This paper brings forward data redundancy and cyclic code to control error rate, carrier wave detects and linear increment back arithmetic to ensure the network speed and fault diagnosis methods of hardware.

11 DCF mechanism is studied,it can be found that system throughput decreases and its collision probability increases if the station number increases because the binary backoff algorithm adopted can not provide even distribution for chosen time interval.

The source is required to send an acknowledgement to the best relay while contending relays will backoff when collision occurs.

A fast and efficient backoff algorithm DBC (Dynamical Backoff Control) is proposed to solve the problem.

It is proved that under the condition that normalized coordinates exist the system must be weakly linearly degenerate if the Cauchy problem for general quasilinear hyperbolic systems with characteristics with constant multiplicity with arbitrary small C 1 initial data always admits a unique global C 1 solution u=u(t,x) on t≥0.

Under the assumption of non-weak linear degeneracy, we obtain the relations between the life-span of classical solution to quasilinear strictly and non-strictly hyperbolic system and the index α of non-weak linear degeneracy under weaker decaying rates of the initial data.