The higher data carrying capacity of access technologies such as HSPA+ and long term evolution (LTE) can be effective in providing mobile broadband services to end-users only when these are complemented by supportive and capable backhauls. Over a period of time, optical fibre has evolved as the most practical wired solution for backhaul as well as for the backbone network, given its extraord-inary capacity. However, its deployment, especially in India, involves multiple challenges such as difficult terrain, long deployment time, logistics issues, heavy government levies for obtaining right-of-way permissions, and cumbersome approval procedures. In view of these challenges, microwave technology has become the most widely used medium for backhaul connectivity. However, microwave does not have the matching capabilities of fibre and therefore, is not sufficient to handle the growing data demand.
Operators in many countries where high speed LTE services have been launched have started exploring new wireless spectrum bands that are scalable and flexible in providing the necessary bandwidth, and allow them to reduce wireless backhaul expenditures. Two such higher frequency bands are the E-Band (71 GHz-76 GHz/81 GHz-86 GHz) and the V-Band (57 MHz-64 MHz), which cater to the increasing capacity/traffic requirements. While the E-Band is optimised for last mile, zero-footprint macrocell backhaul, the V-Band is optimised for microcell/ small cell backhaul.
With operators installing backhaul solutions in these bands, mobile network architecture is evolving from a single-layer access network to a multilayer access network. In a multilayer network, macrocells provide capacity and coverage while microcells or small cells provide high capacity hotspots.
The small cell technology in the V-Band enables mobile carriers to reduce the load on their networks and deliver data services seamlessly and cost effectively to end-users by riding on a partner Wi-Fi network. This process, known as Wi-Fi offload, works efficiently since all smartphones come preconfigured to access data services over a Wi-Fi network in the range of a mobile network. Meanwhile, macrocells in the E-Band can effectively fill gaps in the backhaul where fibre cannot be deployed or needs to be complemented.
Regulatory framework
According to the ITU Radio Regulations, the 71 GHz-76 GHz and 81 GHz-86 GHz bands are available for fixed line as well as mobile services. Many countries have opened the E-Band for outdoor point-to-point communication.
The Federal Communications Commission (FCC) was the first to regulate and allocate E-Band spectrum in the US in 2003 through a light licensing approach, followed by Ofcom in the UK in early 2007. In the light licensing approach, the spectrum charge comprises only the cost of administering the allocation process. As the E-Band allows a high level of frequency reuse, the process for allocation of frequencies can be automated, thus keeping the cost of administration low. Regulators worldwide are also following FCC and Ofcom?s lead, by allocating this spectrum in a steady manner. Australia and Russia are some examples of spectrum in this band being utilised for backhaul connectivity.
In comparison, the 60 GHz band is a licence-exempt spectrum band in countries like the US, the UK, Australia and Japan. Although the ecosystem for this band is less developed and the equipment available for it is also expensive, efficient planning can solve the bandwidth crunch.
Commercial availability
Equipment for both the V-Band and E-Band is commercially available from a number of manufacturers. Traditional vendors like Ericsson, NEC, Huawei, Alcatel-Lucent, Nokia and ZTE are the biggest players in the E-Band market while microwave vendors such as DragonWave, Intracom, SIAE and Siklu are giving them tough competition. Some of them are even developing their own chipsets, giving stiff competition to chipset vendors such as Qualcomm and Broadcom.
In the V-Band space, products are being sold by companies like BridgeWave Communications, LightPointe, DragonWave, Inc., Proxim Wireless, Sub 10 Systems and Siklu. Samsung is also emerging as a key player in this domain. It has reportedly developed a Wi-Fi technology with speeds that are up to five times faster than the current speeds being used. This new 60 GHz Wi-Fi technology is capable of enabling record breaking data transmission speeds of up to 4.6 Gbps. The current Wi-Fi speed for consumer electronic devices stands at around 866 Mbps or 108 MB per second.
Case for India
The requirement for mobile backhaul capacity is anticipated to grow significantly due to the increasing use of latest multimedia and other data-centric applications, especially in urban areas. The large-scale launch of LTE networks will only escalate this demand. Given the spectrum crunch in the industry, exploring the option of using unlicensed spectrum bands for data offloading has become a necessity for telecom operators. Policymakers, therefore, need to formulate guidelines for using this spectrum.
The Telecom Regulatory of India has proposed to the Department of Telecommunications (DoT) that the usage of high capacity backhaul E-Band and V-Band should be explored for allocation to telecom service providers in order to increase broadband penetration in the country. The department also seems to be in favour of promoting the use of these spectrum bands. It is soon likely to seek the regulator?s views on freeing up the 60 GHz frequency band for Wi-Fi offload deployments in order to address a potential spectrum crunch in the 2.4 GHz band, which is currently used for delivering Wi-Fi services. DoT is also likely to seek the views of the regulator on potential changes in the licence norms and interconnect agreements of internet service providers, which will have to partner with mobile carriers to facilitate such Wi-Fi offload services.
Conclusion
Summing up, with the growing data proliferation, there is a greater need to frame appropriate guidelines for carriers in the E-Band and V-Band in line with the international trend. These bands can help operators cater to the high throughput needs that will be generated by the roll-out of technologies like LTE.
