LTE vs WiMax:
The Future of Mobile Broadband in the United States

LTE vs WiMax: The Future of Mobile Broadband in the United States

High Speed Broadband Services (HSBS) is one of the rapid technological advancements the world has seen over the past century. The primary reason for HSBS was to deliver a high speed Internet service capable of supporting multimedia applications to the subscriber. During the latter part of this technological evolution, HSBS was mainly focused on wireless applications. This movement would latter be coined as Broadband Wireless Access (BAC). BAC was designed to provide services in a wireless environment capable of providing users with the same capability as that of wired broadband. Over the past decade, there have been major technological advances and innovations with wireless broadband such as LTE and WiMax. WiMax began as the standard for 4G technologies but has succumbed to LTE. As it stands, LTE is a more reliable system that has far greater potential than WiMax in the broadband wireless systems spectrum.

History of WiMax To fully understand Worldwide Interoperability for Microwave Access (WiMax) you have to go back to the beginning where it all started. Cellular phone companies and service providers in the mid 1990’s were looking for alternative ways to provide Internet access to both businesses and individuals. They wanted to develop a system that was comparable to the capacity, speed and dependability of a hardwired system all the while preserving the flexibility, low costs and simplicity of a wireless network. This lead to the idea of using fixed broadband wireless networks. This network gained an abundance of attention for two kinds of static wireless broadband technologies that it used which were Multi-channel Multipoint Distribution Services (MMDS) and Local Multipoint Distribution Services (LMDS) (Feldman, n.d.). MMDS was designed to provide a way for residential broadband services and local television network distribution. LMDS was designed as a way to increase the speed of and bridge Metropolitan Area Networks (MAN) on University campuses and larger corporations. These technologies were hindered by high costs and a lack of standards, which prevented them from being universally fielded. This resulted in the Institute of Electrical and Electronics Engineers (IEEE) devising 802.16 protocol as the standard for LMDS in 1999 (Shaw, 2013). The 802.16 standard functioned using a point-to-point radio link network, which used line-of-sight transmissions. The frequency range it used was from 10 GHz to 66 GHz and was finally released in 2001. However, this standard had restricted capabilities so developers focused on the part of the IEEE 802.16 that operated in the range of 2 GHz to 11GHz (Feldman, n.d.). Later in 2001, the WiMax Forum was founded to both market and promote the IEEE 802.16 standard. It was then that the 802.16 standard was coined WiMax. In subsequent years the IEEE released newer versions of the standard. 802.16a was released in 2003 and broadcasted data through non-line of sight radio channels. This differed from the original standard of using line of sight transmissions. The forum then released the 802.16-2004 standard in 2004, which combined the updates from all the previous standards. This standard extended the WiMax service range to a 30-mile radius thus allowing the dispersion of networks between hundreds of terminals. Up to this point in time, WiMax was a fixed system. In 2005, the IEEE released the first mobile WiMax system: the 802.16e standard (Zeraya Admin, 2013). This standard supported over 2,000 subcarriers and increased network security. WiMax was first implemented in South Korea in 2007 with the first United States (US) system implemented in by Clearwire (now Sprint) in 2008. The IEEE continued to improve the specifications of WiMax to further improve its capabilities. The next major 802.16 standard released was 802.16m and which increased data speeds up to 1 Gbps. The IEEE had planed to get the subsequent 802.20 standard approved in the near future. This standard had been nicknamed as Mobile-Fi. As of now, the 802.20 standard is no longer being developed. As of November 2013, there were as many as 477 WiMax operators worldwide (Shaw, 2013). The WiMax Forum then announced three licensed spectrum profiles in an effort to decrease cost and drive standardization. These segments of the spectrum were 2.3 GHz, 2.5 GHz and 3.5 GHz. 2.5GHz is the biggest segment available in the US (US Department of Commerce, 2003).

How WiMax Works
WiMax works similar to how its predecessor, WiFi, does but over a larger area and is more secure. A WiMax system consists of two major components, which are the tower and receiver. The receiver is either a small box or card that is frequently constructed into devices such as laptops or installed on a home for personal use (Mitchell, n.d). The towers are similar to those of telephones. They transmit signals to clients within a certain range at a low frequency. Each individual tower is capable of transmitting signals to other towers over a higher frequency to provide stronger signals. This process is pictured in figure 1.0
Benefits of WiMax The WiMax Forum has created goals to make high quality data and voice communications more affordable. These goals have been implemented into WiMax, thus giving customers and carriers the following benefits:
• Non-Line of Sight Service (NLOS) -This allows more customers to be supported per cell site.
• Improved Quality of Service (QoS) - improves signal quality for data-rich applications such as video streaming and gaming.
• Higher Data Rates - increased data rates up to 1 Gbps download speed under perfect conditions. Speeds are ultimately increased throughout the network by supporting smaller cell sizes.
• Coverage and Range - Using longer antennas to increase cell size which allows more customers to connect to a carrier’s network. This also allows carriers to provide service in rural areas.

