Recondition Battery Guide
As we are now acutely aware, a Bluetooth device consumes current, and thus can have an influence on the battery life of any Bluetooth-enabled product. For products with powerful batteries inherent to their normal use, a laptop being the primary example, it will not be a significant issue. For smaller products like mobile phones and PDAs, it could impact on the overall time available for use. We have examined the power consumption on the headset and AG scenario, which is restricted in its functionality, but a multifunctional product like a PDA will have many varying needs for power, dependant upon what activity it is involved in exchanging a business card, waiting for an e-mail, or Web browsing will all involve different connection models.We will now consider this in a reallife situation.To try to get an objective view of the effect on battery life of the Bluetooth functionality in a PDA, it is necessary for us to make some assumptions. These assumptions are variables but will give us...
The most recent standard is WAP 2.0, published in 2002. It adds support for the standard Internet communication protocols IP, TCP, and HTTP. It also allows applications to work over all existing and coming wireless 3G technologies. It provides a rich application environment, which enables delivery of information and interactive services to digital mobile phones, pagers, PDAs, and other wireless devices. It addresses the unique characteristics of wireless devices. These devices have hardware limitations (e.g., small screens, limited battery life, and limited memory) requiring special attention to user interface design (e.g., one-finger navigation).
In practice, most devices will need to support low power modes. Consider the case of a desktop PC. It is connected to mains power, so it has no need to save power. However, it could communicate with a battery-powered Bluetooth mouse, which will want to use sniff mode to extend its battery life. If the PC does not support sniff mode, the mouse cannot use it, and so its battery life can be seriously compromised by lack of features in the PC.
The advancements in handheld devices are one of the key drivers of ubiquitous networking, and these devices are improving its capabilities at exponential rates. However, due mainly to their size restrictions, these devices suffer from a number of limitations. These limitations include but are not limited to inadequate processing capability, restricted battery life, limited memory space, slow expensive connections and confined host bandwidth (Sharmin, Ahmed & Ahmed, 2006). To address these limitations,
Current handheld PCs offer considerably longer battery life than notebooks because they do not have hard drives, CD-ROMs, or floppy drives.This makes it possible for users to work for hours, and in some case weeks, without having to worry about losing power. Most Palm-size PCs use AAA batteries that last for 20 hours to several weeks, while handheld-size PC batteries last from 8 to 15 hours on a single battery charge. Mobile phone battery technologies offer 130 hours standby and 5 hours talk time as standard. Key consideration when adding Bluetooth technology to any product is the additional power consumption inevitably reducing the overall battery life of the product. This is a serious consideration in products that are normally static, where battery life has not been an issue before and size constraint is predefined. Table 1.4 illustrates some of the currently available rechargeable battery technologies indicating the respective weight energy density.
The most power-hungry components in RF systems are the amplifiers used to boost a signal immediately prior to transmission and to boost the received signal to an intelligible level immediately alter its reception. 802.11 stations can maximize battery life by shutting down the radio transceiver and sleeping periodically. During sleeping periods, access points buffer any unicast frames for sleeping stations. These frames are announced by subsequent Beacon frames. To retrieve buffered frames, newly awakened stations use PS-Poll frames.
To save battery power, stations may shut off the antenna units in 802.11 network interfaces. While stations are sleeping, access points must buffer frames for them. Dozing stations periodically wake up to listen to traffic announcements to determine whether the access point has any buffered frames. When stations associate with an access point, part of the saved data is the Listen Interval, which is the number of Beacon intervals that stations wait between listening for Beacon frames. The Listen Interval, shown in Figure 4-26, allows mobile stations to indicate how long the access point must retain buffered frames. Higher listen intervals require more access point memory for frame buffering. Access points may use this feature to estimate the resources that will be required and may refuse resource-intensive associations. The Listen Interval is described in Chapter 7.
So, if power management has the potential to make your application unusable or infuriatingly slow, why bother with it Used in the correct way, the Bluetooth power management modes have the potential to extend the battery life of your device significantly, yet be completely transparent to the user. In general, users do not like having to lug about heavy batteries or recharge their devices frequently. A typical mobile phone has a small battery and yet can last several days without recharging. If adding Bluetooth functionality to such a phone reduces its average battery life significantly, it is unlikely to be popular with the user. Power management at both the hardware and software levels of Bluetooth technology is therefore necessary in order to make these networks viable. A further benefit of application power management is that the energy savings are independent of the underlying technology.This means that if through power management you double the battery life of your device, this...
