that the same broadcast data rates would then be to reduce the cell information is to be simultaneously provided to multiple size, thereby increasing the cell-edge receive power. mobile terminals, often dispersed over a large area However, this will increase the number of cells to cover corresponding to a large number of cells as shown in a certain area and is thus obviously negative from a cost- Figure 4.4-20. The broadcast/multicast information may of-deployment point-of-view. be a TV news clip, information about the local weather However, as discussed above, the provisioning of conditions, stock-market information, or any other kind broadcast/multicast services in a mobile-communication of information that, at a given time instant, may be of network typically implies that identical information is to interest to a large number of people. be provided over a large number of cells. In such a case, When the same information is to be provided to mul- the resources (downlink transmit power) needed to tiple mobile terminals within a cell it is often beneficial to provide a certain broadcast data rate can be considerably provide this information as a single 'broadcast' radio reduced if mobile terminals at the cell edge can utilize transmission covering the entire cell and simultaneously the received power from broadcast transmissions from being received by all relevant mobile terminals multiple cells when detecting/decoding the broadcast (Figure 4.4-21a), rather than providing the information data. by means of individual transmissions to each mobile ter- Especially large gains can be achieved if the mobile minal (unicast transmission, see Figure 4.4-21b). terminal can simultaneously receive and combine the Broadcast area Figure 4.4-20 Broadcast scenario. OFDM transmission CHAPTER 4.4 Broadcast Unicast Figure 4.4-21 Broadcast VS. unicast transmission. (a) Broadcast and (b) unicast. broadcast transmissions from multiple cells before transmitted mutually time aligned. In this case, the decoding. Such soft combining of bro