Nokia has announced its latest patent infringement lawsuit, this time against Chinese handset maker Oppo. The two companies signed a licensing deal in 2018 but it expired last month and Nokia says the smaller firm rejected offers to renew the agreement, and extend it to 5G patents. The Finnish firm has been increasingly active in enforcing its patents through litigation in recent years. This has been partly sparked by its need to monetize its IP assets more aggressively, as its primary revenue streams came under competitive and price pressures. And the sale of its devices business to Microsoft in 2016 meant that it was no longer justifying its technology development costs through differentiation in its own products. Instead, they need…