For most applications, if a connection exists between two or more Bluetooth-enabled devices, one of the Bluetooth low power modes can be used to extend the battery life of either some or all of these devices. In fact, power-managed devices can be in one of four states, listed in order of decreasing power consumption active, hold, sniff, and park mode. Each of these low power modes will be described, along with a discussion of what type of applications will and will not be suitable for it.
Equipment established in the stratosphere, i.e. installed on airhips, airplanes, helicopters or their combination, is collectively designated as High Altitude Platform (HAP) equipment. Links comprising this equipment will be part of the global telecommunication infrastructure, in co-operation with either wideband satellite systems or terrestrial WDMA optical networks or UMTS systems 126.96.36.199 . Frequency ranges for HAP systems have already been allocated by WRC-97, and later WRC-2000 the vicinity of 48 GHz, 18 to 32 GHz, 1885 MHz to 2170 MHz, and for interconnection of HAP's the adjacent IR range (800 to 1600 nm). At present, development is in progress in the fields of the required devices, circuits subsystems (tehnology of laser links between instabil terminal sites, phase controlled antenna systems, high efficiency solar cells and storage batteries). In addition, propagation measurements are in progress, especially for investigating propagation within buildings, further the screening...
The properties of coils were well known by the middle of the nineteenth century. If a coil was put in an electrical circuit it was known to retard the current, i.e. the current rose more slowly than otherwise. A simple example of a circuit containing a self-inductance is shown schematically in Fig. B5.i(a). When the switch is closed the current is first zero but then rises gradually to a value determined by the battery voltage and the resistance, I0 V R as may be seen in Fig. B5.i(b). The time constant determining how fast the current increases is equal to L R.
While the prime goal of data broadcasting is reducing the overall access time, most practical systems also need to consider the messaging overhead. On the other hand, the load of the real-time systems often change in a dynamic fashion. Hence, the broadcast system needs to be robust enough to adapt itself online with the system dynamics. The basic motivation behind the lazy data request strategy 31 is to not send the request for the data item but wait. The particular data item might already be broadcasted due to an explicit request by other clients. This will result in saving of message passing in the uplink channel and battery power of the mobile terminal. It proposes a new dynamic bounded waiting strategy that contains two parts in the schedule index section and data section. The client can use the index section to get a predicted estimate of the item to be broadcasted in the near future. The server chooses a set of data items and the items are batched together for broadcast. The...
In terms of the component nodes, the sensor networks can be classified in general into two categories homogeneous sensor network and heterogeneous sensor network. In a homogeneous sensor network, the sensor nodes have identical capabilities and functionality with respect to the various aspects of sensing, communication, and resource constraints. In a heterogeneous sensor network, each node may have different capabilities and execute different functions. For example, some nodes may have larger battery capacity and more powerful processing capability and some may aggregate and relay data other nodes may only execute the sensing function and not relay data for other nodes. A homogenous sensor network is simpler and easier to deploy, while a heterogeneous network is more complex and its deployment more complicated because different types of nodes must be dispensed in specified areas.
In order to predict the lifetime of a sensor network and compare the quality of different algorithms and protocols, energy models for the computation and communication energy dissipation at nodes, as well as battery models used to depict battery capacity and behavior, should be specified. model, discharge rate-dependent model, and relaxation model. In the linear model, the battery is treated as linear storage of current. The maximum capacity of the battery is achieved regardless of the discharge rate. The discharge rate dependent-model considers the effect of battery discharge rate on the maximum battery capacity. Because the battery capacity is reduced as the discharge rate increases, a battery capacity efficiency rate is introduced that varies with the current and is close to one when the discharge rate is low it approaches zero when the rate becomes high. The relaxation model is more complicated because it also takes into account the relaxation phenomenon of real-life batteries.
Early mobile stations (MSs) were designed as car phones. They were too bulky to be carried around and had to be powered by the battery of the car. Today, there are compact lightweight MSs with internal rechargeable batteries. They can be carried by hand and are personal phones rather than car phones.
