Code division multiple access system providing variable data rate access to a user

A code division multiple access radio transmitter unit comprising

• means for receiving a digital bit stream from a user at one of a plurality of source bit rates,
• adjustable coding means, responsive to a user input selecting one of said plurality of source bit rates, for assigning one or more spreading codes for spreading and transmitting the user digital bit stream received at the selected bit rate to a channel bit rate which at least equals the highest bit rate of said plurality of source bit rates;
• and wherein
• said plurality of source bit rates includes a bit rate which is a multiple M of the basic bit rate R, where M is a number having an integer portion I greater than or equal to one and a fractional portion m, where 0<m<1, said user input selecting a particular user source bit rate by identifying a basic bit rate multiple M.

A code division multiple access radio transmitter unit comprising

• means for receiving a digital bit stream from a user at one of a plurality of source bit rates,
• adjustable coding means, responsive to a user input selecting one of said plurality of source bit rates, for assigning one or more spreading codes for spreading and transmitting the user digital bit stream received at the selected bit rate to a channel bit rate which at least equals the highest bit rate of said plurality of source bit rates;
• and wherein
• said adjustable coding means includes
• a serial-to-parallel means, responsive to a user's input identifying a basic bit rate multiple M, where M is a number having an integer portion I greater than or equal to one and a fractional portion m, where 0<m<1, for converting a received user bit stream, which is M times a basic bit rate R, into I+1 basic bit rate streams, wherein at least one of the I+1 basic bit rate streams can transmit at the fractional rate m,
• M encoder means for spreading each of the I+1 basic bit rate streams, using a different spreading code C, into I+1 channel bit rate signals, and
• means for combining the I+1 channel bit rate signals into one channel bit rate signal and modulating the channel signal onto a carrier signal for transmission from the code division multiple access radio transmitter unit.