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Monday, 18 August 2014

How far are Ugandan 4G networks “4G”?

By Sam Agona
At least three Ugandan telecom companies have announced their rollout of LTE – 4G. Orange Uganda  announced their LTE roll out after MTN Uganda did in April 2013 and Smile Telecom earlier. This heedlessly is the development any world citizen with interest in ICT is keen to experience.  On several occasions network service providers launch products and invite mainstream media people and social media junkies from around town, to broadcast information, and this is done without question. However, such gatherings can be duped using “internet bandwidth spools”  making the network momentarily seem markedly fast thus comprehensible as something new has been done by the telecom company in question.
Mobile network antennas:  Adopted from:  Tabula Inc.
It is important to note that the Ugandan telecom market (and all other markets) are so liberalized that extreme marketing ploys (with help of background technology) can be used to canvas and package products which are later on sold to customers, and in a case where products are not as genuine, no penalty to a service provider is levied by the regulatory body. This piece however is not motivated towards business aspects but rather technical.
You can be sure that when MTN launched their LTE, they promised flabbergasting speeds and access, but the picture below should show you how far market ploys can go. Needless to stress the author was equally a victim of it. Leave alone the fact that it cannot scale down its 4G to 3G in areas where its 4G coverage is non existent. This virtually made MTN 4G useless. 
MTN's LTE hardly sees its own network: Photo by Author 
To ascertain whether Ugandan ISPs are rolling out real 4G or fabricated 4G, it is supreme understanding what 4G is and what it takes to have a 4G network. 4G technology is meant to provide “ultra-broadband” access for mobile devices, and in 2008 the ITU created a set of standards that networks must meet in order to be considered 4G, known as the International Mobile Telecommunications Advanced (IMT-Advanced) specification. A true 4G network:
- Must be based on an all Internet protocol (IP) packet switching and circuit-switched technology.
- Use OFMDA multi-carrier transmission methods or other frequency-domain equalization (FDE) methods instead of current spread spectrum radio technology.
- Peak data rates must be close to 100 megabit per second for a user on a highly mobile network and 1 gigabit per second for a user with local wireless access or a nomadic connection.
- Must also be able to offer smooth handovers across differing networks without data loss and provide high quality of service for next-gen media.
- Eliminate the Parallelism of parallel circuit-switched and packet-switched network nodes using Internet Protocol version 6 (IPv6).
Imperative to recall is, 4G represents a significant evolution over existing 3G standards, most notably is the removal of IP address limitations, increased data transfer rates and smooth handovers of clients over heterogeneous networks. Now, wireless infrastructure is divided into two major segments, common for all generations of wireless technologies.
1.      Radio Access Network (RAN)
2.    Core Network (CN)
Different portions of the wireless infrastructure will be affected by equipment changes as wireless service providers upgrade their network from one generation to the next. Paramount to note is that, some portions of the network may be reusable while other portions may require completely new equipment, all of which depends on the particular wireless technology being adopted. All the modern 4G networks evolved from 2G through to the current 4G. However to keep this article manageable, the author settles to discuss changes that have to occur in a network from 2.5G to 3G and 3G to 4G. 1G to 2G and 2G to 2.5G (oh the author equally ignores 3.7G because it does not have any clear backbone technological changes that define it, it is more of a marketing ploy) is ignored on the assumption that prominent companies no longer use analog voice (1G) wireless technology (AMPS – Analog voice). The author also “unrealistically assumes” the networks are already 2.5G enabled (with packet data capabilities at least), something not “real” in far to reach parts of Uganda.
2.5G to 3G:
In the transition from 2.5G to 3G, only the Radio Access Network portion of the network is required to be upgraded (assuming the network already had RAN upgraded to GERAN). Then 2.5 G GERAN has to be upgraded to 3G UTRAN. This involves replacing all BTS with “Node B” network elements and replacing all BSC with RNC network elements. 3G UMTS can reuse previous generation (2G and 2.5G) circuit switched infrastructure for voice applications (MSC, HLR/VLR) and can also reuse 2.5G GPRS packet switching infrastructure (SGSN, GGSN) for packet data applications, in other words, the Core Network may not require any upgrade.  Figure below, denotes parts that (in red) require introduction in a bid to attain 3G status.
A telecom company will invest heavily financially in a 3G network expecting an increase in data to be traversed over the network substantially (to justify investment). On speculative grounds, this may mean the transport capacity of the RAN backhaul, connecting the remote cell site nodes which are BTS and NodeB to the central site nodes comprised of BSC and RNC, may require upgrading. On several occasions, bonding multiple T1/E1 lines using ATM IMA (Asynchronous Transfer Mode Inverse Multiplexing) is a trick towards upgrading the RAN backhaul network for 3G networks.