Security in WiMax WiMax systems were devised from the start with an ample amount of protection in mind. The standards WiMax employs include state of the art techniques to ensure privacy for user data and to prevent unauthorized access. In the WiMax architecture, the privacy sublayer in the WiMax message authentication code (MAC) handles security. The major features of security in WiMax are support for privacy, support for faster handover, control measures, device and user authentication and flexible key management protocol (Albentia Systems, 2011). In the privacy support phase, the user data is encoded using robust cryptographic schemes. This process supports both Triple Data Encryption Standard (3DES) and Advanced Encryption Standard (AES). This phase also uses either a 128-bit or a 256-bit key to derive the encryption, which is produced during the authentication phase. The key generating is regularly refreshed for added security. The next phase of security is the authentication phase. In this phase the authentication structure is based on the Internet Engineering Task Force (IETF) Extensible Authentication Protocol (EAS) (Ahuja & Collier, 2010). The EAS supports a plethora of credentials such as smart cards, digital certificates, and username and passwords. The next security phase is flexible key management which uses the Privacy and Key Management Protocol Version 2 (PKMv2). This allows for the secure transmitting of keying material from the base station to the mobile station in the WiMax infrastructure. The keys are periodically refreshed and reauthorized. In the control messages protection phase, over the air transmissions are protected using various message digest schemes. Two of these schemes are the cipher based message authentication code (CMAC) and the hash based message authentication code (HMAC) (Albentia Systems, 2011). In the final security phase, fast handover support, WiMax mobile stations use pre-authentication with a specific target base station to allow quicker re-entry.

History of LTE Long-Term Evolution (LTE), which is commonly marketed as 4G LTE, is a wireless data communications technology standard designed to replace CDMA and UMTS better known as 3G technologies. Japanese company NTT Docomo first proposed it in 2004. In 2005, studies on this new standard commenced and in 2007 the LTE/SAE Trial Initiative (LSTI) alliance was formed. This alliance was designed as a platform for global collaboration between operators and vendors whose goal was to verify and promote the LTE standard. In December 2008, the LTE standard was officially finalized. TeliaSonera was the first company to launch LTE service on December 14, 2009 in Sweden. Soon after, North American carriers started rolling out their own LTE networks in a limited capacity. When these networks were first being promoted, they were touted as 4G technologies, which was not the case. The first LTE networks developed were in fact not 4G technologies. It is commonly referred to as a “3.9G” system by many engineers and authors who are intimately familiar with this subject (Ulasien, 20113). LTE release 10, which is dubbed LTE-Advanced, is the true 4G evolutionary stage and has only recently been implemented. It is important to note that both LTE and LTE-Advanced are the same technology. It will just have extra additions that allow it to meet the 3GPP standards outlined to consider itself a true 4G technology. LTE is currently the global standard for 4G networks and is supported by all major cellular communication companies in the industry (Keston, 2014). It offers both the speed and capacity to handle the ever-growing rapid increase in data traffic. 65% of the world’s population is slated to have LTE coverage by 2019 (4G Americas, 2014).

How LTE Works LTE is different from previous telecommunication standards in that is uses an Internet protocol (IP) system to transfer data. This allows it to transmit large packets of data instead of small ones like CDMA, GSM and UMTS does. LTE also incorporates digital signal processing, which allows it to better adjudicate the transfer of data packets (Nohrborg, 2013). Cellular devices communicate with cell towers via the downlink and unlink. The downlink is when their tower sends a signal to the device; the uplink is the opposite process. LTE utilizes what is called Orthogonal Frequency Division Multiple Access (OFDMA) digital modulation scheme on the downlink (4G Americas, n.d.). OFDMA was designed to achieve high peal data rates in high spectrum bandwidth. OFDMA allows LTE to achieve download rates of 100 MBps or higher. This method is highly flexible in channelization, which is essential for LTE employment since LTE operates in various radio channel sizes (4G Americas, 2014). The sizes range anywhere from around 1.4 MHz to 20 MHz. On the uplink, LTE employs Single Carrier Frequency Division Multiple Access (SC-FDMA). This access method is similar to OFDMA but is more power efficient. Figure 2.0 shows a graphic representation of LTE at work.

