WO2007135227A1

WO2007135227A1 - Communications device

Info

Publication number: WO2007135227A1
Application number: PCT/FI2007/000140
Authority: WO
Inventors: Tatu Kemppainen
Original assignee: Elcoteq Se
Priority date: 2006-05-24
Filing date: 2007-05-24
Publication date: 2007-11-29
Also published as: FI20060508L; FI20060508A0

Abstract

An assembly comprising a portable communications and/or data transfer device (HD), such as a mobile telephone, a PDA or a comparable communications/data transfer device, that includes a first mass memory (CM), and a portable media/data source (SD), such as a multimedia device or an MP3 player or a comparable media/data source, that includes a second mass memory (MM), whereby in the assembly the communications/data transfer device and the portable media/data source can communicate with each other over a wireless communication connection (BT), which is optionally a RF connection, an IR connection or a Bluetooth™ connection. The invention is characterized in that, in order to speed up access to data on the portable media/data source (SD) from the communications/data transfer device (HD), the first mass memory is a cache memory of the second mass memory in order to load desired data/media/applications to the first mass memory over the wireless connection (BT).

Description

Communications device

The present invention relates to communication and data transfer. More particularly, the present invention relates to an assembly that comprises a portable communications and/or data transfer device, for example a terminal device of a mobile telephone network, such as a mobile telephone, a PDA, or a comparable device suitable for communication and/or data transfer, that includes a first mass memory, preferably a first hard disc, and a portable media/data source, such as a multimedia device, an MP3 player or a comparable media/data source, that includes a second mass memory, preferably a second hard disc, whereby in the assembly the communications device and the portable media/data source can communicate with each other over a wireless communication connection, which is optionally a RF connection, an IR connection or a Bluetooth™ connection.

In connection with the present invention the term "communications device" refers to mobile stations, such as mobile telephones, PDAs (Personal Digital Assistant) and comparable devices intended for presenting, processing and/or storing media/data in order to utilize digital media/data. The term "media/data source" refers to various devices intended for storing media/data and/or applications, such as mass memories and comparable memory means.

Nokia and Samsung, for example, have released mobile station models with a mass memory, the models integrating a hard disc as a mass memory, whereby the mobile station in question is more generally operable as a device suitable for utilizing digital media/data. The size of the hard disc and the added value the device thus provides to the user are clearly connected; the larger the hard disc, the better, as this allows utilizing various kinds of functions in the device. However, the price, size and reliability of the device become problems, as they set limits to placing the device equipped with a hard disc on the market in large volumes. Another problem may be that gaining access to the necessary data on a large hard disc may always cause delay.

A telephone model with a 4 GB hard disc, for example, is previously known. The telephone is primarily intended for storing music in a digital format. Judging from the large range on the market, there is a need for a larger mass memory in a device for storing music (not to mention video clips, for example) in the market.

A scenario can be anticipated where more and more individual devices will be attempted to be provided with large mass memories and/or replaceable memory means. The size of the memory may be relatively small when the device is acquired, and the user has the option to purchase more mass memory, a replaceable memory means or comparable memory capacity for the device.

It is typical of known memory technology that, due to technical, production-related and commercial reasons, memories with lower access times are more expensive in relation to a memory unit than memories used as mass memories proper; as a result, memories with lower access time are also smaller than mass memories proper.

Generally, there are two essentially different RAM types, namely cache memory and buffer memory. US 2006/0015664 proposes as a technical solution the application of the buffer memory principle to wireless data transfer between two hard discs.

A cache is a memory/memory area functioning as RAM, where data is stored temporarily and to which a computer/processor has faster access than to ordinary memory. When a computer/processor processes data, it first searches data in the cache and, if it finds the data, in which case the data is previously processed data, the processor need not search the data in another memory/memory area, which would be slower. It is generally previously known that the primary functional purpose of a cache is to speed up access to data. A cache is often described in terms of its levels in relation to the processor. An Ll cache is typically on the same circuit chip as the processor; an L2 cache is usually a separate static RAM, i.e. SRAM, chip, whereas RAM proper is typically a dynamic RAM, a DRAM, chip. The term "disc cache" is also often used in connection with a cache, referring to a special area of a RAM memory where data read from a hard disc and latest used is stored. According to prior art, therefore, a cache is linked to a processor or another memory through a wired/fixed connection.

