Tran Minh Trung

Ph.D., Hanoi University of Science and Technology – School of Electronics and Communications

ITRC Project (BrOMA)

Posted by trungtm on June 22, 2007

Research Topics

  • Research on a service model for next generation mobile internet access systems, performance comparison and analysis of existing access systems.
  • Research on core technologies for wireless access for next-generation mobile internet access systems
  • System level performance analysis of wireless access technologies in multi-cell environments and research on improvement methods.
  • Performance analysis of linkages between proposed access systems and network technologies

In these topics, now we are focusing on finding the way to increase system performance at network and MAC layer.

  • Optimal uplink scheduling in multi-cell environment
  • TCP performance improvement
  • Flow based MAC protocol
  • Voice support over multi-channel MAC protocol


  1. T.M.Trung , J. Mo “VMcMAC: A multi-channel MAC protocol for voice over wireless Ad-hoc networks,” , IEEE Communications Letters , vol. 11, no. 5, May 2007.
  2. T.M.Trung , J. Mo, and S.-L. Kim, “A Flow-Based Media Access Control (F-MAC) for Wireless Ad-Hoc Networks” , IEICE Transactions on Communications , Vol. E89-B (3), p.756-763, 2006.

Posted in Research Projects | Leave a Comment »

Optical Burst Switching (OBS) Networks

Posted by trungtm on June 22, 2007

I. Research Topics

Since Optical Burst Switching (OBS) Networks do not have internal buffers of intermediate routers, the path for burst packets must be reserved through control packets. However, the fact that the blocking probability becomes relatively high results in lower performance. One of main issues on OBS networks is how to reduce the blocking probability for high performance. Another is to provide Quality of Service (QoS) for many kinds of traffic types such as video and audio. To satisfy the expected QoS, the parameters like bandwidth and delay should be guaranteed. For these purposes, we have focus on the following two topics.

  1. Burst level congestion control Edge node of OBS networks generate burst packet. Core node forwards the burst packet onto another core node or edge node. The edge node ‘ s generating the burst packet may be controlled by using feed back mechanism for high throughput. This project investigates the effect of feed-back types and messages and designs the optimal feedback system for high throughput.
  2. Transport protocol on OBS networks The performance of TCP is tightly related to packet loss. The high blocking probability originates the low performance of TCP on OBS networks. To overcome the limitation, we propose new mechanism of loss recovery and congestion control in TCP for high throughput of TCP on OBS networks.
  3. OBS-NS simulator OBS-NS simulator was developed in 2004. We manage and improve the OBS-NS simulator and will add new features proposed in our project.

This project is sponsored by Optical Internet Research Center (OIRC) and Korea Science and Engineering Foundation (KOSEF)

Extra topics

  1. Traffic Grooming in WMD optical networks .

II. Publication

  1. T.M.Trung , N.T.T.Thao, J.H.Mo, “A Simple Cost and Time Efficient Traffic Grooming Algorithm” , in Proc. The 4th International Conference on Optical Communications and Networks (ICOCN2005) & IEEE Traffic grooming workshop, Boston, USA, 2005.

III. Released OBS-NS source code

  1. Download link:
  2. Document:

Posted in Research Projects | Leave a Comment »

Interfaces of Wireless MAC in ns-2

Posted by trungtm on June 16, 2007

Source: Zhibin Wo (WINLAB)

The relationship of MAC could be found in ns-mobilenode.tcl.

The source code:

# The following setups up link layer, mac layer, network
# interface and physical layer structures for the mobile
# node.
Node/MobileNode instproc add-interface { channel pmodel
lltype actype type qlen iftype anttype topo inerrproc
outerrproc ecproc}
{$self instvar arptable_ nifs_ netif_ mac_ ifq_ ll_
imep_ inerr_ outerr_ fec_

	# Link Layer
	$ll arptable $arptable_
	$ll mac $mac
	$ll down-target $ifq

	if {$imepflag == "ON" } {
		$imep recvtarget [$self entry]
		$imep sendtarget $ll
		$ll up-target $imep

        } else {
		$ll up-target [$self entry]
	# Interface Queue
	$ifq target $mac
	$ifq set limit_ $qlen
	if {$imepflag != ""} {
		set drpT [$self mobility-trace Drop "IFQ"]
	} else {
		set drpT [cmu-trace Drop "IFQ" $self]
	$ifq drop-target $drpT
	if { $namfp != "" } {
		$drpT namattach $namfp

        # Mac Layer
	$mac netif $netif
	$mac up-target $ll

	if {$outerr == "" && $fec == ""} {
		$mac down-target $netif
	} elseif {$outerr != "" && $fec == ""} {
		$mac down-target $outerr
		$outerr target $netif
	} elseif {$outerr == "" && $fec != ""} {
		$mac down-target $fec
		$fec down-target $netif
	} else {
		$mac down-target $fec
		$fec down-target $outerr
		$err target $netif

Actually, from top to down path, the structure is ll —> ifq —-> mac —> netif . for packets going up, it is netif —> mac —>ll. Thus, ifq is only used for down path of . however, a scheduler is also only useful to handle outgoing packets. Thus, if we want to implement a scheduler, we have to use something to replace this “ifq” and remake the interface in tcl script.

Posted in NS2 for Wireless | Leave a Comment »

WiFlex: Multi-Channel Cooperative MAC protocol for Heterogeneous Wireless Devices

Posted by trungtm on June 16, 2007

Incompatible wireless protocols in the ISM band are proliferating, creating increasingly complex co-existence problems. This paper proposes a family of compatible protocols that address the requirements of a wide range of devices, from small sensor nodes to media centers. The family is based on an OFDM physical layer and on a distributed multi-channel asynchronous MAC protocol that supports priorities and radios that can modulate different amounts of bandwidth. The MAC protocol is shown to be collision-free. The performance of the protocols is evaluated using a multichannel extension of NS-2 that also models capture effects. The evaluation results demonstrate the high performance of theprotocols and the coexistence of devices with different characteristics and of applications with different requirements.

Posted in Working papers | Leave a Comment »