The first half is the 42-month (1,260-day) testimony of the witnesses, and the two witnesses are killed when the beast is raised.
Not everyone sees it this way...
Rev 11:3 And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth.
3-1/2 years.
Rev 11:4 These are the two olive trees, and the two candlesticks standing before the God of the earth.
Rev 11:5 And if any man will hurt them, fire proceedeth out of their mouth, and devoureth their enemies: and if any man will hurt them, he must in this manner be killed.
Rev 11:6 These have power to shut heaven, that it rain not in the days of their prophecy: and have power over waters to turn them to blood, and to smite the earth with all plagues, as often as they will.
Rev 11:7 And when they shall have finished their testimony, the beast that ascendeth out of the bottomless pit shall make war against them, and shall overcome them, and kill them.
I don't see this as the Beast ascending at this time, rather it is referring to the Beast that ascended 3-1/2 years prior.
Rev 11:8 And their dead bodies shall lie in the street of the great city, which spiritually is called Sodom and Egypt, where also our Lord was crucified.
Rev 11:9 And they of the people and kindreds and tongues and nations shall see their dead bodies three days and an half, and shall not suffer their dead bodies to be put in graves.
Rev 11:10 And they that dwell upon the earth shall rejoice over them, and make merry, and shall send gifts one to another; because these two prophets tormented them that dwelt on the earth.
Rev 11:11 And after three days and an half the Spirit of life from God entered into them, and they stood upon their feet; and great fear fell upon them which saw them.
The resurrection at the return of Christ...
Rev 10:7 But in the days of the voice of the seventh angel, when he shall begin to sound, the mystery of God should be finished, as he hath declared to his servants the prophets.
The seventh and last trump. Notice this...
Rev 8:12 And the fourth angel sounded, and the third part of the sun was smitten, and the third part of the moon, and the third part of the stars; so as the third part of them was darkened, and the day shone not for a third part of it, and the night likewise.
Rev 8:13 And I beheld, and heard an angel flying through the midst of heaven, saying with a loud voice, Woe, woe, woe, to the inhabiters of the earth by reason of the other voices of the trumpet of the three angels, which are yet to sound!
The last three trumpet plagues are called 'woes'...
Rev 9:12 One woe is past; and, behold, there come two woes more hereafter.
Rev 9:13 And the sixth angel sounded, and I heard a voice from the four horns of the golden altar which is before God,
So now the sixth trumpet or second woe occurs leaving one more trumpet and woe to happen...
Rev 11:12 And they heard a great voice from heaven saying unto them, Come up hither. And they ascended up to heaven in a cloud; and their enemies beheld them.
Rev 11:13 And the same hour was there a great earthquake, and the tenth part of the city fell, and in the earthquake were slain of men seven thousand: and the remnant were affrighted, and gave glory to the God of heaven.
Rev 11:14 The second woe is past; and, behold, the third woe cometh quickly.
Rev 11:15 And the seventh angel sounded; and there were great voices in heaven, saying, The kingdoms of this world are become the kingdoms of our Lord, and of his Christ; and he shall reign for ever and ever.
This is the return of Christ and the resurrection of the dead. The Two Winesses have performed their work during the same 3-1/2 years the Beast has been in power.
Rev 11:12 And they heard a great voice from heaven saying unto them, Come up hither. And they ascended up to heaven in a cloud; and their enemies beheld them.
Same resurrection Paul spoke of in I Cor 15, I Ths 4 and Heb 11.
The tribulation, the Beast power and the Two Witnesses are concurrent.
