Efficient single-hop directional multichannel system

Abstract

A shared directional multichannel for efficiently transmitting k=( log p n choose (p-1) concurrent, non-interfering transmissions from a set of m≧k source stations, each having p transmitters, to a set of n destination stations, each having one receiver, without active repeater components. The multichannel architecture permits implementation of an efficient single-hop multichannel system using optical star couplers in a manner that limits the power spreading loss to the n/p value known for bus-oriented networks instead of n 2 /p. Several coupling stages are employed, each stage having a plurality of identical substantially-square directional couplers, to obtain channel concurrency k, which is an improvement over the concurrency p available in bus-oriented networks, without the higher power spreading loss normally arising from the larger number of connections between each source station and every destination station.

I claim: 
     
       1. A shared directional multichannel system for scheduled uniform traffic of up to k concurrent transmissions from m source stations to n destination stations, each said destination station including one receiver input, each said source station including p transmitter outputs and all said source stations being partitioned into at least one source station group such that no more than one said source station group contains less than k source stations, wherein k, m, n and p are positive non-zero integers and m≧k=(  log p  n  choose (p-1), the system comprising: a first stage including at least (p*k) first directional couplers, each said first directional coupler having  n/p  outputs and no more  m/k inputs, all said inputs of each said first directional coupler being connected to transmitter outputs from a respective source station group;   a second stage including n second directional couplers, each said second directional coupler having at least k inputs and one output, said output being connected to a destination station receiver input; and   interconnection means for coupling said first stage to said second stage by connecting said first directional coupler outputs to said second directional coupler inputs in a manner such that the l th  transmitter output of the i th  source station within each said source station group is connected to the receiver input of the j th  destination station, where the modulo p sum of the digits of (j modulo p) in positions corresponding to unit digit positions in (i radix 2) is equal to (l-1).   
     
     
       2. The shared directional multichannel system of claim 1, wherein: p=2 and each said source station includes two transmitter outputs.   
     
     
       3. The shared directional multichannel system of claim 2 for scheduled uniform traffic of up to (k+1) concurrent transmissions from said source stations, wherein: said source stations being partitioned into at least one source station group such that no more than one said source station group contains less than (k+1) source stations; and   said interconnection means further includes means for connecting the l th  transmitter output of the (k+1) th  source station within each said source station group to the receiver input of the j th  destination station, where the parity of binary integer j is equal to (l-1).   
     
     
       4. The shared directional multichannel system of claim 3, wherein: said first directional coupler includes at least one optical star coupler;   said second directional coupler includes at least one optical star coupler; and   said interconnection means includes means for conducting optical signals.   
     
     
       5. The shared directional multichannel system of claim 4 wherein: said optical star coupler stages comprise a plurality of smaller optical star couplers interconnected to form a single larger said coupler.   
     
     
       6. The shared directional multichannel system of claim 1, wherein: said first directional coupler includes at least one optical star coupler;   said second directional coupler includes at least one optical star coupler; and   said interconnection means includes means for conducting optical signals.   
     
     
       7. The shared directional multichannel system of claim 6 wherein: said optical star coupler stages comprise a plurality of smaller optical star couplers interconnected to form a single larger said coupler.   
     
     
       8. The shared directional multichannel system of claim 1 wherein: one or more source stations within at least one said source station group and the respective connections are absent.   
     
     
       9. A shared directional multichannel system for scheduled uniform traffic of up to k concurrent transmissions from m source stations to n destination stations, each said destination station having one receiver input, each said source station having two transmitter outputs and all said source stations being partitioned into at least one source station group such that no more than one said source station group contains less than k source stations and all said source station groups being partitioned into z clusters of no more than  m/kz  groups, wherein k, m, n, and z are positive nonzero integers, m≧k=  log 2  n  and z=m/kx is selected to minimize the value of {max(x,y)*max(m/(2x), n/(2y))} where y=√n/2, said system comprising: a first stage including  2kz  first directional couplers, each said first directional coupler having  √n/2  outputs and no more than  m/kz inputs, all said inputs of each said first directional coupler being connected to transmitter outputs from a respective source station group;   a second stage including  2√n  second directional couplers, each said second directional coupler having at least  kz/2  inputs and √n  outputs;   first interconnection means between said first stage and said second stage for connecting said first directional coupler outputs to said second directional coupler inputs such that the l th  transmitter output of the i th  source station within each said source station group is connected to the receiver input of the j th  destination station, where the i th  digit of binary integer j is equal to (l-1);   a third stage of n third directional couplers, each said third directional coupler having two inputs and one output, said output being connected to a destination station receiver input; and   second interconnection means between said second stage and said third stage for connecting said second directional coupler outputs to said third directional coupler inputs such that the l th  transmitter output of the i th  source station within each said source station group is connected to the receiver input of the j th  destination station, where the i th  digit of binary integer j is equal to (l-1).   
     
