FORM 2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION [See section 10, Rule 13] WIRELESS TRANSMISSION DEVICE, WIRELESS RECEIVING DEVICE, AND METHOD FOR TRANSMITTING ENCODED DATA; PANASONIC CORPORATION, A CORPORATION ORGANIZED AND EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 1006, OAZA KADOMA, KADOMA-SHI, OSAKA 571-8501, JAPAN THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED. DESCRIPTION Technical Field The present invention relates to a radio transmitting apparatus, a radio receiving apparatus and an encoded data transmitting method that performs error correcting coding on transmission data and transmits the encoded data. Background Art Application of MBS (Multicast Broadcast Service) to various radio communication systems (e.g. 3GPP, WiMAX) is under study or is being started. Furthermore, there are demands for further increases in capacity such as streaming delivery concurrently with higher quality. One technique to improve quality of MBS is application of coding technique. That is, as shown in FIG.1, a first method is a method using low rate error correction code (FEC: Forward error correction) (see FIG.1A) and a second method is a method using erasure correction code (ECC) as an outer code of FEC (see FIG.1B). FIG.l shows a packet configuration example using systematic code. Here, R in FIG.l denotes a coding rate (where 0Lw, ECC control section 410 sends an ON signal to ECC operation switching section 420 and thereby switches to ECC mode. In ECC mode, radio communication apparatus 400 operates in the same way as radio communication apparatus 100 of Embodiment 1. ECC operation switching section 420 is set ON/OFF based on the ON/OFF switching signal received from ECC control section 410. When ECC operation switching section 420 is set to ON, transmission data is inputted to erasure correction encoding section 110. Therefore, in ECC mode, ECC transmission data in addition to the FEC transmission data is transmitted from radio communication apparatus 400. On the other hand, when ECC operation switching section 420 is set to OFF, the transmission data is not inputted to erasure correction encoding section 110. Therefore, in FEC mode, only the FEC transmission data is transmitted from radio communication apparatus 400. Furthermore, the following control can be performed in FEC mode. That is, since transmission scheduler 105 does not transmit ECC transmission data, time and frequency resources regarding ECC transmission data are not allocated. Furthermore, control information generation section 160 does not generate control information based on the allocation information regarding the ECC transmission data. Furthermore, error correcting coding block generation section 135, CRC adding section 140, error correcting coding section 145, FEC bit selection section 150 and modulation section 155 do not operate on the ECC transmission data. As described above, according to the present embodiment, it is possible to adaptively switch between ECC mode and FEC mode according to the size of transmission data. When a sufficient effect of ECC mode cannot be achieved (that is, when the transmission data size is small), this allows the mode to switch to FEC mode and thereby eliminates the necessity of carrying out processing which is particularly performed in ECC mode. Therefore, power consumption of radio communication apparatus 400 can be reduced. Furthermore, since the radio terminal apparatus on the receiving side need not perform ECC decoding operation, either, it is possible to reduce power consumption. As the criterion to switch between ECC mode and FEC mode, the magnitude relationship between predetermined value Lk and L_ECC/L_FEC may be used instead of the magnitude relationship between predetermined size Lw and transmission data size Ld. In this case, a numerical value obtained by normalizing a bit length for performing erasure correction coding with a bit length for performing error correcting coding is compared with predetermined value Lk and it is thereby possible to perform more accurate mode switching. (Embodiment 4) Embodiment 4 will adjust the criterion to switch between ECC mode and FEC mode according to a QoS requirement of MBS data. FIG. 14 is a block diagram illustrating a configuration of radio communication apparatus 500 according to Embodiment 4. In FIG. 14, radio communication apparatus 500 includes QoS requirement identifying section 510 and ECC control section 520. QoS requirement identifying section 510 identifies the QoS of which MBS data to be transmitted is required, and sends the identified QoS requirement to ECC control section 520. ECC control section 520 adjusts the criterion to switch between ECC mode and FEC mode based on the QoS requirement. That is, ECC control section 520 adjusts a threshold (that is, predetermined size Lw, predetermined value Lk) based on the QoS requirement. When MBS data is data that allows little delay, such as real-time data, ECC control section 520 adds an offset value for reducing Lw or adds an offset value for reducing Lk. This makes the condition to switch to FEC mode stricter and positively using ECC can secure receiving quality of MBS. (Embodiment 5) When the size of transmission data alone is not equal to or greater than a predetermined reference value, Embodiment 5 will combine a plurality of pieces of transmission data before erasure correction coding processing and assume the combined transmission data to be a target of erasure correction coding. FIG. 15 is a block diagram illustrating a configuration of radio communication apparatus 600 according to Embodiment 5. In FIG.15, radio communication apparatus 600 includes transmission scheduler 610, data combining section 620, control information generation section 630 and subcarrier allocation section 640. Transmission scheduler 610 allocates time and frequency resources to transmission data. Furthermore, transmission scheduler 610 determines a coding rate, M-ary modulation value, coding block length (or information bit size) and transmission data size used in allocated resources. Furthermore, when transmission data inputted to erasure correction encoding section 110 satisfies condition (1) or (2) below, transmission scheduler 610 controls data combining section 620 so as to combine a plurality of transmission data packets. (1) When transmission data size Ld is smaller than predetermined size Lw (Ld