Multi-access communication system

1. A method for optimizing a network parameter in a set of network parameters in a multiple access wireless communication system comprising a plurality of terminals and a multi-access receiver which communicates using a frame comprising a plurality of slots, wherein each terminal has an active state for transmitting, and an inactive state during which the terminal is prevented from transmitting, and stores a probability of transmission p which, during an active state, the terminal uses to determine whether to transmit in a frame, and the multi-access receiver has a first field of view and is configured to successfully decode up to m transmissions in each slot of a frame from terminals in the field of view, wherein the network parameters comprise (p, n, m, ε) where p is the probability of an active terminal deciding to transmit in a frame when in the active state, n is the number of slots per frame, m is the number of simultaneous transmissions that a multiuser can successfully decode in a single slot, and ε is the probability of failure of a terminal to successfully transmit a message whilst in a field of view of the multiple access receiver, and the method of optimising a network parameter comprising:

selecting the network parameter and numerically solving q=1−pQ(m,λ) and

K

0

=

1

-

ɛ

1

/

F

1

-

ɛ

⁢

λ

*

⁢

n

to optimise λ* where 1−q is the proportion of terminals that succeed in transmitting in a frame and Q is the gamma function, K 0 is the number of new terminals that enter the field of view each frame, F is the number of frames a terminal is in the field of view for, λ=k/n and k=pK and where K is the number of active terminals in the field of view; and

updating the optimized network parameter in at least one of the multi-access receiver and the plurality of terminals.

2. The method as claimed in claim 1 , wherein the method is performed by the receiver and the receiver transmits changes to the system parameters to the plurality of terminals.

3. The method as claimed in claim 1 , wherein the method is performed as distributed optimization method in each of the plurality of terminals.

4. The method as claimed in claim 3 , wherein the receiver transmits K the number of active terminals in the field of view to the terminals.

5. The method as claimed in claim 3 , wherein each terminal estimates K, the number of active terminals in the field of view by counting the number of acknowledgement messages transmitted during a frame.

6. The method as claimed in claim 1 , wherein the transmission probability depends upon the number of failed transmission attempts.

7. A multi-access receiver for use in a multiple access wireless communication system comprising:

a plurality of terminals; and

a multi-access receiver,

wherein each terminal comprises:

a transmitter configured to transmit a message during a slot of a frame to the multi-access receiver when in an active state,

a memory, and

a terminal processor,

wherein when the terminal is in an active state the transmitter is permitted to transmit a message and when the terminal is in an inactive state the transmitter is prevented from transmitting, and the memory configured to store a probability of transmission p which during an active state, the terminal processor uses to determine whether to transmit in a frame; and

the multi-access receiver comprises:

a receiver for simultaneously receive m transmissions in each slot of a frame, and

a multiuser decoder for decoding the received transmissions; and

a multi-access receiver processor,

wherein the multi-access receiver processor is configured to perform a method for optimizing a network parameter in a set of network parameters, wherein the network parameters comprise (p, n, m, ε) where p is the probability of an active terminal deciding to transmit in a frame, n is the number of slots per frame, m is the number of simultaneous transmissions that a multiuser can successfully decode in a single slot, and ε is the probability of failure of a terminal to successfully transmit a message whilst in a field of view of the multiple access receiver, and the method of optimising a network parameter comprising:

selecting the network parameter and numerically solving q=1−pQ(m,λ) and

K

0

=

1

-

ɛ

1

/

F

1

-

ɛ

⁢

λ

*

⁢

n

to optimise λ* where 1−q is the proportion of terminals that succeed in transmitting in a frame and Q is the gamma function, K 0 is the number of new terminals that enter the field of view each frame, F is the number of frames a terminal is in the field of view for, λ=k/n and k=pK and where K is the number of active terminals in the field of view; and

transmit transmitting the optimized network parameter to the plurality of terminals.

8. The multi-access receiver as claimed in claim 7 wherein the transmission probability depends upon the number of failed transmission attempts.

