In addition to Ericsson, No. 4 Alcatel-Lucent SA's market share rose in the quarter, as both companies benefited from their strong positions in the fast-growing North American market.
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Investments in the new LTE mobile networks in North America helped lift the overall mobile network equipment market 21 per cent above the year-ago level, to $9.7 billion, Dell'Oro said.
Ericsson's market share rose to 40 per cent from 35 per cent a year ago, while Nokia Siemens Networks and Huawei Technologies saw their market shares drop to 18 per cent and 16 per cent, respectively.
The two closest rivals of Ericsson both controlled 20 per cent of the market a year ago, but suffered in early 2011 from their weaker position in North America.
To improve its position there, Nokia Siemens bought Motorola's network gear business in April.
Alcatel-Lucent saw its market share rise to 15.5 per cent in the quarter from 14 per cent a year earlier.