Wireless Ad Hoc and Sensor Networks

Background on Networking 7TABLE 1.1ATM Service Category AttributesAttributeTrafficparametersConstantBit RatePeak cellrateCell delayvariabletolerancereal time-Variable BitRatePeak cell rateSustainablecell rateMean Bit RateCell delayvariabletoleranceATM Layer Service Categorynon real time-Variable BitRatePeak cell rateSustainablecell rateMean Bit RateCell delayvariabletoleranceUnappliedBit RatePeak cellrateAvailable BitRatePeak cell rateCell delayvariabletoleranceQoSparametersCell delayvariationmaximum Celltransfer delayCell delayvariationmaximum Celltransfer delayCell loss ratio Cell loss ratio Cell loss ratio Cell loss ratioConformancedefinitionsGeneric cellrate algorithmGeneric cellrate algorithmGeneric cellrate algorithmDynamicGCRAFeedback Unspecified--- Specifieddelay variation (CDV), maximum packet or cell transfer delay (maxCTD),and packet loss rate or cell loss ratio (CLR). For instance, Table 1.1 presentsthe overview of traffic and QoS parameters.The goal of traffic management in an Internet or ATM network is tomaximize network resource utilization while satisfying each individualuser’s QoS. For example, the offered loading to a network should be keptbelow a certain level to avoid congestion, which, in turn, causes throughputdecrease and delay increase. Next we highlight a set of QoS control methodsfor traffic management.1.2 QoS ControlConsider the data communication between two users in a network whoare separated by a network of routers or packet switches, referred to asnodes for brevity. If the source has a message that is longer than themaximum packet size, it usually breaks the message up into packets andsends these packets, one at a time, to the network. Each packet containsa portion of the message plus some control information in the packetheader. The control information, at a minimum, includes the routinginformation (IP destination address for the Internet, or virtual channelidentifier for FR and ATM networks) that the network requires to be ableto deliver the packet to the intended destination.