The strength of your Wi-Fi signal does have an affect the speed of your Internet connection. There are a number of factors that can also reduce the strength of your Wi-Fi and the quality of your connection. These issues can include the number of devices connected to your network, how close you are to the access point and objects between you and your access point.
Wi-Fi Strength over Distance
The closer you are to your access point, the better your connection to the wireless network. Most connection managers allow you to right-click and view the properties of your connection; one of the options displayed will be the speed of your connection. When you connect to your wireless network, you'll also see the strength of the network displayed in a radio wave or bar graph. If you have all the levels filled, it means you've got maximum signal strength; the fewer bars, the weaker and slower your connection.
The Near/Far Issue
You're going to encounter more problems with your network when there are a lot of devices actively connected. With multiple devices connected to the Internet, devices closer to the router will get higher speeds while devices further away from the router will have slower speeds and even a spotty connection. This can be easily remedied by moving closer to the router and turning off devices that do not require an active connection to the Internet whenever possible.
Most basic routers use wireless-G, which uses a 2.4GHz radio frequency. Unfortunately, a lot of common household devices also use the 2.4Ghz frequency. These include cordless phones, baby monitors and even microwaves. The more devices in your household that use this frequency, the harder it is for your computer and router to communicate over the noise. Move away from these devices, and turn them off to ensure the least amount of interference. Your Wi-Fi signal can also be degraded by the number of solid objects between you and the access point; a router under your desk will have more obstacles than one high on your shelf.
You'll have a weaker connection If you're on the edge of your router's effective range.The average wireless router range varies, anywhere from 60 to 150 feet indoors -- though this depends on your router. Routers placed in a central part of your home will broadcast more efficiently than one placed in the corner of a room off the side. Changing the wireless channel can also help reduce interference from other wireless networks; you can change the channel in your router administration page. You can also remove devices that cause interference or add devices designed to boost your Wi-Fi signal strength.