IP, broadband,and multimedia-based development
The wireless telecom network of the not too distant future will be constructed on IP bears, which will exhibit a much higher level of security, reliability, manageability, and operability. The next generation IP network will also utilize the core technology of the IP network to build a bigger, faster, more secure, trustworthy and operable network. Likewise, it will make provision for more flexible services, on the basis of the telecom design concept, that would envision the construction of an IP network with guaranteed telecom service quality and a profitable commercial model.
With ever increasing broadband service requirements, it is very important to appropriately utilize limited radio resources in order to provide broadband wireless transmission. By focusing on such aspects as high data rate, high spectrum utilization, lower transmitting power, and flexible service configuration, the wireless mobile telecom system of the future will be able to improve its transmission capacity and rate of wireless communication by 10 times, or even as much as hundred times. Features of various access technologies will also permit a hierarchical seamless coverage system to be built, and a "universal radio environment" to be formed. In addition, interoperability will be able to be implemented among various systems. Presently, this seems to be the most reasonable and necessary course to take for the future wireless and mobile telecom system.
Providing multimedia services for subscribers appears to be a definite development trend for the telecom service of the future. Furthermore, the creation of a more diversified media will be able to meet the personalized requirements of subscribers. The development of multimedia services places greater requirements on the network such as: having higher flexibility, a larger capacity, faster speed, more powerful vitality, better interoperability, and stronger service support capability.
Expediting 3G enhanced technology and product development
As the market promotes 3G products, potential for the data service market will also be activated. In the 3G high-speed platform, a service provider will be able to implement services quite easily. As competition continues to stiffen with different and new technologies emerging every day, 3G enhanced products will expedite this development in order to meet the rapid increase in the data market.
- HSDPA/HSUPA
The evolution of WCDMA wireless interfaces: This includes such new and enhanced technologies as R99 radio interface technology, HSDPA, and HSUPA. At present, 3GPP is engaged in researching the long-term evolution of UTRAN and UTRA.
Currently, each WCDMA equipment provider plans to release HSDPA equipment for commercial use by the end of 2005, or sometime in the early part of 2006. DoCoMo is also expected to release its HSDPA commercial network near the end of 2005. The phase rate of HSDPA will be about 3.6 Mbps.
The primary purpose for 3GPP releasing HSDPA is to enhance the throughput of the downlink packet service for non-real time packet services, which also has the potential to be used for streaming services. HSDPA serves as a supplement to R99 radio interface and also shares the same operator as the R99 channel. The operator is used only to add the dedicated channel for HSDPA. In terms of product implementation, it is relatively simple, and the hardware does not need to be modified. Only the software needs to be upgraded. HSDPA is based on the air interface of R99, and uses the following technologies to improve the downlink peak rate.
AMC (Adaptive Modulation and Coding): The adaptive modulation and AMC belong to the adaptation area. The basic principle of AMC is to change the modulation and code formats in order to adapt to the channel condition in the system restricted scope. In the HSDPA, QPSK or 16 QAM modulation is used.
HARQ (Hybrid Automatic Repeat Request): ARQ technology in R99 fundamentally conforms to stop-and-wait protocol. However, in HSDPA, the N-channel stop-and-wait protocol is used. As a result, transmission efficiency is improved greatly. Principally, HARQ is the integration of the ARQ and Forward Error Correction (FEC). The HARQ is also a link adaptive technology. In the AMC, the explicit C/I measurement is used to set formats of the modulation formats. In the HARQ, information from the link layer is used in order to make a re-transmission judgment. Wrong data blocks are also used in combination with the re-transmitted data in order to obtain certain gains.
Fast data invoke: Invoke algorithm controls the allocation of shared resources and determines the action of the whole system. The invoke algorithm should transmit data instantaneously to a subscriber who has the best channel condition. As a result, the subscriber data rate and data throughput will be instantaneous and operate at a maximum peak during every moment of its operation. During this process, the grade and equity of each subscriber will also be considered. HSDPA technology also has the ability to quickly adapt to any fast changes in the channel. Here, the invoke function unit is put in Node B, instead of the RNC. Meanwhile, the TTI is shortened to 2ms.
