BERLIN — When Nokia, the world’s largest maker of mobile phones, sued Apple, Samsung, LG and eight other competitors within six weeks beginning in October, it said it was conducting a routine defense of its intellectual property.

But for cellphone makers and suppliers accustomed to swapping valuable technologies, the suits filed by Nokia were far from standard.

Like many cellphone makers, Nokia is fighting the economic downturn. The company, which is based in Finland, has laid off thousands of employees this year to counter falling sales and profit and its slipping share of the global market, which fell to 35 percent in the third quarter, from 41 percent in the second.

Bill Tai, a partner at Charles River Ventures, a technology investment firm, said the new legal aggressiveness was “a natural evolution” similar to what took place in the semiconductor and desktop computer businesses during difficult or competitive times.