NEC研製高速精確WiMAX電波傳播模擬器

NEC Develops High Speed/Precision WiMAX Radio Propagation Simulator

October 1, 2007 -- NEC Corporation announced the successful development of a new Worldwide Interoperability for Microwave Access (WiMAX) radio propagation simulator, RADIOSCAPE-WiMAX. The new simulator is expected to realize the analysis and display of the service area and transmission performance of WiMAX (1) systems after their adoption in Japan next year.

WiMAX has been attracting attention as the next generation broadband wireless-access technology expected to enable low-cost communication services, such as high capacity mobile data communication by mobile phones and PC cards, and wide-area fixed wireless access to resolve the digital divide.

By introducing new space/frequency utilization concepts, such as Multiple-Input Multiple Output (MIMO (2)) and sub-channelization, WiMAX systems are expected to realize the transmission of large volumes of data in limited-frequency bands and frequency reuse between base stations. However, existing area-planning tools cannot estimate quantitatively or precisely the effects of these kinds of new technologies, resulting in inefficient area planning. NEC has developed RADIOSCAPE-WiMAX to realize efficient area planning after the future adoption of WiMAX systems.

New functions were added to RADIOSCAPE®(3), a radio propagation simulator developed by NEC for wireless LAN and 3rd generation mobile phone systems, to allow application to future WiMAX systems. The features of the newly developed radio propagation simulator RADIOSCAPE-WIMAX include the following:

(1) Accelerated calculation by hierarchized MIMO characteristic simulation technology
A large amount of complex calculation needs to be processed for WiMAX area planning that incorporates MIMO, hindering efficient area planning. To improve this process, NEC has developed the world’s first hierarchized MIMO characteristic simulation technology, realizing high speed and high precision simulation of increased transmission capacity by MIMO technology. For example, calculation processing for base stations located at 1km intervals in all 23 wards of Tokyo would require 52 days to be processed, but NEC’s newly developed technology can cut this time to 1.3 days, ensuring efficient WiMAX area planning.

(2) Highly precise frequency planning by inter-sub-channel interference simulation technology
WiMAX employs sub-channelization, which achieves an increase in the number of frequency channels. However, interference between sub-channels differs to that of inter-channel interference in conventional radio communication, making it difficult to estimate any transmission performance degradation. NEC has incorporated an interference characteristic model into the new simulator to enable frequency planning based on highly precise interference simulations and effective utilization of limited-frequency bands.

NEC has confirmed the precision of RADIOSCAPE-WiMAX through indoor/outdoor radio propagation tests, which show that the new simulator not only maintains a high level of estimation precision similar to that of RADIOSCAPE® but also achieves simulation that is 40 times faster than conventional ray-launching methods.

Utilization of this simulator will enable quantitative evaluation of system capability of specific environments and equipment during the phase of WiMAX equipment planning and system implementation. Consequently, phased equipment planning appropriate to the number of users and the volume of traffic can be achieved.

NEC expects this technology to provide comprehensive support to network operators when WiMAX service commences on a nationwide scale, and to facilitate adjustment of the frequency distribution of high-speed wireless communication services offered to residents in local communities.

NEC is currently planning to introduce the new simulator into its total WiMAX solutions offering next year.

Please refer to the attachment for further details on RADIOSCAPE-WiMAX.

NOTES
(1). Worldwide Interoperability for Microwave Access (WiMAX): is a radio specification which has been standardized by the IEEE 802.16 committee as a broadband wireless access system to connect the last mile. WiMAX is a name used in the WiMAX Forum, an industry organization. There are two types of WiMAX: fixed WiMAX (IEEE 802.16-2004) that targets fixed communication in areas where there is difficulty using optical and DSL lines, and mobile WiMAX (IEEE 802.16e-2005) that targets high-speed mobile communication. MIMO is planned to be adopted in mobile WiMAX.

(2). Multiple-Input Multiple-Output (MIMO): is a communication technology, in which multiple antennas are allocated to the transmitting and receiving devices, and transmission capacity is increased by spatial multiplexing. Ideally, multiple transmission paths can be created virtually; the number of created transmission paths is the same as the number of antennas allocated in the transmitting device or the receiving device, whichever is less. As a result, the transmission capacity is multiplied by the number of created paths. In reality, the increase in transmission capacity differs depending on the radio propagation performance at each point; therefore, simulation of the MIMO characteristics is very important.

(3). RADIOSCAPE®: is NEC’s original 3-dimensional radio propagation analysis tool, which supports the area planning of networks such as the mobile phone and wireless LAN networks. By inputting 3-dimensional map data and floor layout, radio propagation performance that takes into consideration the mutual effect of indoor and outdoor conditions can be estimated seamlessly.

RADIOSCAPE is a registered trademark in Japan of NEC.