LTE-Advanced As mentioned earlier in this paper, LTE and LTE-Advanced (LTE-A) are the same technology. LTE-A is merely and upgraded version of LTE, which meets true 4G requirements. With that being said, the focus of LTE-Advanced is higher capacity. This was done by implementing new functions such as carrier aggregation and increasing the use of multi-antenna techniques and support for relay nodes (Wannstrom, 2013). As Wannstrom mentions, “The most straightforward way to increase capacity is to add more bandwidth”. Carrier aggregation does this by combining multiple carriers at the device as shown in Figure 3.0. This in turn increases the user rates across the cell coverage area. Carrier aggregation also binds fragmented spectrum together. In LTE-Advanced, relay nodes are simply low power base stations that deliver enhanced capacity and coverage at cell edges (edge of cell tower signal bubble). This function can also be used to connect to remote areas without a fiber connection. This is due in part to the relay node being connected via a radio interface. Security in LTE Now let’s take a look at security for a second. Security in mobile communications is at the forefront of the media these days due to recent intelligence leaks. Since WiMax is not as prevalent as LTE this paper will go into detail only in security as it deals with LTE. LTE is a highly secure mobile broadband technology and is more secure than its 2G and 3G predecessors. The most important issue in wireless communications is in the network access security. This is what safeguards the user equipment’s communications with the network over the air interface. This particular portion of the network is its most vulnerable (Paolini, 2012). Network access security uses four main techniques to protect this, which are authentication, confidentiality, ciphering and integrity protections. During the authentication phase, the network and user equipment verify each other’s identities. Next, the evolved packet core (EPC) then verifies that the user equipment is not a cloned device and is approved to use the network’s services and vice versa. In the confidentiality phase, the user equipment’s identity is protected by avoiding the transmission of the individual mobile subscriber identification (IMSI) whenever possible over the air interface (EventHelix, 2012). The network thus identifies the user equipment using temporary identities. In the ciphering phase, the information is encrypted so intruders cannot read the signaling messages or data passed over the network. In the last phase, integrity protection, the network detects any attempt by intruders to modify signaling communications. LTE further implements integrity protection and ciphering in the Access Stratum and Non-Access Stratum, something legacy networks did not. Now that we have covered security at the network access level, this paper will discuss security at the network domain level. In a fixed network, information is often exchanged between two nodes. This interaction also needs to be secured. The network utilizes Internet engineering task force (IETF) security protocols to do this (Paolini, 2012). First the two nodes will authenticate each other using the Internet key exchange version 2 protocol. After which integrity and cyphering are added using Internet protocol encapsulating security payload (IP ESP). These are just some of the ways LTE secures transmission which are far more advanced than how legacy networks secure information. LTE security protocols make it by far much harder for an intruder to gain access and exploit data being transferred over the network. Companies that provide WiMax and LTE in the United States Up until this point this paper has focused on the history and functionality of both WiMax and LTE. Beginning with this section, this paper will start narrowing the focus to WiMax and LTE in the United States. In the United States there is a plethora of cellular service providers who offer LTE with the major ones being Verizon, AT&T, Sprint and T-Mobile. Of these providers, Verizon, AT&T and Sprint offer true 4G with the role out of their LTE-Advanced networks (Keston, 2014). Unfortunately, most cell phones are not designed for these networks. True LTE (carrier aggregation) capable handsets are just starting to become readily available. Clearwire was the first U.S. company to offer WiMax in the United States. It has since been bought out by Sprint. Sprint has since announced they will transition their networks to LTE and end its WiMax network by the end of 2015. As the major supporter of WiMax in the United States, Sprint’s announcement has been a major blow to domestic support for WiMax. Smaller organizations still employ WiMax in select cities, universities and businesses.

Future Plans for WiMax As it stands with all the major players in the telecom industry supporting LTE, the future of WiMax as a stand-alone technology seems very bleak. Realizing this, the WiMax Forum set forth plans to precede into the LTE dominated era. The future of WiMax can be viewed in three distinct directions. One of these directions is the integration of WiMax with LTE. In the latter part of 2012, the WiMax Forum seemingly realized WiMax was losing the battle with LTE. It then approved requirements for WiMax to be able to coexist and harmonize with LTE networks (Aldmour, 2013). This is viewed as putting WiMax on life support. A second direction outlined is employing WiMax as a private network, which supports aviation, utilities, and similar industries, which require dependable networking to manage operations. This method has often been termed “wireless Ethernet”. The third direction is for WiMax operators who hold amounts of Time Division Duplezing (TDD) spectrum to continue to grow within its traditional markets. This is the least likely approach if WiMax is expected to last beyond the next 5 years (Aldmour, 2013). The best option for WiMax is to integrate with LTE networks, which will give the technology greater flexibility and range. This option will still led to the eventual demise of WiMax in the United States as LTE continues to improve. It is safe to say that WiMax has lost the battle of 4G wireless technologies in the United States.

