Broadcasting method and radio apparatus

Abstract

A processing unit sets the time interval before packet signals are broadcast, using a carrier sense multiple access (CSMA) scheme. A modem unit and an RF unit broadcasts the packet signals at the time intervals set by the processing unit. The RF unit and the modem unit receive a control signal broadcast from an access control apparatus at a predetermined frequency. The processing unit sets the time interval, during which the control signal is receivable, to a time length shorter than the time interval for the remaining cases.

1 - 7 . (canceled) 
     
     
         8 . A terminal apparatus, comprising:
 a first transmitter unit configured to broadcast, given a frame in which are time-division multiplexed a first period in which broadcast of an OFDM packet signal from an access control apparatus is possible and a second period available for CSMA/CA communication between terminal apparatuses, an OFDM packet signal in the second period within an area formed around a position of the access control apparatus, using CSMA/CA in which DIFS and CW are used;   a second transmitter unit configured to broadcast an OFDM packet signal outside the area formed around a position of the access control apparatus irrespective of a frame construction, using CSMA/CA in which DIFS and CW are used; and   a receiver unit configured to receive, in the first period of a frame, an OFDM packet signal for identifying the second period from the access control apparatus within the area formed around a position of the access control apparatus,   wherein the first transmitter unit identifies the second period by referring to the packet signal received by the receiver unit,   the receiver unit also receives, outside the area formed around a position of the access control apparatus, an OFDM packet signal for identifying the second period from another terminal apparatus within the area formed around a position of the access control apparatus, and   the second transmitter unit configured to identify the second period outside the area formed around a position of the access control apparatus by referring to the packet signal from the other terminal apparatus received by the receiver unit, and to broadcast an OFDM packet signal in the second period, using CSMA/CA in which DIFS and CW are used.   
     
     
         9 . A terminal apparatus, comprising:
 a first transmitter unit configured to broadcast, given a 100 msec frame in which are time-division multiplexed a first period in which broadcast of an OFDM packet signal from an access control apparatus is possible and a second period available for CSMA/CA communication between terminal apparatuses, an OFDM packet signal in the second period within an area formed around a position of the access control apparatus, using CSMA/CA in which DIFS and CW are used;   a second transmitter unit configured to broadcast an OFDM packet signal outside the area formed around a position of the access control apparatus irrespective of a construction of a 100 msec frame, using CSMA/CA in which DIFS and CW are used; and   a receiver unit configured to receive, in the first period of a 100 msec frame, an OFDM packet signal for identifying the second period from the access control apparatus within the area formed around a position of the access control apparatus,   wherein the first transmitter unit identifies the second period by referring to the packet signal received by the receiver unit,
 the receiver unit also receives, outside the area formed around a position of the access control apparatus, an OFDM packet signal for identifying the second period from another terminal apparatus within the area formed around a position of the access control apparatus, and 
 the second transmitter unit configured to identify the second period outside the area formed around a position of the access control apparatus by referring to the packet signal from the other terminal apparatus received by the receiver unit, and to broadcast an OFDM packet signal in the second period, using CSMA/CA in which DIFS and CW are used. 
   
     
     
         10 . The terminal apparatus according to  claim 8 , wherein the receiver unit establishes timing synchronization by referring to the received OFDM packet signal. 
     
     
         11 . The terminal apparatus according to  claim 9 , wherein the receiver unit establishes timing synchronization by referring to the received OFDM packet signal. 
     
     
         12 . A transmission method, comprising:
 receiving, given a frame in which are time-division multiplexed a first period in which broadcast of an OFDM packet signal from an access control apparatus is possible and a second period available for CSMA/CA communication between terminal apparatuses, an OFDM packet signal from the access control apparatus in the first period within an area formed around a position of the access control apparatus, the OFDM signal identifying the second period;   identifying the second period by referring to the received packet signal;
 broadcasting an OFDM packet signal within the area formed around a position of the access control apparatus in the second period of the frame, using CSMA/CA in which DIFS and CW are used; 
   broadcasting an OFDM packet signal outside the area formed around a position of the access control apparatus irrespective of a frame construction, using CSMA/CA in which DIFS and CW are used;
 receiving, outside the area formed around a position of the access control apparatus, an OFDM packet signal for identifying the second period from another terminal apparatus within the area formed around a position of the access control apparatus; 
   identifying the second period outside the area formed around a position of the access control apparatus by referring to the packet signal received from the other terminal apparatus; and   broadcasting an OFDM packet signal in the second period outside the area formed around a position of the access control apparatus, using CSMA/CA in which DIFS and CW are used.