Performance comparison of data serialization schemes for ETSI ITS car-to-X communication systems

Wireless Car-to-X communication is about to enter the mass market in upcoming years. The non-licensed, but reserved bandwidth for such communications is relatively narrow in terms of the few usable channels and the expected number of communicating entities. Among other communication aspects, data serialization schemes that allow compact encoding as well as fast encoding and decoding are required. Compact representation of data helps in keeping a minimal bandwidth overhead in the wireless channel. Moreover, since delay is an important performance parameter in Car-to-X communication, the processing time of the serialization / deserialization schemes shall be kept to a minimum. So far, no detailed analysis of different data serialization schemes for Car-to-X communication regarding important properties such as runtime, memory consumption and encoded output length has been published. In this work, we provide a performance comparison analysis between the standardized ASN.1, the binary representations, Google Protocol Buffers and Efficient XML Interchange format (EXI), all of them as alternative strategies for data serialization. Standardized data content for CAM, DENM and the security envelope are used in the conducted study. We conclude that ASN.1 encoding on the facility layer shows the best performance, outperforming Google Protocol Buffers and EXI. However, for the case of encoding the security envelope, ASN.1 is outperformed by a binary encoding scheme in most cases, while EXI encoding outperforms all other schemes. This implies that standardization efforts for the security envelope should recondsider the recent shift from binary encoding towards usage of ASN.1. Instead, the Efficient XML Interchange format should be considered for this purpose.