WSNs consist of large numbers of distributed nodes that organize themselves to form a multihop wireless network. Each node consists of one or more types of sensors, an embedded processor, small memory, and a low-power radio transceiver. Generally, these nodes are battery powered and coordinate among themselves to achieve a common task. Compared to nodes in a generic WAHN operating under IEEE 802.11 2 or Bluetooth 3, 4 protocols, these nodes are extremely small in size and possess limited energy resources. The transmitting power and thus the communication range are much lower, which is largely compensated by a higher density of nodes in most cases. WSNs can have distributed, hierarchical, or clustered architectures, as illustrated in Figure 28.1. Node troubleshooting and battery replacement possible
Energy consumption is reduced in EC-MAC due to the use of a centralized scheduler, as in Bluetooth. Therefore, collisions over the wireless channel are avoided, thus reducing the number of retransmissions. Additionally, mobile receivers are not required to monitor the transmission channel as a result of communication schedules. The centralized scheduler may also optimize the transmission schedule so that individual mobiles transmit and receive within contiguous transmission slots. This scheme highlights the fact that scheduling algorithms that consider mobile battery power level in addition to packet priority may improve performance for low-power mobiles. Techniques used to minimize the energy consumption and performance of EC-MAC in this regard are discussed in detail in Sivalingam et al. 6 .
After the service directory information has been obtained, the laptop might suddenly decide to close down the connection to the cellular phone. In case the laptop wishes to gather service directory information from several devices present in the area, it seems sensible to close down all the links, since one device can utilize only a limited number of links at a given point of time and a lot of battery power will be consumed if the links are kept alive.
In the Service Searching model, the user (or application) selects which service they wish to use and then are presented with a list of available devices that present that service. From a user-experience point of view, this is clearly a better model. Unfortunately, this model still causes a problem. The most obvious time to do a service search is during the discovery process, an operation which most users find takes too long already.You could conceivably cache the service lists of remote devices, but this cache would need to be quite large to be useful and it would be difficult to know when your cache was out-of-date. On a large device that has lots of CPU time and battery power to waste making regular inquiries in the background, Service Searching might be a good model, but on a small device it seems like overkill. Rather, it seems to make more sense to use the Class of Device (CoD) information returned during inquiry to do the same kind of service-based filtering. While the...
Recent developments with electric field tags relate to the development of transponder smart card systems for toll road applications. Here the tags are active (that is they have a battery) but only consume battery power after the tag is 'activated' by passing through a high-energy activation field. Thereafter, the tag can send receive data with an overhead reader and can adjust the data representing the balance remaining in the smart card after the toll fees are deducted. Such applications are proposed in the 2.45 GHz frequency band and more recently in the 5.8 GHz band. A separate category also exists of 'active' tags (battery powered). These tags are 'beacon' tags, that is they are not interrogated by a reader, but wake themselves up from a low power 'sleep mode' periodically and broadcast their identity before returning to 'sleep mode'. By broadcasting on a fixed frequency, a sensitive receiver tuned to that frequency and within close proximity to the tag will receive the identity...
Telecommunication is the transmission of speech information acoustic signals in electromagnetic form through the subscriber's line where. among other factors, their symmetrical transmission, their amplification by the Central Battery power, the matching between the telephone xchange and telephone set, all serve for bridging the distance between the subscriber and the telephone exchange with the minimum of deterioration. A typical implementation of electroacoustic system when the amplifier sends signals with increased voltage to the loudspeakers in order to decrease the transmission losses (so called 100-Volts system) can also be called telecommunication.
A lower battery voltage reduces the voltage swing from the active devices. This, in turn, requires a larger current for the same output power. A greater output current increases I2R losses including that of the output active device and matching network, for the same Q. Employing a larger output device to overcome the series IR losses results in greater shunt output resistance losses. A larger output device for a fixed bias current may result in lower gain due to a reduction in f . Linearity and or efficiency are degraded for a fixed knee voltage with smaller supplies. Larger devices employed to overcome some of these limitations increase the die size and cost. All of this, while challenging, tends to favor III-V devices, such as GaAs MESFETs, because of their high low-field mobility.
In a telecommunication installation the main consumer, requiring usually the most energy supplied, is the telephone exchange. For the supplying DC voltage is required, having usually a nominal voltage of -48 Vdc. The most important requirement for the supply is the continuity, i.e. the powering system must not interrupt even for a second the supplying of the DC voltage. Otherwise the built-up connections would disconnect (in case of the exchanges it would necessitate the reprogramming of the exchange, which in the given case could block the provisioning of telecommunication services for hours in a region). Rectifiers fed from the public mains produce the required DC voltage. However, these units can only provide the DC voltage, if the required mains voltage is available. Since the continuity of DC current supplying is to be ensured, and the uninterruptible supply cannot be assured only from the AC current side, the DC current needs to be directly stored. The most suitable for this...
