The Development Of 3g Technology And The Progress Of The Issues Raised (figure)

The world's first 3.5G cellular network-based high-speed downlink packet access (HSDPA) technology

, introduced significant changes indicating their support for packet data service is. HSDPA network with high data rates, and reduce the packet waiting time, thereby providing home broadband services with a new rival service. However, HSDPA only for the downlink and uplink through enhanced access to more benefits.

People do not doubt praised the HSDPA of 14Mb / S downlink data. This is a very important feature of this technology can provide with the WiFi performance of rivals, while it also improves the mobility, security and ease of use features of cellular networks, HSDPA marks an important step in the development of cellular networks, devoted to downlink chain Road packet data system optimization. HSUPA (High Speed Uplink Packet Access) to expand this enhanced uplink packet data.

3G network in progress With the introduction of HSDPA, an important aspect of managing the air interface to the wireless network controller (RNC) to move or 3G base stations in the NodeB (Node B). This feature is moved closer to air interface, means that 3G systems can respond faster wireless link between the user and the NodeB quality change, and user data requirements. Which effective control, allowing a higher data throughput and greater cellular capacity.

HSDPA's high data rates is through the use of advanced channel coding and modulation techniques to achieve, the technology goes wrong, can quickly re-transmission, use of these features, NodeB receives from each of the users about the quality of the downlink channel information.

Time when information quality is very good, NodeB can transmit very high data rates, from self-confidence error protection channel coding algorithm for very little. With the decline in channel quality, effective user data rate would be lower, because there must be more errors NodeB protection, send the enhanced for more information. Depends on the environment, the user channel quality may change rapidly, while the NodeB must respond quickly in order to maintain maximum efficiency in air interface.

HSDPA Another major advantage is to shorten the packet transmission period or interval (TTI). The smallest HSDPA TTI 10ms down from Release99 HSDPA system of 2ms, the following advantages: First, make NodeB to each user to quickly respond to perceived changes in channel quality; more importantly, reduces the transmission of each packet waiting time, said of waiting time data packet transmission and its successful reception and decoding time delay between.

For many services, such as IP phones (VoIP) or interactive Game, too long of waiting time will quickly reduce the quality of service. In the bridge automatic repeat request, to allow rapid retransmission of packet errors, reduce waiting times through the network, enabling cellular operators to provide very wide range of services.

HSUPA needs HSDPA is given to improve efficiency and service, the next step will be to apply similar concepts to the uplink. HSUPA enhanced uplink is sometimes called, it represents the latest 3GPPRelease6 technology, its purpose is to provide the best uplink packet data support.

As multimedia communications services has been popular as high-quality cameras have become standard in most phones. In addition, symmetric services (such as voice and VoIP) applications will begin to grow, it can provide more efficient bandwidth applications.

Recent years, TCP / IP has become a common packet data transmission organizations, HSDPA physical (PHY) and media access control (MAC) layer, is suitable to support this higher level of agreement. However, downlink TCP / IP services require a corresponding response packet sent to the uplink, while for high-speed downlink, which may be generated in the uplink for a considerable load.

Uplink response if lost or delayed, then the TCP / IP can also modify the link quality (by reducing the downlink data rate). Sent to the general Release99 with uplink channel response to match the HSDPA downlink configuration and, on the uplink bandwidth and latency is concerned this is not helpful.

HSUPA features HSUPA many features and enhancements can be directly traced back to HSDPA. In addition, the new question is to balance the uplink air interface requirements to effectively manage and expensive to control signaling to achieve the complexity of the relationship.

HSUPA HSDPA so as to provide enhanced data rates, fast packet retransmission institutions, and can reduce the packet waiting time. HSUPA uplink data rates of the theoretical maximum of up 5.76Mb / S. Achieve this performance for an adaptive channel coding technology, which under conditions of load and adjust the channel volume of error correction. HybridARQ (HARQ) packet transmission technology and 2msTTI copied from HSDPA.

Support high data rates and lower TTI handheld devices and infrastructure for the designers made a number of complex problems and challenges. For mobile phones, to support high data rate for wireless, baseband and protocol must have a lot to consider. Need more DSP, ASIC faster and more memory to handle a large number of user data and faster data processing.

Reduce TTI require that the phone must be more quickly re-send the request and the response from the network control signaling. High data rates need to improve the PF level transmitter quality components to ensure reliability of coding data.

Achieve these features take time and will increase the phone's manufacturing cost. For this reason, according to support different data rates and different TTI, the mobile phone is divided into six categories. Lower class to adapt to lower mobile data rates (from 700Kb / S start), but only certain types of treatment 10msTTI.

Infrastructure manufacturers face the same problem, need to update the NodeB to support the structure of higher quality and improved wireless receiver baseband processing. Most cellular operators are required based suppliers of aircraft from the initial release will be able to provide high data rate support.

Control and scheduling And HSUPA biggest problem is not related to data transmission by the physical air interface, but its management. HSUPA must be carefully controlled to ensure air interface required for each user uplink bandwidth, to prevent many users want to send data at the same time, caused by cellular overload. This is a task scheduling algorithm.

HSUPA and HSDPA the same scheduling algorithm is placed in the NodeB, the to respond quickly to changing channel conditions and user data requirements. This raises an interesting question.

For HSDPA, NodeB downlink control all users to share resources and deal with all the information needed. For the HSUPA, the situation is more complicated, because the uplink

by: pipi

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