling the cognitive radio, spectrum sensing plays an important role in the detection of an occurrence of an incumbent or available radio frequency [1].
Cognitive radio technology makes it possible to share the same spectrum band temporally or spatially between heterogeneous systems in order to improve the utilization of the spectrum [2]. However, the secondary system should not cause harmful interference to the primary system. Therefore, spectrum sensing is per-formed by the secondary signal to check whether the primary signal occurs or not. The performance of spectrum sensing is evaluated by using the probability of missed detection ( PMD ) and the probability of false alarm ( PFA ) [3, 4]. PMD denotes the probability that the secondary signal does not detect a primary signal even though the primary signal exists. Thus, the secondary signal causes a severe interference to the primary signal. On the other hand, PFA denotes the probability that the secondary signal detects a primary signal even though the primary signal does not exist. In this case, the utilization of the spectrum decreases as the secondary signal does not use the current band anymore. It has been known that there is a tradeoff between PMD and PFA according to the sensing threshold [5 - 7]. If the sensing threshold is increased, PMD is increased, but PFA is decreased. Therefore, it is important to determine a suitable value of the sensing threshold for the cognitive radio environment.
In an ad hoc network, a communication node controls its own transmit power according to the distance to its correspondent node [8]. If an ad hoc node uses the band of the primary system as the secondary system, the amount of interference from the ad hoc node to the primary system depends on the strength of the transmit power of the ad hoc node. Moreover, in spectrum sensing, the sensing threshold is a criterion to judge whether the primary system receives harmful interference or not; thus, we can expect the sensing threshold to be related to the transmit power of the secondary system. Therefore, in this study, we focus on the determination of the sensing threshold in a cognitive radio-based ad hoc network environment. First, we model a cognitive radio system in the ad hoc network and present a condition in which the primary and the secondary systems can coexist on the same channel without harmful interference from each other. Then, we derive a suitable value of the sensing threshold for efficient spectrum sharing and decide the sensing time required for reliable spectrum sensing against channel fading.
The rest of this paper is organized as follows: in Section II, the system model and the operation of the proposed sensing threshold control algorithm are presented. In Section III, the performance of the proposed scheme is analyzed. In Section IV, numerical and simulation results are presented. Section V concludes this paper.
Fig. 1 illustrates a system model for the considered cognitive radio ad hoc network. The primary system is regarded as a one-way broadcast system, such as a wireless microphone; therefore, a primary receiver (PR) always receives the signal from a primary transmitter (PT). As the secondary system, we consider a pair of ad hoc nodes. Namely, two secondary users (SU) perform peer-to-peer communication by using the same frequency band as the primary system and use a transmit power control (TPC) mechanism according to the distance between them.
rp: radius of PT coverage.
rs: radius of SU coverage.
d: distance between SU and PR.
Pp: transmit power of PT.
Ps: transmit power of SU.
Pn: background thermal noise power.
γrx: signal-to-interference-plus-noise ratio (SINR) received at PR.
γreq: minimum required SINR at PR.
λ: sensing threshold of SU.
System model for cognitive radio ad hoc network. SU: secondary user, PR: primary receiver, PT: primary transmitter, TPC: transmit power control.
Previous studies have dealt with issues of TPC for spectrum sharing in a cognitive radio system [9 - 13]. As a common approach, an SU first senses the power level of a PU and then controls its transmission power within a specified range such that the SU does not interfere with the PU. However, the SU sometimes cannot decrease its transmission power below a certain power level to guarantee the transmission rate required by the quality-of-service (QoS). In this case, the SU should change the currently used channel to another one in order to not interfere with the PU. Unlike the above scenario, in our approach, the SU first controls its transmission power according to the QoS requirement and then senses the PU signal. In order that the SU’s transmission has no influence on the PU, the SU decides a sensing threshold based on the predetermined transmission power and performs spectrum sensing by using the decided sensing threshold.
where the function of path loss is given by L ( x ) = x -α where α denotes the path loss exponent and x represents the distance between the transmitter and the receiver.
The regulation for a shared spectrum provides information about the primary system, such as Pp, rp, and γreq [15]. In addition, the SU can estimate the path loss exponent α and the noise power level Pn in a given channel [16]. Therefore, the sensing threshold λ prop given by (3) depends only on the transmit power of the SU, Ps. In other words, the sensing threshold should be decreased as the transmit power is increased, which implies that the SU should detect the primary signal more sensitively as it causes more interference by increasing its transmit power.
1) The SU decides its transmit power by TPC considering the distance with the other SU.
2) The SU decides its sensing threshold by using (3).
3) The SU performs spectrum sensing (e.g., energy detection) by using the decided sensing threshold.
4) If the detected power is greater than the sensing threshold, the SU does not use the current channel and changes to another channel immediately.
5) If the detected power is smaller than the sensing threshold, the SU continues to use the current channel and performs spectrum sensing next time.
6) Every time the SU changes its transmit power, it recalculates the sensing threshold.
For the performance evaluation, we