s. The broadcaster can select which combination of segments to use; this choice of segment structure allows for service flexibility. Transmission occurs in continuous flow, minimizing delays in signal acquisition when the user switches from one channel to another. However, this also means that the receiver must be powered on continuously while programs are being viewed. Consequently, power consumption becomes a significant design challenge for handset manufacturers [27]. ISDB-T systems are characterized as follows: MPEG-2 interface: the input signals to the system and output signals from the system conform to the MPEG-2 TS specifications. Digital contents can be simul- taneously transmitted with the appropriate modulation schemes and appropriate bit-rates for each type of content integrated in the ISDB stream. A control signal called TMCC (Transmission and Multiplexing Configuration Control) informs the receiver of the multiplexing and modulation configuration. Partial reception (reception of only one OFDM segment at the center of a group of segments) makes some of the services to be received by a lightweight, inexpensive narrow band receiver [27]. 1seg is a mobile terrestrial digital audio/video and data broadcasting service based on ISDB-T. ISBD-T is designed in such a way that each channel is divided into 13 segments, with a further segment separating it from the next channel. An HDTV broadcast signal occupies 12 segments, leaving the remaining (thirteenth) segment for mobile receivers. Thus the name, "1seg" or "One Seg". One Seg is also primarily used in Japan. ISDB-T uses hierarchical modulation and provides the choice of three different modulations DQPSK, 16-QAM, 64-QAM on each segment. ISDB-T also allows switching to two or three SDTV channels instead of one HDTV channel (multiplexing SDTV channels). Each channel is further divided into 13 segments as shown in Figure 9.17. 1seg uses only single segment, and the remainder can be allocated as: One 12-segment HDTV program, three 4-segment SDTV programs, one 8