Radio Resource Management in MIMO-OFDM-Mesh Networks: Issues and Approaches

D Niyato, E Hossain

For me, this was an introduction to rrm in multihop ofdm-mimo networks. I also learned about reinforcement learning algorithms.

CAPTURE EFFECT IN IEEE 802.11 BASIC SERVICE AREA UNDER INFLUENCE OF RAYLEIGH FADING AND NEAR/FAR EFFECT

Zoran Hadzi-Velkov Boris Spasenovski

The article proposes two models for the capture effect.

Multiuser OFDM with Adaptive Subcarrier, Bit, and Power Allocation

Cheong Yui Wong, Roger S. Cheng, Member, IEEE,
Khaled Ben Letaief, Senior Member, IEEE, and Ross D. Murch, Senior Member, IEEE


The idea and the algorithm to assign carriers to users in ofdma.

Could NACKs be useful in relay-assisted networks?

In WLAN IEEE 802.11, there is only positive acknowledges. Nevertheless, in a relay-assisted network, a negative acknowledgement might help the relay to decide whether it is in a favorable position to re-send the packet.

IEEE 802.11n Development: History, Process and Technology

Eldad Perahia

Today I re-read this article and I think it is very interesting. I think that CSMA/ECA should be included in upcoming standards.

nc for cellular

has anyone thought about using network coding for intra-cell calls?

Investigating the Validity of IEEE 802.11 MAC Modeling Hypothesis

K.D. Huang, K.R. Duffy, D.Malone and D.J. Leith

I should verify our model for CSMA/ECA to double-check whether we are using the (A3) and (A4) hypothesis or not. In any case, as the authors concede, the violation of hypothesis (A4) does not affect goodput predictions.

On the Shaping Introduced by IEEE 802.11 Nodes in Long-Range Dependent Traffic

David Rincón , David Remondo , and Cristina Cano

If we change CSMA/CA for CSMA/ECA, would the results presented in the paper differ?

Non-Saturation and Saturation Analysis of IEEE 802.11e EDCA with Starvation Prediction

Paal E. Engelstad and Olav N. Osterbo

This paper was very clarifying for me in many ways. It uses Markov Chains and presents an extension to take into account AIFS.

TCP Muro

There are two problems with current TCP:
- The slow start in high bandwith-delay links.
- The persistent p2p flows that consume most of the Internet's bandwith.

I believe that if the growing of the congestion window could be modified to increase also as a function of time at the beginning, the two problems would be solved. Or, at least, alleviated.

Game-theoretical approach to CSMA/ECA

It might be possible to show that a deterministic backoff after successes and a random backoff after failures is the nash equilibrium of a game.

Or maybe the nash equilibrium is a bit more complex: using a random backoff only if the collision resulted from a random backoff. This leads to a quick convergence protocol, a bit unfair by those that not find their place (slot) immediately.

Online Estimation of RF Interference

Nabeel Ahmed, Usman Ismail, Srinivasan Keshav and Konstantina Papagiannaki

In enterprise networks in which the thin access points are managed by a single controller, there is much room for optimization. As a example, interference between access points can be prevented if a conflict graph is available.

The authors implement a novel mechanism to build such conflict graph. Instead of using lengthy bandwidth probes, they introduce the concept of microprobes. The idea is to attempt transmission from two access points simultaneously. If one of the access points hold the transmission until the other has finished, it means that the two access points are in carrier-sense range, which is quite common in enterprise networks.

The lack of ack may indicate that the APs are hidden from one another, and the simultaneous transmission prevented the receiver to correctly decode the packet.

The implementation of the idea poses a variety of challenges. The APs have to be sychronized, and the delay ellapsing from the controller order to the actual probe has to be minimized. Further, the network has to be silenced before the probe. Then it is necessary to accurately measure the MAC service time. The authors solved all the problems and attained an accuracy comparable to the one obtained from traditional bandwidth probes.

The advantage of the microprobes is that they can be performed in a few ms, which allows to build the conflict graph during the network normal operation (no downtime required).

I am particularly interested in the possibility to tinker with the wlan card microcode, since it would allow me to build a testbed of my idea.

panacea

The idea is pretty simple:do not decrement the backoff counter of stations in deterministic mode in busy slots.

A Capacity Analysis for the IEEE 802.11 MAC Protocol

Y.C. Tay and K.C. Chua

The article presents a model of IEEE 802.11 that is completely different from Bianchi's approach and thus provides different insights in the protocol. I would say it is a must read and a strong candidate for our wireless seminars.

System Centric and User Centric Queueing Models for IEEE 802.11 based Wireless LANs

Kamesh Medepalli and Fouad A. Tobagi

The authors make use of queueing theory to analyse DCF. Hopefully this article helps me to understand Boris model. The ultimate goal is to model CSMA/ECA

A Singular Choice for Multiple Choice

Gudmund S. Frandsen Michael I. Schwartzbach

Multiple-choice-test theory. It is not clear to me whether it is applicable to multiple-choice multiple-answer tests.

A wireless sensor networks MAC protocol for real-time applications

E. Egea-Lopez Æ J. Vales-Alonso Æ A. S. Martınez-Sala Æ J. Garcıa-Haro Æ
́ ́ ́
P. Pavon-Marino Æ M. V. Bueno Delgado
́ ̃
This protocol has some similarities with our proposal CSMA/ECA.

Education Should Consider Alternative Formats for the Dissertation

Nell K. Duke; Sarah W. Beck

The authors explain that traditional dissertations suffer from two shortcomings. First, they have an extremely limited readership. Often, the members of the jury are the only readers of the dissertation. Then, the heavy tome gathers dust in the library archive.

Second, writting the dissertation is a one-time tremendous effort that does not train the researcher for her future proffessional writting activities, which include soliciting funds in project proposals and disseminating the results in the form of articles in scholary forums.

The authors advocate for a dissertation in the form of articles ready to be sent for publications. The articles should stem from a single research project, but they may include different methodologies and present different conclusions.

I completely agree with the rationale of the paper.

A tutorial survey on vehicular ad hoc networks

H. Hartenstein, K. P. Laborteaux

This review will be very helpful in preparing our paper for VTC.

... roadside units.
... 802.11p -> Csma also in vehicular networks
... periodical and event-driven traffic
... congestion in the roadnetwork might translate into congestion in the radio access network

A new technique for satellite broadcast channel communication

F.Borgonovo and L.Fratta

The authors propose an hybrid aloha/reservation protocol. It behaves as aloha until a collision occurs. Then switches to reservation.

I am specially interested in this sentence:
Moreover we can say that the S-ALOHA technique is very suitable for low traffic, single-packet, condiditions even if a control scheme has to be used to guarantee the system stability.

and cites this paper:
Lam, S. and Kleinrock, L. "Packet Switching in a Multiaccess Broadcast Channel: Dynamic Control Procedures"

FreeMAC: Framework for Multi-Channel MAC Development on 802.11 Hardware

Ashish Sharma, Elizabeth M. Belding

The authors present a solution for multi-channel wifi. What really impressed me is the high degree of control over the network interface that is achieved. If I had the chance to reproduce their work, it would be applicable to suppress acks or to test our csma/eca proposals.

Using chunk collision avoidance to optimize p2p live

When a group of nodes under the same authoritative domain (or ISP) collectively download a P2P video stream, it is desirable to minimize inter-ISP traffic. Ideally, each chunk of the stream would be downloaded by one of the nodes from an external peer, and then shared among all the nodes under the same ISP. If the same chunk is downloaded from external sources by to different peers of the same ISP, we can say that a "collision" happened. Enhanced collision avoidance techniques from MAC layer can be used in order to optimize the P2P live streaming download.

Will IPTV ride the peer-to-peer stream?

Marfia, G., Sentivelli, A., Tewari, S., Gerla, M. and Kleinrock, L.

The article concludes that ADSL's asimmetry is the main obstacle in the way of high-quality P2P IP TV.

Multiuser Detection in Large Systems with an unknown Number of Users

Adrià Tauste Campo, Albert Guillén i Fàbregas and Ezio Biglieri

It addresses the same problem as the previous article. To my particular taste, this was much more understandable than the previous one, even though it is still ongoing work.

Large-system analysis of a CDMA dynamic channel under a Markovian input process

Ezio Biglieri∗ , Emanuele Grossi† , Marco Lops† , and Adrià Tauste Campo


It addresses the problem of a communication system with an unknown number of users. It is curious that to see that the estimation of the number of users is completely different from what I have been reading so far. Even if the problem statement might sound similar, it is actually a completely different problem.

