Medium access control scheme for data transmission on code division multiple access (CDMA) wireless systems

• US 5,828,662 A
• Filed: 06/19/1996
• Issued: 10/27/1998
• Est. Priority Date: 06/19/1996
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Krzymien, Witold, Jalali, Ahmad, Mermelstein, Paul
• Primary Examiner(s): Patel, Ajit
• Application Number:
  US08/666,828
• Time in Patent Office: 860 Days
• Field of Search: 370/320, 370/321, 370/324, 370/335, 370/337, 370/342, 370/347, 370/350, 370/441, 455/422
• US Class Current: 370/335
• CPC Class Codes: H04W 56/0085 detecting a given structure in the signal

Abstract

A synchronous discontinuous transmission medium access control (SDTX-MAC) method and apparatus for more efficiently using existing uplink channels by sharing these uplink channels between multiple terminals engaged in bursty data transmission. This is accomplished by assigning each mobile terminal an individual time slot and by not requiring each mobile terminal to broadcast its identity. This results in a reduction in the number of receivers on each base station and a reduction in the length of the synchronization message.

Claims

1. A code division multiple access (CDMA) communication system comprising a base station and a plurality of assigned mobile terminals coupled at least one said base station, wherein said base station communicates with said plurality of assigned mobile terminals using at least one transmitter and at least one receiver to transfer at least one of many data bursts, and said transmitter and receiver communicate using a plurality of communication channels comprising:

forward link channels which include a pilot channel, a synchronization channel, at least one paging channel, at least one forward traffic channel, and at least one reservation response channel;

reverse link channels which include at least one access channel, at least one reverse traffic channel, and at least one synchronous synchronization-reservation channel; and

means for establishing a communication link between said base station and said plurality of assigned mobile terminals.

2. A code division multiple access (CDMA) communication system as recited in claim 1, wherein said means for establishing a communication link further comprises:

means for maintaining contact between said base station and a first of said plurality of assigned mobile terminals;

means for synchronizing transmissions between said base station and the first of said plurality of assigned mobile terminals;

means for adjusting the transmitting power of the first of said plurality of assigned mobile terminals so as to allow the transfer of said data bursts; and

means for terminating said communications link.

3. A code division multiple access (CDMA) communication system as recited in claim 2 wherein said synchronous synchronization-reservation channels transmit a PN code identifying the sector of the cell that the transmitting mobile terminal is in.

4. A code division multiple access (CDMA) communication system as recited in claim 3 wherein said synchronous synchronization-reservation channels for transmitting a preamble are each divided into a plurality of frames and said frames are further divided into a plurality of time slots, each said time slots corresponding to an individual mobile terminal.

5. A code division multiple access (CDMA) communication system as recited in claim 4 wherein said preamble transmitted on assigned synchronization-reservation channel time slot comprises at least one repetition of the PN code in one time slot.

6. A code division multiple access (CDMA) communication system as recited in claim 5 wherein said base station synchronizes to said mobile terminal using said preamble, and said base station transmits a channel assignment message on one of said reservation response channels.

7. A code division multiple access (CDMA) communication system as recited in claim 5 wherein the mobile terminal uses said channel assignment message to transmit data at the assigned time slot.

8. A method of operating a code division multiple access (CDMA) communication system comprised of a plurality of mobile terminals operating in sector of a cell which is assigned to a base station, wherein said base station communicates with said plurality of assigned mobile terminals using at least one transmitter and at least one receiver to transfer at least one of many data bursts, the method comprising the steps of:

maintaining a constant link between said base station and said plurality of mobile terminals with a pilot signal;

accessing said base station by a first of said mobile terminals with an origination message;

assigning a synchronous synchronization-reservation channel time slot to the first mobile terminal by said base station in response to said origination message;

synchronizing the first mobile terminal with said base station using said assigned time slot;

sending a channel assignment message to the first mobile terminal after the base station synchronizes with the first mobile terminal;

broadcasting data frames from said plurality of mobile terminals to said base station on a traffic channel designated by said channel assignment message sent by said base station; and

turning off said transmitter of said first mobile terminal once said broadcasting is completed by said first mobile terminal.

9. A method of operating a code division multiple access (CDMA) communication system according to claim 8 wherein said accessing step comprises the sub-steps of:

sending said origination message from said first mobile terminal to said base station wherein said origination message contains packet data; and

receiving said origination message sent by said first mobile terminal at said base station.

10. A method of operating a code division multiple access (CDMA) communication system according to claim 9 wherein said assigning step comprises the sub-steps of:

setting aside said synchronous synchronization-reservation channel time slot and a channel assignment for use by said first mobile terminal in an assignment message by said base station;

transmitting said assignment message from said base station to said first mobile terminal; and

receiving said assignment message at said first mobile terminal.

11. A method of operating a code division multiple access (CDMA) communication system according to claim 10 wherein said synchronizing step comprises the sub-steps of:

tuning said transmitter of said first mobile terminal to said channel assignment assigned in said assignment message;

transmitting a synchronization message from said first mobile terminal to said base station at said assigned time slot and on said synchronous synchronization-reservation channel contained in said assignment message;

receiving said synchronization message sent by said first mobile terminal at said base station; and

synchronizing said base station to the mobile using a preamble contained in said synchronization message sent by said first mobile terminal.

12. A method of operating a code division multiple access (CDMA) communication system according to claim 11 wherein said transmitting step comprises the sub-steps of:

assigning a reverse traffic channel and a send time to said first mobile terminal in said channel assignment message;

transmitting said channel assignment message from said base station to said first mobile terminal using a reservation response channel;

receiving said channel assignment message at said first mobile terminal on said reservation response channel; and

tuning said transmitter on said first mobile terminal to said reverse traffic channel assigned in said assignment message.

13. A method of operating a code division multiple access (CDMA) communication system according to claim 12 wherein said broadcasting step comprises the sub-steps of:

transmitting from said first mobile terminal at least one of a plurality of data frames on assigned said reverse traffic channel designated by channel assignment message to said base station; and

receiving said at least one data frame at said base station transmitted by said first mobile terminal.

14. A method of operating a code division multiple access (CDMA) communication system according to claim 12 wherein said transmitting sub-step comprises

transmitting a PN code identifying the sector of the cell the said mobile terminal is transmitting from which results in a reduction of the number of receivers the base station is required to have.

15. A method of operating a code division multiple access (CDMA) communication system as recited in claim 14 wherein said sending sub-step further comprises

dividing said synchronous synchronization-reservation channels into a plurality of frames;

subdividing said plurality of frames into a plurality of time slots;

assigning each of said mobile terminals to a corresponding time slot; and

transmitting a preamble on said assigned synchronization-reservation channel time slot during said assigned time slot.

16. A method of operating a code division multiple access (CDMA) communication system as recited in claim 15 wherein said transmitting sub-step comprises

repeating a PN code at least once in said one time slot.