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problem is significantly mitigated. In effect, if a mobile device detects a Bluetooth beaconthen it is very likely that the beacon is only a few meters away. In contrast, an 802.11beacon may be detected even if it is two buildings away. So, we could take advantage ofthis feature to yield an indoor localization scheme that is inexpensive and easy to deploy.Another benefit of Bluetooth is that the transceivers are extremely inexpensive, costingless than 3 USD in bulk. In addition, Bluetooth transceivers are designed for low powerconsumption.The following table summarizes the advantages and disadvantages of Bluetoothtechnology with respect to indoor localization:AdvantagesDisadvantages• Most modern mobile phones areBT enabled• Inexpensive (cheaper than wirelessLAN components and adapters)• Short range, higher accuracy• Low power consumption• Short range, need for more accesspoints to cover the same area• Low data rate, slower update ofposition• RF Band is shared, possibleinterferencesTable 1: Advantages and disadvantages of Bluetooth technology4.1.2 Indoor localization using Wi-FiThe IEEE 802.11 wireless Ethernet standard is becoming increasingly popular and hasbeen deployed in many indoor environments. With the prevalence of wireless LANinfrastructure as well as the ever decreasing cost of wireless access points, the use ofwireless access points as a basis for location determination becomes an attractive option.Wi-Fi location determination systems use the popular 802.11 network infrastructure todetermine the user location without using any extra hardware [33] [40] [42] [43] [44] [45] .The only additional hardware requirement for such a system is a Wi-Fi card (thereceptor), if it is not present, although many modern mobile phones are Wi-Fi enabled.Most indoor localization systems are based on the fingerprinting technique as cell-basedmethods rely in more short ranged technologies, such as Bluetooth. However, a simplediscovery system using Wi-Fi could be developed, by reducing the transmission power.21
In order to estimate the user location, wireless Ethernet devices measure signal strengthof received packets. This signal strength is a function of the distance and obstaclesbetween access points and the receptor. The system might need one or more referencepoints (access points) to measure the distance from. Triangulation on signal strengthfrom multiple access points could be the most natural technique to be applied butunfortunately, in indoor environments, the wireless channel is very noisy and the radiofrequency (RF) signal can suffer from reflection, diffraction and multipath effect, whichmakes the signal strength a complex function of distance. To overcome this problem,Wi-Fi location determination systems uses a priori radio map (wireless-map), whichcaptures the signature of each access point at certain points in the area of interest.Systems that make use of a wireless-map work in two phases: training phase andestimation phase. During the training phase, the system constructs the wireless-map. Inthe estimation phase, the vector of samples received from each access point is comparedto the wireless-map and the “nearest” match is returned as the estimated user location.However, the accuracy of this method usually depends on a meticulous calibrationprocedure that consists of physically moving a wireless client to many different knownlocalizations, and sometimes orientations, inside a building.The following table summarizes the advantages and disadvantages of Wi-Fi technologywith respect to indoor localization:AdvantagesDisadvantages• Higher data rates (11Mbps), fasterupdate of position• Longer range (approx. 100 meters),need for less access points to coverthe same area• Relatively inexpensive hardware(though more expensive comparedto BT)• Use of the existing wireless LANinfrastructure, no additionalequipment (except Wi-Fi adapterfor user’s terminal, if needed)• RF Band is shared, possibleinterferences• Not all modern mobile phones areWi-Fi enabled (fewer than BT)Table 2: Advantages and disadvantages of Wi-Fi technology22
Page 1: ATHENS UNIVERSITY OF ECONOMICS AND
Page 5 and 6: AbstractMobile phones or Personal D
Page 7 and 8: Chapter 7: Implementation of an app
Page 9 and 10: List of TablesTable 1: Advantages a
Page 11 and 12: suffering from memory and orientati
Page 13 and 14: Chapter 2Smart Homes2.1 Smart Homes
Page 15 and 16: • Automate specific tasks that a
Page 17 and 18: Fig. 1: A smart home solution 1It i
Page 19 and 20: lighting strips and passive infra-r
Page 21 and 22: The Amigo project [10] is a joint e
Page 23 and 24: However, inside a building, that un
Page 25 and 26: with co-ordinates in the form of la
Page 27 and 28: At last, the utilized technology mu
Page 29: In this work we concentrate on achi
Page 33 and 34: 4.2.1 Cell-based methodsCell-based
Page 35 and 36: correlation between distance and si
Page 37 and 38: thus increasing the storage and mem
Page 39 and 40: egions. Examining images based on t
Page 41 and 42: Chapter 6Implementation of an indoo
Page 43 and 44: 6.3 Experimental environment, hardw
Page 45 and 46: Fig. 10: The database table that st
Page 47 and 48: Fig.12: The matching stageThe query
Page 49 and 50: 6.6 Future workIn this section we p
Page 51 and 52: According to the Eye Diseases Preva
Page 53 and 54: Fig. 14: Use of image processing te
Page 55 and 56: list, printing the best match as th
Page 57 and 58: Chapter 8Conclusion8.1 ConclusionMo
Page 59 and 60: [13] Gilles Virone, Norbert Noury,
Page 61 and 62: [40] Andrew M. Ladd, Kostas E. Bekr
Page 63: [65] X. Chen and A.L. Yuille, “A

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