Comparison ZTE MF825 vs ZTE Jetpack 890L

- USB modem. Modems in the form factor of a USB stick connected to a computer, laptop or other devices through an unoccupied USB port. These can be both the simplest devices for serving one client device (to which the modem is directly connected), and more advanced models with support for working in Wi-Fi networks and the ability to wirelessly distribute the Internet to several gadgets. To access the World Wide Web, USB modems provide a slot for a SIM card.

- Portable router. Mobile routers for Internet access, without fail with a built-in Wi-Fi module. Wi-Fi modems are capable of simultaneously working with several connected devices, in addition, they are battery-powered and can be used completely autonomously - without the need to connect to a computer and a power outlet. It is advisable to use portable routers in cases where a fixed connection to the Internet is difficult or completely absent (in the country, outdoor recreation, as backup equipment for accessing the global network).

Wi-Fi connection speeds, more precisely, Wi-Fi standards supported by a modem with the appropriate capabilities (see "Type", "Connection").

— Wi-Fi 3 (802.11g). A further development of the Wi-Fi 1 (802.11b) standard, developed primarily for increasing connection bandwidth (2.4 GHz) and introduced in 2003. 802.11g hardware is fully backwards compatible with 802.11b, so even the simplest of today's Wi-Fi devices support both of these standards.

— Wi-Fi 4 (802.11n). The Wi-Fi standard, which is a further development of the formats described above — in particular, by supplementing them with support of MIMO technology (distribution of input and output between several antennas). Introduced in 2009. The main operating frequency is 2.4 GHz, but there are devices supplemented with a 5 GHz band.

— Wi-Fi 5 (802.11ac). Built on top of 802.11n, introduced late 2013. The main improvements were the increase in the number of streams at the second frequency (5 GHz) and the introduction of more advanced MIMO and modulation standards, which increased the throughput accordingly.

The largest number of devices that can be simultaneously connected to the modem via Wi-Fi (see "Connection").

The presence of this limitation is due to the fact that processing network requests from several devices at once requires a fairly large amount of computing resources, and there are not so many of them in miniature electronics like wireless modems. However, even inexpensive models can support about 5 – 6 devices, which is more than enough for most cases; and in more advanced modems, this number can reach 10.

The greatest distance at which the modem's built-in router is capable of providing communication via the Wi-Fi interface (see "Connection").

It should be taken into account that in fact the range strongly depends on a number of factors that are not related to the main specs of the modem: the presence of interference and obstacles in the signal path, the specs of the Wi-Fi module of the connected device, the battery charge in this device or the modem itself, etc. Therefore, the actual range indicators can be noticeably lower than the claimed ones: for example, when working through a wall, they are noticeably reduced. However, this spec quite clearly describes the overall range of the device, and comparisons of different models on it are quite acceptable.

Also note that it does not always make sense to purchase a device with a maximum range — although a long range provides additional convenience, it requires high transmitter power, which significantly increases the size and price of the modem. Therefore, when choosing, it is worth proceeding primarily from the intended scenarios of use. For example, if you need a 3G connection to access the Internet on the road from your tablet, a range of several metres will be enough. But for installation in a large private house, it makes sense to look for a model with increased effective range.

The 4G (LTE) mobile connection speed supported by the modem.

All modern LTE equipment is assigned one or another category (Cat.3, Cat.4, Cat.6, Cat.7, Cat.9, Cat.12, Cat.13, Cat.16, Cat.18, Cat.19, Cat.20, Cat.22), on which the transmission speed directly depends. This paragraph specifies both this category and specific speed indicators, moreover, in two parameters — for reception and for transmission. The transmission speed is always much lower, but given the specifics of mobile Internet access, this is usually not critical.

Note that equipment with different speed categories will be quite compatible with each other, however, the throughput will be limited by the capabilities of the slower device. It is also worth saying that this paragraph indicates the theoretical maximum; practical amounts can be noticeably lower (depending on the quality of the network coverage and the features of specific electronics). However, a modem with a higher speed category will perform faster in fact.

Data transfer technologies supported by the modem.

— GPRS. The oldest communication technology in use today. It was developed as a standard for GSM cellular networks, allowing data to be transmitted in parallel with voice communications and text messages, as well as charging network access by the amount of data transmitted, and not by connection time (as in the previous CSD standard). At the time of its creation, it was very progressive, but now it is considered completely obsolete and is used only in cases where more advanced standards cannot be used.

— EDGE. A technology created as a modification of the GPRS described above, which would increase the channel throughput and improve communication reliability. Otherwise, this standard is completely similar to GPRS in terms of its main practical features.

— W-CDMA. One of the early third generation ( 3G) communication standards. Used in UMTS networks. One of the main advantages of such networks is the ability to build networks based on the existing GSM infrastructure. Therefore, UMTS, and specifically W-CDMA, is being used by many mobile operators in the early stages of their transition from 2G to 3G.

— HSUPA. Third generation (3G) communication technology, an evolution of W-CDMA described above. The name...stands for "High-Speed Uplink Packet Access" — high-speed packet data transmission in the "from the subscriber" direction. This, in fact, describes the purpose of this technology: it increases the speed of data transfer from the modem to the base station, which can be useful for some specific tasks — for example, video communications.

— HSDPA. Further, after HSUPA, improvement of the W-CDMA standard (see above). It belongs to third generation (3G) networks, but is considered an “extended” standard, which is why HSUPA-enabled networks can be referred to as 3.5G, 3G+, etc. The name itself — "High-Speed Downlink Packet Access" — translates as "high-speed packet data transmission from the base station to the device."

