100 likes | 1.08k Views
TSI (Time Slot Interchange). 24. 23. 2. 1. a. 1. Let the contents of time slots 1 through 24 be as shown on the incoming line. The switch configuration requires data in slot 1 to be read into slot 24 and vice versa, and data in slot 2 to be read into slot 23 and vice versa. c. d. b. a.
E N D
TSI (Time Slot Interchange) 24 23 2 1 a 1 • Let the contents of time slots 1 through 24 be as shown on the incoming line. • The switch configuration requires data in slot 1 to be read into slot 24 and vice versa, and data in slot 2 to be read into slot 23 and vice versa c d b a permutes as per switch configuration and reads out b 2 writes in order of arrival 24 23 2 1 a b d c d 23 c 24 M. Veeraraghavan
.... .... .... .... .... .... .... .... .... .... .... .... k k n n n k n k k k n n 2 2 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 From space switch to T-S-T switch • The intermediate stage switch is a single switch of size: TSI 1 TSI 1 TSI 2 TSI 2 TSI N/n TSI N/n Replace each first-stage and every last-stage switch by a TSI. Replace multiple intermediate-stage switch with a single time-shared space switch. The intermediate stage switch is reprogrammed for each of the k time slots. M. Veeraraghavan
B1 A1 D1 B1 t=1 B1 B1 A1 2 x 3 (TSI 1) 3 x 2 (TSI 3) Connected to A and B L1 L3 Connected to A and B t=2 D1 C1 L2 L4 t=3 C1 A1 3 x 2 (TSI 4) D1 C1 Connected to C and D 2 x 3 (TSI 2) Connected to C and D C1 A1 B D VIEW WITH ANIMATION D1 A C Program the two sets of TSI stages and the intermediate space stage accordingly A->C, B->A, C->D, D->B The time to send three slots between 1st stage and 2nd stage is the same as the time to receive two slots into the 1st stage. D1 could have been sent in the first slot on L2 because it could have been sent out on L4 in time slot 1 and then switched around by TSI 4 to the appropriate slot going to D M. Veeraraghavan
Programming the switch • Means setting the operational behavior of all the TSIs and the time-shared space switch • Previous slide example: • TSI1: TS1->TS1; TS2->TS2; blank->TS3 • TSI2: blank->TS1; TS1->TS2; TS2->TS3 • TSI3: TS1->unmapped; TS2->TS1; TS3->TS2 • TSI4: TS1>TS1; TS2->TS2; TS3->unmapped • time-shared switch • at time = 1, cross-over • at time=2, direct • at time=3, cross-over M. Veeraraghavan