herefore, the MS does not have to decode the entire superframe headers at every superframe instance, if there is no change in system information. CHAPTER 9 The IEEE 802. 16m Physical Layer (Part I) Physical P-SFH IE/ Channel S-SFH IE Insertion Encoding Modulation Encoding/ Mapping Precoding to P-SFH/ S-SFH FIGURE 9-64 Physical processing of the P-SFH/S-SFH information element [2] 9.15 3GPP LTE PHYSICAL LAYER PROTOCOLS This section describes the physical layer procedures in 3GPP LTE Releases 8 through 10, in order to provide the reader with sufficient technical background to understand and contrast the similarities and differences between the IEEE 802. and 3GPP LTE. The main functional elements of the physical layer processing and control signaling are described in the following sections [95-117]. 9.15.1 Multiple Access Schemes The 3GPP LTE uses asymmetric multiple access schemes in the downlink and uplink. The multiple- access scheme in the downlink is based on OFDMA with a cyclic prefix and a single-carrier frequency division multiple-access with cyclic prefix is used in the uplink. The OFDMA scheme is particularly suited for frequency-selective channels and high data rates. It transforms a wideband frequency- selective channel into a set of parallel flat-fading narrowband channels. This ideally, allows the receiver to perform a less complex equalization process in the frequency-domain, i.e., single-tap frequency-domain equalization. The 10 ms radio frame is divided into 10 equally sized subframes. Each subframe is further sub-divided into two slots of 0.5 ms length. The basic transmission parameters in the downlink are shown in Table 9-15. The CP length is chosen to be longer than twice the maximum delay spread and propagation delays in the radio channel. For 3GPP LTE, the normal CP length is set to 4.69 us, enabling the system to tolerate delay variations due to propagation over cells up to 0.7 km. Note that the insertion of CP increases the Layer 1 overhead and hence reduces the overall throughput. An extende