https://www.reuters.com/article/us-xiaomi-coolpad-lawsuit/xiaomi-sued-for-alleged-patent-infringement-ahead-of-blockbuster-ipo-idUSKBN1IC11L >Chinese smartphone maker Coolpad Group said its unit has sued three group firms of Xiaomi, which last week filed for a Hong Kong IPO that could be worth up to $10 billion, for patent infringement.