Advanced Heterogeneous Wireless Communication Technique using ...

2016 International Conference on Next Generation Intelligent Systems (ICNGIS)

Advanced Heterogeneous Wireless Communication Technique using Vertical Handover Scenario Sagar Shriram Salwe1 , Student Member, IEEE, Krishna Naik2 , Member, IEEE Electronics Engineering Department Defence Institute of Advanced Technology Pune, Maharashtra Email: sagar [email protected] , [email protected] Abstract—Wireless network existing in the present generation of communication is homogeneous wireless network, which work in between the same connectivity up to the particular region with specified data rate by standard. We are proposing a heterogeneous wireless network which work in coexistence with other network, which evolve together to communicate over a large region of operation and provide Always Best Connected (ABC) mode and improve the user experience in communication. The vertical handover mechanism proposed is mobile assisted and governed by physical layer handover using received signal strength as a threshold criteria. For simulation purpose we considered Bluetooth and Wi-Fi simulink model as both are working in ISM band. Simulations are performed in Matlab simulink environment.

I. I NTRODUCTION Smart mobile in todays world involve different communication scheme (Bluetooth, Wi-Fi, GSM, CDMA, IR communication). All these communications scheme work independently without interference, as all are operating with the different frequency of operation, variation in power level of transmitter and different modulation scheme. Homogeneous wireless communication is an intra-network which communicate within the same network, with an horizontal handover mechanism. By using this mechanism mobile node can extend region of operation by changing base station and by changing channel parameters. Heterogeneous wireless communication works by internetwork communication between the different communication technologies such as Bluetooth, Wi-Fi, GSM, CDMA using vertical handover mechanism. This paper proposes handover between the heterogeneous operating wireless technology. IEEE 802.21 is an Media Independent Handover (MIH) standard developed for communication among the heterogeneous wireless technologies [1]. The standard developed for handover scenario is independent of the media. Various wireless technologies which are with the different data, sample rate and region of operation. By using vertical handover scenario the limited access of particular communication scheme, overcome by other communication schemes with enhanced high data rate and large coverage (Region) of operation. Thus the wireless network formed by vertical handover scenario forms heterogeneous wireless network. For simulation purpose we considered vertical handover of Bluetooth data through the Wi-Fi in physical layer by

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adjusting the raw data sample and data rate adjustment by using the delay adjustment and buffer adjustment mechanism. Next generation wireless networks will go beyond the pointto-point or point-to-multi point paradigms of classical wireless networks. They will be based on complex interactions, where the involved nodes cooperate with one another in order to improve the performance of their own communication and that of the global network. Cooperative communications based on relaying nodes have emerged as a promising approach to increase spectral and power efficiency, network coverage, and to reduce outage probability [2,3]. In this paper we proposed a new mechanism to cater the complexity between various networks by considering two basic network technologies like WLAN and WPAN [4]. Here we are considering the high data transmission by using Bluetooth communication scheme.

Fig. 1. Future Global Communication Mechanism

Future trends in the wireless technology are to share and exchange data between the different wireless technology. The future devices can able to share data within the diverse technologies with the help of vertical handover. The vertical handover helps to achieve this by changing the media from one communication scheme to another by using MIH function which will be based on the signal strength, bandwidth of operation or by considering transferred packet rate. So by this we can use the best from the technology and can explore more features such as power level reduction, data rate increment and increase in range of operation. In paper we considered the Bluetooth frequency hoppping and Wi-Fi 802.11b model from Matlab simulink environment.

