21 research outputs found
Analysis and evaluation of decentralized multiaccess Mac for ad-hoc networks
In mobile ad-hoc radio networks, terminals are mobile and
heterogeneous, the architecture of the network is continuously
changing, communication links are packet oriented and radio
resources are scarce. Therefore, mechanisms on how to access
the radio channel are extremely important in order to improve
network efficiency and, when needed, to guarantee QoS.
However, due to these network harsh conditions, decentralized
Medium Access Control (MAC) protocols designed
specifically for ad hoc networks are scarce. In this paper we
present a novel decentralized multiaccess MAC protocol for
Ad Hoc networks. This MAC protocol is an hybrid CDMATDMA
in which a cross layer approach has been followed in
order to maximize network throughput. A theoretical analysis
of the system is presented ending up with closed expressions
for the throughput and delay of the network and some
simulations are presented to evaluate the performance of the
system.Postprint (published version
PHY-MAC dialogue with multi-packet reception
Cross-layer design has been considered
recently as a new approach when designing MAC
protocols in systems with diversity such as CDMA.
This paper goes one step further in the cross layer
design by proposing a PHY-MAC dialogue involving
the exchange of parameters such as BER and active
users. By means of this PHY-MAC dialogue, system
performance can be improved. A two-stage receiver is
used at PHY level. The first stage tracks active users
while the second stage is a data demodulator. The
Modified Dynamic Queue Protocol (MDQP) is
proposed as the MAC protocol of our system. When
the knowledge of active users is possible, it is
demonstrated by simulations that MDQP outperforms
DQP.Postprint (published version
Decentralised multi-access MAC protocol for ad-hoc networks
In ad-hoc radio networks, mechanisms on how to access the radio channel are extremely important in order to improve network efficiency and, when needed, to guarantee QoS.
Traditionally, Medium Access Control (MAC) protocols in ad hoc networks have been designed to face off the well known
collision resolution problem. However, when using advanced signal processing techniques, general assumptions on collisions and
packet loss are no longer valid. Besides, little has been reported about MAC algorithms dealing with multiaccess channels in ad hoc networks. In this paper, we present a novel decentralized multiaccess MAC protocol for Ad Hoc networks. This MAC
protocol is an hybrid CDMA-TDMA in which a cross layer approach has been followed to dinamically adapt to the traffic load. Closed expressions for the throughput and delay of the network are presented as a function of the multipacket reception
capability of the receiver, the number of codes and the packet retransmission probability.Postprint (published version
Informe de qualitat de l'aire de Barcelona
Salut ambienta
LAMAN: Load Adaptable MAC for Ad Hoc Networks
<p/> <p>In mobile ad hoc radio networks, mechanisms on how to access the radio channel are extremely important in order to improve network efficiency. In this paper, the load adaptable medium access control for ad hoc networks (LAMAN) protocol is described. LAMAN is a novel decentralized multipacket MAC protocol designed following a cross-layer approach. Basically, this protocol is a hybrid CDMA-TDMA-based protocol that aims at throughput maximization in multipacket communication environments by efficiently combining contention and conflict-free protocol components. Such combination of components is used to adapt the nodes' access priority to changes on the traffic load while, at the same time, accounting for the multipacket reception (MPR) capability of the receivers. A theoretical analysis of the system is developed presenting closed expressions of network throughput and packet delay. By simulations the validity of our analysis is shown and the performances of a LAMAN-based system and an Aloha-CDMA-based one are compared.</p
La configuració de les autoritats de competència. Un model per a la regulació d’organismes independents i per a la reforma de l’administració pública
La política de competència contribueix decisivament a un funcionament eficient i equitatiu de l'economia. I és que, només en un marc de competència es pot garantir la millor assignació possible de recursos que maximitzi la generació de béns i serveis. A més, la política de competència té també un interessant component equitatiu en la mesura que actua com a mecanisme que vetlla per l'absència de barreres injustificades a l'entrada al mercat - facilitant doncs un marc igualitari en termes d'oportunitats - i pel fet que contribueix a garantir que els grans operadors competeixin entre sí de tal manera que se'n vegin beneficiats els consumidors i usuaris (en preus, qualitat i innovació).
Els mecanismes a disposició de les autoritats de competència són rellevants. En relació a les administracions públiques les poden sancionar quan actuen com operadors, criticar la regulació que emeten i fins i tot impugnar-la davant dels tribunals. Les temptacions per tal que una autoritat de competència no sigui veritablement independent són significatives.
Davant d’aquest risc, el document se centrarà en desenvolupar un condicionant necessari per tal que el seu funcionament sigui òptim: la seva independència.
S'exposarà com es pot assegurar que les autoritats de competència gaudeixin de la independència que la seva actuació exigeix a través de l'anàlisi d'elements com: la forma jurídica que adopta la institució, la gestió del seu propi personal i garanties d'estabilitat del mateix, la gestió econòmica del pressupost que se li assigna i com determinar-lo, el nomenament i les causes de remoció dels seus alts càrrecs així com la rendició de comptes de la institució.
L'interès del document va més enllà de les autoritats de competència. Les seves conclusions poden ser extrapolables a organismes reguladors i, tot plegat, pot constituir la llavor d'una nova manera de funcionar de les administracions públiques
PHY-MAC dialogue with multi-packet reception
Cross-layer design has been considered
recently as a new approach when designing MAC
protocols in systems with diversity such as CDMA.
This paper goes one step further in the cross layer
design by proposing a PHY-MAC dialogue involving
the exchange of parameters such as BER and active
users. By means of this PHY-MAC dialogue, system
performance can be improved. A two-stage receiver is
used at PHY level. The first stage tracks active users
while the second stage is a data demodulator. The
Modified Dynamic Queue Protocol (MDQP) is
proposed as the MAC protocol of our system. When
the knowledge of active users is possible, it is
demonstrated by simulations that MDQP outperforms
DQP
Analysis and evaluation of decentralized multiaccess Mac for ad-hoc networks
In mobile ad-hoc radio networks, terminals are mobile and
heterogeneous, the architecture of the network is continuously
changing, communication links are packet oriented and radio
resources are scarce. Therefore, mechanisms on how to access
the radio channel are extremely important in order to improve
network efficiency and, when needed, to guarantee QoS.
However, due to these network harsh conditions, decentralized
Medium Access Control (MAC) protocols designed
specifically for ad hoc networks are scarce. In this paper we
present a novel decentralized multiaccess MAC protocol for
Ad Hoc networks. This MAC protocol is an hybrid CDMATDMA
in which a cross layer approach has been followed in
order to maximize network throughput. A theoretical analysis
of the system is presented ending up with closed expressions
for the throughput and delay of the network and some
simulations are presented to evaluate the performance of the
system
Decentralised multi-access MAC protocol for ad-hoc networks
In ad-hoc radio networks, mechanisms on how to access the radio channel are extremely important in order to improve network efficiency and, when needed, to guarantee QoS.
Traditionally, Medium Access Control (MAC) protocols in ad hoc networks have been designed to face off the well known
collision resolution problem. However, when using advanced signal processing techniques, general assumptions on collisions and
packet loss are no longer valid. Besides, little has been reported about MAC algorithms dealing with multiaccess channels in ad hoc networks. In this paper, we present a novel decentralized multiaccess MAC protocol for Ad Hoc networks. This MAC
protocol is an hybrid CDMA-TDMA in which a cross layer approach has been followed to dinamically adapt to the traffic load. Closed expressions for the throughput and delay of the network are presented as a function of the multipacket reception
capability of the receiver, the number of codes and the packet retransmission probability