Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a CDMA cellular communications system
DCFirst Claim
1. An apparatus for reducing collisions between transmitted messages in a communications network, said apparatus having a unique identification code, said apparatus comprising:
- processor means for providing a message;
a timing generator for providing a delay time in response to said unique identification code;
an encoder for delaying said message by said delay time; and
a transmitter for transmitting, at a time determined in accordance with said unique identification code, said delayed message to a receiver.
0 Assignments
Litigations
0 Petitions
Accused Products
Abstract
Collisions between messages simultaneously transmitted by multiple spread-spectrum transmitters are reduced by distributing the transmissions over the available resources of the receiver. The transmitters may be mobile stations and the receiver may be a base station in a CDMA cellular telephone system. Each mobile station uses one or more randomization methods to distribute its transmissions. In the first randomization, the mobile station time--delays its transmissions by a number of chips of the PN code with which it spreads the transmitted signal. A hash function produces the number from an identification number uniquely associated with that mobile station. In a second randomization, the mobile station randomly selects the PN code. In a third randomization, the mobile station inserts a random delay between successive message transmissions or probes if it does not receive an acknowledgement after a predetermined timeout period. A predetermined number of such transmissions is called a probe sequence. In a fourth randomization, the mobile station inserts a relatively long random delay between successive probe sequences if it does not receive an acknowledgement of any probe in the sequence. The noise level is reduced by minimizing transmission power. The mobile station increments the power of successive probes within each probe sequence. The first probe of each probe sequence is transmitted at a predetermined level.
-
Citations
85 Claims
-
1. An apparatus for reducing collisions between transmitted messages in a communications network, said apparatus having a unique identification code, said apparatus comprising:
-
processor means for providing a message; a timing generator for providing a delay time in response to said unique identification code; an encoder for delaying said message by said delay time; and a transmitter for transmitting, at a time determined in accordance with said unique identification code, said delayed message to a receiver. - View Dependent Claims (2)
-
-
3. An apparatus for reducing collisions between transmitted messages in a communications network, said apparatus having a unique identification code, said apparatus comprising:
-
processor means for providing a message and at least one random number; a PN code sequence generator for randomly selecting a PN code sequence from a predetermined set of PN code sequences in response to a random number received from said processor means; a timing generator for providing a delay time in response to said identification code; an encoder for delaying said message by said delay time; and a transmitter for transmitting said delayed message to a receiver, said transmitted delayed message being a direct sequence spread spectrum signal spread using said PN code sequence having a chip rate wherein said delay time is equal to or greater than one chip. - View Dependent Claims (4, 5, 6, 7, 8)
-
-
9. A method for reducing collisions between messages in a communications network having a plurality of transmitters and at least one receiver, each of said transmitters having a unique identification code, said method comprising the repeated steps of:
-
generating a message; delaying said message by a delay time corresponding to said identification code; and transmitting said delayed message at a time determined in accordance with said unique identification code, said transmitted message having a power level. - View Dependent Claims (10)
-
-
11. A method for reducing collisions between messages in a communications network having a plurality of transmitters and at least one receiver, each said transmitter having a unique identification code, comprising the repeated steps of:
-
randomly selecting a PN code sequence from a predetermined set of PN code sequences; generating a message; delaying said message by a delay time corresponding to said identification code; modulating said delayed message with said PN code sequence; and transmitting said delayed message, said transmitted message having a power level. - View Dependent Claims (12, 13, 14, 15)
-
-
16. In a communications device, an apparatus for reducing collisions between messages of said communications device and other communication devices in a communications network, said apparatus comprising:
-
processor means for providing a timing signal in accordance with a unique identification code, and for providing a message in response to said timing signal; and transmitter means for transmitting said message at a time determined in accordance with said unique identification code. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
-
-
31. In a communications device, an apparatus for reducing collisions between messages of said communications device and other communication devices in a communications network said apparatus comprising:
-
processor means for providing a timing signal in accordance with a unique identification code, and for providing a message in response to said timing signal, wherein said processor means further includes means for generating a first random number within a backoff delay range of numbers and means for providing a second timing signal responsive to said first random number and said timing signal and means for further delaying the provision of said message in response to said second timing signal; an encoder for encoding said message for transmission according to a predetermined coding format; and transmitter means for transmitting said message. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
