Picochip Ltd., which Mindspeed recently acquired, and ASTRI began their close collaboration on the LTE femtocell reference design in the middle of 2008, supporting both LTE frequency division duplexing (FDD) and TD-LTE. The two companies demonstrated the world’s first TD-LTE femtocell prototype at Mobile World Congress 2009, and have been working on a combined design supporting both LTE FDD and TD-LTE over the last several years.
The company also supports dual-mode concurrent operation with 3G high-speed packet access (HSPA+) and including time division synchronous code division multiple access (TD-SCDMA). Although TD-LTE had low visibility and demand just two or three years ago, industry analyst firm Informa has projected that 40 percent of LTE users will be served by the technology by 2015. While the TD-LTE and LTE FDD are substantially similar, the key difference is that LTE FDD uses paired spectrum, with one band for the uplink and a second for the downlink. TD-LTE, instead, uses unpaired spectrum, carrying uplink and downlink traffic on the same frequency by switching between the two.
“Unlike reference designs that use ‘example code’ or ‘demo-ware,’ this is a fully tested, verified and deployable carrier-class TD-LTE baseband system,” said Dr. Naser Adas, vice president and general manager, wireless and customer premises equipment (CPE), at Mindspeed.