An item of footwear is intended for sports practice and is used to protect the feet and legs of a user. The phase lock oscillator and the communication equipment can flexibly adapt to variances in environment conditions and maintain stable and high service quality. The mobile terminal inserts a first predetermined set of fields onto a first frame structure received from the packet switched network, and then forwards the inserted first frame structure to the data terminal equipment. The spacing between the elements comprise the pairs and the spacing between pairs reduces ambiguities. The present invention is of especial benefit to autonomic and on-demand computing architectures.