9. A terminal for use in a multiple access wireless communication system comprising:

a plurality of terminals; and

a multi-access receiver comprising:

a receiver for simultaneously receive m transmissions in each slot of a frame; and

a multiuser decoder for decoding the received transmissions,

wherein each terminal comprises:

a transmitter configured to transmit a message during a slot of a frame to the multi-access receiver when in an active state;

a memory; and

a processor,

wherein the processor is configured to control the mode of operation of the terminal, and when the terminal is in an active state the terminal is permitted to transmit a message and when the terminal is in an inactive state the transmitter is prevented from transmitting, and the memory stores a probability of transmission p which during an active state, the processor uses to determine whether to transmit in a frame, and

the processor is further configured to perform a method for optimizing a network parameter in a set of network parameters, wherein the network parameters comprise (p, n, m, ε) where p is the probability of an active terminal deciding to transmit in a frame, n is the number of slots per frame, m is the number of simultaneous transmissions that a multiuser can successfully decode in a single slot, and ε is the probability of failure of a terminal to successfully transmit a message whilst in a field of view of the multiple access receiver, and the method of optimising a network parameter comprising:

selecting the network parameter and numerically solving q=1−pQ(m,λ) and

K

0

=

1

-

ɛ

1

/

F

1

-

ɛ

⁢

λ

*

⁢

n

to optimise λ* where 1−q is the proportion of terminals that succeed in transmitting in a frame and Q is the gamma function, K 0 is the number of new terminals that enter the field of view each frame, F is the number of frames a terminal is in the field of view for, λ=k/n and k= p K and where K is the number of active terminals in the field of view.

10. The terminal as claimed in claim 9 , wherein the multi-access receiver transmits K the number of active terminals in the field of view to the terminals.

11. The terminal as claimed in claim 9 , wherein each terminal estimates K, the number of active terminals in the field of view by counting the number of acknowledgement messages transmitted during a frame.

12. The terminal as claimed in claim 9 , wherein the transmission probability depends upon the number of failed transmission attempts.

13. A multiple access wireless communication system comprising:

a plurality of terminals;

a multi-access receiver; and

a network operations center in communication with the multi-access receiver,

wherein the multi-access receiver comprises:

a receiver for simultaneously receive m transmissions in each slot of a frame; and

a multiuser decoder for decoding the received transmissions, each terminal comprises:

a transmitter configured to transmit a message during a slot of a frame to the multi-access receiver when in an active state,

a memory, and

a multi-access receiver processor,

wherein when the terminal is in an active state the transmitter is permitted to transmit a message and when the terminal is in an inactive state the transmitter is prevented from transmitting, and the memory stores a probability of transmission p which during an active state, the multi-access receiver processor uses to determine whether to transmit in a frame, and

the network operations center comprises:

a network operations center processor configured to perform a method for optimizing a network parameter in a set of network parameters, wherein the network parameters comprise (p, n, m, ε) where p is the probability of an active terminal deciding to transmit in a frame, n is the number of slots per frame, m is the number of simultaneous transmissions that a multiuser can successfully decode in a single slot, and E is the probability of failure of a terminal to successfully transmit a message whilst in a field of view of the multiple access receiver, and the method of optimising a network parameter comprising:

selecting the network parameter and numerically solving q=1−pQ(m,λ) and

K

0

=

1

-

ɛ

1

/

F

1

-

ɛ

⁢

λ

*

⁢

n

to optimise λ* where 1−q is the proportion of terminals that succeed in transmitting in a frame and Q is the gamma function, K 0 is the number of new terminals that enter the field of view each frame, F is the number of frames a terminal is in the field of view for, λ=k/n and k=pK and where K is the number of active terminals in the field of view; and

communicating the optimized network parameter to the multi-access receiver for transmission to the plurality of terminals.

14. The multiple access wireless communication system as claimed in claim 13 , wherein the transmission probability depends upon the number of failed transmission attempts.