ch10

Question 1

QoS-aware bandwidth provisioning

Know what it is (and alternative to QoS traffic management)

Answer 1

QoS control

• admission control on connections/flows
• hard QoS guarantees
• efficient use of resources

Bandwidth provisioning

• No QoS control machanisms
• No QoS quarantees
• Inefficient
• widely used

QoS traffic management uses coarse traffic measurements on a large time scale, which is inaccurate

Question 2

Bandwidth provisioning square-root formula
Know what the formula tells, and understand its simplicity (no
derivation needed)

Answer 2

p + a * sqrt(p)
Where p is the load of the system
The a depends on the characteristics of the individual flows and the QoS requirements
The QoS measure used is the probability that the traffic supply exceeds the available bandwidth over some interval, is below some small fixed number eta

Question 3

Mobile ad-hoc networks (MANETs)

Know what they are, and what main applications are

Answer 3

Peer-to-peer like system where

• users/devices act as network nodes
• Multiple wireless hops
• Self-organizing system

Initial developments in military
Now used in vehicular networks, sensor networks, etc.
vehicles talking to each other
Basically good for connecting same-type devices to one another without existing infrastructure

Energy efficiency is very important, battery lifetime

Question 4

Multi-hop communication in MANETs

Understand the idea, and relation to single-hop WiFi

Answer 4

single-hop manet, eg. wifi, has reduces throughput when the number of users in the system exceeds some threshold
Flow transfers are initiated at random times

Multi-hop: packets are sent through multiple devices in linear network
Low throughput due to interference among nodes
Possibility for relay node, however, may cause bottleneck
Since the data can take multiple paths there is not a single point of failure

Question 5

Relay node

Know what it is, and what the problem is in data transport

Answer 5

Sources transmit flows to a destination via a Relay Node
Capacity shared among source and relay nodes
The relay node is the bottleneck node as all communication goes through it.

Have to decide whether to do equal sharing between relay node and source nodes, or unequal, where relay node gets share that’s
m times larger
With more flows/sources in the system, the delay goes up exponentially

Question 6

5G networks
Understand the application possibilities, that it combines
cellular networks and ad-hoc communications (not “just the
successor of 4G”)

Answer 6

Faster bitrates
Not just successor of 4G, but it uses/allows for:
New communication paradigms, by combining cellular and ad-hoc type of communications
Enabler for Internet of Things
Network “softwarization”:
- Higher flexibility, which enables many new applications
Integrates networking and cloud computing