Publié le 22 février 2013
Looking forward to Mobile World Congress
The Mobile World Congress (MWC) is the primary industry event for the mobile communications industry. Every year major industry players get together to share their achievements and explore the future of technology and services. There will be a significant amount of exhibition space at the event, sessions dedicated to applications, and terminals and systems running over mobile networks. There will also be a significant number of companies sharing their solutions for improving the infrastructure. I predict that the three major industry changes that will be the focus of infrastructure companies at the MWC 2013 show are as follows:
- LTE Deployment
- DAS/Small Cells and Heterogeneous Networks (HetNets)
- Evolution of Radio Access Network Transport
According to ABI research, so far 91 million LTE devices have been shipped to customers around the globe. Over 95% of these devices were sent to North America, Korea and Japan. A large number of these devices are still being used on 3G networks, because LTE subscription adoption is lagging the device shipments. Nevertheless, it is anticipated that the number of LTE subscriptions will have risen to over 600 million by the end of 2016.
The primary objectives behind deploying LTE networks are to add new capacity by exploiting previously unused spectrum (digital dividend or 2.6 GHz band) while relying on the most spectrally efficient wireless technology choice. Mobile network operators (MNOs) aim to decrease their unit costs (dollars per megabytes delivered) while moving ahead with the new network deployment.
LTE deployments change some fundamentals of mobile networks, including:
- Flatter radio access network (RAN) that requires fundamental change at the backhaul level (addressed as a distinct item).
- Higher scale in core networks that allow for both centralized and distributed network designs relying on a common IP/MPLS transport network.
- Introduction of real-time services over IP transport that require quality-of-service differentiation across the core, transport and radio access networks.
- More intelligence for the operations of the network using technology components such as self-optimizing networks (SON), minimization of drive testing (MDT), and deeper inspection of user traffic for rapid troubleshooting and monitoring.
DAS, Small Cells and Heterogeneous Networks
Even with additional spectrum and the introduction of LTE networks, there will be geographical areas in mobile networks where demand is projected to exceed the capacity provided by the macro layer. Initially, the majority of such demand/capacity mismatch will be indoors, e.g., in high-rise buildings, airports, hotels and shopping malls. There may also be outdoor locations, such as stadiums and core downtown shopping districts. The industry’s answer to this demand/capacity mismatch is centered on three key areas:
- Distributed antenna systems (DAS) were traditionally used as indoor coverage-improvement solutions. In the last few years, indoor DAS are also being deployed as capacity enhancement, especially if existing cabling plants (ideally fiber, but also Cat6) allow for the addition of more remote radio heads. A more interesting recent trend is the adoption of DAS for outdoor environments. In a single cell site, this is typically done as a coverage-enhancement solution, since the fiber link replaces the coax cable between the bottom of the tower electronics and the top of the tower antenna. This saves around 2 dB for the link budget. A more recent use of DAS-like architecture is Cloud RAN (C-RAN), where a centralized base-band unit connects to multiple remote radio heads over a large area (up to 20 km). Major deployment work in preparation for the introduction of DAS lies in deploying and characterizing fiber plants to support connectivity between central electronics and remote radio units.
- Small cells have been around for a long time for mobile networks, but they have become more important with the increase in data traffic demand. Currently, industry has settled on pursuing operator-managed small-cell deployments both indoors and outdoors. This is contrary to the earlier push by some operators to adopt subscriber-controlled femtocells. Primary deployment work for small-cell introduction is the deployment of suitable backhaul transport capable of providing the needed capacity and allowing the level of synchronization at the right operational price point.
- Heterogeneous Networking refers to the combined use of multiple layers of RANs, as well as multiple radio-access technologies. One important aspect of HetNet is coordination among layers of radio coverage (e.g., macro, micro and pico), combined use of wide-area mobility technology such as HSPA or LTE, and local area networking technology such as Wi-Fi. The primary work needed to make HetNet a reality involves building network intelligence capabilities, implementing and deploying network controllers, integrating legacy elements to new nodes, and coordinating resource allocation (such as frequency in LTE-A) among different radio network layers dynamically.
Evolution of Radio Access Network Transport
Transport networks for RANs have been undergoing a significant change since 2007/2008, when mobile operators started to deploy high speed packet access (HSPA). The introduction of high-throughput radio interfaces and the significant difference between maximum and average data rates over the radio interface necessitated the introduction of packet-based transport technologies. Since the inception of LTE deployments in 2010, this trend has accelerated. Going forward, eventual deployment of LTE-A will require higher throughput and time/phase synchronization among base stations. Furthermore, deployment of C-RAN requires that metropolitan transport networks be able to carry fronthaul traffic (between centralized baseband units and distributed remote radio heads). It is expected that future transport networks will have a converged architecture, where both fronthaul and backhaul traffic will be transported over a variety of physical-layer options.
The following list highlights specific changes taking place in transport networking for RANS:
- Higher throughput for the transport is driven by higher peak bandwidth of LTE and LTE-A, as well as LTE-A coordinated multipoint (CoMP) requirements.
- The need for integrated QoS due to mixing packet-based synchronization traffic, real-time customer traffic (such as voice and video) and background best-effort traffic on the same transport link in order to provide the best efficiency.
- Synchronization requirements for mobile networks are moving towards incorporating time/phase synchronization in addition to the traditional frequency synchronization. Specifically, LTE-A accelerates this change.
- Fronthaul transport requirements are rather new and have become important with the deployment of C-RAN. Currently, the only transport choice for fronthaul is fiber, either point-to-point or CWDM/DWDM multiplexing formats. It is expected that in the future, more efficient (possibly compressed) interfaces will allow hybrid transport architecture for fronthaul and backhaul.
- A diverse set of physical layer protocols is already a reality, but will become even more important with massive deployment of small cells. Use of copper-based transport options along with various wireless transport technologies will allow small cells to be deployed and operated at the right cost levels.
With all the glamour and glitz surrounding terminals and applications, infrastructure will probably take the back seat at this year’s MWC. However, I am confident that many attendees will be flocking to the event to hear the latest product pitches for infrastructure. This is going be a good show. Now let’s hope that the new venue is easy to access, as I’m planning to get there by public transport.