Future Plans for LTE A few years ago, WiMax had the advantage of precedence over LTE. Fast-forward to present day and WiMax no longer has an advantage over LTE. All of the major cellular communication companies are supporting LTE as the technology of present and future. This leads to its future looking very bright. 3GPP plans to release future updates to LTE technology, which will improve coverage, provide a far higher and steady data rate, and to meet the ever-growing high traffic demand. It will take LTE and especially LTE-A roughly a decade to control the cellular coverage in the United States (Kramer, 2014). This is due to the sheer amount of upgrading network operators need to do to their networks. Some provisions of current LTE releases have not even been employed yet. One of these provisions that are viewed as essential to the future of LTE is self-organizing networks (SONs). SONs are designed to make networks easier to plan, configure, manage and optimize. New high-level frequencies such as 3550 to 3650 MHz will also be found, extending 4G and making way for 5G. Research continues into 5G with forecasts predicting it being rolled out between 2022-2025 (4G Americas, 2014). 5G are expected to use these wider bandwidths and higher frequencies to achieve much greater data rates than its predecessor. It is important to note that 5G will not necessarily be an entirely new technology as 4G was. 5G will still be based on LTE technology. Some of the following concepts and capabilities of 5G that have been discussed are:

• Data rates of 10 Gbps or higher, roughly 10 times that of 4G
• Wide radio channels
• Low latency of about 10 times lower than that of 4G.
• The using of unlicensed and licensed frequency bands
• Spectrum sharing
• Simultaneous connections between user equipment and multiple base stations. This would also allow for user equipment to span multiple access technologies and frequencies.
• Smart networks that can perform functions automatically based on user activity or location

The planned gradual migration from LTE to LTE-Advanced is depicted in Figure 4.0

Technological Implications in the U.S. While WiMax may be on its last leg in the United States, LTE is continually gaining momentum. LTE is the standard 4G technology in which all major mobile communication networks will be built off of. It will allow for companies to add more users to their networks as well as solve the ever-increasing demand for data. Like WiMax was slated to be, LTE has taken up the mantle of potentially being used in public services sectors such as public safety, transportation, traffic lights, utility, aviation, etc. LTE continues to redefine the mobile communications landscape in the United States and will continue to do so over the next couple decades.

Comparison and Contrast of WiMax and LTE WiMax and LTE are both 4G technologies that are quite similar. They both are all IP technologies, support advanced MIMO and use similar modulation technology based on OFDM. Now besides those similarities, LTE and WiMax have many differences. WiMax uses channel bandwidths of up to 40 MHz while LTE uses different channel bandwidths from 1.4 MHz to 100 MHz (Bartolic, 2014). LTE uses different modulations for both the uplink and downlink while WiMax uses the same modulation for both. WiMax has frame duration of 5 ms and LTEs is 10 ms. WiMax can only handle speeds up to 75 mph while LTE can handle up to 280 mph. It is cheaper to build a WiMax network than it is for an LTE network. Some of the major advantages LTE has over WiMax deal with its backwards compatibility with previous mobile technologies and its better power consumption for mobile terminals. WiMax is a better choice in terms of cost efficiency in developing countries (Evslin, 2008).

Conclusion Mobile broadband technology has become the leading edge in both development and innovation for networking, application development and computing. Currently, more smartphones are shipped than personal computers. This creates an ever increase in the demand for faster access to data. Based on all the evidence outlined in this paper, it is clear which mobile broadband technology will lead the United States into the future. WiMax once had a sizable advantage over LTE; it has since been relegated to a niche technology. While WiMax still may be appropriate under certain circumstances, it will never directly compete with LTE again. The end of the WiMax market already appears over. LTE is the current global standard for mobile broadband technologies that will lead the world into the next decade, with the United States leading the world in LTE deployment. LTE will address market needs by implementing carrier aggregation, Wi-Fi integration, operation in unlicensed bands and other features. Both LTE and LTE-Advanced will remain the most robust of the mobile broadband technologies and an optimum infrastructure for realizing the potential of the wireless market. The next decade (2020s) looms the possibility of 5G technology, which could create an entirely new stage that will not only offer blazing speeds but could potentially be an effective alternative to wired broadband.

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