A buffer is also a memory/memory area functioning as RAM, shared between system devices and program routines operating on different speeds and with different priorities. The buffer enables every system device or program routine to operate without assistance from another. In other words, for the buffer to be efficient, the size of the buffer and the algorithms for transferring data into and out of the buffer must be taken into account in the design of the data transfer bus. It is also previously known that the functional purpose of the buffer as such is to support the coordination of the different functions of the system devices and program routines.

An object of the present invention is to eliminate or at least essentially alleviate the above-mentioned problems and weaknesses and enable such a scenario where a communications and/or data transfer device proper is accompanied by a separate media/data source over a wireless connection, preferably a mass memory device suitable for storing media/data. Thereby it is possible, as necessary, to load desired media/data/applications from the media/data source to the communications and/or data transfer device for processing and utilization on the communications and/or data transfer device. Generally, an object of the present invention is thus to provide a new and inventive assembly where access to data on the media/data source takes place in an organized manner. This object can generally be achieved by means of the assembly according to the invention, for example so that, in order to speed up access to data on the portable media/data source from the communications and/or data transfer device, the first hard disc functions as a cache memory of the second hard disc, whereby it is possible to load desired data/media and/or applications to the first hard disc over the wireless connection, as necessary. Therefore, the present invention is based on the idea that the cache principle is applied to accessing data on another memory over a wireless connection. According to one aspect of the present invention, a smaller hard disc on the communications/data transfer device, being a host device, functions as a cache memory and a larger mass memory on the portable media/data device, being a slave device and connected to the communications/data transfer device over a wireless connection, functions as the mass memory proper. According to the invention, the first memory essentially functions as a cache memory, as the delay of the wireless connection would otherwise make the access time long, the elimination of which problem is one of the most essential objects of the present invention.

According to the invention, in order to minimize access times, as it is typical that the data to be accessed is generally local data stored in a mass memory, a large part of searches provided by processors are arranged to take place to a memory with a lower access time.

Therefore, the basic idea of this invention is to utilize the principle of a cache memory in order to manage the separate memories in the assembly according to the invention. Thereby the small hard disc, i.e. the first mass memory, of the communications/data transfer device, which is a telephone, for example, functions as RAM and the second hard disc, i.e. the second mass memory, located in the portable media/data device and arranged over a wireless connection from the first mass memory, is the mass memory proper. Thereby it is possible to transfer or load media/data from the second mass memory to a RAM memory, i.e. the first mass memory, as necessary. The following advantages can be mentioned. It is not necessary to hold all applications continuously in the memory of the device; rather, only desired applications can be loaded as necessary to be utilized in the device. The size and mass of the communications/data transfer device can be reduced, as the size of the necessary mass memory can be kept smaller. The operating principle of a cache memory is previously known, so a high operational reliability can also be maintained. It can be generally stated about a cache memory that the use of a cache memory is based on the fact that at any given time memory searches are usually repeatedly directed at the same local areas in the memory. This is called "locality of reference". This is utilized in the present invention so that by using some suitable algorithm such memory areas are transferred from the memory proper to a memory having a lower access time. Thereby the average memory access time is reduced.

In the following, the present invention will be described in terms of a preferred embodiment thereof by reference to the attached drawing, where FIG. 1 shows a block diagram of the assembly according to the invention.

The embodiment in the figure shows a solution where a user of the invention has a separate peripheral device SD with a large mass memory MM. A connection between the peripheral device and a mobile telephone with a smaller mass memory CM is set up by means of a wireless connection BT. The wireless connection may be, for instance, a RF connection, an IR connection or Bluetooth™, which is a RF connection type, or another wireless connection. In practice, IR is the most clumsy one of these in such an application. As having only a wireless connection between the two mass memories would cause a considerable delay in the access time, the smaller memory functions as a cache memory of the larger memory. Thereby a significant improvement in access time is achieved, for which (it probably cannot be said that the "hit ratio" is a feature of access time; rather, it describes the relationship between the mass memory and the cache memory, which in turn depends on the size difference between said memories and the algorithm used) a value, "hit ratio", can be calculated. Hit ratio = (misses+hits)/hits.