The HSDPA is mainly used to enhance the downlink packet data rate, while the HSUPA is used to enhance the uplink rate. However, the uplink links do not share the same power resources with downlink links. The power of the downlink link is provided by Node B, while the uplink link power is derived from each terminal. However, there is a near-far problem for the uplink link, so power control is necessary. Therefore, enhancement of the downlink link data rate is not applicable to the uplink link. The HSUPA uses the BPSK modulation mode. The uplink transmission rate is improved through multi-code transmission, HARQ technology, the fast data invoke algorithm, as well as by the spread spectrum factor, with its SF equaling 2 or 4. The frame length is 10ms. The 3GPP once discussed the feasibility of attaining a 2ms frame length, but seems to be unattainable at present. Theoretically, the uplink peak transmission rate can be as high as 5.76Mbps.
- 3GPP2
So far, only 3GPP2 has released the standard for 1xEV-DO Rev.0. China"s cdma2000 1x EV-DO Rev.0 series of reference technical files have also been released. In addition, approval of the corresponding industry standard has also been passed. It includes such features as: air interface technology, A interface, equipment technology and test methods. 1x EV-DO Rev.0 was originally designed for asymmetrical wireless data service, but it has some disadvantages whenever subscribers"decide to utilize new services. In regards to the disadvantages of having 1x EV-DO Rev.0, 3GPP2 submits their corresponding improvement solution in DO Rev.A.
Improve the reverse link throughput: The peak rate of the reverse link in DO Rev.A can reach as high as 1.8Mbit/s.
Enhanced QoS support: Here, the physical layer, MAC layer, and higher layer are further improved to support the QoS. With this new enhancement the forward link can additionally support smaller data packets, which is suitable for transmitting delay-sensitive small packets. This also allows forward multiple subscribers to send packets at the same time in order to reduce waiting time. In addition, the RLP and MAC support the classification of multiple flows. The backward link can then adopt the sub-packet for the transmission, which can reduce the average transmit delay, while the MAC layer adopts the Traffic-to-Pilot (T2P), which can effectively reduce the delay and jitter of delay-sensitive services. In order to improve the handover speed, the reverse DSC channel is added to prevent service interruption and delay during the handover. Furthermore, the enhanced RLP is now able to support a more flexible QoS. And finally, the enhanced timeslot mode can substantially reduce the connection setup time of the delay-sensitive service.
Improvement of the forward link: DO Rev.A supports a much higher (3.1Mbit/s) and lower rate (4.8kbit/s), which can effectively improve the throughput when good traffic channel conditions exist. With the rate grade of the forward traffic channel being extended to 14 rate grades, it is then able to support larger or smaller packets. The utilization of radio resources is markedly improved through fast adjustment of the forward channel quality. A large data packet can then be supported. The largest data packet at the physical layer can reach as high as 5120bits, and the maximum data rate can surge as high as 3072kbit/s. Small data packets are also able to be supported, which would include the following three data packets -- 128bits, 256bits, and 512bits. Additionally, a packet in the physical layer can carry the multiple security layer packets of one or more subscribers. Moreover, the waste of resources decreases when using small packets, which effectively improves the system throughput.
Better support of 1X/DO dual-mode operations: In order to obtain CS information, a connection is established between the DO system and 1X circuit network. The network side structure of the 1xEV-DO Rev.A is then changed so that the EV-DO BSC can support the IOS A1 interface of the 1X system, thus allowing it to receive the CS message, in the form of paging messages and short messages, which are sent from the 1X MSC. In the application layer of the DO Rev.A air interface, the Circuit-Switched Service Notification Protocol (CSSNP) is added to encapsulate the CS message to specific data packets, and transmit it to the dual-mode terminal, through tunneling protocol defined on the EV-DO air interface. In the application layer, the multi-mode capability detection protocol is added in order to support the negotiation of the terminal and the handset, so that the network can ascertain the status of the handset, so that it can determine whether it is: a dual-mode terminal, single-module terminal, dual-receive/dual-transmit, or dual-receive/single transmit. As a result, the system side can then make the corresponding decision, based on to the negotiated results.
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