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Comparison of three mainstream 3G technologies in communications
Comparison of three mainstream 3G technologies in communications
13 May 2024 at 12:26am
With the continuous development of mobile value-added services, moving to 3G (3rd Generation, third generation mobile communications) is an inevitable choice for major mobile operators.cell phone jammer Compared with the first two generations of systems, the main feature of the third generation mobile communication system is that it can provide a variety of mobile multimedia services. Its transmission rate supports 144kb/s in a high-speed mobile environment and 384kb/s in a slow-moving walking environment. , supports 2Mb/s in static state. GPS jammer Its design goal is to provide greater system capacity and better communication quality than the second-generation system, and to better achieve seamless roaming around the world and provide users with voice, data and multimedia services. various services, and good compatibility with existing second-generation systems must also be considered. signal jammer
There are currently three main 3G standards accepted by the ITU: WCDMA, CDMA2000 and TD-SCDMA. CDMA is the abbreviation of Code Division Multiple Access (Code Division Multiple Access) and is the technical basis of the third generation mobile communication system. The first generation of mobile communication systems used frequency division multiple access (FDMA) analog modulation. The main shortcomings of this system were low spectrum utilization and signaling interference with voice services. The second generation mobile communication system mainly uses the digital modulation method of time division multiple access (TDMA), which increases the system capacity and uses independent channels to transmit signaling, which greatly improves the system performance. However, the system capacity of TDMA is still limited, and handover Performance is still not perfect. The CDMA system shows great potential for development due to its simple frequency planning, large system capacity, high frequency reuse coefficient, strong anti-multipath capability, good communication quality, soft capacity, and soft handover.
1. WCDMA
The full name is Wideband CDMA. This is a 3G technical specification developed based on the GSM network. It is a broadband CDMA technology proposed by Europe. It is basically the same as the broadband CDMA technology proposed by Japan and is currently being further integrated. This standard proposes the evolution strategy of GSM (2G)-GPRS-EDGE-WCDMA (3G). GPRS is the abbreviation of General Packet Radio Service (General Packet Radio Service), and EDGE is the abbreviation of Enhanced Data rate for GSM Evolution (GSM Evolution with enhanced data rate). These two technologies are called 2.5-generation mobile communication technologies. According to the restructuring plan, the new China Unicom will rebuild its 3G network according to the plan.
2. CDMA2000
CDMA2000 is a broadband CDMA technology developed from narrowband CDMA (CDMA IS95) technology. It is mainly promoted by the United States. This standard proposes an evolution strategy from CDMA IS95 (2G) - CDMA20001x - CDMA20003x (3G). CDMA20001x is called the 2.5th generation mobile communication technology. The main difference between CDMA20003x and CDMA20001x is the application of multi-carrier technology, which increases the bandwidth by using three carriers. Before the reorganization, China Unicom was using this plan to transition to 3G and had built a CDMA IS95 network. According to the reorganization plan, the entire network will be transferred to "New China Telecom".
3. TD-SCDMA
The full name is Time Division-Synchronous CDMA (Time Division Synchronous CDMA), which is a 3G standard proposed by my country's Datang Telecom Company. This standard proposes a direct transition to 3G without going through the 2.5 generation intermediate link. It is very suitable for the upgrade of GSM systems to 3G. According to the reorganization plan, "New China Mobile" will be constructed according to this standard and has been initially completed and put into trial operation in some areas.
Comparison of three technical standards
WCDMA, CDMA2000 and TD-SCDMA are all broadband CDMA technologies. Wideband CDMA further expands the standard CDMA concept, extending the signal over a relatively wider frequency band, thereby reducing propagation problems caused by multipath and attenuation. It has greater capacity and can use different bandwidths according to different needs. It has strong anti-fading and anti-interference capabilities, supports multi-channel simultaneous calls or data transmission, and is compatible with existing equipment. WCDMA, CDMA2000 and TD-SCDMA can all provide a data transmission rate of 2Mbit/s in a static state, but there are still big differences in some key technologies among the three, and the performance is also different.
1. Duplex mode
WCDMA and CDMA2000 both use FDD (frequency division digital duplex) mode, and TD-SCDMA uses TDD (time division digital duplex) mode. WCDMA and CDMA2000 can support normal communication of mobile terminals at a speed of about 500 kilometers per hour, while TD-SCDMA can only support normal communication of mobile terminals at a speed of about 120 kilometers per hour. TD-SCDMA is at a disadvantage in high-speed moving environments such as highways and railways.
2. Chip rate and carrier bandwidth
A high chip rate can effectively utilize frequency selective diversity and spatial receiving and transmitting diversity, and can effectively solve multipath problems and fading problems. WCDMA has the most advantage in this regard. In terms of carrier bandwidth, the higher the bandwidth, the more users can be supported, and the less likely network congestion will occur during communication. In this regard, WCDMA has obvious advantages. The TD-SCDMA system adopts TDD duplex mode, so it only needs to occupy a single 1.6M bandwidth, so TD-SCDMA has the highest utilization rate of frequency resources.
3. Smart antenna technology
Smart antenna technology is a key technology used by TD-SCDMA and has been patented by Datang Telecom. Currently, neither WCDMA nor CDMA2000 has adopted this technology. A smart antenna is a bidirectional antenna installed on the base station site to obtain directivity, and can also reduce interference between and within cells. These characteristics of smart antennas can significantly improve the spectral efficiency of mobile communication systems.
