Transmission Power Control Methods For Wireless Networks

Transmission Power Control Methods For Wireless Networks

Prachi Waghmare

MITCOE

Prof .Sunil .B. Somani

Associate Professor,MITCOE

Prof. Anjali.R. Askhedkar

AssistantProfessor,MITCOE

Abstract

Mobile Adhoc network is an infrastructure-less multihop network where each node communicates with other directly or indirectly through intermediate nodes. As most of the todays routing protocol are based on fixed power for transmission. We take an alternative approach of variable range transmission .Transmit power control is important in wireless Adhoc network as it can impact on battery life and the traffic carrying capacity of the network. We can investigate the effect of common power and the impact of variable range for signalling overhead of a routing protocol as a function of transmission range which maximizes the capacity available to nodes .we compare how routing protocols based on common range and variable range impact number of system performance metrics such as connectivity, traffic carrying capacity and power conserving properties of wireless networks. For simulation NS2 is used.

Key words-MANET,power control, traffic capacity.

1. Introduction

   The problem in wireless network is the choice of power level as power has multidimensional effect on the performance of the whole system. Power levels affect the connectivity of network and consequently the ability to deliver the packets .The transmission power control approach can be extended to determine the optimal path that minimizes the total transmission energy required to deliver data packets to the destination,in contrast to simply establishing correct and efficient routes between pair of nodes ,one important goal of routing protocol is to keep the network functioning as long as possible .This goal can be achieved by minimizing mobile nodes energy not only during active communication but also when they are inactive. Communication energy required to transmit and receive data packets or energy during inactive periods. The active communication energy can be reduced

   by adjusting each nodes radio power just enough to reach the receiving node but not more than that. This transmission power control approach can be extended to determine the optimal routing path that minimizes the total transmission energy required to deliver data packets to the Destination .Another approach to save the inactive energy is by switching its mode of operation into sleep/power-down mode or simply turn it off when there is no data to transmit or receive .Another important approach is load distribution where it is required to balance the energy usage among the nodes and to maximize the network life time by avoiding over utilized nodes when selecting a routing path. The following table shows approach and the suitable protocols.

   Table I: showing Protocols for different approach

   Approach		Protocols	Goal
   Minimum active communication Energy	Transmission Power Control	MER COMPOW	Minimize the total transmission energy
   	Load Distribution	LEAR	Distribute the load to energy rich nodes
   Minimize Inactive Energy	Sleep/power Down Mode	SPAN	Minimize energy consumption during inactivity

2. Proposed work

   We review the protocol which aims to operate all nodes at a common power level which is chosen to be the smallest power level at which the network is connected .Now the question is what should be the common power ?choosing an excessively high power level causes excessive interference and low power results in fewer links and

   hence network partitioning. The power has to be just right, the network is still connected and there is no excessive interference. In [2] the authors suggest that, when considering the physical layer only, reducing the transmission power is a better approach because this increases the traffic carrying capacity of the network second, power control affects the Connectivity of the resulting network. By a connected network, we mean a network in which any node has a potential route of physical links (or forwarding nodes) to reach any intended receiver node. A high transmission power increases the connectivity of the network by increasing the number of direct links seen by each node, but this is at the expense

   3

   2

   no.of nodes

   1

   Transmission Range Vs Nodes

   60

   40

   Rmin

   20

   0

   Broadcast Range

   Fig 1: Transmission Range Vs Nodes

   From the figure we come to the conclusion that value of

   of reducing network capacity. In [3] the authors assume

   that all nodes use the same common transmission power.

   m in

   R

   com

   decreases as the density of nodes increases .The

   This power is varied until a connected tree is constructed. We show that the use of a minimum spanning tree can lead toward a lower total weight than a tree based on common-range transmission links that minimally avoids network partitions .The type of power control used can also impact the connectivity and performance of the network layer. Choosing a higher transmission power increases the connectivity of the network. Routing protocols can take advantage of fully connected networks to provide multiple routes for a given source-destination pair in cases where some nodes or links fail however; this goal is achieved at the expense of reducing network capacity and energy-savings. In addition, power control impacts the signalling overhead of routing protocols used in mobile wireless ad hoc networks. Higher transmission power decreases the number of forwarding hops between source-destination pairs, therefore reducing the signalling load necessary to maintain Common-Range Transmission Control. We analyze the case where all nodes use a common transmission range (Rcom) to communicate with peer nodes in the network. This case is of particular importance because a common transmission range approach is the foundation of most routing protocols in ad hoc networks

   com

   1. Common Range Transmission :we investigate the case where all nodes use a common transmission range(Rcom).it is not possible to arbitrarily reduce Rcom to any value there is a lower bound which is defined as Rm in the critical transmission range for connectivity of

      n randomly placed nodes in A square meters is

      traffic carrying capacity of the network is bounded by the value of range which motivates the study of variable range.