     
       10. The shared directional multichannel system of claim 9 for scheduled uniform traffic of up to (k+1) said concurrent transmissions from said source stations, wherein: said source stations are partitioned into at least one station group such that no more than one said source station group contains less than (k+1) source stations; and   said first and second interconnection means each further includes means for connecting the l th  transmitter output of the (k+1) th  source station within each said source station group to the receiver input of the j th  destination station, where the parity of binary integer j is equal to (l-1).   
     
     
       11. The shared directional multi-channel system of claim 10 wherein: said first directional coupler includes at least one optical star coupler;   said second directional coupler includes at least one optical star coupler;   said third directional coupler includes at least one optical star coupler; and said first and second interconnection means include means for conducting optical signals.   
     
     
       12. The shared directional multichannel system of claim 11 wherein: said optical star coupler stages comprise a plurality of smaller optical star couplers interconnected to form a single larger said coupler.   
     
     
       13. A shared directional multichannel system according to claim 9 wherein: said first directional coupler includes at least one optical star coupler;   said second directional coupler includes at least one optical star coupler;   said third directional coupler includes at least one optical star coupler; and   said first and second interconnection means include means for conducting optical signals.   
     
     
       14. The shared directional multichannel system of claim 13 wherein: said optical star couplers comprise a plurality of smaller optical star couplers interconnected to form a single larger said coupler.   
     
     
       15. The shared directional multichannel system of claim 9 wherein: one or more source stations within at least one said source station group and the respective connections are absent.   
     
     
       16. A method for interconnecting a first set of m source stations of k types, each said source station having p transmitter outputs, to a second set of n destination stations, each said destination station having one receiver input, such that each source station is uniquely connected to every destination station by a single-hop directional connection whereby collision can be avoided by scheduling no more than k concurrent transmissions from said m source stations, wherein k, m, n and p are positive nonzero integers and m≧k=(  log p  n  choose (p-1)), the method comprising the steps of: partitioning said m source stations into at least one source station group such that no more than one said source station group contains less than k source stations; and   connecting the l th  transmitter output of the i th  source station within each said source station group to the receiver input of the j th  destination station, where the modulo p sum of the digits of (j modulo p) corresponding to unit digit positions in (i radix 2) is equal to (l-1), each said connection including a first link between said l th  transmitter output and an input of the first in a series of at least two coupling stages, each said coupling stage having a plurality of substantially square directional couplers, each said substantially square directional coupler including a first plurality of coupler inputs and a second plurality of coupler outputs where said first and second pluralities are substantially equal, with the outputs of each said coupling stage connected to the inputs of the immediately subsequent coupling stage,   a penultimate link between an output of the last in said series of at least two coupling stages and an input of a final coupling stage of at least n number of final directional couplers, each said final directional coupler having p inputs and a single output, and   a final link between the j th  output of said final coupling stage and the receiver input of said j th  destination station.     
     
     
       17. The method of claim 16, wherein: p=2 and each said source station includes two transmitter outputs.   
     
     
       18. The method of claim 17 for uniform traffic of up to (k+1) concurrent transmissions, wherein: in said partitioning step no more than one said source station group contains less than (k+1) source stations; and   said connecting step includes the step of connecting the l th  transmitter output of the (k+1) th  source station within each said source station group to the receiver input of the j th  destination station, where the parity of binary integer j is equal to (l-1).   
     
     
       19. The method of claim 18 wherein m=n, further including the step of co-locating every said source station within said first set with one respective said destination station within said second set. 
     
