A major technical challenge that femtocell designers initially faced was the need to manage potential interference. It takes up to two years to install conventional base stations, during which time radio engineers meticulously plan a station's position and radio characteristics to avoid interference. However, such an approach is not viable in the case of femtocells, deployed potentially in their millions at random. Functionally, AT&T has deployed femtocells on the same frequencies as both the hopping channels for GSM macrocells and with UMTS macrocells. They have tested thousands of femtocells, and found that the femtocells are deployed, the more uplink interference is reduced.
Although LTE and WiMAX can provide even higher data rates, the can only achieve this when the signal quality is very high. In practice the average data rates in the conventional macrocell environment may not be very much greater than those on today's 3G networks. In the future, LTE femtocells could provide the best possible environment for locally streaming high-definition media around the home while concurrently supporting traditional cellular services.
At the time of writing there are 16 commercial deployments of femtocell systems around the world. Vodafone’s ‘Sure Signal’ femtocell service in the UK has had considerable success, so much so that Vodafone has recently launched a service in Spain, this time targeted at business users. Elsewhere in Europe, femtocells are already available in France and Portugal. In Japan, traditionally regarded as the world’s leading mobile market, the three largest operators – NTT DoCoMo, KDDI and Softbank - all offer the technology. They have also been the first to embrace advanced femtocell applications. Elsewhere in Asia, operators have deployed femtocells in China (China Unicom) and Singapore. In the US, the three largest mobile operators – Sprint, Verizon and AT&T – all offer the technology. According to analysts ABI Research, there are currently around 60 consumer trials internationally, suggesting that there will be many more deployments will by the end of the year.
The concept of bringing the mobile network into homes and offices turns traditional cellular thinking on its head, yet the technology holds so many benefits for customers and operators alike that its appeal is undeniable. As with so many technologies, the jump from initial concept through to commercial reality has involved a number of challenges. However, the industry has worked to resolve these and, as the major commercial launches currently taking place testify, they have been highly successful.
The potential regulatory implications are not expected to impinge on the uptake. Femtocells operate in the same spectrum as existing networks and have the same degree of control by the operator, so raise relatively few new regulatory concerns. The European Radio Spectrum Committee has stated that it is reasonable to assume that femtocells will comply with the existing technical licensing conditions and that the proliferation of femtocells will be supported in the context of more efficient use of spectrum.
Informa Telecoms & Media has predicted that the femtocell market will experience significant growth over the next few years, reaching just under 49million femtocell access points in the world market by 2014 and 114million mobile users accessing mobile networks through femtocells during that year. Femtocells represent a major new opportunity for the mobile industry and provide a service for customers where a demand for better coverage and faster data already exists.
参考：Ingenia Articles
