Which company developed the 4G communication technologies, LTE-TDD and LTE-FDD respectively? Among them, for the upgrading and consumption of existing 3G base stations?

Divided into two parts: standard and product. Standards are finally defined and published by 3gpp in conjunction with many companies and standardization organizations. All manufacturers in the industrial chain must follow the text, and products are entities that all manufacturers conduct research and development and sales, and products must be developed according to standards. Therefore, both tdd and fdd lte standards are released by 3gpp, and the products developed include Huawei, ZTE, Ericsson, Nokia, Alcatel-Lucent, Datang and so on.