Challenges and risks involved in m-commerce:
The term m-commerce was coined by Kevin Duffy, the director of Group Telecom of Logical, in February 1997.Several definitions have been suggested for m-commerce. The Durlacher Mobile Commerce Report defines m-commerce as .any transaction with monetary value that is conducted via a mobile telecommunications network. This definition is fairly rigid, and makes a very clear-cut distinction between m-commerce applications and other mobile applications.

The challenges to the emergence of m-commerce do not end with limited resources. The bandwidth currently available is not ideal. The effective bandwidth, as quoted by m-commerceworld.com, is somewhere around 9kbps. This further hinders the advent of sites containing graphics and user-friendlier interfaces, in turn discouraging users from opting for m-commerce.
M-commerce or mobile e-commerce represents the using of mobile devices for communication and implementation of electronic commerce transaction or any transaction with monetary value achieved through mobile devices. M-commerce appeared due to the rapid evolution of the mobile devices and connection among internet became more accessible regardless of the geographical location of the person who connects to the Internet.

M-Commerce applications are obtained by the two methods:
• supplement or extend existing applications, which involves the addition of new tools to improve more efficient the access to E-Commerce applications existing through mobile devices;
• Innovative requires the development of new services and new applications for M-Commerce to facilitate access through mobile devices; in this category of applications are not used old e-commerce applications; new applications are designed from the beginning.
Security for mobile devices and applications for these devices is provided in the following aspects:
• Authentication foxmd in the M-Commerce applications with virtual identity verification (Ivan et al., 2012), the request of personally identifiable information and checking them with the information previously provided in the registration; according to (Marian, 2009) authentication is the process of establishing or confirming the accuracy and reliability of information relating to the identity or origin of an entity. The authentication process is divided into two parts:
- The first part is to identify the entity that is done by presenting an identifier associated with the entity that authenticates;
- The second step is the verification and validation entity that authenticates.
In the M-Commerce applications used is that user authentication. The user authentication involves the two steps in sequence:
• User identification;
• Claimed identity verification and validation.
The manufacturers of both mobile phones and security software have to ensure that their products reflect those new trends in user behavior.
Android powered phones have already been attacked by virus-carrying apps which can potentially steal personal information saved on those devices.

Google, the developer of Android, have assured the public that the next version of that software will be a lot more robust. Still, what is clear is that at the moment criminals are a step ahead and this could be stopping shoppers from fully endorsing m-commerce.

Apple took a more cautious approach and individually reviews each app before it is available to download by iPhone and iPad users. This, however, has been criticized by the developers as too restrictive. It seems that customer safety and their demand for new software do not currently always go hand in hand.

On the other end of the spectrum are payment service providers, who may not want to support technology which could potentially put buyers at risk. That is why they may delay their endorsement of mobile payments until most of threats are removed.

Some of the issues making the mobile payment platform open to cybercrime at the moment is the fact that devices can wirelessly access unsecure networks and the software powering them is often not robust enough to protect sensitive information required to complete purchases.

There is also the problem of phones being lost with sensitive information saved on them. That data could be then used by criminals to make fraudulent purchases.

It will take time for parties involved in the set-up, implementation and the delivery of mobile payments to identify all the risks and prevention methods. E-commerce businesses who decide to introduce it now will be taking on a lot more unidentified risk than those who decide to wait and have the benefit of hindsight when setting up their platforms.

Nevertheless, it can be safely assumed that mobile payments are here to stay, as a growing number of consumers want to be able to make purchases on the go.

Global Positioning System (GPS) is the only system today that is able to locate the exact position of a GPS receiver anywhere on earth anytime, anywhere, and in any weather. GPS works by having 24 satellites in space orbiting earth. These satellites are positioned in such a way that in theory it is always possible to receive signals from 4 or more satellites anywhere on earth anytime. The main strength of GPS is that it provides precision of up to 10 meters.
This is a revolutionary breakthrough in location detection and its precision has caused great interest in military, commerce and private sectors.
There are several disadvantages in GPS. Power consumption for one is a major hindrance for mobile computing. This is crucial as electrical power is always in short supply even for modern mobile computing. Due to satellite reliance, GPS cannot be used indoors effectively and it is subjected to blockages by tall buildings outdoors. Sky scrapers in the cities create an ‘urban canyon’ that block coverage of satellites, causing significant problems for users in cities. The physical topology of a network refers to the configuration of cables, computers, and other peripherals. Physical topology should not be confused with logical topology which is the method used to pass information between workstations. Logical topology was discussed in the Protocol chapter.
Main Types of Physical Topologies
The following sections discuss the physical topologies used in networks and other related topics. * Linear Bus * Star * Tree (Expanded Star) * Considerations When Choosing a Topology * Summary Chart
Star Topology Many home networks use the star topology. A star network features a central connection point called a "hub" that may be a hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet.
Compared to the bus topology, a star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN. (If the hub fails, however, the entire network also fails.)
Star-Wired Ring
A star-wired ring topology may appear (externally) to be the same as a star topology. Internally, the MAU of a star-wired ring contains wiring that allows information to pass from one device to another in a circle or ring. The Token Ring protocol uses a star-wired ring topology.
Ring Topology In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.
To implement a ring network, one typically uses FDDI, SONET, or Token Ring technology. Ring topologies are found in some office buildings or school campuses.
Bus Topology Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. A single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector. A device wanting to communicate with another device on the network sends a broadcast message onto the wire that all other devices see, but only the intended recipient actually accepts and processes the message.
Tree Topology Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices. This bus/star hybrid approach supports future expandability of the network much better than a bus (limited in the number of devices due to the broadcast traffic it generates) or a star (limited by the number of hub connection points) alone.
Mesh Topology Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.
A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.
Hybrid Topology
A combination of any two or more network topologies. Note 1: Instances can occur where two basic network topologies, when connected together, can still retain the basic network character, and therefore not be a hybrid network. For example, a tree network connected to a tree network is still a tree network. Therefore, a hybrid network accrues only when two basic networks are connected and the resulting network topology fails to meet one of the basic topology definitions. For example, two star networks connected together exhibit hybrid network topologies. Note 2: A hybrid topology always accrues when two different basic network topologies are connected.

Ethernet bus topologies are relatively easy to install and don't require much cabling compared to the alternatives. 10Base-2 ("ThinNet") and 10Base-5 ("ThickNet") both were popular Ethernet cabling options many years ago for bus topologies. However, bus networks work best with a limited number of devices. If more than a few dozen computers are added to a network bus, performance problems will likely result. In addition, if the backbone cable fails, the entire network effectively becomes unusable

References:
Source: file:///C:/Users/t1541md/Desktop/10.1.1.19.4489.pdf IVAN, I., MILODIN, D., & ZAMFIROJU, A. (2013). Security of M-Commerce transactions. Theoretical & Applied Economics, 20(7), 59-76.
Source: http://www.edrawsoft.com/Network-Topologies.php