The advanced digital technology combined with encryption provides a secure wireless communications network. Cell sites that are smaller and closer together provide a stronger signal for cellular phones and lower power requirements. This results in better building penetration and fewer dropped calls provided there are sufficient cell sites. Broadband PCS will have smaller, lighter handsets and longer battery life.
RF power amplifiers for mobile phones are large-signal devices with power gain that drive the antenna, usually through a switch or a filter. They dramatically impact battery life (talk time), particularly at high power levels, and require good linearity in some cases (TDMA, CDMA). Power amplifiers require good thermal design, including IC layout and suitable packaging.
PowerNow technology was developed primarily to extend battery life on mobile systems. Therefore the experiments were conducted on a laptop system rather than a desktop PC. Instead of inserting a current probe into the laptop, system power was simply measured during the experiments. The laptop's system power is drawn from the power converter at approximately 18.5 V DC. Instead of using an oscilloscope or digital ammeter to take exact CPU power measurements at very high frequencies, a simpler approach used a large capacitor to average out the DC current drawn by the entire laptop. This method works primarily because of the periodic nature of these tests.
Includes multiple access, modulation, error correction, fast power control, load control, channel coding and interleaving, rate adaptation, spreading and control channels schemes used for MS to access point communications. RNS link layer functionality includes outer power control, admission control, channel allocation, packet scheduling and handoff control. 'Power-aware' physical and link layer schemes are highly desirable to lengthen the MS battery life. The RNS components include the MS, the access points (BS, or Node B), and the access point controllers (BSC, or RNC).
An 802.11 NIC will draw current at a couple of hundred milliamps. Batteries under this load will last from a couple of hours to a day or so, depending on the size of the battery. These are constraints for most applications, but it is beneficial to indicate the amount of battery life that users will realistically need. In the design, you can utilize this information to decide whether to activate power management, specify larger batteries, or determine an effective battery-charging plan.
The second limiting factor is voltage drop. If the battery voltage is kept constant with increase in length, the effectiveness of the signalling and conversation will be limited. This is due to IR drop of the line. The IR drop of the line varies with resistances of the battery used in the system, telephone set resistance and the allowable resistance of the subscriber loop. VB Battery voltage Rt Telephone set resistance. Example 3.1. If the minimum current required for carbon microphone is 23 mA, battery voltage is 50 V, the battery resistance is 400 ohm and the telephone set resistance is 200 ohms, calculate the loop resistance limit.
The RRC is responsible for detecting and efficiently using the available radio resources. It manages handover, dynamic frequency selection, station alive absent, power saving, and power control. The RRC selects the frequency range on which the communication will be conducted and, when needed, it decides to move to a different frequency range. This is done based on the AP CC own channel measurements as well as the mobile station channel measurements. To preserve the battery power of the stations, the RRC defines when and for how long to put the MTs into sleep mode. The lengths of sleep intervals are negotiated between the AP CC and the MTs.
The discontinuous transmission mode takes advantage of the fact, that during a normal telephone conversation, both parties rarely speak at the same time, and thus each directional transmission path has to transport speech data only half the time. In DTX mode, the transmitter is only activated when the current frame indeed carries speech information. This decision is based on the VAD signal of speech pause recognition. The DTX mode can reduce the power consumption and hence prolong the battery life. In addition, the reduction of transmitted energy also reduces the level of interference and thus improves the spectral efficiency of the GSM system. The missing speech frames are replaced at the receiver by a synthetic background noise signal called Comfort Noise (Figure 6.3). The parameters for the Comfort Noise Synthesizer are transmitted in a special Silence Descriptor (SID) frame.
The major advantage of wireless networks is that network access does not require nodes to be in any particular location. To take full advantage of mobility, nothing can constrain the location of a node, including the availability of electrical power. Mobility therefore implies that most mobile devices can run on batteries. But battery power is a scarce resource batteries can run only so long before they need to be recharged. Requiring mobile users to return frequently to commercial power is inconvenient, to say the least. Many wireless applications require long battery life without sacrificing network connectivity. Power management is designed around the needs of the battery-powered mobile stations. Mobile stations can sleep for extended periods to avoid using the wireless network interface. Part of the association request is the Listen Interval parameter, which is the number of Beacon periods for which the mobile station may choose to sleep. Longer listen intervals require more...