2016 International Conference on Next Generation Intelligent Systems (ICNGIS)



II. H ANDOVER AND IT ’ S TYPES Mobility is the most important feature of wireless communication system. Usually, continuous service is achieved by supporting hand off (or handover) from one cell to another. Handoff is the process of changing the channel (frequency, time slot, spreading code, or combination of them) associated with the current connection while a call is in progress. It is often initiated either by crossing a cell boundary or by a deterioration in quality of the signal in current channel. Handoff is divided into two broad categories hard and soft handoff. In hard handoff, current resources are released before new resources are used which is break before make; in soft handoff, both existing and new resources are used during the handoff process which is make before break. Poorly designed handoff schemes tend to generate very heavy signaling traffic and, thereby, a dramatic decrease in quality of service (QoS). The other broad classification of handover on the basis of connectivity at the other end are horizontal handover and vertical handover. Horizontal handover is within same access technology whereas the vertical handover is the mobility between two diverse access technology, based on the quality of signal, bandwidth, cost and user dependent [4]. III. H ANDOVER M ECHANISM IN P HYSICAL L AYER Generally the handover mechanism is being proposed in L2 and L3 layer this will produce the decrease in handover latency and losses [6,12]. In the proposed handover we considered the physical layer switching of raw data over the efficient communication technology [7,8,9]. This handover is based on the Received signal strength which is calculated by Friis transmission equation. When handover takes place from the network with low data rate and short range of operation to the high data rate and long region of operation is the upward vertical handover. When the handover takes place from high data rate to low data rate is downward vertical handover which is as shown in figure 3.

Pr =

Pt Gt Gr  4πd 2

 (1)

λ

As shown in table I the wireless technologies generally used in any mobile device consist of Bluetooth, Wi-Fi, GSM and CDMA communication scheme. All these are diverse technologies comes under the WPAN, WLAN and WRAN services [10]. The network formed by coexisting the different wireless connectivities is the Global communication network because the network formed will cover all over the globally available different communication technology . Bluetooth and Wi-Fi are the two technologies which are popular in present scenario. As it operated peer to peer and in the same frequency band or share the same bandwidth of 2.4 Ghz ISM band. They are freely available without the infrastructure mode of communication [11]. Bluetooth is with the low data rate and transmitter power. Whereas Wi-Fi is with the high data rate and large region of operation. Here in this paper we are considering the handover mechanism between the ISM band operating technologies. As they are mutually exclusive level of operation and provide some advantage and disadvantages such as Bluetooth is with disadvantage of low data rate and low range of 10 m distance only. Advantage of Bluetooth is the low power of transmission 1mw (0 dBm). Thus less power consumption by the device and sufficient rate of data transmission. When we observe Wi-Fi which is with High data rate of operation which is in range of 1 to 11 Mbps, with the large range of operation up to 100 m distance. But Wi-Fi is with the disadvantage of high power consumption by an device. Transmit power is also high for large range of operation[11].

Fig. 2. Heterogeneous overlay network

The handover mechanism used for switching in between the different wireless networks is done by using the received signal strength Indication which will be different from one connectivity to another connectivity. The Received Signal Strength Indication (RSSI) calculation is done by using the Friis transmission equation.

Fig. 3. Flowchart of RSSI based switching Mechanism

As shown in the flowchart whenever mobile start to transfer the data at that time it will first approach the technology which is with the low power consumption which is dependent on the transmit power. Thus the mobile will approach to Bluetooth

2016 International Conference on Next Generation Intelligent Systems (ICNGIS)

TABLE I: RSSI calculation parametrs for varoius communication scheme Parametrs used in simulations Sr.No.

Parameter

Bluetooth

Wi-Fi

GSM

1

Standards

IEEE 802.15.1

IEEE 802.11a,b,g,n

GSM developed by ETSI

2

Transmitter Power

1mw

10mw

8W (39 dBm)

3

Gain of TX and RX Antenna

3 dBi

3 dBi

0 dBi

4

Range of operation

10 meter

10-100 m

in Km range

5

Frequency of operation

2.402-2.481Ghz

2.402-2.483Ghz

890-915, 935-960 Mhz

6

Threshold condition

-60dbm

-80 dBm

-90 dBm(On average)