The hit ratio and the improved access time are provided in a practical application where the size of the hard disc CM in the mobile station HD is 4 GB and the size of the hard disc MM in the media/data device SD is 60 GB, for example. When the present invention is compared with generally used RAM application targets, of which we can mention the internal architecture of a computer, for example, the size of the RAM, which is the hard disc of the mobile station, in relation to the mass memory of the media/data device is very large in this case. Accordingly, it can be assumed that the hit ratio is very likely to be higher than 0.9. In the following example calculation it is assumed that the hit ratio is 0.9.

It is estimated that the access time of the hard disc within the mobile station HD is 10 ms. The access time from the media/data device SD is composed of the access time of the hard disc proper and the access time of the transmission path BT. The transmission path may be a RF connection, and IR connection or a Bluetooth connection. However, the Bluetooth connection is the most advantageous one. When the processor, i.e. CPU, of the mobile station HD searches data and the data can be found in the memory of the mobile station CD, i.e. the cache memory, we use the term "hit". In contrast, if the data cannot be found in the cache memory but it must be accessed in the slower mass memory MM of the media/data device, we use the term "miss". The "hit ratio" = (misses + hits) / hits.

Generally, the hit ratio is equal to or higher than 0,9, which means that at least 9 searches out of 10 are directed at the cache memory. The "hit ratio" is an important indicator when verifying the efficiency or quality of the cache memory in the system.

Let us assume that the decoding of the media and/or data takes place in portions of 100 kB. In this case, the access time to the mass memory MM of the media/data device SD is the access time required for the disc plus the time required for the transmission of 100 kB over the wireless connection BT. In this case, the transmission time of 100 kB is 139 ms, and thus the total access time is 10 ms + 139 ms = 149 ms. It is assumed in the above example that both of the hard discs are equally fast as such (access time 10 ms); the access time to the larger hard disc is increased by the additional time, or delay, introduced by the wireless connection.

Let as repeat the parameters obtained so far: hit ratio 0.9, cache access time 10 ms and mass memory access time 149 ms. On these parameters, the average access time becomes 24.9 ms. Therefore, with this cache memory arrangement (and assumptions), the access time has been speeded up from 149 ms to 24.9 ms.

Generally, there are three different algorithms for selecting the content of RAM:

• Associate Mapping (AM),

• Direct Mapping (DM) and

• Set-associate Mapping (SaM).

However, the selected algorithm is not essential for the operation of the present invention; accordingly, we do not point out any of the algorithms as the preferred one to be applied to provide the desired functionality. Thus any of the above-mentioned three algorithms can be used in the present invention. However, it should be noted that the selected algorithm has an effect on the hit ratio.

The invention has been explained above by way of example only. This does not limit the scope of the present invention in any way, but various alternative solutions and variations and functionally equivalent solutions are possible within the scope of the invention as defined by the attached claims.

Claims

1. An assembly comprising a portable communications and/or data transfer device (HD), for example a terminal device of a mobile telephone network, such as a mobile telephone, a PDA, or a comparable device suitable for communication and/or data transfer, that includes a first mass memory (CM), preferably a first hard disc, and a portable media/data source (SD), such as a multimedia device or an MP3 player or a comparable media/data source, that includes a second mass memory (MM), preferably a second hard disc, whereby in the assembly the communications device and the portable media/data source can communicate with each other over a wireless communication connection (BT), which is optionally a RF connection, and IR connection or a Bluetooth™ connection, characterized in that, in order to speed up access to data on the portable media/data source (SD) from the communications and/or data transfer device (HD), the first hard disc functions as a cache memory of the second hard disc, whereby desired data/media and/or applications can be loaded to the first hard disc from the second hard disc over the wireless connection (BT), as necessary.

2. An assembly as claimed in claim 1, characterized in that the mobile telephone (HD) includes a smaller hard disc, which functions as a cache memory (CM) of a larger hard disc in the portable media/data source (SD).

3. An assembly as claimed in claim 2, characterized in that in the joint use of the communications and/or data transfer device (HD) and the portable media/data device (SD) over the wireless connection (BT) the communications and/or data transfer device is a host device and the media/data source is a slave device and in that the use of the smaller mass memory (CM) of the host device as the cache memory of the larger mass memory of the slave device is enabled by the slowness of the wireless connection that causes a delay in the access time.

4. An assembly as claimed in any one of claims 1 to 3, characterized in that, in order to minimize access times, as the data to be accessed is local data stored in the second mass memory, the majority or at least an essential part of the searches provided by processors of the Communications and/or data transfer device are arranged to take place to the memory with the lower access time, being the first mass memory.