How is a femtocell different from a GSM repeater, Wi-Fi router and macro cell? Who uses what uplink?

    A post on femtocells showed that one can easily get confused about what equipment is used: what is a base station, what is Femto AP, how does it all relate to Wi-Fi, and so on. The topic has a simple explanation about various types of equipment and the classification of base stations for multi-standard cellular networks.

    Network hierarchy

    If you want to know what a thing is hanging on a neighboring house and how it creates cellular coverage for you, welcome to cat.

    The first thing to understand is that prefixes like macro-, pico-, etc. do not characterize the change in the quantitative parameters of the base station, they only indicate the place of the class in the hierarchy.

    Macro (large)

    Base station

    Sector antennas

    These are standard base stations on which the operator’s mobile network is built. The principles of operation, the transport solutions used are given in any article on the architecture of cellular networks. The main transport at the moment is standard SDH-TDM networks, but the moment of mass transition to IP / Ethernet is getting closer. They are characterized by high power - up to 60W, large coverage radius - 10 ... 100 km, large mass-dimensional indicators (rack up to 200 kg). There are varieties of macro base stations - such as Distributed BTS, but this is not essential in this classification. There are any standard approved for use in Russia: GSM / UMTS / CDMA in the future - LTE .

    Microcell (10 -6 )

    Micro base station

    A very common solution in the networks of a large operator. In fact, it is a compact version of the first type, with stripped-down characteristics in terms of base capacity, radiated power - up to 5 ... 10W, coverage radius - 1 ... 5 km and mass-dimensional characteristics (compact body weighing up to 50 kg). Used by the operator where it is difficult to install a macro base station, or where high power and capacity are not required. For example: large shopping centers, office complexes, remote villages, etc. Often used in conjunction with a Distributed Antenna System (DAS), consisting of cables and antennas, wired throughout the building. Antennas can look variously, for example, as in the subway:

    Panel antennas

    There are also GSM / UMTS / CDMA standards in the future - LTE.

    Pico or nano base station (10 -12 and 10 -9 )



    This is a more exotic option. Low power base station for office / home use. As the basic transport network, it uses only IP / Ethernet networks, in which the necessary band is reserved for the transmission of traffic generated by the base station. Typical power up to 0.2W, dimensions - approximately from a laptop. Despite its small size, it is still a base station that belongs to the operator and cannot be transferred to the subscriber for independent launch and use. They are usually installed in offices of corporate clients, or in places of possible concentration of users - in restaurants, hotels, etc.

    Technically, there may also be GSM / UMTS / CDMA in the future - LTE. However, now there is a practice - that pico / nano base stations are called only low-power GSM standard bases.

    Femtocell or femto-access point (10 -15 )

    Home Femtocell

    Femtocell is not a base station anymore - it is an Access Point. The difference in terminology appears due to the fact that this equipment was initially focused on use as a home or office, and it is assumed that the owner is the user. Transport is only IP / Ethernet, and both the channel allocated by the provider and the public Internet. The fundamental difference from all other types of base stations is auto-configuration when connected to the transport network and connected to the operator’s network. Femto AP independently evaluates the radio parameters at the launch point, selects the best settings for itself, and is activated if the operator permits it. For data protection - all interaction with the operator’s equipment begins only after the creation of the IPSec tunnel. Typical radiated power - up to 0.1W,
    The same GSM / UMTS / CDMA standards, in the future - LTE. However, now Femto AP is strongly associated only with the UMTS (3G) standard, in the future a mass appearance of such LTE devices is expected.



    This equipment is included in the review solely due to the fact that many also consider it equipment for creating a cellular network. It's a delusion! A repeater is just an external signal amplifierfrom the macro station, and its purpose is to broadcast a signal from the street into the building. The repeater does not create additional network capacity, that is, if the donor base station is overloaded, the telephone will also not be able to use the phone inside the building due to congestion. Despite the apparent simplicity of the device and installation - the correct configuration of the repeater requires specific skills and devices to control the created coating. Moreover, according to Russian law, only a company that has the appropriate licenses can own such equipment, as well as install and run it. Often it is impossible to use a repeater, since it requires the installation of an external antenna on the facade of a building that receives a signal from a macro base station.

    There are options for a wide variety of repeaters. Different power, performance and standards. The most widespread in the networks of operators are repeaters with high gain, GSM / UMTS standards. They are used to organize communication in hard-to-reach areas (for example, with a height difference), as a temporary solution until the launch of a full-fledged base station of one of the types described above.

    Who will sort it out: Wi-Fi router or femtocell?

    What is better than such a Femto AP than my native Wi-Fi router? The answer is very simple - these are completely different types of equipment! All the base stations described above are designed to create a mobile network of GSM / UMTS standards, voice and packet services are available in these networks, which you can get using a telephone supporting GSM / UMTS standards. The usual Wi-Fi router is just a wireless extension cable for copper cable from your provider, and only package services can be provided for you, including: Voice / Video over IP (for example Skype).
    Anyone (or certain people listed by you) can enter the coverage area of ​​a femtocell with a 3G phone without Wi-Fi and gain access directly to the operator’s network.

    There are femtocell models equipped with a Wi-Fi transmitter, and in this way you can use both UMTS and Wi-Fi networks using one CPE, but do not forget that these are not competing, but complementary technologies.

    Hopefully now the confusion is resolved. If something else remains, ask in the comments, I will try to answer in detail.

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