Digital Microwave Corp., a wireless-telephone equipment maker with fiscal 1998 sales of $310.5 million, said it will fire about 165 employees, or 15% of its work force, in response to slowing demand and increased competition. The company warned in April that sales and profit margins would be hurt by the economic slowdown in Asia. Last month, Digital Microwave said sales for the quarter ended June 30 wouldn’t meet expectations because of delayed orders from an unnamed customer and slowing worldwide demand. Digital Microwave said it will cut costs to improve profit margins, although it won’t scale back product development. The San Jose-based company said it expects to report fiscal first-quarter sales of $45 million to $50 million. Digital Microwave shares closed unchanged at $7.63 on Nasdaq.