Home Node B and Femtocells
Now that the radio spectrum is being fully utilized and as the spectral efficiency of WCDMA/HSPA is very mature, it is a challenge how to improve capacity and coverage to manage the next 5–10 years predicted data growth using the existing installed base station sites. Pushing the spectral efficiency further gets more difficult and opting to use smaller cells will eventually be a necessity to permit more capacity and higher data rates for the end users.
With a potentially high penetration loss from outdoor to indoor on the order of tens of dBs, there is an excellent opportunity to build very small and isolated indoor cells which have very high signal quality, few users per site, and which only interfere marginally with the wide area network outside. As shown in Figure 19.1, there are many product options to provide indoor coverage, such as active or passive distributed antenna systems (DAS), Pico base stations utilizing the normal 3GPP architecture and Femto base stations that use the special architecture discussed in this chapter. The differentiating factors are required user capacity, needed quality of service and importance of coverage. For the zero-touch and plug & play market use cases, the dedicated 3GPP radio technology is the Home Node B (HNB) which belongs to the Femto segment ...