Is Your 4G Mobile Phone Really Getting 4G Speed?
While AT&T and Verizon lead the mobile operator industry in LTE (Long-Term Evolution) deployments, consumers complain that the 4G experience is not what they thought it would be. That may be due to two separate reasons: First, LTE is not a true 4G technology, and second, the mobile backhaul network they are using cannot support even LTE, much less 4G. However, carriers and equipment manufacturers are diligently working to correct that.
4G, LTE, LTE-Advanced, and WiMAX
The world’s best wireless connection method when it comes to mobile phones is currently 3G, especially for mobile Internet. 3G stands for “third generation” of the evolutionary path of the mobile phone networks. The fourth generation is 4G.
The biggest differences between 3G and 4G are data rate support and the existence of compliant technologies. There are a bunch of technologies that fall under 3G, including WCDMA, EV-DO, and HSPA. Although a lot of mobile phone companies are quick to dub their technologies 4G, such as LTE, WiMAX, and UMB, none of these are actually compliant to the specifications set forth by the 4G standard. These technologies are often referred to as Pre-4G or 3.9G. The progression of the technologies is shown in the following figure.
WCDMA is the standard that most GSM carriers moved to when upgrading to 3G. Parts of the WCDMA standard are based on GSM technology. WCDMA networks are designed to integrate with GSM networks at certain levels. Most WCDMA phones include GSM as well, for backward compatibility. WCDMA borrows certain technology ideas from CDMA, as the name implies, but it is actually very different than and incompatible with phones and networks that use “CDMA” technology. In Europe and Asia, WCDMA was first deployed in the all-new 2100 MHz frequency band. In North America, WCDMA was deployed in the existing 1900 MHz (PCS) and 850 MHz (cellular) bands, as well as the newer 1700 MHz (AWS) band.
In the US, 3G has two flavors:
- EV-DO (Evolution Data Optimized) is a 3G mobile broadband technology used by Verizon, Sprint, and Alltel that provides typical download speeds of 600-1400kb/s (with bursts up to 3100kb/s). While you can purchase separate modems for use while on the go, this technology is also incorporated directly in the 3G mobile phones.
- HSPA (High Speed Packet Access) is another 3G technology that is used by AT&T and T-Mobile. Its advantage, which AT&T marketed very well, is that you can transfer both voice and data at the same time, whereas with EV-DO, you cannot.
3G technologies use a hybrid of circuit switching and packet switching. Circuit switching is a very old technology that has been used in telephone systems for a long time. The downside to this technology is that it ties up the resource for as long as the connection is kept up. Packet switching is a technology that is very prevalent in computer networks but has since appeared in mobile phones as well. With packet switching, resources are only used when there is information to be sent. The efficiency of packet switching allows the mobile phone company to squeeze more conversations into the same bandwidth.
The maximum data rates for 3G technologies are 14Mb/s for the downlink and 5.8Mb/s for the uplink.
4G refers to the next wave of high-speed mobile technologies that will be used to replace current 3G networks. The two top contenders are LTE and WiMAX, both of which are IP-based networks that are built from similar, yet incompatible, technologies. Sprint and Clearwire are currently offering 4G WiMAX service in the US, while Verizon and AT&T have built out networks utilizing LTE.
In March 2008, the International Telecommunications Union-Radio communications sector (ITU-R) specified a set of requirements for 4G standards. Named the International Mobile Telecommunications Advanced (IMT-Advanced) specification, the 4G standards set peak speed requirements for 4G services at 100Mb/s for high mobility communication (such as from trains and cars) and 1Gb/s for low mobility communication (such as pedestrians and stationary users). So far, these speeds are only reachable with wired connections. Neither LTE nor WiMAX fit these criteria, even though they are being marketed as 4G technologies. LTE is only capable of 100Mb/s maximum, while WiMAX tops out at 54Mb/s; therefore, falling very far from the intended target. A newer version of LTE, called LTE Advanced, is expected to exceed the 4G standards. Below is a diagram showing the elements of an LTE network.
Mobile WiMAX Release 2 (also known as WirelessMAN-Advanced or IEEE 802.16m) and LTE Advanced (LTE-A) are IMT-Advanced (4G)-compliant, backwards-compatible versions of the above two systems. Some believe that WiMAX will disappear in favor of LTE-A, but that remains to be seen.
The Mobile Backhaul Network
The current hype surrounding mobile backhaul is small cell technology, but it is not yet deployed in actual production networks. The current mobile backhaul network still consists of mostly microwave to connect the macro cell to the aggregation node, and Carrier Ethernet to connect aggregation nodes, as shown in the following diagram. The fiber aggregation network is Carrier Ethernet, WDM, or, in older networks, still SONET/SDH/TDM.
The evolution using LTE-Advanced will be a heterogeneous network that will likely include small cells, super-size macro sites, several variations of microwave, and Carrier Ethernet both on fiber and in microwave. This is depicted in the following diagram.
New Technologies to Support 4G
The new technologies in the network that are needed to support Gigabit to the smartphone include both wired and wireless:
- Small Cells: These include femto, pico, metro, and micro cells. Each type covers different ranges and may use different frequency bands. As the names imply, femto has the shortest range of 10m, a picocell’s range is 200m, metro is 1-2km, and micro is 1-2km. While metro and micro have the same range, the types of equipment they use may be quite different. Metro is specifically designed for urban areas, while micro can be used in both rural and urban areas. Carriers started to work small cells to improve coverage for 3G networks. For 4G, they are considered a necessity.
- New Spectrum: We have been hearing about this for many years now and various auctions in different countries have opened up new frequency bands for telecommunications networks.
- 10G/40G/100G Carrier Ethernet: Most Ethernet connections in the mobile backhaul networks are now 1Gb/s or below. But with 4G-enabled devices on the verge of utilizing 1G connections, networks need to be quickly upgraded through the higher data rates.
- G-PON: No carriers in the US are talking about leveraging their FTTH networks yet, but this is already starting to happen in Japan.
- IP/MPLS: This is the packet switching technology that will eventually take over the backhaul network, according to most mobile experts.
Equipment and Connectivity for Mobile Backhaul
Network equipment used in mobile backhaul networks ranges from simple Ethernet routers to microwave transponders. The table below lists the relevant network equipment, its use in the network, its connectivity content, and several notable equipment vendors that supply it.
The microwave transmission systems are used at the cell site, while the multi-service platforms and Carrier Ethernet switches may be used at cell sites or throughout the backhaul and aggregation networks. The different parts of the networks are shown in the diagram below.
Mobile Backhaul Connectivity Opportunities
Bishop & Associates’ forecast for Ethernet connectors and cables in the mobile backhaul network over the next five years is detailed below.
Clearly there is an opportunity for Ethernet-based components in the mobile backhaul network. Learn more in Bishop’s upcoming report on the market, available later this summer.
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