   2. Variable Range Case

OVEHEAD PACKETS

In this the transmission power is varied and the effect of this variance is compared with signalling load and network partition

CONTROL OVERHEAD

10

5

OVERHEAD

1 2

3

POWER

4 5

0

Fig.2: Signalling Load Vs Power

Fig.2 shows the signalling overhead of the routing protocol versus the transmission power and node speed. As shown in Fig.2 the number of signalling packets is low for high transmission power values and grows in an exponential manner when the transmission range approaches the minimum common transmission range

(1 )

Aln n / n

. (1)

TRANSMISSION DELAY

0.8

0.6

0.4

0.2

0

1

1

5

4

3

TIME

2

DELAY 1

Fig.3: Transmision Delay Vs Time

As shown in fig 3 the Delay is reduced with respect to time .

THROUGHPUT

throughput3

throughput2

throughput1

THROUGHPUT

250000

200000

150000

100000

50000

0

1 2 3 4 5

POWER

Fig.4 :Throughput Vs Power

As shown in figure 4 the throughput considerably increases with the variation in transmit power which is a good option to constant power transmission

3) Conclusion

Power control improves network throughput. It reduces the retransmission Probability or increases the network spatial reuse ratio .Results indicate that a variable-range transmission approach can outperform a common-range transmission approach in terms of power savings and increased capacity. We can balance the power consumption over the network .firstly with common range and then we can go for the variable range transmission.

References:

1. B Chen, K Jamieson,Balakrishnan R Morris,"SpanEnergy- Efficient Coordination Algorithn for Topology Maintenanc in Ad Hoc Wireless", Proc,ACM Mobicom'01 .

   Delay3

   Delay2

   Delay1

2. P.Gupta and P. R. Kumar, Critical Power forAsymptotic Connectivity in Wireless Networks,'', in StochasticAnalysis pp. 547-566

3. Swetha Narayanaswamy, Vikas Kawadia, Sreenivas,and

   P. R. Kumar, Power Control in Adhoc Networks COMPOW protocol,'' proc of European Wireless 2002.Next Generation Wireless Networks: Technologies, Protocols, Sevices and Applications .pp. 156-162, Feb 2002.

4. P. Waghmare.S. Somani, and A. Askhedkar,Power control Methods for Wireless Networks, proc NCFAEE pp.27-29,

March 2011

[5 Eun-Sun Jung, Nitin H. Vaidya , A Power Control MAC Protocol for Ad Hoc Networks, (MobiCom2002), Atlanta, Georgia, USA, Sept. 2002.

1. J. Gomez and T. Campbell ,Variable-Range Transmission Power Control in Wireless Ad Hoc Networks, IEEE transactions on mobile computing, vol. 6, no. 1, January 2007

2. S.Singh and C.S. Raghvendra, PAMAS power aware multi-access protocol with signaling for ad hoc networks, ACM SIGCOMM computer Communication review vol 28 Issue 3,july 1998

3. P. Gupta and P.R Kumar , The Capacity of wireless

   Networks, IEEE Trans.Information Theory, vol.46, no.2, 2000

4. Chansu Yu, Ben Lee and Hee Y Youn, Energy Efficient Routing Protocols for Mobile Ad Hoc Networks,Wireless Communications and Mobile Computing Vol 3, Issue 8, pp 959973, December 2003

5. S.Doshi and T.Brown, Minimum Energy Routing Schemes for a Wireless Adhoc Network, IEEE Infocomm 2002

6. D.B.Johnson and D.A.Maltz , The Dynamic Source Routing protocol for Mobile Adhoc networks, Draft IETF 2003

[12]S.Y.Ni,Y.C Tseng,Y.S.Chen and J.P Sheu, The Broadcast Problem in a mobile Ad Hoc Networks, proc ,ACM Mobicom,1999

1. T.Brown,S.Doshi and X.Zhang Optimal power aware routing in a wireless Ad hoc network ,IEEE LANMAN 2001 Workshop proceedings,pp.102-105

2. S.Singh, M.Woo and C.Raghvendra , Power aware routing in mobile Ad hoc networks, Proc of MOBICOM,1998,pp.181- 190

3. Xiao-Hui Lin, Yu-Kwong Kwok, and Vincent K. N. Lau , New Power Control Approach forIEEE802.11AdHocNetworks,

The IEEE 2002 International Symposium on Personal, indoor and Mobile Radio Communication Proceedings