High-Performance Wireless Ethernet

Heegard, Coffey, Gummadi, Murphy, Provencio, Rossin, Schrum, Shoemake

A review of IEEE 802.11 in its early stages with emphasis on coding.

learning MAC protocol for sensor networks

Assume a network of sensor that periodically transmit some data. The period T is the same for all the sensors. Assume also that the time required to tranmsit a packet is much shorter than the period Tx << T. Then we propose a MAC protocol that, in case of collision, re-attempt transmission after a random period of time R, Tx<< R << T. After a successful transmission, the sensor delays exactly T the new transmission attempt.

After the learning period, the system will operate collision-free. Further, each node will transmit deterministically each T seconds. The receiver can sleep for most of the time, and only wake up when it knows that there will be an incoming packet.

Weighted Fair Uplink/Downlink Access Provisioning in IEEE 802.11e WLANs

Feyza Keceli, Inanc Inan, and Ender Ayanoglu

A comprehensive solution to the uplink/downlink unfairness in EDCA. The goodies include:
i) Fully .11e compliant.
ii) Smooth interaction with TCP.
iii) Maintains the priorities of the queues.
iiii) Satisfactory QoS for real-time flows.

EBA: An Enhancement of the IEEE 802.11 DCF via Distributed Reservation

Jaehyuk Choi, Joon Yoo, Sunghyun Choi, Member, IEEE, and Chongkwon Kim, Member, IEEE

Very interesting paper. I need to organize my thoughts. The core idea is brilliant: the stations advertise their backoff values. I have the feeling that the proposed implementation can be improved.

Merits: It proactively prevent collisions from the very beginning. In comparition, CSMA/ECA has a transitory operation with performance similar to legacy CSMA/CA. In can tolerate a large number of stations delivering acceptable throughput and fairness.

Shortcomings: It requires the modification of the MAC headers, which makes the coexistence with legacy stations trickier. The collision avoidance mechanism relies in additional signaling included in those header. If errors or collisions occur, that signaling is lost and the operation of EBA falls to the same as legacy CSMA/CA.

A Reservation-Based Enhancement of IEEE 802.11 DCF Protocol

Mehdad N. SHIRAZI†a) , Nonmember, Oyunchimeg SHAGDAR†† , Suhua TANG†† , Masanori NOZAKI††† ,
Youiti KADO††† , and Bing ZHANG† , Members

An Explanation for Unexpected 802.11 Outdoor Link-level Measurement Results

Giustiniano, D. Bianchi, G. Scalia, L. Tinnirello, I.
This is a hands-on paper. Very well written and interesting. It shows that the combination of atheros chipset and madwifi drivers present a weird effect because of the particular use of the diversity concept.

Performance Evaluation of R-ALOHA in Distributed Packet Radion Networks with Hard Real-Time Communications

Te-Kail Liu, John A. Silvester and Andreas Polydoros

They analyze R-Aloha, which is very similar to CSMA/ECA. And they also use markov chains, so the parallelisms arise. Nevertheless, since there is no reservation in CSMA/ECA, there are also some differences. Anyway, there is still many things I can learn and reuse in this paper. By the way, which is the difference between p[] and Pr{}?

Aloha Packet System with and without Slots and Capture

Lawrence G. Roberts

This paper is written using a typing machine. The author considers the capture effect for satellite communication.

Capture Effects of Wireless CSMA/CA Protocols in Rayleigh and Shadow Fading Channels

Jae Hyun Kim, Member, IEEE, and Jong Kyu Lee, Member, IEEE

The performance of CSMA/CA is computed, taking into account the capture effect. I was surprised that they also considered the case in which acks are ommitted.

IMS-controlled ethernet domains for networked services delinvery

D.Tolle, A.Plankl, G.Butscher

Using ethernet as a transport plane for IMS

Application Layer FEC in IPTV Services

M.Luby. T.Stockhammer, M.Watson

Forward Error Correction has many applications in IPTV distribution. I was thinking that it maybe also particularly useful for P2P live streaming.

Game Theory for Wireless Engineers

Allen MacKenzie, Luiz DaSilva

A superb book to get a flavor about what game theory is about.

Congestion-Aware Rate Adaption in Wireless Networks: A Measurement-Driven Approach

P. Acharya, A. Sharma, E. Belding, K. Almeroth and K. Papagiannaki

Channel Busy Time is used to detect congestion.A functionality of the MadWifi driver is used to obtain CBT in real time. It is also detailed how the ill-implemented auto-rate fallback aggravates the congestion situation. A new rate adaptation mechanism is proposed and the overall performance is notoriously improved in congested networks.

Can I add a VoIP call?

Garg and Kappes

So many interesting things in five pages.

The main limitation comes from packet loss, reported to be 16%.

Quoting:While in wired networks (such as Ethernet) choice of codecs is highly effective in dealing wiith network load, in 802.11 networks, this is not the case.

Performance Analysis of the IEEE 802.16 Wireless Metropolitan Area Network

Worth reading to learn a bit about .16. The results and plots are naive.

A WAITING-TIME DEPENDENT BACKOFF ALGORITHM FOR QOS ENHANCEMENT OF VOICE OVER WLAN

Jing Chi Yajuan Wang Bo Xia Ruozhou Lin Xian Gao

The authors propose to adjust the backoff window as a function of the time that the packet has been waiting to be sent. After a certain threshold, the backoff window is reduced for each new attempt. When the packet has been excessive delayet, it is simply discarded.

Detecting MAC Layer Collision Abnormalities in CSMA/CA Wireless Networks

Alberto López Toledo, Xiaodong Wang

Really interesting. I have some minor doubts that I would ask to Alberto when I have the chance.

IEEE 802.11s: WLAN Mesh Standardization and High Performance Extensions

Guido R. Hiertz, Yunpeng Zang, Sebastian Max, Thomas Junge, Erik Weiss, Benedikt Wolz,
RWTH Aachen University
Dee Denteneer, Philips Research
Lars Berlemann and Stefan Mangold, Swisscom


The headache of wireless mesh networks. It seems that there is no magic formula to solve the problem. To limit interference while maximizing space reuse. The article suggests the use of beacons to separate traffic of the stations and mesh nodes. This beacons would also include SNR measurements, reservation information...

Maybe the solution lies in the use of smart antennae. I would comment it this afternoon with Pere.

SIP-BASED MOBILITY MANAGEMENT IN NEXT GENERATION NETWORKS

STEFANO SALSANO AND ANDREA POLIDORO, UNIVERSITY OF ROME TOR VERGATA
CHIARA MINGARDI AND SAVERIO NICCOLINI, NEC EUROPE LTD.
LUCA VELTRI, UNIVERSITY OF PARMA

I see a parallelism betwen this paper and the previous one. In both cases a problem (mobility/multicast) has been atttempted to solve at the network layer for a long time and, now, efforts are focused at the application layer.

Opportunities and Challenges of Peer-to-Peer Internet Video Broadcast

By Jiangchuan Liu, Member IEEE , Sanjay G. Rao, Bo Li, Senior Member IEEE , and Hui Zhang

This is the paper for the next journal club.

Network Coding for Efficient Multicast Routing in Wireless Ad-hoc Networks

Jingyao Zhang, Pingyi Fan, Member, IEEE, and Khaled Ben Letaief, Fellow, IEEE

Network coding might be efficient for multicast in adhoc and sensor networks. This papers deal with the problem of finding which nodes have to be encoders.

Topological Design of Interconnected LANs Using Hopfield Neural Networks

Shih-Tsung Yang and Anthony Ephremides

Hopfield Networks are applied to LAN interconnection for minimal delay.

Performance anomaly of 802.11b

Martin Heusse, Franck Rousseau, Gilles Berger-Sabbatel, Andrzej Duda

When a slow station shares the channel with fast stations, all the stations experiment low throughput. This problem is alleviated when using TCP, since the lost packets prevent that the TCP windows fully open.

This reference is also important. It is the one to cite when referring to short-term unfairness in DCF.

An analysis of short-term fairness in wireless media
access protocols,

IEEE 802.16 Mesh Schedulers: Issues and Design Challenges

Najah A. Abu Ali,Abd-Elhamid M. Taha and Hossam S. Hassanein Hussein T. Mouftah

My intention was to get a feeling about mesh in 802.16... As I was reading, I was overwhelmed by the immense number of issues that one has to take into account... I wonder whether such a complex operation mechanisms would even work in a real implementation.

