BeiDou Integration in Cellphones and Tablets, Preferred Architecture for Consumer Products

F. van Diggelen, K.W. Tan

Abstract:	This paper presents single chip BeiDou/Galileo/GLONASS/GPS/QZSS/SBAS architecture for use in cell phones and tablets. The paper also shows how multi-system issues are addressed, and how Assisted-GNSS operates with BeiDou. In particular we address the following issues: • Receiver intersystem RF bias with a tri-band front-end. BeiDou uses a different RF section than GPS/Galileo/QZSS/SBAS and GLONASS, thus there is a receiver intersystem bias between BeiDou and each of these other systems. Not just because BeiDou is on a different frequency, but also because of the different RF path through the receiver. We explain how this bias is calibrated and removed. • In the space-segment there are intersystem biases, primarily caused by differences in time standards. We discuss time management and show how the different systems can be made interoperable. • Effect of secondary code: one of the largest differences between BeiDou and GPS is the presence of a 20ms secondary spreading code in BeiDou. This has profound influence on consumer device architecture, where the cost of supporting fully parallel search capabilities could be prohibitively high (in terms of percentage change in the cost of GNSS in cell phones). Luckily, by leveraging A-GNSS information, we can use GPS to help with BeiDou acquisition; thus putting the “A” back into the C/A code. And sometimes the opposite is true, and BeiDou can help with GPS acquisition. We will discuss these issues, as well as the wider issues of more complicated codes, such as “memory codes” in other GNSS systems. • BeiDou Assistance. In order to get the benefits mentioned above, we need infrastructure deployment for BeiDou assistance in accordance with 3GPP standards. We will discuss what is available, and what is left to do. • Coverage outside of China. Europeans can see more BeiDou satellites than Galileos. At the time of writing (March 2013) they could see approximately twice as many. Thus, when used in a multi-GNSS receiver, BeiDou is far from being just a regional system. We will provide comprehensive analysis of coverage and benefits in the European market. • Finally we will show all the above in practice, explaining and showing how first fixes can be computed with no more than one of each satellite type.
Published in:	Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013) September 16 - 20, 2013 Nashville Convention Center, Nashville, Tennessee Nashville, TN
Pages:	2814 - 2820
Cite this article:	van Diggelen, F., Tan, K.W., "BeiDou Integration in Cellphones and Tablets, Preferred Architecture for Consumer Products," Proceedings of the 26th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2013), Nashville, TN, September 2013, pp. 2814-2820.
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