HSUPA Solution Enabling a New 3G Experience

Release Date:2008-07-24  Author:Zhu Junman  Click:

What makes their 3G life so exciting? The answer is HSUPA, the next hot topic after HSDPA, which enables high uplink data speed, short service response time, and perfect user experience.

Features of HSUPA
As we know, 3GPP Release 99 (R99) offers a maximum speed of 384kbps, and then HSDPA defined in 3GPP R5 supports higher speed 3G services. But HSDPA only delivers improved downlink performance. HSUPA is introduced to improve uplink data speed and system efficiency. It can achieve a uplink peak data rate of 5.76Mbps, bringing a more satisfying user experience.

HSUPA is the enhanced uplink technology specified in 3GPP R6. With HSUPA, operators can provide more interactive and high-speed multimedia services, such as video conferencing, online games, email, DVD quality video, MMS. These flexible and powerful services can help telecom operators improve branding, develop more individual and enterprise users, and increase profits.

Technical Principles of HSUPA
Similar to HSDPA, HSUPA introduces new physical channels including E-DPDCH, E-DPCC, E-AGCH, E-RGCH, E-HICH and two MAC entities, known as MAC-es and MAC-e. In order to support fast scheduling function at NodeB, the decentralized scheduling is moved from RNC to NodeB. With key technologies including Hybrid Automatic Repeat Request (HARQ), NodeB fast scheduling, 2ms short frame, and multi-code transmission, HSUPA improves the uplink service bearing capability and frequency utilization, greatly enhancing the network performance.

HARQ: HARQ is an error correcting technology, which can lower requirements on wireless channel quality, control uplink interference, reduce transmission delay, and increase uplink data transfer rate.

NodeB fast scheduling: With the introduction of decentralized fast scheduling at NodeB, user's data transmission rate can be scheduled up to 2ms, based on channel conditions and cell loads.

2ms short frame: In HSUPA both 2ms short frame and 10ms frame are supported. The 2ms short frame length allows to minimize Round Trip Time (RTT) in the NodeB controlled HARQ, reducing the fast scheduling response time as well.

Multi-code transmission: E-DPDCH supports multiple frequency spreading codes from SF2 to SF256, and multi-code transmission like 2xSF4, 2xSF2, 2xSF2+2xSF4, etc. By the use of multi-code transmission, HSUPA can increase the uplink data rate up to 5.76Mbps.

Constructing a Perfect HSUPA Network  
HSUPA with multiple advantages is attracting an increasing level of interest. Combining HSDPA with HSUPA is quickly becoming the most popular UMTS evolutionary choice. HSPA-enhanced UMTS network will enable subscribers to enjoy more diversified and exciting services. Therefore, it is critical to study how to build a HSUPA network or how to upgrade the exiting UMTS network to HSUPA rapidly and at a low cost.

HSUPA is usually deployed on top of R99/HSDPA network on the same carrier, sharing cell resources such as power and codes with R99/HSDPA. It is necessary to evaluate the impact of HSUPA on the existing UMTS system. With patented HSUPA simulation tool, ZTE conducted research on the impact of HSUPA on the R99/HSDPA network when HSUPA and R99/HSDPA operate on the same frequency, and concluded that the introduction of HSUPA puts higher requirements on the upgradeability of power resource, baseband processor and other aspects of NodeB.

  • Since HSUPA adds a set of new physical channels and some MAC entities, it is required that the existing base stations can be upgraded to support HSUPA, to protect initial network investment while quickly responding to market requirements.
  • HSUPA adds three downlink physical channels including E-AGCH, E-RGCH, E-HICH, which all consume downlink code resources. With the increase of the number of users to access the HSUPA network, there will be a shortage of downlink code resources and new carriers should be introduced to bear HSPA traffic.
  • According to the simulation results, one E-AGCH consumes 5% to 7% of downlink transmission power output in a cell, and one E-HICH or E-RGCH consumes about 5% of downlink transmission power output, which will exert a certain influence on the R99/HSDPA downlink coverage and capacity.

It can be seen from the above analysis that, if R99, HSDPA and HSUPA are deployed on the same carrier in the initial phase of network construction, the baseband processing unit of NodeB should be able to be upgraded to support HSUPA key technologies and algorithms, and the amplifier with higher transmit power can be deployed when necessary. If HSDPA and HSUPA are deployed on an independent carrier, the NodeB should be able to be upgraded to support multiple carriers and HSPA function. Using high performance and scalable UMTS system equipment to build 3G network can protect the initial network construction investment, reducing CAPEX and OPEX.

ZTE's HSUPA Solution
As a leading provider of telecommunication solutions in industry, ZTE launched cost-effective, high performance end-to-end HSUPA solutions in 2006. It is worth mentioning that ZTE's self-developed Radio Resource Management (RRM) algorithm solves the mutual influence problem that occurred during HSDPA/UPA simultaneous transmission at the highest possible rates.

Taking HSUPA into consideration, ZTE's UMTS system was designed to support HSUPA and HSDPA. The baseband processing board in NodeB has special HSUPA processing module, which can handle HSPA and R99 services simultaneously, guaranteeing large HSPA throughput. Only a software upgrade is needed to support the migration path from HSDPA, to HSUPA and even HSPA+.

ZTE, based on its independently developed Doherty and DPD technologies, has developed 20W, 40W, 60W serial Power Amplifier (PA), meeting the requirements of R99/HSDPA/HSUPA multi-carrier networking. Meanwhile, the high efficiency PA can reduce power costs by 50% compared with traditional base stations.

To meet the development needs of UMTS networking, ZTE's UMTS base stations support smooth expansion from 1 carrier to 4 carriers, which can help realize flexible R99 and HSPA networking on a single carrier, dual carriers or multiple carriers.

The 3GSS system, ZTE's HSPA simulating platform released in 2006, can provide diverse HSUPA scheduling algorithms and support different HSUPA throughput configurations. It can implement performance simulation of various application scenarios like single-carrier networking or multi-carrier networking, providing the theoretical basis for HSUPA network deployment.    

Conclusion
Attracted by the high performance of HSPA, more and more mobile operators are deploying or planning to deploy HSUPA/HSDPA network to deliver quality services to subscribers anytime and anywhere. ZTE, specializing in providing end-to-end solutions for operators, has launched the commercial version of HSUPA system and HSUPA terminals, helping operators build future-oriented 3G network.

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