Adaptative Optimization of IEEE 802.11 DCF Based on Bayesian Estimation of the Number of Competing Terminals

A. López Toledo, T. Vercauterenm and X. Wang
Sequential Monte Carlo methods combined with a Bayesian approach is use to estimate the number of competing terminals to optimizw DCF parameters.

Voice Capacity Analysis of WLAN with Channel Access Prioritizing Mechanism

X. Ling,Y.Xeng,W. Shen, J. Mark

Most of the research in WLAN performance departs from the assumption of saturated stations. This was my motivation to write the WONS paper. In this article, the issue is solved in an elegant way. As a plus, they are capable to take into account different classes for QoS.

The article itself is divided in two parts. The first one studies the competition for the channel between VoIP and saturated sources in adhoc networks. The second part deals with the AP bottleneck problem when infrastructure operation. IMHO there is no tight relationship between the two parts of the articles, because the focus is placed in different problems.

Nevertheless, the article is well written, and will be an inspirations (and references) sources when writing my own articles.

C-PRMA: A Centralized Packet Reservation Multiple Access for Local Wireless Communications

G. Bianchi, F. Borgonovo, L.Fratta, L. Musumeci, M.Zorzi

Centralized PRMA is an extension of PRMA that includes a centralized scheduler that handles traffic hetereogeneity. IMHO the complexity is overwhelming.

The paper will be useful because its thorough introduction.

T ree Algorithms for Packet Broadcast Channels

JOHN I. CAPETANAKIS

This paper introduces the concept of tree algorithms. The address space is divided in two halves. In two successive slots, the one is devoted to the first halve and the second to the second halve. If there is a collision, the address spaces is subsequently divided in two. Again the stations belonging to the first part transmit in the first slot while the stations included in the second part transmit in the second slot. This algorithm is repeated until all the stations have transmittet their packets.

Even though the proposal is theoretically sound and leads to throughput of 0.3-0.4 packets per slot, it probably present practical disadvantages. It was proposed in 1979 and we have not seen any implementation yet.

Design and Analysis of Cross-Layer Tree Algorithms for Wireless Random Access

Xin Wang, Member, IEEE, Yingqun Yu, Student Member, IEEE, and Georgios B. Giannakis, Fellow, IEEE

The reading of this paper resulted in many additional taks to do:
- There is a formula that is clearly wrong. Must find out what's goin' on
- It talks about tree algorithms for contention. What are this TA exactly?
- In the jitel paper, I didn't explain how to calculate the efficiency for the BEB case.
- The authors neglect the slots different lengths. Why? Is it because in 802.16 all the slots have equal length?
- Should I include this paper in the related work?

Mobile Privacy in Wireless Networks–Revisited

Caimu Tang, Member, IEEE, and Dapeng Oliver Wu, Senior Member, IEEE

The authors detail the privacy requirements for mobile dives and propose a mechanism to attain such privacy. It is based on Elliptic Curve Cryptography and thus does not place overwhelming burden on the mobile device.

Analysis of the Stability and Performance of Exponential Backoff

Byung-Jae Kwak,Nah-Oak Song,Leonard E. Miller

An extensive analysis of Exponential Backoff and its asymptotic properties is provided. Unfortunately, the truncated exponential backoff which is the one that actually appears in real implementations is not considered.

A Capacity Analysis for the IEEE 802.11 MAC Protocol

Y.C. TAY and K.C. CHUA

Very interesting paper. The author provide a number of claims related to DCF that enhance the understanding of the protocol. They already highlight that the optimal transmission probability is a function of the packet length and the number of active terminals.

IEEE 802.11 Wireless Local Area Networks

Brian P. Crow, Indra Widjaja, Jeon Geun Kim, Prescott T. Sakai

Even thoug I could not finish the paper (the scanning is horrible) I had to write a comment. These guys already obtained results than me... and it was back in the 20th century :-P

VARIABLE BIT RATE VOIP IN IEEE 802.11E WIRELESS LANS

FRANK HAIZHON LI, UNIVERSITY OF SOUTH CAROLINA UPSTATE
YANG XIAO AND JINGYUAN ZHANG, UNIVERSITY OF ALABAMA

The article presents CAC for VBR VoIP calls. The variable bit-rate is a consequence of the on-off nature of the calls. The authors present a time-based admission control mechanism that uses token-bucket and relies on the observation information to decide whether to accept a new call or not. Additionally they propose that the AP accesses the channel with priority to solve the uplink-downlink unfairness.

EVALUATION OF SIGNALING LOADS IN 3GPP NETWORKS

DARIO S. TONESI AND LUCA SALGARELLI, UNIVERSITY OF BRESCIA
YAN SUN AND THOMAS F. LA PORTA, PENNSYLVANIA STATE UNIVERSITY

The article compares the signaling load of 3GPP release 99 to release 5. The long SIP text messages and the higher number of messages are responsible of increased signaling traffic.

sempre 16

Quan una estació ha d'elegir un backoff després de transmetre un paquet amb èxit, calcula un valor aleatori entre 0 i CWmin. Per què no elegir sempre 16? D'aquesta manera després d'un transitori amb col.lisions, el sistema es comportaria com un TDMA.

z-mac: a hybrid mac for wireless sensor networks

Injong Rhee, Ajit Warrier, Mahesh Aia and Jeongki Min

I got the idea of what a hybrid protocol is. A combination of csma and tdma. It seemed to me that the proposal is excruciatingly complex and tedious. However, i must check the following references:

[13] K. Jamieson, H. Balakrishnan and Y. Tay. Sift:A MAC protocol for event driven wireless sensor networks

[19] Y. Tay, K. Jamieson, and H. Balakrishnan. Collision-Minimizing CSMA and its applications to wireless sensor networks

Optimal Constant-Window Backoff Scheme for IEEE 802.11 DCF in finite Load Single-Hop Wireless Networks

Hicham Anouar and Christian Bonnet

The authors propose using an optimal fixed window which is computed as a function of the number stations. There is a weird assumption related to a "normalized packet length". I found a few details that could be useful in refining my own paper.

I was surprised to see that they have a journal version of the same paper.

SOSIMPLE: A Serverless, Standards-based, P2P SIP Communication System

David A. Bryan and Bruce B. Lowekamp, Cullen Jennings

I read this as an introduction to P2PSIP, before attempting to understand the RFCs.

Batch and Sequential Bayesian Estimators of the Number of Active Terminals in an IEEE 802.11 Network

Tom Vercauteren, Alberto Lopez Toledo

Following Toledo's trail, I read this paper in which the authors describe how to estimate the number of active stations in a IEEE 802.11 network. Bayesian algorithms are used to construct a number of off-line and on-line estimators with different degrees of complexity and accuraci.

Event thought I could not grasp the mathematical core, the references will be quite useful, since I am also working on optimizing the network performance for a variable number of stations. Further, the description of the simulations can be used as a reference for future works.

A Robust Kolmogorov-Smirnov Detector for Misbehavior in IEEE 802.11 DCF

Alberto Lopez Toledo and Xiaodong Wang

The proposal is to measure the number of empty slots between transmissions of a given station. Then use the K-S technique to estimate the cdf and compare to the expected cdf. When the actual cdf clearly differs from the expected cdf, it is inferred that the node is missbehaving.

Stability and Performance of the R-ALOHA Packet Broadcast System

SHUJI TASAKA

R-Aloha differs from Aloha in the fact that a stations implicitly obtains a reservation for the channel whenever it successfully transmits a packet. The slots are grouped in frames, and the station obtains a reservation in each frame. This idea is interesting because in steady state operation, collisions are avoided and the system operates as in tdma.

The mathematical tool used in the analysis is Equilibrium Point Analysis (EPA)

Enhancement of IEEE 802.11 Distributed Coordination Function with Exponential Increase Exponential Decrease Backoff Algorithm

Nah-Oak Song, Byung-Jae Kwak, Jabin Song, Leonard E. Miller

Short paper that proposes an alternative to the doubling of the contention window and evaluates the new proposal using simulation

Stability of Binary Exponential Backoff

JONATHAN GOODMAN et al

Hard-core mathematical stuff. It comes at no surprise since the paper is written in a mathematical institute. Maybe the references are of some use.