Figure showing parts that need to be introduced into a 2.5G network to make it 3G: 
Adopted from:  Tabula Inc.
3G to 4G:
Unlike in 2.5 to 3G where the core network is unchanged, in the transition from 3G to 4G, both the RAN and the Core Network need to be upgraded.  In the RAN, the 3G NodeB network elements is succeeded by 4G eNodeB. Of prominence to mention is, 4G RAN has a simpler architecture and consists of a single hierarchy containing only eNodeB elements. Some of the features normally implemented by the 3G RNC are embedded into eNodeB, while some of the RNC features are brought into the 4G Serving Gateway or into the Mobility Management Entity (MME).
Unlike in the RAN where selective changes are made, in the Core Network, entire infrastructure needs to be replaced. The older 3G network is an overlay network, with separate and distinct equipment handling only voice circuit switching and distinct equipment handling only packet data.

Figure showing changes that take place on a 3G network to attain LTE: 
Adopted from:  Tabula Inc.
Moreover, the 3G GPRS Core Network is largely based on ATM technology, this does not work with the 4G architecture where the Core Network Evolved Packet Core (EPC) is simplified and flatter through an “all-IP” network, with all applications – voice, video and data – running over this common IP network. This is what makes migration to 4G expensive because it requires completely new infrastructure equipment in the Core Network.
The RAN backhaul also needs to be upgraded since the bandwidth capabilities of 4G will be at least an order of magnitude greater than that for 3G (This probably explains why MTN Uganda 4G is strictly around MTN Towers and Nonyi Gardens). Unlike in 3G, in 4G using bonded T1/E1 lines is undesirable. By the fact that the bandwidth granularity for T1/E1 is 1.5Mbps/2Mbps, an enormous number of T1/E1 lines would be required to support 4G backhaul bandwidth which may be in the order of 1-2Gbps. Newer backhaul technology such as Carrier Ethernet may be more attractive from a cost-per-bit angle of reasoning. 
 A picture of the author working on Azimuth/ Elevation of a Radio Network: 
Photo taken by: Akena Martin Luluga 
Data modems (3G to 4G), the CPE side of the network
When MTN Uganda rolled out their 4G, the author acquired their Modem thinking he would achieve speed on 4G and where there is no 4G, it would scale down to 3G, but to his dismay and despair, this did not happen, outside the 4G zone, it completely had no connectivity leaving abandonment of the modem as the only option.
The difference between 3G and 4G technologies lie in data speeds (among others) with 2-3 Mbps for 3G while 4G achieves up to 5-30 Mbps (actual current 4G speeds). Further, 4G LTE uses a completely different radio technology which is OFDM, MIMO against 3G's WCDMA. This therefore means you may have to change data modem to use 4G in Uganda something MTN Uganda has done, but their limited coverage is no bargain for buying a new modem.
A true 4G system embraces both voice and data (as per ITU specifications).  With maximum surety, MTN 4G does not embrace voice calls, it also very abstract to them such that, in a situation where you forget your 4G SIM card number, they cannot retrieve it for you. Probably the needed to implement a mechanism known as Circuit Switched Fallback (CSFB) technology that works on 3GPP and 3GPP2 networks to allow them make calls on a 3G platform. CSFB also offers battery life advantages of single-radio solutions, LTE data speeds, and reliability/ubiquity of 2G/3G voice thus reverse inter-operability. But like mentioned earlier, we don’t know their back-end technology, so we can only suggest as much.
To conclude, MTN’s 4G is largely cited in this piece, because the author tested largely on their network to come up with the conclusions, besides MTN is the player with the largest coverage (GSM) and market share thus powerful towards market dictates. Ugandan service providers claiming to have deployed 4G networks need to come up with a technical explanation, they need to justify their failure to cover several parts of upcountry districts with 2G but claim to have made such severe changes to their systems in Kampala and surrounding areas to provide 3G and LTE. Otherwise I strongly believe, MTN Uganda and Orange are just using the 4G ploy to gain more market and sell more products.

“This piece is dedicated to my fallen media friend Ms. Susan Namasaba (RIP), you were such a queen and I know how much you loved works of knowledge”

1 comment:

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