Evolved EDGE

Evolved EDGE is a bolt-on extension to the GSM mobile telephony standard, which extends the previous EDGE upgrade to achieve theoretical speeds of up to 1 Mbit/s with relatively low cost and ease. Also called EDGE Evolution, it promises real world downlink speeds of up to 600kbit/s with seamless transitions to and from 3G coverage, which should serve to extend the life of GSM networks in areas where the additional cost to go full 3G isn't necessarily justified.[1] As of 2009, there are no commercial networks which support Evolved EDGE standard (3GPP Rel-7).

There is a considerable research and development happening throughout the world[1] for this new technology. As of 2008, there are many major wireless network & infrastructure providers who have invested in this technology. However successful trial has been made by Nokia Siemens and "one of China's leading operators" demonstrated in a live environment.[1]

Motivation

The main intention of increasing the existing EDGE throughput is that many operators would like to upgrade their existing infrastructure rather than invest on new network infrastructure. Mobile operators have invested billions in GSM networks, many of which are already capable of supporting EDGE data speeds up to 236.8 kbit/s. With a software upgrade and a new device compliant with Evolved EDGE (like an Evolved EDGE smart phone) for the user, these data rates can be boosted to speeds approaching 1 Mbit/s (i.e. 98.6 kbit/s per timeslot for 32QAM). Many service providers may not invest on a completely new technology like 3G networks.

Major features

Reduced Latency

With Evolved EDGE come three major features designed to reduce latency over the air interface.

In EDGE, a single RLC data block (ranging from 23 to 148 bytes of data) is transmitted over four frames, using a single time slot. On average, this requires 20 ms for one way transmission. Under the RTTI scheme, one data block is transmitted over two frames in two timeslots, reducing the latency of the air interface to 10 ms.

In addition, Reduced Latency also implies support of Piggy-backed ACK/NACK (PAN), in which a bitmap of blocks not received is included in normal data blocks. Using the PAN field, the receiver may report missing data blocks immediately, rather than waiting to send a dedicated PAN message.

A final enhancement is RLC-non persistent mode. With EDGE, the RLC interface could operate in either acknowledged mode, or unacknowledged mode. In unacknowledged mode, there is no retransmission of missing data blocks, so a single corrupt block would cause an entire upper-layer IP packet to be lost. With non-persistent mode, an RLC data block may be retransmitted if it is less than a certain age. Once this time expires, it is considered lost, and subsequent data blocks may then be forwarded to upper layers.

Downlink Dual Carrier

With Downlink Dual Carrier, the handheld is able to receive on two different frequency channels at the same time, doubling the downlink throughput. In addition, if second receiver is present then the handheld is able to receive on an additional timeslot in single-carrier mode, because it may overlap the tuning of one receiver with other tasks.

Higher Modulation Schemes

Both uplink and downlink throughput is improved by using 16 or 32 QAM (Quadrature Amplitude Modulation), along with turbo codes and higher symbol rates.

See also

References

External links

This article is issued from Wikipedia - version of the Tuesday, February 04, 2014. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.