     
       20. The method of claim 16, further comprising, following said partitioning step, the step of: selecting said first and second pluralities of inputs and outputs for said series at least two coupling stages of substantially square directional couplers so that the arithmetic product of the at least two said second pluralities of coupler outputs is substantially equal to (n/p).   
     
     
       21. The method of claim 16, wherein m=n, further including the step of co-locating every source station within said first set with one respective said destination station within said second set. 
     
     
       22. The method of claim 16, wherein said concurrent transmission, said transmitter outputs, and said receiver inputs include optical signals. 
     
     
       23. A method for interconnecting a first set of m source stations of k types, each said source station having p transmitter outputs, to a second set of n destination stations, each said destination station having one receiver input, such that each source station is uniquely connected to every destination station by a single-hop directional connection whereby collision can be avoided by scheduling no more than k concurrent transmission from said m source stations, wherein k, m, n and p are positive nonzero integers m≧k=(  log p  n  choose (p-1)), the method comprising the steps of: partitioning m source stations into at least one source station group such that no more than one said source station group contains less than k source stations; and   connecting the l th  transmitter output of the i th  source station within each said source station group to the receiver input of the j th  destination station, where the modulo p sum of the digits of (j modulo p) in positions corresponding to unit digit positions in (i radix 2) is equal to (l-1), each said connection including a first link between said l th  transmitter output of the i th  source station and an input of a first coupling stage of at least (p*k) number of directional couplers each having  n/p  outputs and no more than n/k  inputs,   a second link between an output of said first coupling stage and an input of a second coupling stage of at least n number of directional couplers having no less than k inputs and one output, and   a third link between an output of said second coupling stage and the receiver input of said j th  destination station.     
     
     
       24. The method of claim 23, wherein: p=1 and each said source station includes two transmitter outputs.   
     
     
       25. The method of claim 24 for uniform traffic of up to (k+1) concurrent transmission, wherein: in said partitioning step no more than one said source station group contains less than (k+1) source stations; and   said connecting step includes the step of connecting the l th  transmitter output of the (k+1) th  source station within each said source station group to the receiver input of the j th  destination station, where the parity of binary integer j is equal to (l-1).   
     
     
       26. The method of claim 25 wherein m=n, further including the step of co-locating every source station within said first set with one respective said destination station within said second set. 
     
     
       27. The method of claim 23 wherein m=n, further including the step of co-locating every source station within said first set with one respective said destination station within said second set. 
     
     
       28. The method of claim 23 wherein said concurrent transmissions, said transmitter outputs, and said receiver inputs include optical signals. .Iadd. 
     
     
       29.  A shared directional multichannel system for scheduled uniform traffic of up to k concurrent transmissions from m source stations to n destination stations, all said source stations being partitioned into at least one source station group such that no more than one said source station group contains less than k source stations, wherein k, m, n and p are positive non-zero integers and m≧k=( log p  n  choose (p-1)), said system comprising: a plurality p of transmitter outputs in each said source station;   a receiver input in each said destination station; and   means for passively coupling optical signals from said source stations to said destination stations such that the power received at each said receiver input is greater than p/n 2  times the power transmitted from the respective said transmitter output. .Iaddend. .Iadd.30. The shared directional multi-channel system of claim 29, wherein said power received at said each receiver input is greater than (p/n/log p  n) times the power transmitted from said respective transmitter output. .Iaddend. .Iadd.31. A shared directional multichannel system for scheduled uniform traffic of up to k concurrent transmissions from m source stations to n destination stations, all said source stations being partitioned into at least one source station group such that no more than one said source station group contains less than k source stations, wherein k, m, n and p are positive non-zero integers, and m≧k= log 2  n , said system comprising:   two transmitter outputs in each said source station;   a receiver input in each said destination station; and   means for passively coupling optical signals from said source stations to said destination stations such that the power received at each said receiver input is greater than 2/n 2  times the power transmitted from the respective said transmitter output. .Iaddend. .Iadd.32. The shared directional multi-channel system of claim 31, wherein said power received at said each receiver input is greater than (2/n/log 2  n) times the power transmitted from said respective transmitter output. .Iaddend.