Raising the Stakes in 3.5 GHz: LTE-Advanced Achieves 1 Gbps

1Gbps LTE-AThe 3 GHz frequency bands stands at the upper limit of what is considered today as viable spectrum for mobile communications. But bands 42 (3400 – 3600 MHz) and 43 (3600 – 3800 MHz) are not only the ‘last frontier’, but more importantly, they provide the widest spectrum of any other band (200 MHz). Additionally, the relatively short wavelength is perfect to enable advanced antenna system technologies based on beamforming and massive MIMO techniques. Couple these with the limited range of propagation that limits interference and the 3.5 GHz band becomes an interesting proposition for capacity starved operators. Read more of this post

Further Enhanced ICIC (FeICIC)

FeICIC LTE-AdvancedGuest post by Faris Alfarhan*

In an earlier post, R10-LTE enhanced inter-cell interference coordination (eICIC) techniques for heterogeneous networks were discussed, along with the concept of small cell range expansion. The purpose of cell range expansion is to offload more traffic from macro cells to small cells and hence achieve larger cell splitting gains. By adding a cell selection bias, the service area of small cells increases and more users are offloaded to small cells. The need for heterogeneous networks interference management schemes stems from the fact that users in the small cell range expansion area are vulnerable to stronger interference signals than useful signals from the associated serving small cell. In the previous post, it was explained how time domain partitioning based eICIC schemes – known as Almost Blank Subframes (ABS) – could be used to control the interference on the data channels in the range expansion region. Further, carrier aggregation based techniques – known as Cross Carrier Scheduling – could be used to control interference on the control channels (such as the PDCCH, PCFICH, and PHICH channels). However, R10 eICIC schemes did not address interference control on cell-specific reference signals (CRS), which cannot be blanked in order to ensure backward compatibility with R8 and R9 UEs. In this post, R11 improvements to eICIC schemes are discussed, along with the shortcomings of R10 eICIC schemes. First, the concept of Reduced Power Almost Blank Subframes (RP-ABS) is explained along with its advantages over ABS. I then discuss the R11 techniques of Further enhanced ICIC (FeICIC) to control the interference on CRS resources. Read more of this post

Carrier Aggregation and the Road to Cognitive Radio and Superwide Spectrum

Carrier AggregationOften, the least hyped technologies are the most effective, get the widest adoption, and have the greatest impact. Carrier aggregation is one such technology that I don’t think it received its fair share of attention. LTE did bring a number of new features that were not available in 3G, such as MIMO. But MIMO was already deployed in other technologies including both Wi-Fi and WiMAX. Carrier aggregation on the other hand developed by the requirement to achieve higher data rates in LTE network. True channel bonding is a feature of Wi-Fi, but it applies to adjacent channels. Carrier aggregation on the other hand combines distinct channels in different bands. From that perspective, I am not aware of any wireless technology that has implemented carrier aggregation. Read more of this post

On LTE-Advanced and Carrier Aggregation

LTE-AdvancedNews of LTE-Advanced is making headlines. SK Telecom aggregated two 10 MHz carriers in 800 and 1800 MHz to achieve 150 Mbps downlink throughput with a version of the Samsung Galaxy S4 handset built upon Qualcomm’s Snapdragon 800 SoC. Verizon announced that its LTE network is nearly complete and suggested carrier aggregation (CA) is the next step. AT&T on the other hand has plans to use carrier aggregation over its 700 MHz unpaired lower D and E blocks. Read more of this post

Evolution of the Air Interface: From 2G Through 4G and Beyond

Below is a link to a recent presentation I made to the local IEEE Ottawa Chapter and the Alliance of IEEE Consultants Network (AICN). I trace the evolution of the air interface of wireless systems from 2G (GSM, CDMA/IS95) through 3G and LTE to LTE-Advanced. Read more of this post

Reaching The Limits of The Physical Layer: The Slow Shift To Enhancing Efficiency.

There is a general view that we are rapidly approaching the capacity limits of the physical layer. But as demand for capacity continues to grow, the supply of capacity is tapering off. What to do about this and how to continue to inject capacity is being addressed at standardization meetings. Let’s take a quick look at some of these techniques and some of their challenges: Read more of this post

Meeting IMT-Advanced Requirements: A Look Under the Hood of Next Generation Wireless Networks.

IMT-Advanced LogoThe International Telecommunication Union (ITU) has just approved LTE-Advanced and WiMAX-Advanced (aka WiMAX 2.0) as part of the IMT-Advanced standards. Aside of marketing catch phrases like “putting fiber optical speed on your mobile phone,” the statements about efficiency – being able to transfer higher data rates in lesser bandwidth – are what the industry will be grappling with. Read more of this post