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--- etc:drafts:epmnets_review [2009/12/01 22:32] – udv
+++ etc:drafts:epmnets_review [2009/12/01 22:54] (current) – udv
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 ==== EPM in WLAN paper analysis ====
-====== article 1. Investigating Depth-Fanout Trade-Off in WiMAX Mesh Networks ======
+====== Article 1. Investigating Depth-Fanout Trade-Off in WiMAX Mesh Networks ======
 In a more recent release WiMAX (IEEE 802.16d),the standard has been extended, introducing the mesh mode to let Subscriber Stations (SSs) communicate through multi-hop transmissions. In its basic version, the mesh mode relies on a centralized approach that organizes all the nodes of a WiMAX network in a tree structure rooted at a particular node, namely the Base Station (BS).
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 The overall bitrate on some long links would be better if they are split, in other words, if the communications between sources and destinations on these links utilize intermediate SSs to rely their data.
-===== article 2. Hybrid WiFi-WiMAX Network Routing Protocol =====
+===== Article 2. Hybrid WiFi-WiMAX Network Routing Protocol =====
 Comparsion of WiFi and WiMAX
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   * its mobility without network connectionbreaks.
+WiFi’s disadvantages include:
+  * its use of the 2.4GHz spectrum, which is susceptible to interference.
+  * Its higher energy consumption when compared to other standards.
+**WiMAX**
+Some important characteristics of WiMAX include:
+  * its use of the microwave frequency band for wireless data transmission
+  * its high transmission speed over long distances.
+  * its use of OFDM (Orthogonal Frequency Division Multiplexing) to enable non-line-of-sight communication.
+  * its multi-channel support for TDD (Time Division Duplex) and FDD (Frequency Division Duplex)
+  * its flexible handling of channels in the 3.5MHz, 5MHz and 10MHz frequencies.
+Some challenges for WiMAX include:
+  * reaching a coverage area of up to 10 miles.
+  * providing wireless broadband and dedicated links.
+  * making the technology more affordable.
+  * allowing access from more remote areas.
+Some of the challenges facing WiMAX include:
+  * Элемент ненумерованного списка improving the signal propagation mechanism because using the atmosphere as the transmission medium has several problems.
+  * increasing the range of band frequencies to provide service to a larger number of users.
+  * providing adequate quality of service for a greater variety of applications.
+  * allowing for increased mobility either through roaming or handoff.
+  * meeting the demand for greater portability by lowering power consumption or increasing battery efficiency.
+  * offering improved security for devices that use different services.
+**Integration**
+Ali-Yahiya et al. propose an architecture where the WiFi and WiMAX networks and their traffic routes are separated by dedicated gateways to provide interconnectivity [6]. The main characteristic of this architecture is that it employs an overlapping area
+between a WLAN and a WMAN hotspot, where they interconnect at a BS and an AP. The WMAN coverage area expands using the WLAN hotspots. More than one
+AP can be located near the limit of the WMAN’s coverage area. The authors assume that WiFi network APs are connected to the WiMAX network by means of a gateway that permits bidirectional interconnectivity. [6].
+To better integrate WiFi and WiMAX technologies, it is important to identify the differences between them, including:
+  * Элемент ненумерованного списка WiFi channels use a specific band frequency while WiMAX permits users to select the channel requirements.
+  * WiMAX uses licensed frequencies while WiFi employs unlicensed ISM frequency bands.
+  * WiFi has a range of approximately 10m while WiMAX can cover several kilometers.
+  * WiMAX is a MAN protocol that provides an alternative to DSL and cable modem technologies, providing broadband access for the last mile as it acts as a backbone for WiFi hotspots.
+The goal of our algorithm is to afford users of ad hoc network broadband service using devices that can select the best route in terms of bandwidth, battery residual energy and distance. Figure 2 shows how a WiFi node accesses a WiMAX network.
+The proposed protocol can carry out the necessary hops to send and receive data within a WiMAX network. If, a connection is broken, the algorithm is designed to automatically reconnect. Figure 3 provides an example of a service connection from a WiFi node physically located inside a MANET network that requests broadband services from the WiMAX network.
+The algorithm is based on the Ad-hoc On Demand Distance Vector (AODV) protocol modeled in OPNET. The following scenario presents a node that functions as a BS/AP gateway.
+===== Article 3. Energy-aware WLAN scanning inintegrated IEEE 802.16e/802.11networks =====
+Vertical handoff (VHO), i.e., handoff across heterogeneous access
+networks, is considered a key feature to bring the next-generation wireless
+communication era. Especially, along with the introduction of the 802.16e
+service,1 the interworking with WLANs, of which a commercial service has
+been operational for years, also attracts great interests.
+Many of challenging issues are involved in VHO: target network discovery;
+VHO decision criteria; efficient IP-layer protocols for mobility management,
+and so on [7]. We in this paper focus on finding target networks. Espe-
+cially, assuming that the 802.16e network is always reachable anytime and
+anywhere,2 we just pay attention to the way how to find WLAN APs.
+  -  ...mobile station (MSTA) always monitors the availability of nearby WLAN APs by attempting to detect the WLAN signal.
+  - ...an MSTA moves only within a specific region, where at least one of WLAN APs is reachable
+...keeping the scan operation of WLAN without any guideline can be practically
+a bad idea in that MSTA is usually battery-powered. Since WLANs are of-
+ten deployed for hotspot services with spotty service coverages, keeping the
+WLAN interface turned on could often mean an inefficient use of energy [8].
+A straightforward approach to resolving this issue is to make the MSTA
+informed of the existence of WLAN APs directly by the network side instead
+of relying solely on the individual scan operation of MSTA.
+We propose a WLAN scanning algorithm, which uses the
+baseline scanning protocol specified by IEEE 802.11 standard [11] without
+an additional terminal module like GPS and enables the MSTA to manage
+the WLAN interface without human intervention. Especially, the proposed
+algorithm can statistically guarantee the scanning time needed until at least a WLAN AP is found.