Using Incompletely Cooperative Game Theory in Wireless Mesh Networks

Liqiang Zhao and Jie Zhang, University of Bedfordshire
Hailin Zhang, Xidian University

The inclusion of game theory in the title might sound scary, but the paper is not complicated. It inspired me the idea of looking for more efficient backoff mechanisms.

new backoff scheme

The current backoff scheme is independent of the number of contending stations. The result is that is desirable to adjust CWmin to its optimum value. I've been thinking about a backoff algorithm that reacts and adapts to the number of active contending stations.

Solutions to Performance Problems in VoIP Over a 802.11 Wireless LAN

Wei Wang, Soung Chang Liew, and Victor O. K. Li
This paper already highlight the main impairments in VoWLAN: Protocol overhead and uplink/downlink unfairness.
Their solution (M-M) consists on multiplexing-multicasting the packets for download. These multicasted packets require strict prioritization to avoid collision.

The main drawback I can see is how could be this combined with level-2 security (WPA) so widespread this days.

The authors also analyze the impact their solution has on delay and the impact of elastic flows on the number of VoIP Streams.

A New Access Control Solution for a Multi-Provider Wireless Environment

ARTUR HECKER et al.

Maybe it is because monday morning, but could not get the point. It was something about 4G and a smart card similar to a sim.

Verification of Common 802.11 MAC Model Assumptions

David Malone and Ian Dangerfield and Doug Leith

Very interesting paper that compare values obtained from the models with those obtained from testbeds. Again, it is something that I was thinking to be necessary. Additionally there are many references I must read.

Inter-Vehicle Communications

Marc Torrent Moreno

This thesis studies IVC based on 802.11p, a variant of 802.11 for vanet. After describing the general characteristics of this kind of networks and introducing a modification of ns-2 specifically for vanets, proposes two new protocols. One for power control that avoids channel congestion, the other for fast propagation of emergency information. The two protocols are evaluated using the simulator.

Design of QoS and Admission Control for VoIP Services over IEEE 802.11e WLANs

Pei-Yeh Wu1, Yu-Chee Tseng1, and Hewitt Lee2

I liked it. It's about something I had been thinking and I think that I can learn something from their work.

ANALYSIS OF RETRY LIMIT FOR SUPPORTING VOIP IN IEEE 802.11E EDCA WLANS

Byung Joon Oh

Not a outstanding paper. But we have to admit that we were not the first that came up with the idea of suppressing/reducing retransmissions.

A new MAC protocol ensuring the multimedia traffic QoS for CDMA networks

Loren Carrasco, Guillem Femenias, Felix Raja

I was curious about this paper from people from my Island. It remebered me to take a look at the on-off model.
I should find some additional information in this paper:
G. Bianchi and F. Borgonovo et al., “C-PRMA: A Centralized Packet Reservation Multiple Acces System for
Local Wireless Communications”, IEEE Transactions on Vehicular Technology, Vol. 46, No. 2, pp. 442–435,
1997.

Uplink RRM for conversational and interactive services in utra-fdd

O.Sallent, J.Perez-Romero, R.Agustí

I read it because it was referenced in the paper i was reviewing.

Do we need Header Compression for VoIP in Wireless LANs?

Rastin Pries, Andreas Maeder and Dirk Staehle

The athors use OpNet simulations to determine the maximum number of calls in IEEE 802.11b,g,e networks. It's a week paper but is so close to our research area that makes it a very interesting reading. I must remember to include references to G711 and G729 codecs in our article.

Multicast Routing in Wireless Mesh Networks: Minimum Cost Trees or Shortest Path Trees

Uyen Trang Nguyen and Jin Xu

The authors present different techniques to build trees for multicast in wireless mesh networks.
SPT: Shortest Path Tree -> The one used on the Internet
MCT: Minimum Cost Tree
MST: Minimum Steiner trees as in wired networks.
MNT: Minimum Number of Transmissions for wireless networks. It accounts for the fact that a wireless transmission can reach various nodes.

The authors conclude that the SPT is better for various reasons. However, it seems to me that MNT should present numerous advantages such as reduced contention and collision. And it definetely present battery saving benefits.

TCP Throughput Enhancement over Wireless Mesh Networks

Li-Ping Tung, Wei-Kuan Shih, Te-Chung Cho and Yeali S. Sun

The article explains the hidden and exposed terminal problems. Using simulations, the authors relate this two effects to tcp performance. Finally, a channel assignment algorithm is proposed that optimizes TCP performance.

On Extending IMS Services to WLANs

Ahmed Hasswa* Abd-Elhamid Taha† Hossam Hassanein*

A proposal to integrate WLAN and IMS using AS. I don't see the point in proposing an alternative to the 3GPP integration.

coca de trampó

300g de farina,
una mica de llevadura,
mitja tassa de saïm i oli,
un ou batut,
julivert,
tomàtiga,
prebe,
tomàtiga,
ceba.
S'unta sa llauna amb mantega.
Posar es saïm i s'oli damunt aigo calenta.
Posar aigo teba en es llevat.
Posar s'ou a da farina.
Posar es saïm.
Posar en una greixonera i pastar.
Posar damunt aigo calenta i tapar amb padaços i diaris.
Deixar tovar.
Estirar sa pasta damunt sa llauna i posar ses verdures.
Enfornar 20 minuts amb es forn ben calent.

IMS signaling over current wireless networks

experiments using the open ims core

Dragos Vingarzan, Peter Weik

Interesting result on the performance(delay and packet loss) of differents radio access networks: WLAN, HDSPA, WCDMA, GPRS. Spoiler: WLANs outperform the rest of the wireless access networks.

Applications and Challenges of the 802.11e EDCA Mechanism: An Experimental Study

Albert Banchs, Arturo Azcorra, Carlos García, and Rubén Cuevas

The articles describes experiments wiht 802.11e and outlines the key issues in wlan performance analysis. A serious candidate for our journal club.

A Throughput and Delay Model for IEEE 802.11e EDCA Under Non Saturation

PABLO SERRANO, ALBERT BANCHS and ARTURO AZCORRA

Much more complete/flexible than our proposal, but it is also much more complex too. Their simulations and results agree astonishingly well. I wish I had an implementation/script to compare my results to theirs... maybe I will devote some time to further understand their proposal and program a solver.

cous-cous

xot
ceba
pastanaga
carabassi
ciurons
bleda
prunes

ginger
colorant
canyella

Throughput analysis and optimal configuration of 802.11e EDCA

a,* b
Albert Banchs , Luca Vollero

At a first glanze, it seemed to me that this paper was irrelevant for my research, since it considers only non-real time traffic. However, the initial description of EDCA provided a piece of information that I was missing until now, which is that the PLCP preamble includes a NAV value accounting for the transmission of the data plus the ack. That means that the rest of the stations will remain silent for that period of time... even if there is a collision and no ack is sent!!!

Summarizing, there are some formulae that might be wrong in my WONS paper. What should I do now?

NIHO: Network Initiated Handovers for next generation ALL IP Networks

Telemaco Melia,Rui Aguiar,Albert Bacnhs, Piotr Pacyna

The paper describes a demo at Barcelona's Infocom in which the network is in charge of initiating handovers in order to better distribute the load among APs, and satisfy the QoS requirements of all nodes.

Pervasiveness in a Competitive Multi-Operator Environment: The Daidalos Project

Rui L. Aguiar, Amardeo Sarma, Dennis Bijwaard, Loris Marchetti, Piotr Pacyna, Ricardo Pascotto

Describes de Daidalus european project which describes a beyond-IMS scenario. In this scenario the services will be created by autonomous service providers and will be discoverable and aggregable. Billing will happen seamlessly. Wireless operators will increase their collaboration to extend availability. The user will appear the network and the services as more intelligent, context-aware and adapted to its profile.

A Fair MAC Protocol for IEEE 802.11-Based Ad Hoc Networks: Design and Implementation

Bensaou, B. Member, Z.F.
Senior Member;

It is an extension of a paper from the same authors back in 2000. It repeats the theoretical framework and proposes some "practical" implementation guidelines.

A Generic Framework for Modeling MAC Protocols in Wireless Broadband Access Networks

Xinhua Ling, Jon W. Mark, and Xuemin (Sherman) Shen, University of Waterloo
Yu Cheng, Illinois Institute of Technology

Disappointing. However, it remembered me the need to include an explanation of the renewal theory in my next article. And to include yet another assumption for the model: no hidden terminal effect.

