Several wireless carriers are bolstering network capacity for this weekend's NATO summit, with some of the improvements staying in place after the event concludes.

AT&T, for example, will have cell sites on wheels, known as COWs, near Daley Plaza and Grant Park. These are temporary installations that will increase capacity for a multiblock radius, said spokesman Jim Kimberly, who compared their deployment to "putting more lanes in the highway." In addition, the carrier is installing distributed antenna systems at McCormick Place, where the summit will be held, and at several hotels where higher traffic is expected. Those antenna systems, which Kimberly said represent bringing in 10 additional cell sites to an area, will stay in place after NATO.

Sprint said it has a COW outside McCormick Place's Lakeside building. It has also enhanced voice and data capacity for four in-building cell sites at the convention hall's north and south buildings and added a cell site to the Lakeside building. The in-building enhancements are permanent.

T-Mobile said it added capacity "at all in-building and outside cell sites serving McCormick Place." This includes sites in the north, south and east buildings, as well as one outside the west building.

Verizon Wireless said it is prepared for increased traffic this weekend but declined to provide details.

"We have taken measures to do everything we can to meet the anticipated demands of our network during the NATO Summit," spokeswoman Andrea Meyer said in a statement. "We will not get into details at this time for security reasons."

U.S. Cellular said it added capacity to its network but did not need to make drastic improvements "because our network in downtown Chicago was already designed to handle large crowds at major events like concerts and festivals."

Clearwire, for its part, said it is not planning any NATO-related network improvements.

"We believe Clearwire's deep mobile broadband spectrum portfolio provides ample coverage and capacity to support an increase in usage on our 4G network during the upcoming NATO conference in downtown Chicago," the company said. | Twitter @VelocityWong