Patent ID: 8107490

Claim:
A communication device comprising: a first unit determining that whether a state is a first state indicating that a transmission medium is in use, a second state indicating that the transmission medium is not in use, or a third state indicating that whether or not the transmission medium is in use is being determined; and a second unit prohibiting a data transmission in the first and third states, and permitting the data transmission in the second state, wherein the first unit comprises: a first determination unit determining that the transmission medium is in use or not; and a second determination unit determining that the state is in the first state when the first determination unit determines that the transmission medium is in use, determining that the state is in the second state when the first determination unit determines that the transmission medium is not in use, and determining that the state is in the third state when the first determination unit determines that whether or not the transmission medium is in use is being determined, and the second unit comprises: a counter incrementing or decrementing a hold value; a counter setting unit setting a count value of the counter as a predetermined value when the second determination unit determines that the state is in the first state, starting incrementing or decrementing of the count value when the state transfers from the first state to the second state, and maintaining an operation of incrementing or decrementing of the counter value of the counter when the state transfers from the second state to the third state; and a third determination unit determining that the data transmission is possible when the second determination unit determines that the state is in the second state and the counter value of the counter is equal to or more than or equal to or less than a threshold value.