Admission Control in IEEE 802.11e Wireless LANs

Deyun Gao and Jianfei Cai, King Ngi Ngan

Lots of stuff. First, a comprehensive explanation of DCF,PCF, EDCA, HCCA... etc. Then, a classification of admission control in model-based and measurement-based and a revision of the proposed alternatives.

more conferences

Copy&Paste from
http://netlab.cs.ucla.edu/cgi-bin/usemod10/wiki.cgi?MyDeadlines

* INFOCOM'08: Passed, Notification: 11/12 [CFP]
* PerCom?'08: 9/4, Notification: 11/16 [CFP]
* WiSec?'08, 9/15, Notification: 12/10/07 [CFP]
* NSDI'08: 10/9, Notification: 12/21 [CFP]
* SIGMETRICS'08, 10/26R, 11/2S, Notification: 2/5/08 [CFP]
* IPSN'08, 10/26R, 11/2S, Notification: 2/5/08 [CFP]
* IPTPS'09, 11/2, Notification: 1/11/08 [CFP]
* ICDCS'08: 11/15, Notification: 3/3/08 [CFP]
* Mobihoc'08: 11/22, Notification: 2/28 [CFP]
* MobiSys'08: 11/26R/12/4S, Notification: 3/4 [CFP]
* Secon;08: 12/4R, 12/11S, Notification: 3/14 [CFP]
* SIGCOMM'08: 1/31 (2007)
* MOBICOM'08: 3/2 (2007)

Analysis of Concatenation and Packing Mechanisms in IEEE 802.11n

Dionysios Skordoulis, Qiang Ni, Usman Ali & Marios Hadjinicolaou

It explains that there are two kinds of aggregation and that they can be combined. These aggregation is required to provide higher bitrates at the MAC SAP.

Toward Efficient Service-Level QoS Provisioning in Large-Scale 802.11-Based Networks

Tarik Taleb, Tohoku University
Abdelhamid Nafaa and Liam Murphy, University College Dublin
Kazuo Hashimoto, Nei Kato, and Yoshiaki Nemoto, Tohoku University

The title/abstract/introduction seemed interesting. There was CAC (in which Cristina has been working), QoS (Boris), and Multirate (Anna). But I finished reading the article with the feeling that it doesn't offer anything new.

Favetes amb xoriç...

ceba i
espinacs/bledes

Proportional fair throughput allocation in multirate IEEE 802.11e wireless LANs

Albert Banchs · Pablo Serrano · Huw Oliver

The paper deals with multirate unfairness in a saturated scenario. The author provide a mathematical analysis and obtain a utility function to maximize. Then, provide differents approaches to achieve fairnes: CWmin tuning and TXOP tuning. Each of this approaches can also be applied in a centralized or distributed fashion.

In my first reading I had the feeling that the approach based on TXOP was somehow flawed, but I have to double-check to confirm.

There are many interesting things in this article, and I think that, after reading it, I can rewrite my own article from a different perspective.

Licence-exempt wireless communication systems

S Kawade and T Hodgkinson

It explains the problems of interferences that wifi deployments suffer from. This is a barrier for the widespread of unlicensed spectrum networks. The overall performance seriously decreases when the number of users/cells is increased, specially in those cases in which there is not careful planning. The authors suggest the use of self-organizing networks that control the output power. My personal opinion is that OFDMA, MIMO, and directional arrays should be other solutions for the problem.

Evaluating the voice capacity of 802.11 WLAN under distributed control

Nidhi Hedge, Alexandre Proutière, James Roberts.

Too many interesting things. It provides a model for the delay, that we might implement to use it to compare it to ours. Additionally, they provide a second-order moment. Their worked is based on Bianchi's.

The second part deals with traffic differentiation and I want to highlight two conclusions. First, using CWmin we can protect VoIP without affecting TCP performance. Second, by means of AIFS, the voice can be protected to the point that TCP flows starve.

They also provide expressions to calculate TCP throughput. I should review the paper after I have included TCP traffic.

Integration of IEEE 802.11 WLANs with IEEE 802.16-Based Multihop Infrastructure Mesh/Relay Networks: A Game-Theoretic Approach to Radio Resource Mana

Dusit Niyato and Ekram Hossain

The authors present IEEE 802.16 as a solution to backhaul traffic from WLANs. They review the state of the art and present a theoretical bargain-game to optimize the transport over the IEEE 802.16 mesh network.

Effective Bandwidth Control Policies for QoS-enabled Wireless Networks

A. Floros

I read it because it was extremely dirty and I didn't want to see it anymore on my table. It does a good job in describing IEEE802.11e admission control. However, their proposal is naive; the end note explaining that the "algorithm" is under patent revision, funny.

A Survey of Web Services in Telecommunications

Donna Griffin and Dirk Pesch

The authors suggest the implantation of SOA in telecommunication networks to facilitate the development of new services and increase revenue. The concepts of WS, SOA and EDA are explained together with the standardization bodies and standards that support them.

Reconfigurable architecture and mobility management for next-generation wireless IP networks

Jyh-Cheng Chen Jui-Hung Yeh Shao-Hsiu Hung Fu-Cheng Chen Li-Wei Lin Yi-Wen Lan

4G involves the integration of different RAN. The authors of the article propose a unique core network to which the different RAN connect. There are different existing mobility management protocols. The authors differentiate between micro-mobility and macro-mobility, and propose RAMP, a protocol that allows the coexistence of the different mobility protocols.

Distributed Contention Window Control for Selfish Users in IEEE 802.11 Wireless LANs

Jin, Y. Kesidis, G.

The authors assume that the users are selfish and don't follow the IEEE802.11 protocol. The users modify the value they use to multiply the contention window after a collision to maximize a utility function. The authors propose a game and find the stability points.

The math is complex.

Capacity of an IEEE 802.11b Wireless LAN supporting VoIP

David P. Hole and Fouad A. Tobagi

The authors present a simple bound for the capacity, and then analyze the number of possible calls taking into account delay, packet loss and desired MOS.

Balancing Uplink and Downlink Delay of VoIP Traffic in WLANs using Adaptive Priority Control (APC)

Sangho Shin,Henning Schulzrinne

The authors propose to increas the txop of the downlink to balance uplink and downlink delays.

tallarins

tallarins
bolets petits
alls tendres
pernil/bacon

journals

Last week I published a list of conference. In this post I will include journals...


MC2R
The Mediterranean Journal of Computers and Networks
IEEE Communication Letters
IEEE Network
Elsevier Computer Networks
International Journal on Wireless Communications and Mobile Computing
International Journal of Communication Systems
Wireless Personal Communications
AEÜ - INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS --->>> They admit letters!!
European Transaction on Telecommunications --->>> They admit letters, up to six pages, 4 figs max.
SpringerLink Wireless Networks
IEEE Transactions on Parallel and Distributed Systems
Wireless Networks (WINET)
Mobile Networks and Applications (MONET)
International Journal of Wireless Information Networks (IJWIN)
Wireless Personal Communications: An International Journal (WPC)
IEICE Transactions on Communications
IEEE Journal on Selected Areas in Communications (JSAC)
IEEE Communications Letters
IEEE Transactions on Wireless Communications
IEEE Transactions on Communications


now, when I have something to submit, it will be easier to find the right place

mac parameter tuning for best effort traffic in 802.11e contention-based networks

It has two totally different parts. The first one addresses some differences between DCF and EDCA backoff and justify the selection of 3 as AIFS paramenter for BE traffic.

The second and more interesting one proposes a dynamic algorithm to adjust the cwmin of BE traffic. If takes into account the wasted time. If most of the time is wasted in collisions, increase CWmin. If most of the time is wasted in backoff, decrease CWmin. It works astonishing well. It maintains the maximum utilization of the network in any load conditions, and even in heterogeneous scenarios with prioritized traffic.

Investigation of Bandwidth Request Mechanisms under Point-to-Multipoint Mode of WiMAX Neworks

Qiang Ni, Alexey Vinel, Yang Xiao, Andrey Turlikov, Tao Jiang

More WiMax, after a brief explanation of the scheduling alternatives it presents an analytical model. I have not quite understood the model. Even though it is essentially different from what I am working on at the 802.11, it could give me some insights in delay analysis in general

A Secure and Service-Oriented Network Control Framework for WiMAX Networks

Kejie Lu and Yi Qian and Hsiao-Hwa Chent

Using a mesh 802.16 deployment requires additional guarantees for security, specially when intermediate nodes are actually end user equipment, not controlled by the network operator. What could actually be useful to me is the security overview, to improve the security section of my article.