Some ofthe specific approaches that have gained prominence in recent years are as follows The dynamic destination-sequenced distance-vector (DSDV) routing protocol (Johnson & Maltz, 1999), wireless routing protocol (WRP Murthy & Garcia-Luna-Aceves, 1996), cluster-switch gateway routing (CSGR Chiang, Wu, & Gerla, 1997), and source-tree adaptive routing (STAR Garcia-Luna-Aceves & Spohn, 1999) are all examples of proactive routing, while ad hoc on-demand distance-vector routing (AODV Perkins et al., 1999), dynamic source routing (DSR Broch, Johnson, & Maltz, 1999), temporally ordered routing algorithm (TORA Park & Corson, 1997), relative-distance microdiversity routing (RDMAR Aggelou & Tafazolli, 1999), and signal-stability routing (SSR Ramanathan & Streenstrup, 1998) are examples of reactive routing. Location-aided routing (LAR Haas & Liang, 1999) uses location information, possibly via GPS, to improve the performance of ad hoc networks, and global state routing (GSR) is discussed in...
In the late nineties the silicium germanium npn transistor is going to production in several foundries. The growing market for RF wireless integration is convincing the silicon foundries to invest in high performance RF silicon technologies rather than GaAs, because of the compatibility of the silicon technologies with the main stream cmos fabrication equipment. UMTS, wireless LANs and other 2Ghz emerging applications will need the 50GHz fT performance of Silicon Germanium SiGe and the low rB for transmit noise and receiver sensitivity performance at low battery power. The
The typical subscriber loop is supplied its battery voltage by means of a battery feed circuit illustrated in Figure 5.3. Battery voltages have been standardized at -48 Vdc. It is a negative voltage to minimize cathodic reaction. This is a form of corrosion that can be a thermal noise source.
Other areas where differences exist are in the devices themselves. When dealing with a radio interface (like a cell phone), we have to be aware of the battery life of the device. Power consumption with lengthy data transfers can be critical. The use of the overall battery life is contingent upon the technology used, but current industry standards allow for 2 to 4 hours of talk time on a portable device (transmission time for data). Anything over that is prone to cut off and produce errors. The digital sets are better equipped to handle the data transfers, but dual-mode phones can be problematic when they are in analog mode.
Once it is accepted that satellites may orbit the Earth the principles involved in communicating, say, across the Atlantic, are simple. A terrestrial station in the US sends a microwave beam up to the satellite. This is then amplified, frequency shifted (in order to avoid interference) and reradiated towards Europe. Does it need a lot of power to do this Let us remember that Marconi needed about 200 kW to send information across the Atlantic. Short waves could do it with a couple of kW, a saving of a factor of hundred. One would think that satellites would need more power because a lot must be wasted in sending fairly wide beams up and down. However using microwaves and a fairly big ground aerial (say 50 m diameter), the beams are not too spread out, so that a power of about 100 W is sufficient at the Earth terminal. Power is obviously at a premium for the transponder in the satellite since it can rely on solar batteries only. A few watts is just about enough.
Of course it will follow that the greater the wire diameter of the loop pair, the less resistance there is per unit length also, the less attenuation there is per unit length. On a particular subscriber loop we must set an attenuation limit and a minimum current flow. The current flow is usually stated as a resistance in ohms. We expect a common battery voltage of -48 V. This is what a high-impedance voltmeter will read anywhere in the loop when no current is drawn, such as a telephone instrument off hook.
Access points buffer frames for mobile stations sleeping in low-power mode. Periodically, the access point attempts to deliver buffered frames to sleeping stations. A practical reason for this arrangement is that much more power is required to power up a transmitter than to simply turn on a receiver. The designers of 802.11 envisioned battery-powered mobile stations the decision to have buffered frames delivered to stations periodically was a way to extend battery life for low-power devices.
With respect to the communication mechanism adopted, four basic architectures of sensor networks exist direct connected, flat ad hoc, peer-to-peer multihop, and cluster-based multihop, as shown in Figure 15.3. Because the number of sensor nodes is usually large and the transmit range of sensor nodes may be limited due to the battery capacity limitations, in general it is cost inefficient and, in many cases, impossible, for each small sensor to communicate directly with the collector. Thus, the direct connected mode is not suitable for large-scale deployed sensor networks.
The input capabilities of current mobile devices, such as cell phones and PDAs, are currently primitive and difficult to use for commercial activities. When natural language voice input is improved, the input of more complex requests, responses, and textual material will be possible. Substantial advances in speech recognition and natural language processing are necessary, and substantial increases in processing power and battery capacity are required before this promise can be realized. Currently, battery power and life are also significant limitations on mobile multimedia devices, restricting the availability of processing, display, and communication. However, small, light, mobile, alcohol-based fuel cells are in prototype and demonstration. When substantial demand develops for more powerful mobile multimedia devices, more powerful batteries will become available.
