By Ritsuko Ando HELSINKI (Reuters) – Nokia is expected to show a steep fall in network equipment sales in its results this week, highlighting the challenge facing management after selling its once mighty handset division to Microsoft for 5.4 billion euros ($7.3 billion). Improved profitability at Nokia Solutions and Networks (NSN) due to cost cutting have helped cushion the companys declining handset business in recent quarters. But with major projects in South Korea and Japan coming to an end, the NSN business, the bulk of Nokias entire business after the handsets sale, is expected to report a 19 percent fall in fourth-quarter sales to 3.2 billion euros and a 17 percent fall for the whole of 2013 to 11.4 billion euros. The decline for NSN would follow a 26 percent fall in third-quarter sales and come as scale has become increasingly crucial to competing against the industry leader for wireless networks, Ericsson, and Chinas Huawei, particularly due to high research and development costs.