Maybe I have not higlighted enough that, when sharing infrastructure, tunneling offers additional value.

TCP ACK Congestion Control and Filtering for Fairness Provision in hte Uplink of IEEE 802.11 Infrastructure Basic Service Set

Feyza Keceli, Inanc Inan, and Ender Ayanoglu

The authors separate the TCP downlink acks in a different queue. By wisely scheduling those acks, they obtain fairness among the uplink flows.

Saturation Throughput Analysis of the 802.11e Enhanced Distributed Channel Access Function

Inanc Inan, Feycza Keceli, and Ender Ayanoglu

Again, an extended Markov chain allows the inclusion of the AIFS and CWmin in the throughput calculation. It makes emphasis in that in the slots immediatly after a busy slot there are different collision probabilities, depending on the AIFS configurations of the stations

conferences for woman (wireless open metropolitan access networks)

LANMAN -over
WMASH -dead
WCNC - Las Vegas, submission due to September
MWCN - over
INFOCOM . deadline July 2, rejection november 12
ACCESSNETS - over
QoSIP 2008 - over
QSHINE Over
ISWCS Over
MOBIQUITOUS Over
WiNTECH Over
IEEE LCN

The list:
http://wireless.cs.tku.edu.tw/~seanwang/html/research.html

Linux for suits: Migrating a mentality

Doc Searls

The author defends that network should be treated as a facility, just as electricity, to support the rest of the economy.

open access networks

@article{edvardsen:oan,
title={{Open access networks}},
author={Edvardsen, E. and Eskedal, T.G. and Arnes, A.},
journal={Converged Networking}
}

A completely different deffinition of the OAN.

Towards an Economic Framework for Network Neutrality Regulation

Barbara van Schewick

A forty-page analysis of the network neutrality discussion. The network providers have incentives to discriminate, even in the case that they do not hold a monopoly position. This discrimination would have disastrous impact on the innovation in the application level and therefore network neutrality should be enforced by regulators.

100+ VoIP Calls on 802.11b: The Power of Combining Voice Frame Aggregation and Uplink-Downlink Bandwidth Control in Wireless LANs

Sangki Yun, Hyogon Kim, Heejo Lee, and Inhye Kang

Very interesting... so many things to summarize! Deals with uplink/downlink unfairness aspects, packet aggregation at the MAC level, E-model.

The key idea is that the channel access is the main overhead in VoIPoWLAN. Thus aggregating packets belonging to the same call at the mac level drastycally boosts the performance.

ensalada grega

Tomàtiga
Formatge Feta
Olives
Orenga
Oli

Performance Analysis of the WLAN-First Scheme in Cellular WLAN Interworking

Song, Jiang, Zhuang

I've been studying IMS-WLAN interworking and there is people in the group focusing on CAC, VoIP QoS in WLAN, and capacity studies in heterogeneous (voice/data) scenarios. Thus this paper promises to bridge this topics.

The different behaviour/capacity of cell and wlan, and the different behaviour of users in both environments (assumed outdoor and indoor) makes it difficult to decide how to assign user to one or the other technology. Since the performance of VoIP on wlan is poor, it seems natural to as many data sessions as possible to the wlan.

wlan sharing - alternatives

This are different alternatives to share wlan.

- Neutral Operator (kth, barcelona...)
- Tunneling (Urbino)
- IMS-like (involving tunnels)
- Radius relay (Eduroam, WISPr)
- Wilmagate (Like Radius relay, without radius)
- Multiple ssid, multiple wlan
- WLAN differentiation using capwap

Maybe it would be interesting to review all the existing alternatives and compare thems in terms of

- convenince
- security
- matureness
- scalability

3GPP TS 23.234

Wireless Local Area Network interworking system description

Describes how a WLAN can be used to access 3gpp ims ps domain. I am specially interested in policy/QoS aspects.

MAC Access Delay of IEEE 802.11 DCF

Taka Sakurai, Hai L. Vu

Even though 802.11 dcf has been extensively studied, it seem that there is still room for more research. In this case, building up previous work by Kwak Song and Miller, the access delay is calculated, obtaining more accurate results than other authors.

Fairness Provision in the IEEE 802.11e Infrastructure Basic Service Set

Inanc Inan, Feyza Keceli, and Ender Ayanoglu

Closely related to our current work, they actually stepped forward. However, it's reconforting to see that other people focus on the same research, it makes you think that it's not completely worthless.

The authors highlight the fact that the default values for the EDCA are suboptimum. Moreover, no fixed set of parameters can fight the uplink/downlink fairness. They provide an analytical model and an extensive set of simulated scenarios involving TCP and UDP traffic.

Implementing a Native IMS Location Service Enabler over a Prototypical IMS Core Network Testbed

Peter Reichl1, Sandford Bessler1, Joachim Fabini2, Rudolf Pailer3, Joachim Zeiss1

It proposes a location architecture that has nothing to do with TS 23.271. It is based on GPS-enabled terminals and integrates with presence information. They have actually implemented a testbed.

IMS Interoperability and Conformance Aspects

Mischa Schmidt, Andreas Wilde and Anett Schülke Henrique Costa

Describes the importance of the interoperability tests organized by various organizations.

Interworking of Wimax and 3GPP Networks based on IMS

Fangmin Xu, Luyong Zhang, and Zheng Zhou

The authors reproduce part of the work of 3GPP in WLAN- IMS internetworking, introduce the QoS capabilities of IMS, and finally describe QoS guarantees, AAA provision, and security. It seems to me that it is not a closed and clear solution, but at least is some talk about our topic of interest.

Location-based services -- an overview of the standards

P M Adams, G W B Ashwell and R Baxter

This documents describe the trajectory and organization of different standard bodies that influence in the location services. Quite useful.

3GPP TS 23.207 V6.6.0 (2005-09)

3rd Generation Partnership Project;
Technical Specification Group Services and System Aspects;
End-to-end Quality of Service (QoS) concept and architecture
(Release 6)

This time we are talking about GPRS and end-to-end. Much more complete than the previous. I clarifies that the AF can be the CSCF. The Gq and Go Interface are also described. It also esplains that both DS (differentiated services) and RSVP can be used to guarantee QoS in the IP core network and remote link. It assumes that since GPRS is used in the local link, the PDP flow already has QoS guarantees.

The diffserv is already supported in WMM, so it seems the more straight-forward approach.

3GPP TS 29.208 V6.6.1 2006-03

3rd Generation Partnership Project,
Technical Specification Group Core Network and Terminals;
End-to-end Quality of Service (QoS) signalling flows (release 6)

This document describes QoS reservation in local IP-CAN for the case of cellular networks. It should not be difficult to adapt it to the WLAN case... the AF and PDF should stay the same... then the SGSN and GGSN should be substited... but for what?

An appendix describes the mapping from SDP parameters to Maximum Authorized parameters

Policy-Based QoS Management Architecture in an Integrated UMTS and WLAN Environment

Wei Zhuang, Yung-Sze Gan,Kok-Jen, and Kee-Chaing Chua

I read it a long time ago, and have re-read it a couple of times since them. It describes some policy-related entities and interactions for wlan-umts internetworking. It can be used as a base, but definetly not as a closed solution. I plan to write a technical report next month. Then it might be converted to an article o can be the basis of my thesis...

ETSI TR 122 934 v6.2.0(2003-09)

Universal Mobile Telecommunications System (UMTS) Feasibility study on 3GPP system to Wireless Local Area Network (WLAN) interworking

It describes differetn scenearios for internetworking, places some requirements, but no technical solutions at all.

Bringing Location Based Services to IP Multimedia Subsystem

Miran Mosmondor, Lea Skorin-Kapov Marko Kovacic

I'm interested in finding out which is the state-of-the-art of collecting, managing and distributing location information in the IMS. This paper presents an architecture that uses SIP mechanisms and the aplication server concept. The application servers ask using a SIP protocol to a centralized entity. This entity interacts with the server that actually contains the location information using MLP.

IMHO, these should not be the way of handling the location information since it should be closely tight to the presence information.

Towards an Innovation Oriented IP Multimedia Subsystem

Gonzalo Camarillo, Tero Kauppinen, Marti Kuparinen, Ignacio Más Ivars

This article proposes a new policy-enforcement mechanism for IMS based on the notify/subscribe methods. This can be very useful to Anna to notify nodes that they must change their codecs.

