By Milana Vinn and Disha Mishra

Jan 29 (Reuters) - Fiber network owner Zayo Group is in the lead to buy the Crown Castle's CCI.N assets in a deal that could be valued at over $8 billion, a source familiar with the matter told Reuters.

Zayo, owned by Sweden's EQT EQTAB.ST and DigitalBridge DBRG.N have outbid buyout firm TPG TPG.O for Crown Castle's assets, said the source, who declined to be identified as the information is confidential.

The sale would include Crown Castle's fiber and small cell businesses, that provide wireless services and technology, Reuters has previously reported.

Zayo and Crown Castle did not immediately respond to Reuters request for comment outside regular business hours.

If the deal goes through, the transaction will come at a time when dealmaking in the fiber industry is heating up, as the rapid growth of fiber broadband provides a major boost to infrastructure providers, making them attractive acquisition targets.

Houston, Texas-based Crown Castle, which has a market value of $38.2 billion, is a telecommunications infrastructure provider that operates more than 40,000 cellular towers across the United States.

Crown Castle rents out towers to wireless carriers such as Verizon VZ.N and AT&T T.N, and has grown its fiber business through several acquisitions. However, the high cost of building fiber infrastructure has weighed on its financial performance, forcing it to consider a retreat from the business and slash spending.

(Reporting by Milana Vinn in New York and Disha Mishra in Bengaluru; Editing by Eileen Soreng)

((Disha.Mishra@thomsonreuters.com;))