4. Handover technology
Both WCDMA and CDMA2000 use handover "soft handover" technology, that is, when the mobile phone moves or the base station currently communicating with the mobile phone is busy and the mobile phone needs to communicate with a new base station, the connection with the original base station is not interrupted first. , but first connects to the new base station, and then interrupts the connection with the original base station. TD-SCDMA uses cross-zone "relay handover" technology. The smart antenna can roughly locate the user's orientation and distance. The base station and base station controller can determine whether the user has moved to another location based on the user's orientation and distance information. If the adjacent area of a base station enters the handover area, the base station controller will notify the other base station to prepare for handover to achieve the purpose of relay handover.
There are currently three main 3G standards accepted by the ITU: WCDMA, CDMA2000 and TD-SCDMA. CDMA is the abbreviation of Code Division Multiple Access (Code Division Multiple Access) and is the technical basis of the third generation mobile communication system. The first generation of mobile communication systems used frequency division multiple access (FDMA) analog modulation. The main shortcomings of this system were low spectrum utilization and signaling interference with voice services. The second generation mobile communication system mainly uses the digital modulation method of time division multiple access (TDMA), which increases the system capacity and uses independent channels to transmit signaling, which greatly improves the system performance. However, the system capacity of TDMA is still limited, and handover Performance is still not perfect. The CDMA system shows great potential for development due to its simple frequency planning, large system capacity, high frequency reuse coefficient, strong anti-multipath capability, good communication quality, soft capacity, and soft handover.
1. WCDMA
The full name is Wideband CDMA. This is a 3G technical specification developed based on the GSM network. It is a broadband CDMA technology proposed by Europe. It is basically the same as the broadband CDMA technology proposed by Japan and is currently being further integrated. This standard proposes the evolution strategy of GSM (2G)-GPRS-EDGE-WCDMA (3G). GPRS is the abbreviation of General Packet Radio Service (General Packet Radio Service), and EDGE is the abbreviation of Enhanced Data rate for GSM Evolution (GSM Evolution with enhanced data rate). These two technologies are called 2.5-generation mobile communication technologies. According to the restructuring plan, the new China Unicom will rebuild its 3G network according to the plan.
2. CDMA2000
CDMA2000 is a broadband CDMA technology developed from narrowband CDMA (CDMA IS95) technology. It is mainly promoted by the United States. This standard proposes an evolution strategy from CDMA IS95 (2G) - CDMA20001x - CDMA20003x (3G). CDMA20001x is called the 2.5th generation mobile communication technology. The main difference between CDMA20003x and CDMA20001x is the application of multi-carrier technology, which increases the bandwidth by using three carriers. Before the reorganization, China Unicom was using this plan to transition to 3G and had built a CDMA IS95 network. According to the reorganization plan, the entire network will be transferred to "New China Telecom".
3. TD-SCDMA
The full name is Time Division-Synchronous CDMA (Time Division Synchronous CDMA), which is a 3G standard proposed by my country's Datang Telecom Company. This standard proposes a direct transition to 3G without going through the 2.5 generation intermediate link. It is very suitable for the upgrade of GSM systems to 3G. According to the reorganization plan, "New China Mobile" will be constructed according to this standard and has been initially completed and put into trial operation in some areas.
Comparison of three technical standards
WCDMA, CDMA2000 and TD-SCDMA are all broadband CDMA technologies. Wideband CDMA further expands the standard CDMA concept, extending the signal over a relatively wider frequency band, thereby reducing propagation problems caused by multipath and attenuation. It has greater capacity and can use different bandwidths according to different needs. It has strong anti-fading and anti-interference capabilities, supports multi-channel simultaneous calls or data transmission, and is compatible with existing equipment. WCDMA, CDMA2000 and TD-SCDMA can all provide a data transmission rate of 2Mbit/s in a static state, but there are still big differences in some key technologies among the three, and the performance is also different.
1. Duplex mode
WCDMA and CDMA2000 both use FDD (frequency division digital duplex) mode, and TD-SCDMA uses TDD (time division digital duplex) mode. WCDMA and CDMA2000 can support normal communication of mobile terminals at a speed of about 500 kilometers per hour, while TD-SCDMA can only support normal communication of mobile terminals at a speed of about 120 kilometers per hour. TD-SCDMA is at a disadvantage in high-speed moving environments such as highways and railways.
2. Chip rate and carrier bandwidth
A high chip rate can effectively utilize frequency selective diversity and spatial receiving and transmitting diversity, and can effectively solve multipath problems and fading problems. WCDMA has the most advantage in this regard. In terms of carrier bandwidth, the higher the bandwidth, the more users can be supported, and the less likely network congestion will occur during communication. In this regard, WCDMA has obvious advantages. The TD-SCDMA system adopts TDD duplex mode, so it only needs to occupy a single 1.6M bandwidth, so TD-SCDMA has the highest utilization rate of frequency resources.
3. Smart antenna technology
Smart antenna technology is a key technology used by TD-SCDMA and has been patented by Datang Telecom. Currently, neither WCDMA nor CDMA2000 has adopted this technology. A smart antenna is a bidirectional antenna installed on the base station site to obtain directivity, and can also reduce interference between and within cells. These characteristics of smart antennas can significantly improve the spectral efficiency of mobile communication systems.
4. Handover technology
Both WCDMA and CDMA2000 use handover "soft handover" technology, that is, when the mobile phone moves or the base station currently communicating with the mobile phone is busy and the mobile phone needs to communicate with a new base station, the connection with the original base station is not interrupted first. , but first connects to the new base station, and then interrupts the connection with the original base station. TD-SCDMA uses cross-zone "relay handover" technology. The smart antenna can roughly locate the user's orientation and distance. The base station and base station controller can determine whether the user has moved to another location based on the user's orientation and distance information. If the adjacent area of a base station enters the handover area, the base station controller will notify the other base station to prepare for handover to achieve the purpose of relay handover.
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