Wi-Fi Speed

Hi,

I've got a Acer Aspire E1-771G-33128G1TMnii (NX.M6GEU.040)

Serial number

NXMG6EU004*********

Purchase date

2014/07/03

It supports Wi-Fi 802.11 b/g/n standard (up to 150Mbps)

The LAN connection is 100Mbps, but over wi-fi I get only 50-60Mbps (even when it's 100% signal and I am in front of wi-fi router of mine).

My laptop connection is the only one to the wi-fi router (TP-LINK TL-WR841ND, also handles N standard for 150Mbps, 2.4GHz).

Sorrounding wi-fi routers: 4 to 7, mostly with poor to fair signal.(6 - poor, 1 - fair)

How many antennas this wi-fi adapter has(in Laptop)? Can it handle inbound 100Mbps? Or 2 antennas on wi-fi router isn't enough to handle 100Mbps. How can I make it possible if so?

My laptop WLAN-card:

Atheros AR956x

N.B.: In short, AR956x hase single channel capability. That means WLAN card can connect to router at 20MHz bandwidth only on speed of 72,2Mbts. If you can switch bandwidth to 40MHz the connection speed will 150Mbts. I've changed Atheros AR956x on my Toshiba L50-A on Intel 6235 (no tweaks or tricks were needed). This WLAN card is dual-channel, supports 2.4GHz and 5GHz networks and on bandwidth of 40MHz connects to my router at 300Mbts speed.

Am I supposed to to replace WLAN-card on my laptop? If so, how?

[edited for privacy-please do not post personal or unique information such as but not limited to full names, email addresses, phone numbers, full serial numbers, etc.]