based on the scnerio in the picture answer the following. Note: the options for the answer are all the same for all parts a- e

A)

Suppose now that an omniscient controller (e.g., a controller that knows the state of every node in the network) can command each node to do whatever it (the omniscient controller) wishes, that is, to send a message, to receive a message, or to remain silent. Given this omniscient controller, what is the maximum rate at which messages can be transferred from C to A, given that there are no other messages between any other source/destination pairs?

B)Suppose now that A sends messages to B, and D sends messages to C. What is the combined maximum rate at which data messages can flow
from A to B and from D to C?

C)Suppose now that A sends messages to B, and C sends messages to D. What is the combined maximum rate at which data messages can flow from A to B and from C to D?

D)Overlapping wireless senders with ACKs. Now suppose we are again in the wireless scenario, and that for every data message sent from source to destination, the destination will send an ACK message back to the source (e.g., as in TCP). Also suppose that each ACK message takes up one slot. What is the maximum rate at which data messages can be transferred from C to A, given that there are no other messages between any other source/destination pairs? [Note that successful ACKs do not count towards data message throughput].

E)Overlapping wireless senders with ACKs (more). Suppose now that A sends messages to B, and D sends messages to C, and suppose that the destination will again send an ACK message back to the source (e.g., as in TCP) and that each ACK message takes up one slot. What is the combined maximum rate at which data messages can flow from A to B and from D to C? [Hint: this is a bit trickier than the previous questions].
Transcribed Image Text:Consider the scenario shown below in which there are four wireless nodes, A, B, C, and D. The radio coverage of the four nodes is shown via the shaded ovals; all nodes share the same frequency. When A transmits, it can only be heard/received by B; when B transmits, both A and C can hear/receive from B; when C transmits, both B and D can hear/receive from C; when D transmits, only C can hear/receive from D. If a node hears two simultaneous transmissions at a time, the messages interfere at that receiver, even through they may not interfere at other receivers, where only one of the messages is heard.[Make sure you understand this paragraph.] Suppose now that each node has an infinite supply of messages that it wants to send to each of the other nodes. If a message's destination is not an immediate neighbor, then the message must be relayed. For example, if A wants to send to D, a message from A must first be sent to B, which then sends the message to C, which then sends the message to D. Time is slotted, with a message transmission time taking exactly one time slot, e.g., as in slotted Aloha. During a slot, a node can do one of the following: (i) send a message (ii) receive a message (if exactly one message is being sent to it), (iii) remain silent. As always, if a node hears two or more simultaneous transmissions, a collision occurs and none of the transmitted messages are received successfully. You can assume here that there are no bit-level errors, and thus if exactly one message is heard at a receiver, it will be received correctly at that receiver. e pas LA alcan 1 B Someth 2 (² EC Ganthan 3 e D then 4
Transcribed Image Text:Aloha. During a slot, a node can do one of the following: (i) send a message (ii) receive a message (if exactly one message is being sent to it), (iii) remain silent. As always, if a node hears two or more simultaneous transmissions, a collision occurs and none of the transmitted messages are received successfully. You can assume here that there are no bit-level errors, and thus if exactly one message is heard at a receiver, it will be received correctly at that receiver. LA other CP 1 B repos 2 EC 3 Suppose now that an omniscient controller (e.g., a controller that knows the state of every node in the network) can command each node to do whatever it (the omniscient controller) wishes, that is, to send a message, to receive a message, or to remain silent. Given this omniscient controller, what is the maximum rate at which messages can be transferred from C to A, given that there are no other messages between any other source/destination pairs? eps 1 message/slot. 2 messages/slot. 0.25 messages/slot (i.e., one message every four slots). 0.5 messages/slot (i.e., 1 message every two slots). 4

Question

based on the scnerio in the picture answer the following. Note: the options for the answer are all the same for all parts a- e

A)

Suppose now that an omniscient controller (e.g., a controller that knows the state of every node in the network) can command each node to do whatever it (the omniscient controller) wishes, that is, to send a message, to receive a message, or to remain silent. Given this omniscient controller, what is the maximum rate at which messages can be transferred from C to A, given that there are no other messages between any other source/destination pairs?

B)Suppose now that A sends messages to B, and D sends messages to C. What is the combined maximum rate at which data messages can flow
from A to B and from D to C?

C)Suppose now that A sends messages to B, and C sends messages to D. What is the combined maximum rate at which data messages can flow from A to B and from C to D?

D)Overlapping wireless senders with ACKs. Now suppose we are again in the wireless scenario, and that for every data message sent from source to destination, the destination will send an ACK message back to the source (e.g., as in TCP). Also suppose that each ACK message takes up one slot. What is the maximum rate at which data messages can be transferred from C to A, given that there are no other messages between any other source/destination pairs? [Note that successful ACKs do not count towards data message throughput].

E)Overlapping wireless senders with ACKs (more). Suppose now that A sends messages to B, and D sends messages to C, and suppose that the destination will again send an ACK message back to the source (e.g., as in TCP) and that each ACK message takes up one slot. What is the combined maximum rate at which data messages can flow from A to B and from D to C? [Hint: this is a bit trickier than the previous questions].

Consider the scenario shown below in which there are four wireless nodes, A, B, C, and D.
The radio coverage of the four nodes is shown via the shaded ovals; all nodes share the
same frequency. When A transmits, it can only be heard/received by B; when B transmits,
both A and C can hear/receive from B; when C transmits, both B and D can hear/receive
from C; when D transmits, only C can hear/receive from D. If a node hears two simultaneous
transmissions at a time, the messages interfere at that receiver, even through they may not
interfere at other receivers, where only one of the messages is heard.[Make sure you
understand this paragraph.]
Suppose now that each node has an infinite supply of messages that it wants to send to
each of the other nodes. If a message's destination is not an immediate neighbor, then the
message must be relayed. For example, if A wants to send to D, a message from A must first
be sent to B, which then sends the message to C, which then sends the message to D. Time
is slotted, with a message transmission time taking exactly one time slot, e.g., as in slotted
Aloha. During a slot, a node can do one of the following: (i) send a message (ii) receive a
message (if exactly one message is being sent to it), (iii) remain silent. As always, if a node
hears two or more simultaneous transmissions, a collision occurs and none of the
transmitted messages are received successfully.
You can assume here that there are no bit-level errors, and thus if exactly one message is
heard at a receiver, it will be received correctly at that receiver.
e pas
LA
alcan
1
B
Someth
2
(²
EC
Ganthan
3
e
D
then
4

Aloha. During a slot, a node can do one of the following: (i) send a message (ii) receive a
message (if exactly one message is being sent to it), (iii) remain silent. As always, if a node
hears two or more simultaneous transmissions, a collision occurs and none of the
transmitted messages are received successfully.
You can assume here that there are no bit-level errors, and thus if exactly one message is
heard at a receiver, it will be received correctly at that receiver.
LA
other
CP
1
B
repos
2
EC
3
Suppose now that an omniscient controller (e.g., a controller that knows the state of every
node in the network) can command each node to do whatever it (the omniscient controller)
wishes, that is, to send a message, to receive a message, or to remain silent. Given this
omniscient controller, what is the maximum rate at which messages can be transferred from
C to A, given that there are no other messages between any other source/destination pairs?
eps
1 message/slot.
2 messages/slot.
0.25 messages/slot (i.e., one message every four slots).
0.5 messages/slot (i.e., 1 message every two slots).
4

Accepted Answer

The question asks for the maximum rate at which messages can be transferred from node C to node A in…