RNC Normal Node, Not Special Parameters Everything Predefined

RNC Normal Node, Not Special Parameters Everything Predefined

Eurane –NS2

NODES

RNC “normal” node, not special parameters… everything predefined

BS has some parameters that can be defined as BW and TTI of the FACH (downlink) and the RACH (uplink)

IUB Configuration between RNC and BS, parameters to be defined are uplink and downlink bandwidth, uplink and downlink delay, queue type of the link and maximum queue size.

UE, in order to be used, BS and RNC must be defined

As part of the routing between the fixed network and the UMTS nodes, a gateway is introduced between the RNC and the last core network node before the UMTS nodes. This last core network node can be seen as the SGSN. It is important to notice that the SGSN and the GGSN are just “normal” nodes of NS2.

TRAFFIC

For the definition of the transport protocol (traffic source/sink) it works the same as in NS2, this means, user can “choose” between TCP or UDP, but in here two new parameters must be defined… fid and prio… fid is the flow identifier and prio is the priority. Each UE should use one flow-id. CAN THIS BE USED FOR HANDOVER OR THIS KILL THE TRAFFIC FROM CN?... Priorities can be set from 0 to priority_max_, which has a standard value of 5. Packets with a lower prio_ value have a higher priority.

TRANSPORT CHANNEL

FACH/RACH: The link layer components of the Forward Access Channel (FACH) and Random Access Channel (RACH), which are both Common channels, are created at the time of the BS and the UE configuration, and only require an “attachment” procedure to an RLC entity.

DCH: The Dedicated Channel (DCH) operates in both the uplink and downlink, and its entire link components, from the RLC at the RNC to the RLC at the UE, need to be created… Only in the case of the DCH is there the possibility to channel switch to the RACH/FACH.

HS-DSCH: The HS-DSCH also has to be fully constructed, as in the case of the DCH, and although it is a downlink transport channel, an uplink return path, fro RLC retransmissions and TCP acknowledgements, is also required. As the HS-DSCh always requires an associated DCH, an uplink DCH is always created alongside the HS-DSCH.

RLC CONFIGURATION

At the RNC, two implementations of Acknowledgement Mode (AM) are available for RLC. The type of RLC (AM or AM-HS) to use is dependent on the transport channel. Two implementation of Un-acknowledgement Mode, UM and UM-HS, are also available, and are basically a functional sub-set of the AM and AM-HS (only ofr HS-DSCH), respectively.

MAC/MAC-HS CONFIGURATION

There are two possible MAC architecture to choose from. The basic MAC used for the DCH and common channels (RACH & FACH), and the more complicated MAC-HS user fro the HS-DSCH.

PHYSICAL LAYER

The physical layer is represented by a standard ns-2 channel object, which is used to connect the BS and the UE. This is combined with the attachment of an error model.

TRACE SUPPORT

Trace files using UMTS nodes and links are very similar to conventional ns-2 tracing. Special UmtsTrace objects are used to trace RLC packets inside the UTRAN and the UE. These trace objects log those files already logged by the normal ns-2 trace objects plus one extra, the sequence number of the RLC packet.

PERSONAL CONCLUSION: From my point of view, this packet is more intended in the part of the UTRAN and the lower layers, instead of focusing in the network and upper layers which are the ones who might be interesting for us… even if most of the functionalities provided by NS2 (described below) might still work, some of them can be damaged or simply reduced by the fact of using Eurane patch, for this particular cas it can be seen that there is nothing about PDP context, QoS among other useful things. NOTE: the functionality of gateway, can be interested to be studied!!!

NS-2

NODES

Node structure consists of two objects: and address classifier and a port classifier. The function of these classifiers is to distribute incoming packets to the correct agent or outgoing link.

All nodes contain at least the following components:

  • an address
  • a list of neighbors
  • a list of agents
  • a node type identifier, and
  • a routing module

a node can be configured by defining the following classifiers:

  • control functions
  • Address and port number management, unicast routing functions.
  • agent management
  • adding neighbors

there are also classifiers of address, multicast, multipath, hash, replicator

ROUTING

In general, every routing implementation in ns consists of three function blocks:

  • Routing agent exchanges routing packet with neighbors
  • Route logic uses the information gathered by routing agents (or the global topology database in case of static routing)
  • to perform the actual route computation
  • Classifiers sit inside a node. They use the computed routing table to perform packet forwarding.

LINKS

The normal link in NS2 is defined first of all, by the two nodes that is linking, with an specified bandwidth and delay characteristics. The link uses a queue. The procedure of having a link also adds a TTL checker to the link.

QUEUE MANAGEMENT AND PACKET SCHEDULING

Queues represent locations where the packets may be held (or dropped). Packet scheduling refers to the decision process used to choose which packets should be serviced or dropped.

DIFFERENTIATED SERVICES

Differentiated Services, is an IP QoS architecture based on packet marking that allows packets to be prioritized according to user requirements. During time of congestion, more low priority packets are discarded than high priority packets.

The differentiated service in NS2 has three major components:

  • Policy: Specified by network administrator about the level of service a class of traffic should receive in the network.
  • Edge router: Marks packets with a code point according to the policy specified.
  • Core: Examines packets code point marking and forwarding them accordingly

AGENTS

Represent endpoints where network-layer packets are constructed or consumed, and are used in the implementation of protocols at various layers. Some of the agents supported in the simulator are different kinds of TCP, UDP, SCTP, RTP, RTCP, Loss Monitor and of course SIP if the patch is applied to NS2.

PACKET HEADERS AND FORMATS

NS2 allows to have Protocol-specific packet headers, New packet headers can be introduced into the simulator by defining a C++ structure with the needed fields, and then modifying some of the simulator initialization code to assign a byte offset in each packet where the new header is to be located relative to others.

MOBILE NETWORKING

Mobile networks mainly covers the internals of a mobile node, routing mechanism and network components that are used to construct the network stack for a mobile node. The components that are covered briefly are Channel, Network interface, Radio Propagation Model, MAC protocols, Interface Queue, Link layer and Address resolution protocol model.

Further extensions are made to this model to allow combined simulation of wired and wireless networks. MobileIP was also extended to the wireless model.

AMONG MANY OTHERS, LIKE… Timers, Error Model, LAN/WLAN (MAC/LL…), Address structure (Hierarchical), Radio Propagation Models, Energy Models, and so on…

PERSONAL CONCLUSION: The main advantage of the “raw” version of NS2 is that all the implemented modules have been tested deeper than the ones of Eurane, and as mentioned before, even if some them can also be used, it compatibility has not been fully tested. Also, even if the documentation about this modules is poor, it is still better than the one existing for patches.

C++

DONE BY HAND

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