High Power Consumption
Different from the existing solutions, some practical installation problems must be solved when 10GBASE-T is actually applied. One is the power consumption per board. According to the test conducted by Japan’s NEC Electronics Corporation in September 2003, the power consumption of their scheme is 8 W in the digital circuit part and 3.7 W in the analog circuit part when using an integrated circuit made of a 90nm semiconductor process. The total power consumption is 11.7W. The power consumption of other companies’ solutions is expected to be generally between 10W and 20W.
Mr. Hattori Akira, deputy general manager of advanced interconnect technology at Fujitsu Laboratories in the United States, said: “Such a large power consumption is limited by heat generation, and switching integrated circuits need to be installed on multiple circuit boards.” Japan’s NEC Electronics Co., Ltd. expects that Improved analog circuit technology and the adoption of the 65nm semiconductor process, “can reduce the total power consumption to 6.2W after 3 years”.
High power consumption will also have an impact on the establishment of the 10GBASE-T market. “For 1000BASE-T, the integrated circuit power consumption of the signal transceiver can be reduced to less than 1 W, that is, if a fan is not required, Users can increase rapidly.” For small PCs, reducing power consumption is a decisive factor.
Key Eye is one step ahead of others in reducing power consumption. In March 2004, the power consumption of the CMOS switch of the analog circuit they prototyped was limited to 1.66W, which has achieved lower power consumption than NEC Electronics expected to achieve in three years. If the power consumption of the digital circuit can also be reduced. The target of the power consumption of the whole signal transceiver of less than 5 W can be achieved.
Reduce Crosstalk With Wireless “MIMO”
Another big problem alongside power consumption is crosstalk (missed calls). The greater the attenuation of the cable, the stronger the leakage of the electric wave, and the crosstalk between the twisted pairs and between the cables will increase. One of the biggest problems of 10GBASE-T is the adjacent line crosstalk (alien crosstalk). “Near-end crosstalk and far-end crosstalk in the cable can be eliminated by the echo cancellation function of the digital circuit,” said Mr. Guan Kemin of NEC Electronics.
Neighbor-to-wire crosstalk is the noise generated from external cables. Since there is no correlation between the transmitted and received edge signals, it cannot be solved by traditional methods. For some Category 6 cables, this adjacent-wire crosstalk can be significant. According to the simulation test of NEC Electronics Corporation of Japan, if more than 6 Category 6 cable bundles are used. The communication of 10Gbit/s cannot be guaranteed due to the influence of adjacent line crosstalk.
The solution to this kind of crosstalk is the MIMO method using wireless technology. Mr. Guan Kemin said that considering the 4 twisted pairs in the cable as 4 antennas, part of the noise in the adjacent line crosstalk sent from the other twisted pair may be canceled.
MIMO is an acronym for Multiple input multi-output. This is a new generation of wireless communication technology. Channel radio waves of a certain frequency are sent and received in parallel using multiple antennas. High-speed transmission is achieved through this multiplexing method. The data communication rate of this technology can exceed 100Mbit/s. This is one of the complementary technologies of the 4th generation of mobile communication (so-called 4G).