The upgrade is designed to deliver faster data download and upload speeds, wider coverage and better voice quality to MTS customers, for an enhanced mobile broadband experience.
MTS will also add to its existing 3G base stations in Turkmenistan, and NSN will provide the core network elements, radio access and services to enable this.
"It is a challenge to install and integrate new equipment into our existing network, without disrupting end-user services," said Andrew Ushatsky, CTO at MTS Group.
"I am sure that our specialists, in cooperation with NSN's experts, will ensure a swift execution of this project, thus improving the quality and safety of voice and internet services for our customers."
NSN will manage the upgrade from network implementation right through to systems integration, and the deal also includes care services for hardware, software and competence development.
Ushatsky expects the upgrade to be completed by the end of 2014.
NSN was the partner of choice for MTS in November last year for the launch of its TD-LTE network in Moscow, and earlier this year Korek Telecom selected NSN to upgrade its network in Iraq.
