From GSM to LTE: An Introduction to Mobile Networks and Mobile Broadband

4.11 Network Planning Aspects

Like in GSM and UMTS, meticulous network planning is essential to ensure a high performing network in as many places as possible and to reduce the effect of interference from neighboring cells and other mobile devices. The following sections describe some of the challenges faced and discuss potential solutions.

4.11.1 Single Frequency Network

Like UMTS, the LTE radio access network reuses a single carrier for all cells. To extend capacity, it is possible to operate several carriers in the same frequency band, although network operators usually take advantage from the up to 20-MHz channel bandwidth that has been specified for LTE. In some bands, 20-MHz channels might not be feasible, however, for a number of reasons:

• Enough spectrum is not available because of several network operators sharing the available spectrum in a small band. An example is band 20, the European digital dividend band. As shown at the beginning of this chapter in Table 4.2, only 30 MHz is available for each direction. If used by more than two operators, the maximum channel bandwidth per network operator is 10 MHz at best.
• Some bands are not suitable for 20-MHz channel, for example, because of a narrow duplex gap between uplink and downlink. This makes it difficult for filters in mobile devices to properly separate the uplink and the downlink data streams in the transceiver. In such bands, more than one carrier might be used if a network operator has been able to acquire more bandwidth. ...