Experiencing with Blending HTTP, RTSP, and IMS

Sohel Q.Khan, Robert Gaglianello, Michael Luna

SIP, RTSP and HTTP use different networks (I gess this refers to the application level).The author proposes to unify this networks to reduce overall complexity and mainteinance costs.

The 3G IP Multimedia Subsystem (IMS): Merging the Internet and the Cellular Worlds

G Camarillo, MA García-Martín

All ablut SIP, compared to the conventional Internet. Specially intereting was finding that the cell information is actually conveyed in SIP messages. It is also explained how policies are enforced. However, a new policy enforcement technique is detailed in a later article.

Service Delivery Platforms in Practice

Christofer J. Pavlovski

I didn't understand what was the article about. However, I realized an evil use of initialism in which SDP stands for Service Delivery Platform -not session description protocol- and OSS is Operational Support Systems -not open source software.

But there is something useful in the article, the fact that gaming, music and gaming are the most cost-effective services for deployment, so I will probably cite it when I write my journal about location.

TCP Fairness in 802.11e WLANs

D. J. Leith, P. Clifford, D. Malone, and A. Ng

In this article the authors present to unfairness issues in 802.11. First, unfairness between uplink flows due to the irregular delivery of ack packets. And then, the unfairness between uplink and downlink flows because all the downlink flows have to be submitted from de same node (the AP). They already suggest using TXOP to fight this last problem. Concerning the former problem, they propose a separate queue for ACK packets.

Our contribution will be quantify the unfairness by means of simulation, propose TXOP values, and show that the separate queue is unnecessary, since the txop alone is enough to solve the problem.

A MAC parameter optimization scheme for IEEE 802.11e-based multimedia home networks

Minyoung Sung; Namhyun Yun

They calculated some delay(rigid) vs throughput(elastic) curves by means of simulation. Then they propose that the AP, depending on the accepted rigid flows and the required delay, decides the most appropriate parameter set.

It did not give me a very good impresion. It reduces the number of possible flows/bitrates. Gives examples that are surprising (required delay 1ms); It obviates the jitter... however it is very similar to the thing we want to do...

A CAPWAP Architecture for Dynamic Configuration of QoS MAC Parameters

A. Banchs∗ , G. Iannello† , P. Serrano∗ and L. Vollero

Our focus has been until now on a single-cell scenario. However, as explained in this article, the aparition of the CAPWAP standard will allow the centralized management of a number of STAs. The QoS management could then also be centralized, providing a better scenario for handling handovers. In the last part of the article, the authors propose a number of rules to determine EDCA parameters. However, it is not clear to me how the first and the second parts are linked.

Experimental Evaluation of TCP Performance and Fairness in an 802.11e Test-bed

Anthony C.H. Ng, David Malone, Douglas J. Leith

The authors build a testbed and compare the results with the ones obtained from analytical models. Additionally they present the uplink/downlink impairment performance (without any citation) and implement and validate a solution presented in other paper (this time there is a citation).

Understanding TCP fairness over Wireless LAN

Saar Pilosof, Ramachandran Ramjee, Danny Raz, Yuval Shavitt and Prasun Sinha

Yet another performance imparement due to the .11/TCP combination. In this case, the culprit is the AP buffer limited size. Discarding a downstream data packet has a greater impact than discarding a (down-going) ACK of an upstream flow.

The anomaly is observed, analyzed and simulated. A solution is also suggested, involving the manipulation of the TCP packets.

The 3G IMS

I got a few ideas from that book. Concerning QoS, I discovered that there are headers that explicitely detail the required bandwidth for the requested flows. I understood when the resource reservation is performed and how a S-CSCF can apply a policy to an INVITE and reject such invite according to the requested codecs.

Concerning the location/position information, I discovered that IMS messages convey the cell information. However, these headers are removed as soon as the messages are forwarded to foreign networks.

is the uplink control enough to guarantee downlink control

Imagine a scenario in which STAs from different providers contend for the bandwith of a single AP. Our reasoning is that the BE downlink traffic will dominate, since P2P and other symmetrical BE applications are not so popular as web browsing or media downloading in wifi scenarions.

802.11e provides us with the tools to control the uplink traffic, by assigning different EDCA parameters to each contending STA. And the one-million-dollar-question is... "Is this uplink control enough to control downlink flows as well".

TCP might help us in that direction, but we will need to simulate to find out... Teach me NS2!

Using the 802.11e EDCF to Achieve TCP Upload Fairness over WLAN Links

D.J. Leith, P.Clifford

It studies the combined contention effects of TCP and DCF on uploading stations. NS2 simulations show a lockout problem that can be solved by giving preference to ack packets.

The authors also explain that in occasions in which the wireless hop is the bottleneck, the TCP dynamics are different from the traditional wired case.

Online Association Policies in IEEE 802.11 WLANs

Gaurav S. Kasbekar, Joy Kuri and Pavan Nuggehalli
Oops I did it again, I read a paper that i cannot understand because I lack the mathematical background. It finds the optimal heuristic for a AP to chose to which AP to attach, and proves that its better that other policies.

There is a reference I want to read:
[6] A. Kumar, E. Altman, D. Miorandi, and M. Goyal, “New insights from a
fixed point analysis of single cell IEEE 802.11 WLANs,” in Proceedings
of the IEEE Infocom, 2005.

joining forces

After reading the last paper it appears clear to me that it is extremely difficult to write a good paper alone. The bibliography is so extense and the concepts so many, that team work is necessary to obtain medium or good results.

A Cross-Layer Approach for WLAN Voice Capacity Planning

Yu Cheng,Xinhua Ling,Wei Song, Lin X. Cai, Weihua Zhuang, Xuemin Shen

Interesting ingredients. A DCF-EDCA model with some similitudes with Boris', the idea of multiplexing downlink flows at the AP, my idea of dropping packets instead of retransmitting. Worth a second read...

Hotspot Traffic Statistics and Throughput Models for Several Applications

Chen Na, Jeremy K. Chen, and Theodore S. Rappaport

Traffic analysis, inbound/outbound, throughput/SNR, blah blah... I'm more interested in a multiple user scenario, and this paper offers a reference...
[13] "Throughput measurements and models of Public IEEE 802.11b Wireless Local Area Networks". However, being the paper from the same authors, I don't fell like reading it. Not now.

Characterizing the IEEE 802.11 Traffic: The Wireless Side

Jihwang Yeo, Moustafa Youssef, Ashok Agrawala

First I have to say that I have not read the complete article. The appendices are so long that maybe it contains 30 pages alltogether. It performs a study listening the wireless medium and the conclusion is that less-than-optimal performance comes from less-than-optimal implementation of the protocol. Control frames are unnecessarily retransmitted and the selection of the bitrate is not in accordance of the actual SNR conditions. It is good to know but, from my point of view, in does not affect our research directly.

On the Performance Characteristics of WLANS:Revisited

Anand Balachadran, Geoffrey M. Voelker, Paramvir Bahl, P. Venkal Rangan

I love this paper.It basically takes all the findings that simulation-guys have been writing tons of papers about and says: this is bullshit, it has nothing to do with real world.

Now, what are the most interesting contributions... first it says that TCP and DCF make good friends, specially when the wireless terminals are clients downloading from the net. In this situation, the download throughput remains constant, no matter how many STAs enter into the network (up to 100).

HOWEVER, when the wlan reaches the saturation point, jitter and delays rise suddenly. This is not good for MM :-)

And this is funny: the automatic rate-adaption in 802.11 actually worsens the performance of .11 . It goes like this: when congestion occurs and a STA loses two consecutive packets due to collisions, the station changes to a lower rate effectively increasing the congestion.

And my conclusions: The DCF-TCP is the perfect team for web browsing, and file downloading from the net. However, as soon as new applications appear such as MM streaming, VoIP, P2P,... dcf can be a disaster. Would .11e be powerful enough to alleviate this situation?

UniWireless: a Distributed Open Access Network

Danilo Severina, Mauro Brunato, Alessandro Ordine, Luca Veltri

Why is this paper important? First because they work on the OAN concept ant present a paper in WMASH every year. Second, because they ignored our contributions and failed to reference us year after year.

Third, and least important, because they introduce SIP register as a new authentication mechanism. The idea is brilliant, and actually is a topic of my interest, but imho the execution is poor. They include new SIP headers and mechanism to solve pass authentication information from proxy to proxy. And my question is ... Why making it so complicate instead of using IMS' well-known and extensevely tested procedures?