Radio transmission makes communications possible to mobile users. Early mobile radio telephone systems used a radio antenna installed on a hill and equipped with a high-power multichannel transmitter. Transmission from the mobile users to the antenna made use of the power supplied by the car battery. These systems provided communications for police, taxis, and ambulance services. The limited amount of available bandwidth restricted the number of calls that could be supported and hence the number of subscribers that could use such systems was limited. For example, in the late 1940s, the mobile telephone service for the entire New York City could only support 543 users CSTB 1997 .
The line circuit uses a feed-bridge to supply the exchange battery voltage to the subscriber's line. This battery voltage is used to operate the conventional telephone instruments, and is used for the subscriber line signaling to identify whether the telephone instrument is 'on-hook' or 'off-hook'. The battery supply needs to be coupled through a high-impedance to the line, to prevent the low impedance of the battery shunting the speech. This task is done by means of a feed-bridge and usually involves two high impedance relay coils, providing supervision of the subscriber's loop. The relay will be operated by a low line impedance and released by a high impedance from the subscriber. This is illustrated in Figure 4.14.
The first major task for the PRISM-2 driver is to initialize the MAC controller chip on the card. The error code is one major clue. Positive result codes indicate that the firmware is at fault, and negative error codes are due to driver faults. Frequently, the error is due to a timeout period expiring retry the operation to ensure that the error is caused by the system and not by a timeout expiration. Firmware problems are rare and generally seen only when the firmware loaded on the card was bad or the firmware load was incomplete. Driver problems are usually due to resource conflicts, especially with I O ports. In some cases, a laptop with 5-volt PCMCIA slots may experience problems with a 3-volt card, though the failure usually happens later in the initialization process. I saw this message on an IBM ThinkPad T21 when the card was inserted, and the system was on battery power. If the T21 was plugged into AC power, however, the driver would load and configure without a hitch.
Once configuration is complete, the AirPort status icon is displayed in the upper-right corner of the screen, next to the speaker volume, battery, and clock icons, provided you haven't turned off those icons. The AirPort icon also indicates radio strength. In Figure B-4, there are several solid wavefronts on the icon. As you move farther from the access point and the signal degrades, the number of bars decreases. When it is clicked, a dropdown command list offers the option of turning the power to the AirPort card on or off, selecting or creating networks, and opening the Internet Connect application to monitor the radio interface. It is quite handy for users to be able to turn off the card at will. When you are out of range of a network, or just not using it, the card can easily be powered down to save battery power.
A two-way radio system generally consists of three types of units a base station at a central dispatching location, mobile stations used in vehicles, and hand-held portables utilizing battery power. In today's business, conventional radio typically will not provide the wide-area communications that most businesses require. The cost for a business to construct its own radio system consisting of multiple tower sites can be too expensive. That's why an SMR system provider is used. Customers pay a small monthly fee to use the service, similar to cellular service. The difference is that you only pay a flat monthly fee, which allows for unlimited communication without high monthly cellular bills There's no per-minute charge
We are all aware that although the lack of cables makes our lives convenient, the simple act of recharging batteries is tiresome. How many of us have picked up our cell phones to make a call and found it needs recharging This even with the vast battery life and battery status indicators in current phone battery technology The ultimate aim with any wireless product is to ensure the time differential between charging sessions will not affect the user's experience in other words, to make sure their products are not connected to the mains longer than they are wireless Long battery life means designs with low power as the primary objective. With any low power application, choice of design configuration is crucial in achieving the power consumption targets that you require for optimum use. Initially, there are the hardware configurations relating to choice of processor, design topology, asynchronous (event-driven) over synchronous (polling) designs. Then there is hardware power management...
Despite their advantages, small sensor nodes like motes are sometimes not capable of performing certain sensing and processing tasks on their own. For example, acoustic beamforming and localization require a fast sampling rate at high accuracy and extensive computing such as fast Fourier transform (FFT) 58 . To meet the requirement of more computing power, larger nodes have also been developed and used in sensor networks. These nodes have significant computing power, large memories, and more I O peripherals, such as Ethernet or PCMCIA connectors. On the other hand, larger nodes consume more power and many are not easy to deploy with a battery power supply.
