On the historical background of the "1" MTK debut of cottage phone and Android

The historical background of "1" MTK debut
If the 1960 is the era of mainframe (Mainframe) , the 1970 's is the era of minicomputer (microcomputer) , then the 1980 is undoubtedly the era of personal computers (PC), And the 1990 's is the era of the Internet. What about after 2000? Perhaps the era of mobile internet.
Similar to the development of the computer, the development of the mobile Internet, it seems to be the same as the hardware improvement as the forerunner, the software boom followed, driving the explosion of the industry-wide explosive growth.

Figure 2. The first generation of mobile phones, commonly known as cellular. Courtesy Http://farm3.static.flickr.com/2711/4149584622_1338223724_o.jpg

In the 1980 's, mobile phones began to be commercially available. The first generation of mobile phones, commonly known as cellular telephones, is characterized by the transmission of analog signals in wireless network communication channels . The transmission of analog signal has two disadvantages, one is power consumption, and the other is the same frequency band can accommodate a small number of users . Because of the power consumption, the cell phone must carry large chunks of battery, resulting in a large volume, shaped like a board brick. Street hooligans fight, often pick up the floor of the board brick hit people, if carrying a mobile phone, when the nasty when you can also use the cellular phone as a board brick.

Figure 3.the hardware architecture of the second generation handset with DSP as the core[4]. Courtesy Http://farm3.static.flickr.com/2751/4146507443_9601fd7d08_o.png

Why is the transmission of analog signals a disadvantage of power consumption and low band capacity? A comparison of the digital signal is clear. If the voice is converted to digital, data compression can be taken to reduce the bandwidth used to transmit voice. At the same time, because the digital signal is easy to handle, so when transmitting the digital voice signal, can use the complex transmission protocol and the control, in order to be in the same frequency band, simultaneously accommodates the more user to call each other. For analog signals, it is difficult to use similar protocols and controls.

The core of the second-generation handset is the digital signal processor, DSP (digitally Signal Processor). The hardware architecture of the second-generation handset, as shown in Figure 3, is divided into three parts.

1.RF chipset (Radio Subsystem)。 It is responsible for modulating-sending, and receiving-demodulation of the wireless signal. Whether sending or receiving, the RF chipset only processes analog signals.

2.Analog Baseband chipset (Analog baseband)。 The chipset consists mainly of two function blocks, RF interface (RF Interface), and audio Interface.
The RF interface is responsible for converting the analog signal received from the RF chipset into a digital signal, forwarding it to a digital signal processor (DSP), and converting the digital signal from the DSP output to an analog signal, which is forwarded to the RF chipset for transmission.
The audio interface is responsible for converting the analog signals received from the microphone into digital signals, which are then forwarded to the DSP for further processing. At the same time, it is responsible for the DSP output digital signal, converted to analog signal, and then forwarded to the horn for playback.

3.Digital Baseband chipset (digitally baseband)。 The chipset consists mainly of two components, a digital signal processor (DSP), and a microcontroller (microcontroller).
The main task of DSP is to perform speech processing, such as noise removal, speech correction, and so on. In addition, the DSP is responsible for the compression and decompression of the voice data stream, encoding and decoding between different formats, encryption and decryption, and so on. If the single-block DSP chip does not function enough, it can also be aided by other special-purpose chips (ASICS).

The microprocessor is responsible for two tasks,1. Handling the Wireless communication protocol, 2. Running the phone operating system.
When a user dials a call to another user, a call channel is first established to connect the calling party with the called Party. The voice digital signal of the dialogue between the two sides is transmitted in this communication channel. The seventh signaling system is responsible for establishing the call Channel [5]. In order to ensure the security of information and improve the efficiency of the system, the method of separating control flow and data flow is adopted, that is, the seventh signaling system is a set of independent system, which is free from the communication channel which carries the voice digital signal.

Signaling number seventh consists of a series of protocols that roughly correspond to the ISO seven layer model of the Wired network protocol, as shown in Figure 4. The microprocessor is responsible for processing the first layer to the third layer protocol of signaling number seventh, MTP1,MTP2,MTP3.

Figure 4. Comparison SS7 Protocol Suite and ISO Protocol Model [6] courtesy http://farm3.static.flickr.com/2742/4152165133_ 959a2cb7a3_o.jpg

Mobile operating system, such as the nucleus RTOS, handles peripheral actions such as boot/shutdown/Lock, screen display, volume control, ringing and vibration, etc. In addition, it is responsible for the operation scheduling (scheduling) of each function module of the handset, as well as the data exchange (IPC) between different processes. Although the status of DSP in the mobile phone is very important, but DSP still accept the mobile phone operating system control. The data that is processed by the

microcontroller is stored in flash memory.

The core task of the second generation of mobile phones is real-time communication, which is represented by the two functions of call and SMS. Around the core of real-time communication, the operating system specifically coordinates the work of each part. The interaction with the user means that it relies on more than 10 keys and a small monochrome LCD display. Nokia 5165, which began sales in 1998, is a classic of the second-generation handset, see Figure 5.  

Figure 5. Second generation mobile phone, Nokia 5165,1998 year
Courtesy Http://i1.phonearena.com/showimage.php?m=Phones.Images&f=image&id=7252&v=default

Reference,
[4] Trends in Hardware Architecture for Mobile Devices. (http://www.inf.fu-berlin.de/inst/pubs/tr-b-04-17.abstract.html)
[5] Signaling System 7, SS7. (http://en.wikipedia.org/wiki/Signaling_System_7)
[6] Comparison SS7 Protocol Suite and ISO Protocol Model. (http://www.kenneyjacob.com/2007/06/05/ss7-backbone-of-mobile-networks/)

On the historical background of the "1" MTK debut of cottage phone and Android