Secure Access to IP Multimedia Services Using Generic Bootstrapping Architecture (GBA) for 3G & Beyond Mobile Networks

Muhammad Sher Thomas Magedanz

What I want to know is how a UE accesses the Internet (for example, for web browsing) in a IMS environment. In this paper the bootstrap procedure that allows a ue to access a IMS services from a generic network. It is somehow related to what I wanted, but not what I wanted...

For me it is more or less clear how the ue accesses sip-based applications through the IMS proxies, but not how non-sip based Internet applications are used...

Comprehensive Analysis of the IEEE 802.11

PETER P. PHAM

It seems that I finally found what I was looking for. This articles might contain the formulas that I can use for my ideas.

Resource Control for the EDCA Mechanism in Multi-Rate IEEE 802.11e Networks

Vasilios A. Siris Costas Courcoubetis

The article uses pricing to obtain best utilization of the wireless channel using EDCA. I had already read some papers about using pricing in response to congestion.

However, I'm more interested in some of the references which can provide me with the formulas/approximations required for my next article.

Performance Analysis and Enhancements for IEEE 802.11e Wireless Networks

Qiang Ni, National University of Ireland

This paper is a *MUST*. The one you should begin with. Well-written, comprehensive,... all you need to know about .11e... specially if you expect to understand any of the others papers.

idea: multi-tiered CAC

It might seem trivial to you, dear reader, but it took me three weeks to realize what's my next pape r about.

This is my conclusion:
Step 1: Take any CAC
Step 2: Say that in addition to differentiate between VO and BE, we want to offer different QoS to paying and non-paying users.

Time to write?

idea: Using neighbour cells population together with to compute roaming probability

The probability that a call roams into our cell highly depends on the number of ongoing calls in the neighbouring cells. This information could be used to compute guard channels etc.

Extending End-to-End QoS to WiFi based WLAN

http://www.cswl.com/whitepapers/qos-wireless-lan.html

Plain and clear. QoS in WLAN and interaction with SIP. It does not specify the details. Which could be our contribution? A problem to be solved (inmho) is the mapping from a codec specified in SDP to a TSPEC, and then (taking into account current traffic conditions) the conversion to EDCA parameters.

WLAN Manager (WM): a Device for Performance Management of a WLAN

Malati Hegde† , S.V.R Anand† , Anurag Kumar† , and Joy Kuri‡

The most useful idea that we can obtain from this article is that the access point controller defined by CAPWAP can be the actual policy enforcement point.

The details about how to obtain "fairnes" understood as giving more throughput to the users with higher rates by recdistributing the packets in the queues and pinging the STA to find out their rates seemed to me a bad idea. Additionally, there are typos. So I decided to read only journal papers from now on. I was surprised when I realized that this was a journal paper :-(

Localizing the Internet, Five Ways Public Ownership Solves the U.S. Broadband Problem

Becca Vargo Dagget

An extensive study of the last mile bottleneck in the U.S. The author defents municipality owned access network to foster competence, assure network neutrality, universal service, higher incomes for the municipality and lower prices for the users.

It contains case studies and success stories.

LocustWorld Mesh explained

Jon@LocustWorld.com

Similary to linux live CDs, LocustWorld provides a boot CD that converts the PC in the node of a mesh network. We sould try it and think how it could be useful to us.

idea- dropping delayed voice packets at the MAC layer

It seems to me that the use of Access Categories in EDCA is unfair by definition. A user might decide to place all its traffic (even if is P2P file sharing ) in a high priority queue. That user will obtain higher bitrates and lower latency at the expense of the users that place each kind of traffic to the appropriate queue.

Additionally, delayed voice packet might be useless at the receptor. If a packet voice is delayed due to retransmission attempts, it will provoke the delay of the rest of the packets in the queue and could happen that all of them had to be dropped because the delay budget has been exceeded.

My proposal is that if a voice packet suffers a collision, it should be dropped and the contention window for the following packet should be doubled. With my proposal, the high priority queues will obtain higher bit rates and lower delays (thanks to shorter AIFS and smaller contention windows). On the other hand, lower priority queues will obtain higher reliability thanks to the retransmission mechanism.

A performance study on the service integration in IEEE 802.11e wireless LAN

Frank Roijers, Hans van den Berg, Xiang Fan, Maria Fleuren

The goal of the article is to compare the influence of different EDCA parameters in the performance metrics of different fluxes by means of simulation.

There is a mistake in fig 3. According to this plot (Fig. 3, right), stations with a lower CWmin (7) obtain a lower throuhput than those with a higher CWmin (31).

The article offer a visual explanation of the effect of tuning the different EDCA parameters.

An Admission Control Heuristic for IEEE 802.11e Wireless LANs

Bechir Hamdaoui, Moncef Elaoud, Parameswaran Ramanathan

It proposes a CAC mechanism similar to the one that Cristina presented in one of the NeTS seminars. The different lays in the model that is used to calculate the delays suffered by the multimedia packets. It seems that the model together with the CAC mechanism successfully predicts the number of VoIP calls that an AP can support, compared to simultion.

It does not contemplate channel errors nor rate adaption.

I lack the mathematical knowledge to fully understand the model and therefore I should re-read the paper and check the different steps one-by-one.

idea

It seems that most of the aspects of 11e and 11r have been studied. So let's focus on the multi-operator environment. Let's assume that two different operators share an access point broadcasting two different ssids. What's the impact of the traffic of one operator on the QoS of the other operator?

Performance Study of Fast BSS Transition using IEEE 802.11r

Sangeetha Bangolae Carol Bell Emily Qi
Her lays the answer to the previous post. The negotiation can be done prior to roaming. Additionally the STA can, can request roaming to different APs, and then choose one to roam.

idea

What happens with QoS negotiation in 802.11r? Should it be negotiated *before* handover? What can we propose?

Integrating SIP and IEEE 802.11e to Support Handoff and Multi-grade QoS for VoIP Applications

Jen-Jee Chen Ling Lee Yu-Chee Tseng
Very complete! It addresses...
(1) Handoff
(2) Multigrade QoS
(3) Multirate
(4) Multiple codecs
(5) A bit of SIP
(6) Call Admission Control
(7) Resource re-Adjustment
What else can we add...
(1) Including location information to estimate the handoff probability (Ph).
(2) Using Boris-Model (Bandwidth-Orinented Resource Inferring System) to calculate the resource utilization of a new flux.

Design of QoS and Admission Control for VoIP Services over IEEE 802.11e WLANs

Pei-Yeh Wu1 , Yu-Chee Tseng1 , and Hewitt Lee2

Very complete and extense (25 pags). A good place to begin with. Explains all the basic concepts. Introduction of tutorial nature. It makes a shy attempt to link SIP and EDCA. It addresses codec selection and Packitization Intervals.

New QoS Control Mechanism Based on Extensions to SIP for Access to UMTS Core Network via Different Kinds of Access Networks

Mehdi Mani, Student Member, IEEE ,Noël Crespi

Very interesting. Bad English. It addresses architectural issues, SIP integration, IMS... . It includes a testbed using WLAN. It lacks the use of EDCA as QoS mechanism. That could be our contribution.

Wireless LAN Resource Management Mechanism Guaranteeing Minimum Available Bandwidth for Real-time Communication

Toshihiko Tamura and Tadashi Ito

Well written paper. It addresses the codec adaptation in combination with SIP and 802.1X. It introduces AP-RMS (AP-Resource Management Service). However, it leaves as future work the task of considering rate adaptation, or EDCA parameter tuning. IMHO, their work can be very well complemented by Boris and Anna's solutions.

A Priority Control Method for High quality VoIP Systems over Wireless LAN

R. Matsukura, H. Ymauchi, S. Okuyama, M. Matsuda, M. Sumioka

Badly written, hard to read. The contributions are not clear. It might be of interest because addresses a topic related to our work.

A Dynamic Load Balancing Scheme for VoIP over WLANs

Chih-Chien Hsu and Shiao-Li Tsao

It proposes re-allocating calls from one ap to another to be able to admit more calls. The most interesting is representing the reallocation problem as a graph. It might be extended to mesh networks.

Low-Resource Routing Attacks Against Anonymous Systems

Kevin Bauer, Damon McCoy, Dirk Grunwald, Tadayoshi Kohno, Douglas Sicker
Interesting description of the Tor anonymazer system and a possible attack against it.

A Novel AP for Improving the Performance of Wireless LAN Supporting VoIP

Thavisak Manodham, Tetsuya Miki

An interesting description of the 802.11 handoff procedure