Swiss


Wireless networks are under increasing strain, as portable hardware increases. Handheld demand, it seems, may ultimately begin to overwhelm the finite capacity of current architecture. Pre-empting an impasse, telcommunications research has begun to consider how systems based around a self-organised hierarchy could enhance performance and function at vast scales.


Next-generation networks for wireless communications


As mobile phones get smarter, there’s a corresponding need for intelligent infrastructures, capable of meeting our insatiable appetite for content. There are over one billion smartphones currently in circulation and, around the mid-teens, it’s anticipated that a rubicon will be crossed. For the first time, mobile internet usage will exceed desktop demand. “The recent multiplication of wireless


devices – including mice, smart phones and tablets – requires some innovative support, if this trend is to be sustained. needs more


Informational


in future may be than current


networks can tolerate” explains Olivier Lévêque, a Swiss researcher based at the École Polytechnique Fédérale de Lausanne. “They aren’t durable in the long term.” A specialist in wireless


c o m m u ni c a t i o n s , Lévêque’s work over the past decade – including a year at Stanford in the US – has begun to challenge some


of the prevalent


suited to permanent, wired networks, its utilisation in a wireless context reveals a number of handicaps. The most tangible of these – woefully


and familiar to


browsers attempting to access the web at peak times – is that, as users increase in number, the communication rates available to them rapidly decay. Nodes in the middle of the network are frequently overloaded, becoming links


in a “The recent multiplication of


wireless devices – including mice,


smart phones and tablets – requires some innovative support,


if this trend is to be sustained”


orthodoxies in the field. Typically, wireless networks exploit a ‘multi-hop’ structure, borrowed from their fixed counterparts. Sending ‘packets’ of data from source to destination, such systems employ a series of intermediate relays. Although this arrangement is well-


50


over-stressed linear


chain.


Moreover, unlike their wired


counterparts,


wireless signals are not isolated as they travel between the points of transmission and reception. Instead, they interact in complex ways – with emissions from neighbouring frequently


units ‘overheard,’


creating interference which jeopardises signal integrity. In conventional strategies, these must be filtered out or suppressed; but, according to theoretical work


published by Lévêque and his associates, they could be radically incorporated into designs which render them an asset. “Claude Shannon – the godfather of


modern information theory – showed in the fifties that in the presence of noise


communication on a channel can only be established reliably at a rate below a certain threshold called ‘capacity’. Above this threshold, the signal would become irreparably


compromised,” explains the


researcher. In the early noughties, numerous papers set out to prove from an information theoretic perspective that interference is indeed a fundamental limitation in wireless networks, preventing their capacity to scale up with the number of users. However, after trying to authenticate it using a negative approach, the impossible proved intriguingly tangible for Lévêque. “Interference


can be treated


constructively,” he contends. By introducing a sophisticated form of co-operation between the various nodes in a wireless network, communications might become far more robust. The scheme would make use of the network nodes as virtual multiple antenna systems within units transmitting and receiving data, allowing numerous streams of information to be simultaneously emitted


and detected. By


collectively Insight Publishers | Projects


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132