Security objectives and appropriate security measures largely depend on the environment scenario in which WMN is used. Analysis of the security issues, relevant threats, and development of a suitable security architecture are possible only with respect to a specific application domain of mesh networks. This can easily be seen when considering different usage scenarios for mesh network technology e.g., a military mesh network where even traffic flow must be kept confidential, a personal area mesh network where all nodes belong to a single person, an operator-controlled mesh network where the nodes constituting the mesh network are under a single administrative control, a mesh network of a small set of mutually trusting users, or a mesh network with users who do not trust or even know each other. It may also be necessary to distinguish different types of nodes, e.g., nodes under user control, infrastructure nodes provided to improve network coverage, or nodes that act as gateways (GW)...
Furthermore, because in most cases sensors have limited available energy (usually battery operated), both energy models for the computation and communication energy dissipation at nodes, as well as battery models used to depict battery capacity and behavior, are important for evaluation and extension of the lifetime of sensor networks. Finally, connectivity is an important property of distributed wireless sensor networks that facilitates development of guidelines regarding several processes involved in design and operation of sensor networks, such as the deployment pattern and density of sensors communication strategies among individual sensors distributed information processing algorithms and routing and or information dissemination strategies. Therefore, this chapter has described several models that analyze the connectivity distribution as the network evolves.
This particular MAC protocol is briefly described here because of its significant contribution toward minimizing the power consumption of nodes in wireless and mobile ATM networks. Goals of this access protocol are to conserve battery power to support multiple traffic classes and to provide different levels of service quality through bandwidth allocation. Although the IEEE 802.11 and Bluetooth standards address energy efficiency, this was not one of the central design issues in developing these protocols. The EC-MAC protocol 6 , on the other hand, was developed with the issue of energy efficiency as a primary design goal.
To the best of our knowledge, there currently exist no routing protocols that are specially designed for hybrid WMNs, consisting of a mix of mobile nodes and relatively static mesh routers. However, this is the most likely WMN architecture to be employed for PSDR communications, especially in the case of IANs. Current WMN routing protocols do not differentiate between the type of nodes in the network and are therefore unable to take advantage of the high degree of heterogeneity. Mesh routers and mesh clients can differ greatly in a number of aspects. Mesh clients are generally resource constrained devices with limited battery power, equipped with only a single radio. In contrast, mesh routers are much less resource constrained and are either powered with high-capacity batteries or have access to mains power. In addition to being more static, mesh routers are also likely to be equipped with higher gain antennas and multiple radio interfaces, resulting in a significantly increased...
The sub-state Connected means that the UE is inside an island. The sub-state Searching is entered when the UE is out of coverage. In the Searching sub-state, the HNAC forces the UE to be in active GPRS state to know its cell ID. It can happen that the UE is in a cell that has no islands nearby. In this case the HNAC can order the UE (via UTRAN) to go to sub-state Waiting to save battery power. When the UE moves to a cell where an island exist it is told to change again to Searching (note that these sub-states are simply optimizations and can exist, or not).
Character displays have typically from 1 to 8 lines by max. 24 characters per line. LCD displays are mostly selected, that are used in a wide variety of products for displaying of numbers, alphanumeric characters and symbols indicating set-up and or status information (i.e. dialling mode, battery charge, field strength, message arrived) of terminals. The simplest 7 or 9 segment displays are acceptable for display of numeric information. Dot -matrix is necessary where alphanumeric information is required. As a minimum, a matrix of 7x5 shall be used for capital letters. Dot matrix of 9x7 with the addition of four rows to accommodate line spacing, lower case ascenders and descenders and accents is more advantageous (i.e. g ).
With DVS, minimum energy consumption results when the processing rate variation is minimized because of the convexity of the energy workload model. Figure 27.9 plots the relative battery life improvement as a function of the variance in workload. Each workload profile is Gaussian with a fixed average workload. Although the average workload might be constant, the battery life improvement from DVS will degrade as the fluctuations in workload increase. FIGURE 27.9 Battery life improvement as a function of duty cycle and active workload in a sensor node compared to a node with no power management. FIGURE 27.11 Battery life improvement in the sensor node compared to a node with no power management as a function of duty cycle and active workload. FIGURE 27.11 Battery life improvement in the sensor node compared to a node with no power management as a function of duty cycle and active workload. Idle mode energy savings, on the other hand, can be significant. If it is assumed that the...