— HSPA+. Today's most advanced third-generation communication standard based on UMTS networks (W-CDMA). Thanks to a number of improvements, it allows to achieve higher speeds than the options described above, approaching fourth-generation networks in terms of capabilities; therefore, sometimes conventionally referred to as 3.75G.

— WiMAX. Initially, WiMAX was created in two versions — "mobile" and "stationary"; the vast majority of modern cellular modems use the second option. It belongs to the fourth generation standards — 4G (whereas "mobile" was a competitor to 3G technologies, although sometimes it is also referred to as a 4th generation connection for marketing purposes). Some time ago, WiMAX was actively promoted as an alternative to wired broadband Internet connection (in particular, as the best option for areas, where it is difficult to reach the cable). However, now this standard is gradually losing popularity — in particular, in connection with the development and promotion of a more advanced LTE (which also does not have a division into "mobile" and "stationary" varieties).

— LTE (up to 173 Mbps). The fourth generation cellular communication standard, the most popular 4G technology today — in particular, due to the fact that it is a further development of W-CDMA/UMTS and can be implemented by improving existing networks (both UMTS and CDMA2000). Another reason for the popularity is the same convenience for both stationary and mobile equipment. On the other hand, when choosing a modem of this standard, you should keep in mind that LTE bands and channels may differ in different countries, so the support of this technology does not guarantee compatibility with a particular network. It should also be taken into account that in some countries LTE networks are only at the deployment stage, and in some they are not available at all.

— EV-DO (Rev.A). EV-DO is a third-generation (3G) data transmission technology used in CDMA mobile networks (not to be confused with W-CDMA, built on another basic standard — UMTS). Note that in some countries this type of 3G network became widespread much earlier than W-CDMA and its modifications, and for a number of technical reasons it is mainly used for data transmission — that is, for the operation of 3G modems. As for Rev.A, this is the second and most common version of the EV-DO standard.

— EV-DO (Rev. B). The third version of EV-DO technology, the development and improvement of Rev.A; see above for details. Here we note that this standard is also often used as a 3G data connection; its coverage area is not as extensive as the previous version, but still covers most major cities and their surroundings. It is also worth considering that in order to use all the features of Rev.B, you need a modem that supports this version, and not all modern EV-DO devices can do this.

When evaluating the capabilities of a modem, note that the speed values given for each technology are the maximum, which in fact is achievable only under perfect conditions. The actual values of the speed, usually, are lower than the potential ones; they may depend both on the specs of the network, signal strength and other technical issues, and on the policy of the operator and the conditions of a particular tariff.

— USB plug. The presence in the design of the modem of its own USB plug, which allows you to connect the device to a computer directly. Such a connection provides a device with a USB port with Internet access, and the power necessary for the operation of the modem is also supplied via USB.

— microUSB. A smaller version of the USB connector (see above), used primarily in Wi-Fi modems (see "Type") that can work autonomously and do not require a constant connection to another device. At the same time, in 3G/4G modems, microUSB usually looks like a socket, not a plug, and a special cable is used to connect. This interface usually plays the role of a general-purpose service connector: the battery is charged through it, and it is also connected to a PC or other device to manage settings, update firmware, etc.

— USB. Wired interface, the most common and universal modern standard used to connect peripheral equipment to various electronic devices, ranging from computers to smartphones and even wireless modems. In this case, the full-size version of the USB connector is meant. It is usually installed in classic modems (see "Type") and has the form of a plug, with which the modem is connected to a control device (PC, laptop, tablet, etc.). Power is usually supplied through the same connector.

— USB-C. Connector, in its functional features similar to the paragraph above. With the exception of the symmetrical form factor and the use of more modern technologies.

— LAN (RJ45). Classic wired connection via a cable with an RJ-45 connector. Also known as "LAN". Nowadays, it is one of the most common methods of wired Internet connection, and is also widely used in local networks. With it, you can connect a laptop or PC directly to the modem via a cable and not bother with a Wi-Fi connection. In addition, such a connection can be faster (depending on the speed of the LAN).

— ExpressCard. A connection interface mainly used in laptops. Peripheral devices of this standard, including wireless modems, have the form of cards, when connected, they are installed in a special slot in the device. It should be taken into account that there are two ExpressCard form factors — 54 mm and 34 mm, and 34 mm cards can be used without restrictions with 54 mm slots, but not vice versa. Therefore, when choosing such a modem, it is worth clarifying the correspondence of its form factor to the planned slot. However, this standard is gradually disappearing from the scene, being replaced by more advanced interfaces — in particular, USB 3.0.

The presence of a connector for an external removable antenna in the modem design. The meaning of all external antennas is described above; here we note that the connector makes it possible to use rather large antennas with the modem, which significantly exceed the capabilities of stock antennas (both internal and external non-removable ones). In addition, the user can choose the antenna at his discretion.

The ability to connect the MIMO antenna (the antenna itself, usually, must be purchased separately).

MIMO technology is used in Wi-Fi communications, as well as in 4G LTE networks (starting with Cat.2). Its general principle is to split the transmitted signal into several transmitting and receiving antennas; at the same time, each of the transmitting antennas broadcasts a signal to all receiving antennas at once (or at least to several of them). This format of operation allows more efficient use of the frequency range, increases the actual data transfer rate, and also increases resistance to interference. But antennas for MIMO are rather bulky, in the case of modems it is difficult to make them built-in; and such feature is required not so often. Therefore, separate external antennas are used to work with this technology.

Note that even in portable Wi-Fi hotspots (see "Type"), this feature is used exclusively for 4G/LTE; Wi-Fi connection is provided by built-in antennas.