7

Modulation Scheme

GFSK

BPSK, QPSK COFDM, CCK, M-QAM

GMSK

8

Range of operation

upto 10 m

10-100 m

in Km

9

No. of Channels

79 Channel each of 1Mhz

14 overlaapping channel of 22Mhz

communication scheme for transmission if the mobile device for reception is in the region of operation, then the data transmission start if it is not then it will approach the data transmission to the hierarchically higher data rate and with the more power consumption technology which is Wi-Fi with the transmit power of 10 dBm and data rate of 1 to 11 Mbps. Whenever the mobile starts the communication by Bluetooth communication scheme at that time it will calculate the received signal strength on the basis of RSSI calculation and will inform the receiver with the beacon signal which informs about the signal strength. Thus when the Bluetooth will cross the 10 m distance at that time it will handover the data to high data rate operating technologies which is being further handover to large region covering wireless technologies such as GSM and CDMA.

25 MHz bandwidth into 124 carrier frequencies spaced 200 kHz apart

showing the hopping sequence of the data transmission. At the Bluetooth receiver simulink model signal strength (RSSI) level is calculated by using the Friis transmission equation, in model speed of the user considered as walking speed and simulation time considered as the travel time for the mobile node. As shown in the table the RSSI is calculated for each communication scheme. From the Region of operation of the communication model the threshold condition is defined. This condition is used in the latch function for switching the Communication from Bluetooth to vertical handover communicating Wi-Fi communication scheme.

IV. R ESULTS

Fig. 5. Spectrum plot and signal strength calculation of Bluetooth

Fig. 4. Simulink model for vertical handover scenario

Here for simulation purpose we considered the Bluetooth and Wi-Fi simulink models from Matlab simulink environment as reference standard model. As shown in the figure 4 the Green block represents the Bluetooth model (commbluetoothfrqhop) Wi-Fi (commwlan80211b) simulink model is shown by pink blocks. This is baseband transceiver model

As shown in Figure 5 the Spectrum plot and the Received signal strength is calculated for the user. When the set threshold condition appears at that time the communication will switch from Bluetooth to Wi-Fi communication scheme. Switching mechanism will work similar to the automatic repeat request (ARQ) concept where the signal always checks for the reception of signal. Feedback signal which is used for the confirmation of data received. In the similar way we use the RSSI signal received from receiver which always correlate with the ARQ message signal if the data transmission is not

2016 International Conference on Next Generation Intelligent Systems (ICNGIS)

there for some period of time at that time it will switch from one connectivity to an another connectivity. For switching from Bluetooth low power signal to Wi-Fi signal with the high power level the receiver should send the enabling signal of high power level. So the high gain power amplifier should be used for the amplification of signal . Bluetooth and Wi-Fi operates at the different modulation and spread spectrum technique. The spread spectrum technique used for the conservation of power level as well as for the protection of signal from detecting by other signal that is the Anti gambling of the signal. Bluetooth uses FHSS (Frequency Hop Spread Spectrum) technique which is itself a secured form of communication scheme where the signal always hops on particular frequency and the receiver only knows when it is being paired with the transmitter device. Bluetooth transfers data at a rate of 1 Mbps which is at a power level of 1 mw (0 dBm). When we compared these values with the Wi-Fi, this data rate and power level is very low. Comparative study shows that the Bluetooth is far better in compared with the power level but restricted with the distance issue and data rate which is comparatively low. We consider the power issue and use it for the switching this will be advantageous so we can able to save the power level of the data at a particular distance.

Fig. 6. Spectrum plot and signal strength after switching to Wi-Fi

As shown in figure 6 at the threshold condition -45 dBm which is shown in figure achieved at that time it will switch from Bluetooth frequency hop scheme to Wi-Fi scheme which is shown with the wide band channel and the QPSK scatter plot. The other mechanism which we consider for the switching purpose is the packet data switching. When we are sending the data on a particular channel then the channel always checks data rate or the bandwidth of operation of the signal. When the data transmission is in the range of 1 Mbps then it will transmit the data by using a Bluetooth concept. Otherwise it will transmit the data by using Wi-Fi connectivity.