In our system the GPRS network is the glue for all the other RANs. It is the primary network having all the control services (paging, etc.). All secondary networks become simpler and can have control services of their own not seen at core level (i.e. they are simply internal optimizations). Almost all of the works in internetworking assume that all these features (including paging) exist in all networks and are seen at core level. IDMP (Misra, 2001) is one of the exceptions stating that they should be customized. The most similar approach to ours was taken by MIRAI (Wu, 2002). Their primary network is a collection of BANs (Basic Access Network). Each BAN contains the usual control services, and is controlled by a CCN (Common Core Network) manager. A user selects a RAN based on a list provided by the BAN considering user location and preferences. Although, the authors consider a long list of issues to help the UE choose the RAN, some too low level or external reasons (e.g. battery...
How often should a mobile station send such a message If it updates its current location (e.g. its cell) rather seldom, the network must perform a paging process in order to search the MS when packets are coming in. This will result in a significant delivery delay. On the other hand, if location updates happen very often, the MS's location is well known to the network (and thus the packets can be delivered without any additional paging delay), but quite a lot of uplink radio bandwidth and battery power is used for mobility management in this case. Thus, a good location management strategy must be a compromise between these two extreme methods.
When stations associate with an access point, one of the parameters specified is the listen interval, which is the number of Beacon intervals between instances when the station wakes up to received buffered traffic. Longer listen intervals enable a station to power down the transceiver for long periods. Long power-downs save a great deal of power and can dramatically extend battery life. Each station may have its own listen interval.
Given these constraints, what type of application would benefit from using hold mode If your application can determine or control the time of its next data transmission, then it can most probably use hold mode for power management. One example of an application that has some degree of control over when its next data transmission should take place is a wireless e-mail delivery system. E-mail is not a synchronous communications medium and messages can take anything from a few seconds to several hours to be delivered to their destination. More importantly, users do not perceive e-mail delivery to be instantaneous and hence would tolerate a small additional delay in favor of extending the battery life of their device.The following sidebar, Power Management Using Hold Mode, discusses in more detail how hold mode can be used by such an application, along with power saving techniques available. A very different application type whose performance will be negatively impacted is a network of...
The modulation technique used on the radio channel is Gaussian Minimum Shift Keying (GMSK). GMSK belongs to a family of continuous-phase modulation procedures, which have the special advantages of a narrow transmitter power spectrum with low adjacent channel interference on the one hand and a constant amplitude envelope on the other hand, which allows use of simple amplifiers in the transmitters without special linearity requirements (class C amplifiers). Such amplifiers are especially inexpensive to manufacture, have high degree of efficiency, and therefore allow longer operation on a battery charge 15,64 .
With respect to energy supply, two parts of the energy supply subsystem can be distinguished. Traditional energy sources are rechargeable batteries and fault tolerance is achieved by providing a back-up battery. The first commercial fuel cells and subsystems that leverage on energy scavenging have recently been demonstrated. Although it appears that fuel cells will be very reliable, some energy-scavenging subsystems, such as the ones converting light into energy, can have very volatile performance. For energy distribution, the standard solution to enhance fault tolerance is to deploy multiple distribution networks.
Up a connection to each device you haven't seen before. Setting up connections will also take up power and shorten your battery life, so you should only ask the Connection Manager to do this if your application will use the information. To get BlueCore to perform an inquiry, use the following call At this point you may be thinking, Why would I want an inquiry to finish before it had collected as many responses as possible .There are two reasons, both to do with the limited resources you have. Firstly, you want to set a timeout because if you leave the device permanently inquiring, it will use up power and shorten battery life. Secondly, you may have to limit the number of responses because you need to store and process responses. Since you don't have an infinite amount of memory available there's a limit to how many responses you can process at one time.
Voice managers have a number of valid points when pointing out the advantages of such an approach. First among these is reliability PBXs, as a component of the PSTN, have a long history of high reliability and availability, with features such as multiple redundant power supplies, integrated battery power inputs for uninterruptible power units, hot-swappable card buses, and robust physical environments. Keeping as much of the telephony processing inside the PBX as possible is one way to address concerns about entrusting voice to the vagaries of data networks.
Bits 14 and 15 are both set to 0 in PS-Poll frames. Mobile stations may elect to save battery power by turning off antennas. Dozing stations must wake up periodically. To ensure that no frames are lost, stations awaking from their slumber transmit a PS-Poll frame to retrieve any buffered frames from the access point. Along with this request, waking stations incorporate the association ID (AID) that indicates which BSS they belong to. The AID is included in the PS-Poll frame and may range from 1-2,007. Values from 2,008-16,383 are reserved and not used.
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