3GPP learning essay

ITU International Telecommunication Union is a United Nations agency headquartered in Geneva, Switzerland, and 3GPP is an organization established under ITU to focus on telecommunications standards and IMT-2000.

There is also PP2. There is a certain competitive relationship with 3GPP and PP2, which can be seen as representing the European and North American standards respectively. 3GPP is dominated by the European system and mainly develops the evolution path of GSM/GPRS-> WCDMA. 3gpp2 mainly studies CDMA-> cdma 2000, which is dominated by North America (closely related to Qualcomm ).

 

Next, let's talk about the generations of telecommunication systems defined in 3GPP.

Technology generation	Overall system name	Access Network System	Core Network System	Remarks
2G	GSM	Geran	CS
2.5g/2.75g	GPRS	Geran	Cs + PS
3G/3.5g/3.75g	UMTS	UTRAN	Cs + PS
3.9 GB	EPS	E-UTRAN	EPC
4G	??

 

 

 

 

Why can't I see "LTE" in the table? In fact, 3.9g is what we call LTE. Accurately speaking, LTE is a project name of 3GPP, and its research result is e-UTRAN. At the same time, there is also a parallel project SAE with LTE. The research center is the core network, and the research result is EPC. However, carriers are used to promoting 4G networks (3.9g in fact) using LTE, so we only recognize LTE. In many documents, LTE, e-UTRAN, Sae, and EPC are often used together.

3GPP released many release versions. r99 is the first version, followed by R4, R5, r6...... and so on. For specific functions of each version, you can use Baidu or Wikipedia. Only keywords are listed here:

R99: Specify the first UMTS 3G network, and define the standard WCDMA for the empty port. The uplink transmission rate is 384 kbps and the downlink transmission rate is 2 Mbps.

R4: Softswitch, control and bearer separation; all-IP core network is proposed.

R5: Proposed IMS domain, which can provide IP multimedia services for PS and CS domains, and is also an important basis for VoIP. proposed that HSDPA can increase the downlink speed to 14.4 Mbps, surpassing cdma 2000.

R6: enhanced IMS domain functions (such as POC and GaN); proposed hsupa to increase the uplink speed to 5.76 Mbps.

R7: HSPA + is defined. The downlink speed is increased to 21 Mbps or even 42 Mbps.

R8: The first LTE version.

The subsequent versions are too far away from commercial use and will not be listed. The latest version is R13.

 

CS domain, PS domain, IMS domain, EPC

The core network of GSM/GPRS and UMTS is composed of CS domain and PS domain.

The CS domain is a circuit domain. From GSM to UMTS, both voice and 3G video phones provide services through CS domain.

The PS domain is a grouping domain that is introduced from GPRS to UMTS to provide data services. The main network elements in the PS domain are sgsn and ggsn.

The IMS domain is proposed to implement all-IP networks, so that both CS and PS domains can access the IP service. IMS domains provide services such as VoIP, group short numbers, and POC.

In Sae, Cs and PS domains are integrated into EPC, sgsn evolved into Mme, ggsn evolved into S-GW (including the original sgsn user plane function) and P-GW:

Sgsn control plane function-> Mme

Sgsn user plane Function + ggsn function-> S-GW, P-GW

 

A related question: how does the operator perform smooth upgrade from GPRS to UMTS to EPS?

3GPP will definitely consider the important issue of smooth upgrade. It is impossible for a carrier to change their mobile phones as soon as they are upgraded.

In fact, the above figure basically shows the relationship between UMTS and GPRS: the core network structure is the same. Of course, the UMTS system supports Geran access. Therefore, if there is still Geran coverage in the absence of Utran base station coverage, the GPRS access will be used.

What is EPC? There is no line drawn on the graph, because it is mainly used to express the evolution changes, rather than the compatibility. In fact, Geran and UTRAN are able to access the EPC core network, if you want to draw a line, UMTS sgsn can be connected with the EPC Mme and S-GW network element. (Geran/UTRAN/E-UTRAN are 3GPP access mode, Sae also supports the non-3GPP access mode, such as WiMAX and so on... not far away)

 

3GPP learning essay