-
-
43. A circuit for reducing collisions between messages of a communications device with other communications devices in a communications network, said circuit comprising:
-
a processor circuit having an output for providing a timing signal determined in accordance with a unique identification code and having a second output for providing a message responsive to said timing signal; and a transmitter having an input coupled to said processor circuit second output, said transmitter for transmitting said message at a time determined in accordance with said unique identification code. - View Dependent Claims (44)
-
-
45. A circuit for reducing collisions between messages of a communications device with other communications devices in a communications network, said circuit comprising:
-
a processor circuit having an output for providing a timing signal determined in accordance with an identification code and having means for encoding a message for transmission as an encoded message according to a predetermined coding format, said processor circuit further including a second output for providing said encoded message responsive to said timing signal and means for generating a first random number within a backoff delay range of numbers and means for providing a second timing signal responsive to said first random number and said timing signal and means for further delaying the provision of said message responsive to said second timing signal; and a transmitter having an input coupled to said processor circuit second output. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56)
-
-
57. A method for reducing collisions between messages in a communications network wherein a time period is divided into slots of predetermined durations and each transmitter has a unique identification code, said method comprising the steps of:
-
(a) providing a message; (b) generating a random number from a first range of numbers; and (c) delaying said message by a number of said slots equal to said random number. - View Dependent Claims (58, 59, 60, 61)
-
-
62. In a spread spectrum communications system in which a plurality of remote stations communicate messages to a base station, an apparatus in each remote station for reducing collisions between messages of said remote stations, said system comprising:
-
processor means for providing a timing signal, wherein said timing signal is determined in accordance with a unique identification code and for providing said message responsive to said timing signal; spreading means for direct sequence spreading said message; and transmitter means for transmitting said direct sequence spread message at a time determined in accordance with said unique identification code. - View Dependent Claims (63)
-
-
64. In a spread spectrum communications system in which a plurality of remote stations communicate messages to a base station, an apparatus in each remote station for reducing collisions between messages of said remote stations, said system comprising:
-
processor means for providing a timing signal, wherein said timing signal is determined in accordance with a unique identification code and for providing said message responsive to said timing signal, said processor means further including means for encoding said message for transmission according to a predetermined coding format and means for generating a first random number within a backoff delay range of numbers and means for providing a second timing signal responsive to said first random number and said timing signal and means for further delaying the provision of said message responsive to said second timing signal; spreading means for direct sequence spreading said message; and transmitter means for transmitting said direct sequence spread message. - View Dependent Claims (65, 66, 67, 68, 69, 70, 71)
-
-
72. In a spread spectrum communications system in which a plurality of remote stations each having a unique identification code communicate messages to a base station, an apparatus in each remote station for reducing collisions between messages of said remote stations, said apparatus comprising:
-
a processor for determining a delay value in accordance with said unique identification code and having an output for providing said message responsive to said delay value; and a transmitter having an input coupled to said processor second output and an output for transmitting said message at a time determined in accordance with said unique identification code. - View Dependent Claims (73, 74)
-
-
75. In a spread spectrum communications system in which a plurality of remote stations each having a unique identification code communicate messages to a base station, an apparatus in each remote station for reducing collisions between messages of said remote stations, said apparatus comprising:
-
a processor for determining a delay value in accordance with said unique identification code and having an output for providing said message responsive to said delay value, said processor further comprising a second output for providing a PN code; an encoder having an input coupled to said processor output and having an output; a spreading circuit having an input coupled to said encoder output, a second input coupled to said processor second output and an output; and a transmitter having an input coupled to said spreading circuit output and an output for transmitting said message. - View Dependent Claims (76, 77, 78, 79, 80, 81, 82, 83, 84, 85)
-
Specification