Free space optical, growable packet switching arrangement
AssigneeAT&T Bell Laboratories
InventorsThomas J. Cloonan, Gaylord W. Richards
Life of this patent
Estimating the term…
Abstract
A growable packet switching arrangement where the number, S, of distribution network stages is reduced by bounding S according to log.sub.2 (max(L,N))<S+1<[log.sub.2 (max(L,N))].sup.2 /2. Since the distribution network is made up of stages of opto-electronic nodes and interconnecting free-space optical link stages, there is no need to transmit input signals using different frequencies. Input signals are instead distinguished based on their spatial location. Accordingly, there is no receiver tunability restriction on L, the number of inputs. Further, because signals are regenerated at each network stage and there is only a 3:1 power loss (approximate) at a given stage, high signal/noise ratios and corresponding low bit error rates are achieved.
Claims29
A packet switching arrangement having L input ports, M intermediate ports and N output ports, where L, M and N are positive integers greater than two, said arrangement comprising
- a distribution network for switching packets from said L input ports to said M intermediate ports without storing full received packets, and
- N/n output packet switching modules, where n and N/n are positive integers with N>n>1, each of said modules comprising
- means for switching packets from a distinct group of m of said intermediate ports to a distinct group of n of said output ports, where m is a positive integer with m>n, and
- means for storing full received packets,
- said distribution network comprising
- S stages of opto-electronic nodes, with each node of at least the first (S-1) of said node stages comprising an X.times.Y switching means, where S, X and Y are positive integers with S>3, X>1, and Y>1, and where log.sub.2 (max (L,N))<S+1<[log.sub.2 (max (L,N))].sup.2 /2, and
- (S-1) free-space optical link stages interconnecting successive ones of said S node stages.
A packet switching arrangement having L input ports, M intermediate ports and N output ports, where L, M and N are positive integers greater than two, said arrangement comprising
- a distribution network for switching packets from said L input ports to said M intermediate ports without storing full received packets, and
- N/n output packet switching modules, where n and N/n are positive integers with N>n>1, each of said modules comprising
- means for switching packets from a distinct group of m of said intermediate ports to a distinct group of n of said output ports, where m is a positive integer with m>n, and
- means for storing full received packets,
- said distribution network comprising
- S stages of opto-electronic nodes, with each node of at least the first (S-1) of said node stages comprising an X.times.Y switching means, where S, X and Y are positive integers with S>3, X>1, and Y>1, and
- (S-1) free-space optical link stages interconnecting successive ones of said S node stages,
- where X=2, Y=2 and the X.times.Y switching means of said each node of said at least the first (S-1) of said node stages and certain links of at least the first (S-2) of said link stages collectively comprise a Banyan network, a Banyan network with omitted link stages, or a topological equivalent to either.
A packet switching arrangement having L input ports, M intermediate ports and N output ports, where L, M and N are positive integers greater than two, said arrangement comprising
- a distribution network for switching packets from said L input ports to said M intermediate ports without storing full received packets, and
- N/n output packet switching modules, where n and N/n are positive integers with N>n>1, each of said modules comprising
- means for switching packets from a distinct group of m of said intermediate ports to a distinct group of n of said output ports, where m is a positive integer with m>n, and
- means for storing full received packets,
- said distribution network comprising
- S stages of opto-electronic nodes, with each node of at least the first (S-1) of said node stages comprising an X.times.Y switching means, where S, X and Y are positive integers with S>3, X>1, and Y>1, and
- (S-1) free-space optical link stages interconnecting successive ones of said S node stages,
- wherein at least one of said (S-1) link stages comprises
- binary phase grating means optically interposed between a first one and a second one of two successive ones of said S node stages, said grating means being responsive to each optical beam transmitted from said first node stage for transmitting a plurality of optical beams to said second node stage and wherein said second node stage is responsive to less than all of said plurality of beams.
Dependencies are inferred from the claim text.