Figure 10.8. In Smartphones the 6 Monolithic is an electronic system, such as a processor, realized on a single die. Next Generation Mobile Communications Ecosystem Serial/Bus Applications Baseband Processor Processor Smartphone 2-chip Solution CPU Core DSP Core Applications GSM Protocols GSM Protocols Shared Memory Codecs Low and Mobile phone one- chip Solution Figure 10.8 Application and baseband processors application processor is a physically separate IC (integrated circuit) connected to a physically distinct baseband processor that is, a two-chip solution. In low end phones the basic band processor is often used as the entire phone processor as shown in Figure 10.8 [15]. The advantage of the two-chip architecture from a software perspective is the application processor does not need to concern itself with the real-time requirements of the network communications. In addition the separate baseband processor can be independently certified and approved to operate on the networks. A classic example of the two-chip architecture is Palm Treo 700wx. It uses Intel PXA272 312 MHz processor with XScale technology (based on ARMv5) and Qualcomm CDMA baseband processor. 10.5 Signal Processing 10.5.1 Speech Coding - Vocoders Speech Coding is all about providing the best quality speech at lower bit rates. The lower the bit rate at which the coder can deliver best quality speech, the more speech channels can be compressed within a given bandwidth. In traditional wired and wireless communication systems, vocoders are designed to encode speech signals that are bandlimited to the narrow-band frequency range of 300 to 3400 Hz. UMTS systems Smart Wireless Devices Table 10.2 AMR codec versions Codec mode Source codec bit-rate (kbps) AMR_12.20 12.20 AMR_10.20 10.20 AMR_7.95 AMR_7.40 AMR_6.70 AMR_5.90 AMR_5.15 AMR_4.75 AMR_SID 1.80 (see notes) Notes: Assuming SID (Silence Descriptor) frames are continuously transmitted. GSM-EFR is the 3GPP TS 26.090 Enhanced Full Rate Speech Codec (also identical to the TIA TDMA-US1 Enhanced speech 