By using this concept of switching mechanism we can save the power before starting the data transfer mode. If we combine this two mode of switching then we an able to save the power also and the data connectivity will be intelligent .When the user will move from Bluetooth to the Wi-Fi. The simulink model of the Bluetooth frequency hopping and the 802.11 b model used in this system. Where the transmitter will send the data first by using an Bluetooth concept and then it switches by using an Friis equation. Power reduction is intended primarily to reduce the interference taking place with the other system which can enhance the system performance. The second main reason for the reduction in power level is to improve the system efficiency and power endurance of the device. Algorithm 1 Vertical Handover Scenario between Bluetooth & Wi-Fi using RSSI 1: procedure M Y P ROCEDURE 2: top: 3: Bluetooth ← ON . 4: d ← V × t. 5: if d < d0 m &RSSI > λ0 then 6: goto top. 7: if d > d0 m &RSSI < λ0 then 8: Enable ← 1 9: W i − F i ← ON . 10: close; As shown in the algorithm distance in between transceiver is calculated. When the distance is less than the threshold condition set in the latch function at that time the data transmission is handover to Wi-Fi. (λ0 is the threshold RSSI condition set and d0 is the threshold distance of operation set in latch.) When communication starts (Transmitter end) Bluetooth is with the sampling rate of 1.5×10−6 second for each sample whereas for Wi-Fi (Transmitter end) is with each sample time of 8.2102 ×10−7 second. Bluetooth is with samples transferred per Frame format of 7744 sample per frame. Wi-Fi is with samples transferred per Frame format of 8192 sample per frame. Thus there is variation of sample rate and sampling time of Bluetooth and Wi- Fi. This problem is resolved by using the Buffer mechanism or by using the delay adjustment mechanism. 1 Delay Adjustment mechanism states that when we transfer data to the different sample rate and timing sequences samples will reach at the receiver end with delay and received samples are not the same as transmitted due to variation in the sample time and sampling rate. Thus the delay occurred in the simulink model is analyzed by Time series data analysis of the data and proper delay is provided at the transmitter and receiver end. By using this mechanism we can recover the transferred data at the Receiver end. 2 Buffer adjustment mechanism used for calculating and buffering the data at the receiver end. The Buffer block

2016 International Conference on Next Generation Intelligent Systems (ICNGIS)

always performs frame-based processing. The block redistributes the data in each column of the input to produce an output with a different frame size. Buffering a signal to a larger frame size yields an output with a slower frame rate than the input [13,15]. Tso =

(Mo − L) × Tsi Mi

(2)

Tsi = Input sample time; Mo = Output Buffer size; L =Buffer overlap; Tso = Output sample time Mi = Input Buffer Size Here for simulation Bluetooth is the input system we considered Tsi i.e. 1.5×10−5 seconds, Tso is the output sample time (Here Wi-Fi i.e. 8.2102×10−7 seconds). Mi is the sample per frame (10), Mo is the Output sample per frame (1024). L is unknown overlap value for synchronization of data between the transmitter and receiver frame structure.Here the value of L calculated from the equation which is 1023. By using this equation the different sample rate and frame rate signals are synchronized by using the vertical handover scenario in heterogeneous wireless network.

V. C ONCLUSION In this paper we considered vertical handover scenario in between the heterogeneous functioning Bluetooth and Wi-Fi technologies. Because both are operating in the same frequency band and providing the feature of Peer to Peer communication with less or high amount of power. Vertical handover between these diverse network provides Always Best Connected network. The simulations are performed by considering the Friis transmission equation for providing threshold condition in latch function and buffer and delay adjustment mechanism used for synchronization. Simulations are performed in Matlab and Simullink environment.

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